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Chapter 1

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Chapter 2

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Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 - Water | Chapter 8 - Fish, Plants and Wildlife | Chapter 8 - Range | Chapter 8 - Timber | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Chapter 14 | Chapter 15
Sierra Nevada Bio-region
Chapter 2: Air, Soils, and Water Resources and Quality

Air Resources


This assessment will focus on the current condition of air resources of the Sierra Nevada bio-region. Human and ecosystem health are directly impacted by pollutants in the layer of the atmosphere closest to the earth’s surface known as the troposphere. Changes in atmospheric composition in other layers have impacts as well however; addressing these issues is beyond the scope of this assessment. This assessment will cover various air quality topics within the Sierra Nevada bio-region; air basins and air districts, sensitive lands, implementation plans, emissions inventory, and ecosystem critical loads.

Air Basins and Air Districts

California is divided into 15 air basins with similar geographical and meteorological features, and some political boundaries (1CARB) (Figure 1). These basins were further divided into a total of 35 air districts whose role is to regulate the air quality within its boundaries (1CARB). The National Forests of the Sierra Nevada bio-region intersect many of these districts, see figure 2. Federal agencies, such as the Forest Service, must meet all regulations put forth by the air districts.

Air Quality Management Districts (AQMD) and Air Pollution Control Districts (APCD) within the Sierra Nevada bio-region:
  • Siskiyou County APCD
  • Modoc County APCD
  • Shasta County AQMD
  • Lassen County APCD
  • Tehama County APCD
  • Butte County AQMD
  • Northern Sierra AQMD
  • Feather River AQMD
  • Placer County APCD
  • El Dorado County AQMD
  • Amador County APCD
  • Calaveras County APCD
  • Tuolumne County APCD
  • Mariposa County APCD
  • San Joaquin Valley Unified APCD
  • Great Basin Unified APCD
  • Eastern Kern APCD
AirBasins.jpg
Figure 1 A map showing location and boundaries of air basins, the Sierra Nevada Bioregion and national forests. Air basins range wildly in size and are subdivided into air districts.

AirDist.jpg
Figure 2 A map showing location and boundaries of air districts, the Sierra Nevada Bioregion and national forests. Air districts range wildly in size and may cover multiple forests.

Sensitive Air Quality Lands

There are two types of sensitive air quality lands. The first being areas with extra protection, and the second being areas with air pollution levels exceeding regulatory guidelines.

Lands with extra protection – Class I

Lands with extra protection are called Class I. Class I areas were established by the Clean Air Act Amendment of 1977 with the criteria of being wilderness or national park with lands over 5,000 acres in existence in 1977 (CAA). No new Class I areas have been designated since 1977 the exception being land additions to existing Class I areas. See figure 3 for a map of the 10 USDA Forest Service managed Class I areas within the Sierra Nevada bio-region. This status is only designated at the federal level and is permanent. Other Class I wildernesses are present within the Sierra Nevada bio-region however; they are not managed by the Forest Service.
The following 10 wildernesses are designated as Class I within the Sierra Nevada bio-region:
  • Ansel Adams
  • Caribou
  • Desolation
  • Domelands
  • Emigrant
  • Hoover
  • John Muir
  • Kaiser
  • Mokelumne
  • Thousand Lakes
ClassIWilderness.jpg
Figure 3 A map showing the location of Forest Service Class I Wildernesses within the Sierra Nevada Bioregion. Class I areas are designated by the Clean Air Act and have extra protection against air pollution.


Lands with air pollution levels exceeding regulatory guidelines-Attainment Status

The pollutants in which concentration levels limits are established for human health are called criteria pollutants (CAA). All lands within the nation are classified by the amount of air pollution present by each criteria pollutant. When lands exceed the regulatory guidelines they are considered sensitive and are designated as non-attainment. These statuses are designated both at the federal by the EPA and state level by the California Air Resources Board, and are re-evaluated periodically. To see a table depicting both federal and state ambient air quality standards for criteria pollutants see table 1.


CriteriaPollutStand3.jpg
Table 1 California and Federal Ambient Air Quality Standards (CAAQS and NAAQS). The pollutants shown in the table are called criteria pollutants.Table adopted from the California Air Resources Board at http://www.arb.ca.gov/research/aaqs/aaqs2.pdf

Attainment Status summary

Areas of the Sierra Nevada bio-region are in state and federal non-attainment status for criteria pollutants (3CARB). Federal ozone 8-hour standard and PM2.5 the front country of the southern sierra bio-region is in non-attainment. PM10 is better with most of the bio-region in unclassified or attainment. Carbon monoxide, lead, sulfur dioxide and nitrogen dioxide are all unclassified or in attainment. California standards for criteria pollutants are stricter than federal with more lands in non-attainment status. For state standards PM10 and ozone, almost the entire bio-region is in non-attainment and non-attainment for PM 2.5 in the southern portion of the bio-region. Standards for sulfates, visibility reducing particles, sulfur dioxide, nitrogen dioxide , carbon monoxide and lead are unclassified or in attainment.

Air Pollution Implementation Plans
When an area’s air pollution is beyond regulatory limits called non-attainment, a plan to reduce pollution is created. This plan outlines how the area will work towards meeting the attainment standards and must be approved by the US EPA. Federal agencies are prohibited from increasing an area’s air pollution that would result in: 1. an area losing attainment status or 2. a worsening of non-attainment status. Federal agencies, such as the Forest Service, must meet all applicable local, state, federal, and tribal implementation plans.

The US EPA has approved the following implementation plans within the Sierra Nevada Bioregional Planning Area (EPA):
  • California Fumigant VOC Regulations and Revisions to the California SIP Pesticide Element for San Joaquin Valley
  • Interstate Transport State Implementation Plan (SIP) for the 1997 8-hour ozone NAAQS and 1997 fine particulate (PM2.5) NAAQS
  • Regional Haze
  • San Joaquin Valley Air Pollution Control District
  • San Joaquin Valley 2008 PM2.5
  • San Joaquin Valley 8-hour Ozone Attainment
  • Federally Mandated Ozone Nonattainment Fee (San Joaquin Valley)
  • Coso Junction Planning Area 2010 PM10 Maintenance Plan

Emissions Inventories and Geographic Distribution of Air Pollution

Emissions types and amount vary between each air district. Yearly emissions inventories by county and air basins are available from the California Air Resources Board(4CARB). The pollutants covered by this inventory are the criteria pollutants of total organic gases (TOG), reactive organic gases (ROG), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter (PM), particulate matter less than 10 micrometers (PM10), and particulate matter less than 2.5 micrometers (PM2.5) see table 2. At this time, the most current inventory is for the year 2010. The Sacramento Valley and San Joaquin Valley air basins are the largest contributor of emissions within the Sierra Nevada bio-region.

Emissions2.jpg
Table 2 A table displaying total emissions by pollutant type for the seven air basins within the Sierra Nevada Bioregion for the year 2010. Figures obtained from California Air Resources Board at http://www.arb.ca.gov/app/emsinv/emssumcat.php


Geographic Distribution of Pollution

There is a general north to south trend of pollution with the Sierra Nevada bio-region (1CARB). Air quality in north, near the Modoc National Forest is generally good as you head south, air quality declines. The Central Valley of California with the surrounding mountain ranges acts as a ‘bowl’ trapping pollution in the valley. The Sierra Nevada bio-region is the eastern boundary of the Central Valley bowl. Pollution levels on the eastern side of the Sierra Nevada mountain range are often lower.

Smoke Regualtions in the Sierra Nevada Bioregion
Smoke from both wildland and prescribed fires effect the air quality in in the Sierra Nevada bio-region. These impacts are short term; meaning that smoke from fires can be severe but are limited to when fires are burning. Smoke often impacts more than a single basin when present and can be transported great distances from its source. California’s Code of Regulations, Title 17 Subchapter 2 Smoke Management Guidelines for Agricultural and Prescribed Burning sets forth smoke management requirements. The requirements set forth by the state are then implemented by air districts. Coordination between the Forest Service and air districts are required for prescribed burning permission. Local air districts have established regulations to minimize smoke impacts from prescribed fires (5CARB).

Factors Influencing Smoke Production and Dispersal from Fire

Meteorology, topography, and vegetation influence smoke characteristics of both wildland and prescribed fire. Meteorology will determine where and how long smoke from a fire will be present through wind patterns. Topography can influence smoke concentrations as mountain ridges can trap smoke into valleys. Vegetation characteristics such as moisture levels, thickness, and structure can influence the amount of smoke produced by a fire. See Figure 4 for an example of smoke in the Sierra Nevada from one fire.

Figure 4 An example of smoke settling into the valleys of the southern Sierra Nevada during the Lion Fire of 2011. Both the topography (steep mountains of the Sierra Nevada) and the meteorology (weather) affected the smoke produced by the fire.

Lion aerial 8-3-11.jpg
Photography courtesy of David Kerr.

Prescribed Fires

The Forest Service current conducts prescribed fire within the Sierra Nevada Bioregion. Prescribed fire does produce emissions however; it may reduce emissions in the future. A study in the western states found that large-scale prescribed fire could reduce carbon emission in the western U.S. by about 20% (Wiedinmyer and Hurteau 2010). The amount of prescribed fire can be limited by the amount of burn days allowed by the California Air Resources Board and can be further regulated by individual air districts. The amount of burn days available can vary year to year as they are influenced by weather patterns.


Ecosystem critical loads

Critical loads are defined as a concentration of air pollution or total deposition of pollutants above which specific negative effects may occur. Critical loads are based on ecosystem responses rather than regulatory guidelines (Pardo et al. 2011).

How Ecosystem Critical Loads are Measured

Responses to air pollution are measured by a sensitive component of the ecosystem known as a ‘receptor.’ There are many types of receptors and some are more sensitive to changes in air quality than others. When critical loads are exceeded, ecosystems are damaged. The range of damage depends on the concentration and length of pollution exposure. Fenn et al. 2010 has developed nitrogen deposition critical loads for various California ecosystems. While ozone is well documented as causing damage to conifers within the Sierra Nevada bio-region, ozone critical loads have not been established (Bytnerowicz et al. 2003).

Impacts to forest lands when air pollution critical loads are exceeded

Critical loads for nitrogen established by Fenn et al (2010) for California ecosystems are exceeded in many places with in the Sierra bio-region (Figure 5). In addition, a California Energy Commission report examined nitrogen deposition ecosystem impacts for a total of 48 different ecosystems in California. Both the report and scientific investigations concluded that nitrogen disposition threatens many ecosystems across the state, including those in the Sierra Nevada bio-region. Both the study and the report link increased invasive plant species, altered lichen communities, and altered mountain lake chemistry with elevated nitrogen deposition rates in California (Fenn et al. 2010 and Weiss 2006).

NDepMap.jpg
Figure 5 A map showing nitrogen critical load assessment within the Sierra Nevada Bioregion. The lands surrounding the Central Valley are most affected by nitrogen deposition.

Regulated Air Quality Monitoring

The Forest Service is required by the Clean Air Act to monitor air quality in Class I wildernesses. Related to the Clean Air Act is the Regional Haze Rule of 1999. The goal of this law is to return haze levels to natural background conditions by the year 2064. Data from the IMPROVE sites will be used to determine regulatory compliance of the Regional Haze Rule. The Forest Service, along with other agencies, monitors Class I wildernesses through the Interagency Monitoring of Protected Visual Environments (IMPROVE) network. This monitoring network measures pollutant concentration as well as visibility, a measurement of how clearly distant objects can be seen.

Other Monitoring Programs

Other air quality monitoring techniques and programs are conducted by the Forest Service and partners beyond the regulatory requirements of the Clean Air Act and the Regional Haze Rule. These purposes of these monitoring programs are to better understand how air pollution is affecting the ecosystems within the Sierra Nevada Bioregion. Examples of additional monitoring techniques include; lake chemistry measurements, lichen community diversity and pollutant concentration in tissues, and pine ozone injury occurrence.

Air Quality Trends Identified

The most continuous and large-scale air quality monitoring for the Sierra Nevada Bioregion is collected by the IMPROVE monitoring network. There are 8 active IMPROVE sites within the bioregion, four of which have been collecting data since the late 1980s -early 1990s. In general, data from the 8 Sierra Nevada Bioregion IMPROVE sites shows that air pollution has been decreasing within the Sierra Nevada Bioregion (FED). Sites in the central and southern portions of the Sierra Nevada Bioregion record higher pollution concentrations and more reduction in visibility. While the overall trend in air pollution is decreasing, levels still exceed regulatory and healthy ecosystem limits in many locations. See the ‘Ecosystem Critical loads’ section for more information.

Air Resource References

Bytnerowicz, A. Arbaugh, M., & Alonso, R. 2003. Ozone air pollution in the Sierra Nevada distribution and effects on forests. Amsterdam, Elsevier. http://www.sciencedirect.com/science/book/9780080441931
"Database Query Wizard." Federal Land Manager Environmental Database (FED). Colorado State University, Cooperative Institute for Research in the Atmosphere (CIRA), n.d. Web. 13 Feb. 2013
CAA. Clean Air Act of 1970; 42 U.S.C. §§ 7401 et seq.
1CARB. 2012. California Air Basins. California Air Resources Board. Retrieved December 5, 2012, from http://www.arb.ca.gov/desig/airbasins/airbasins.htm
2CARB. 2012. ARB’s Geographical Information System (GIS) Library. California Air Resources Board. Retrieved December 5, 2012, from http://www.arb.ca.gov/ei/gislib/gislib.htm
3CARB. 2012. Air Quality Standards and Air Designations. California Air Resources Board. Retrieved December 5, 2012, from http://www.arb.ca.gov/desig/desig.htm
4CARB. 2008. California Emissions Inventory Data. California Air Resources Board. Retrieved December 5, 2012, from http://www.arb.ca.gov/ei/emsmain/emsmain.htm
5CARB. 2011. Smoke Management Program. California Air Resources Board. Retrieved December 5, 2012 from http://www.arb.ca.gov/smp/smp.htm
EPA. 2012. Air Actions, California. Environmental Protection Agency, Pacific Southwest, Region 9. Retrieved December 5, 2012, from http://www.epa.gov/region9/air/actions/ca.html#calwide
Pardo, Linda H., M. J. Robin-Abbott, and Charles T. Driscoll. 2011. Assessment of Nitrogen Deposition Effects and Empirical Critical Loads of Nitrogen for Ecoregions of the United States. General Technical Report NRS-80. Newtown Square, PA: U.S. Dept. of Agriculture, Forest Service, Northern Research Station.
Weiss, S. B. 2006. Impacts of Nitrogen Deposition on California Ecosystems and Biodiversity.
California Energy Commission, PIER Energy-Related Environmental Research.
CEC-500-2005-165.

Additional climate change/air resources references to consider (reviewed in TACCIMO: http://goo.gl/Lg3Bn)):

Bedsworth, L. (2011). Air quality planning in California’s changing climate. Climatic Change, DOI 10.1007/s10584-011-0244-0, 1-18.
Fenn, M. E., Allen, E. B., Weiss, S. B., Jovan, S., Geiser, L. H., Tonnesen, G. S., … Bytnerowicz, A. (2010). Nitrogen critical loads and management alternatives for N-impacted ecosystems in California. Journal of Environmental Management, 91, 2404-2423
Hurteau, M., & North, M. (2008). Mixed-conifer understory response to climate change, nitrogen, and fire. Global Change Biology, 14. doi:10.1111/j.1365-2486.2008.01584.x
Kleeman, M. J. A preliminary assessment of the sensitivity of air quality in California to global change. (2008). Climatic Change, 87 (Suppl 1), S273- S292.
Mahmud, A., Hixson, M., Hu, J., Zhao, Z., Chen, S. –H. & Kleeman, M. J. (2010). Climate impact on airborne particulate matter concentrations in California using seven year analysis periods. Atmospheric Chemistry and Physics, 10, 11097 – 11114.
Mahmud, A., Tyree, M., Cayan, D. & Motallebi, N. (2008). Statistical downscaling of climate change impacts on ozone concentrations in California. Journal of Geophysical Research, 113 (D21103), 1 -12. doi:10.1029/2007JD009534
Preisler, H. K., Zhong, S., Esperanza, A., Brown, T. J., Bytnerowicz, A., & Tarnay, L. (2010). Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California. Environmental Pollution, 158, 778 – 787.
Steiner, A. L., Tonse, S., Cohen, R. C., Goldstein, A. H., & Harley, R. A. (2006). Influence of future climate and emissions on regional air quality in California. Journal of Geophysical Research, 111 (D18303), 1-22.
Tingey, D. T., Laurence, J. A., Weber, J. A., Greene, J., Hogsett, W. E., Brown, S. & Lee, E. H. (2001). Elevated CO2 and temperature alter the response of Pinus ponderosa to ozone: a simulation analysis. Ecological Applications, 11(5), 1412 – 1424.

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Soil Resources


General Soil Resource Description

Soils are a product of soil forming factors including climate, organisms, landscape relief, parent material, and time. These factors follow some general patterns across California and the Sierras such as the change in soil with elevation and climate (Dahlgren et al. 1997, Zinke 1983). This produces patterns in soils and soil development that are described in individual forest soil surveys. Each of the forests has a soil resource inventory or survey with maps of soils and interpretations for their use and management.

There are certain soils and soil landscapes that merit special consideration and management. These include soils of meadows and fens. Meadow soils are mapped in forest soil surveys in broad and general map units. In addition, there are several inventories and maps of meadows covering parts or all of the Sierra bio-region (Fryjoff-Hung & Viers, 2012). Meadow soils are generally alluvial soils, susceptible to disturbance and gully erosion, and meadow soils frequently include organic soil horizons. Fens have organic soils and support a unique and rare environment. Fens are not mapped in soil surveys, but some have been separately inventoried at the forest-level.

Soils generally regarded as “sensitive” to management impacts are less resistant to changes in physical, chemical, or biological soil properties resulting from specific uses or disturbances associated with various management activities. Also, sensitive soils may be less resilient, meaning they are less able to naturally recover from disturbances, via processes such as freeze-thaw cycles, bioturbation, and root activity. Sensitive soils are relatively more susceptible to degradation of ecological integrity, soil quality, and hydrologic function (defined in FSM 2550.5). Locations of such soils can generally be mapped based upon specific soil attributes or characteristics that make them less resistant or less resilient. Examples of sensitive soils include:

  • Highly erodible soils (high and very high Erosion Hazard Rating) – susceptible to erosion, nutrient loss
  • Shallow soils (< 20 inches deep, Hydrologic Soil Group-D) – susceptible to runoff, erosion, nutrient deficits
  • Fine-textured soils (clay loams and clays, fine-silty to very-fine particle size classes) – susceptible to compaction, less physically resilient
  • Soils with shallow A-horizons (< 4 inches) – susceptible to displacement, nutrient loss, burn damage
  • Poor site-quality soils (Forest Survey Site Class 5-7, lands not suitable for timber harvest) – susceptible to nutrient deficits, burn damage
  • Aquic/Hydric soils (meadows and fens) – susceptible to rutting, puddling, loss of hydrologic function
  • Soils on steep slopes (> 50 percent) – susceptible to erosion, displacement, and exacerbation of various physical impacts
  • Soils derived from granitic saprolyte – susceptible to erosion and mass wasting
  • Soils with persistent past impacts (e.g. topsoil displacement) – susceptible to cumulative impacts
  • Wildfire affected soils (high soil burn severity) – susceptible to erosion, cumulative impacts

Management has historically managed soil impacts by limiting the percent area of a management unit affected by heavy machinery for timber harvest activities (conventionally < 15% area), regardless of soil type or sensitivity. Different strategies have been used to limit livestock impacts within grazing allotments, typically by limiting season of use and monitoring vegetative cover. Regardless of the sensitivity of particular soils to particular types of impacts, the ecological consequences of particular impacts are not always presumable. For example, all soils are more or less susceptible to compaction; however productivity consequences of compaction may be negative, benign, or even beneficial for particular soils or sites; Powers et al. (2005) was novel in this landmark finding. In turn, different soil functions may be differently affected by a given disturbance. For example, compaction may increase waterholding capacity, benefiting productivity in a moisture-limited environment, but it may reduce infiltration and saturated hydraulic conductivity (Ksat), negatively affecting soil hydrologic function in a high-rainfall environment. Thus it is most useful to regard sensitive soils as soils where the management risks are greater, where consequences of impacts are more likely to be negative (depending on the degree, extent, and duration of impacts), and warranting a more cautious management approach to prevent adverse soil impacts or cumulative effects. Mapping sensitive soils/sites and utilizing a suite of risk ratings is a worthwhile and practical management approach for the soil resource, placing priority on preventing adverse impacts rather than mitigating them afterward.

Resource Condition

Soils provide several key functions in the forest environment: 1) site productivity – ability to support vegetation, 2) hydrologic function – ability to absorb and hold water; 3) buffering capacity – ability to absorb chemical and nutrient flux without loss of function; and 4) carbon sequestration – ability to capture and store carbon (Forest Service Manual - Soil Management Manual, regional supplement R5 FSM 2550, 2012-1).

Site productivity is a function of climate and a soil’s ability to supply plants with air, water, and nutrients in the growing season. Soil productivity in the Sierra’s generally follows an elevation and climate trend, peaking at an elevation with most favorable combination of growing season, precipitation, temperature, and soil development. There are various measures one could map to express site productivity. One measure is the soil interpretation for forest site productivity - the Forest Survey Site Class rating - that can be found in forest soil inventories. Other indicators include the available water capacity attribute of soil inventories, and broad-scale maps of annual evapotranspiration.

Soil hydrologic function includes water infiltration, subsurface flow, surface runoff generation, and soil water storage, and is expressed in the soil properties - hydrologic soil group, permeability, and available water capacity. Hydrologic soil group expresses the potential for a soil to produce surface runoff when thoroughly wet. Soil permeability expresses the rate of water movement through soils. The available water capacity is a measure of plant available water and is greatest in deep soils. These soil properties are included in forest soil surveys.

Buffering capacity is the ability of a soil to accept and neutralize chemical additions without significant changes in soil properties such as pH, which would affect nutrient availability and cycling. It is largely determined by a combination of soil properties including cation exchange capacity, base saturation, and organic matter content. Buffering capacity is not generally a concern in the Sierras or in California, as management activities do not usually directly deposit foreign chemical additions to the soil, such as fertilizers, herbicides, or biochar. The Air Section discusses the concerns with components and distribution of atmospheric deposition and the potential concerns for the forest environment.

Soil carbon sequestration is a function of numerous factors and has been mapped at a very broad scale (Sundquist et al. 2009). Soil organic carbon is distributed vertically in the soil profile – in the duff and litter of the O horizon and in the underlying mineral soil. The quantity in the O horizon varies by climate and vegetation and fluctuates with the incidence of fire. The amount of organic carbon in the mineral soil varies by site and with soil depth (Zinke et al. 1984), being most concentrated in the topsoil, though overall C content can be substantial in the subsoil, particularly for deep soils. Soil C is relatively more stable than the O horizon, but the organic carbon in the near surface mineral soil may be susceptible to loss by oxidation in high severity fire or may be eroded.

The forest soils and their functions are subject to alteration and degradation during use and management of forests. Roads displace soils, timber harvest activities displace and compact soils, fuel management activities compact soils and export nutrients and leave areas of bare soils, grazing compacts soils and reduces cover. Fire suppression has indirect effects on the soil nutrient cycle, including accumulation of organic matter and nutrients in litter and duff layers, and increases the incidence of high severity fire and its effects on erosion and nutrient flux.

In addition to management activities, soils are affected by natural disturbance events including high intensity storms, landslides, and wildfires. Fires release nutrients, volatilize nutrients, and expose bare soils to erosion. Larger and higher severity wildfires have the potential to have a cumulative effect on overall nutrient cycles and erosion.

Site Productivity Function

Site and soil productivity can be affected by conversion of a site, soil erosion, organic matter and nutrient loss, and compaction, with effects generally declining in that order. Conversion of use may be reversible or recoverable with future management inputs, but loss of soil itself by erosion is not recoverable in human lifespans. Likewise, loss of organic matter, nutrients, and compaction effects can be mitigated to some extent with management intervention. Therefore it is considered most important to keep the soil on-site, and then address soil quality as circumstances warrant.

  • Conversion of use.

    Forest site and soil productivity is affected most basically by conversion of land area to another dedicated use. In California, there are some xxxx miles of Forest Service roads which take approximately xxx acres or xx % of the land base out of primary production (assuming an average width of xx feet). Some conversion is necessary and unavoidable in the use and management of the forests for recreation, transportation, timber management, and for fire suppression. The road system is concentrated to a degree on the most productive soils because of the timber there. Some of the impact of conversion may be offset by trees on the road margin which capture the canopy space, light, and soil moisture. Roads and landings (permanent landings as part of a permanent harvest access system) are the most common conversions; trails, rock quarries, and administrative sites such as campgrounds, facilities, and special-use sites are additional conversions that can have additional direct and indirect impacts on soils in the immediate vicinity. While some conversion of use is unavoidable, it is good to bear it in mind that they often come with impacts to natural systems and soils, and usually require ongoing maintenance to mitigate undesirable effects.

  • Erosion Summary

Soil erosion affects the ability of soil to supply nutrients and water for vegetative growth. Soil erosion can be divided into surface (sheet), rill, and gully erosion, as well as mass wasting and in-stream channel and bank erosion. In an unmanaged forest, there is usually minimal surface, rill, or gully erosion on an annual basis, because continuous duff and litter layers are effective at protecting the soil from raindrop impact and dissipating runoff energy. Where surface cover is removed by wildfire, infrequently large amounts of erosion may occur. Mass wasting and channel/bank erosion are also episodic in the unmanaged forest, occurring in connection with peak rainfall and runoff events and following wildfire. While episodic post-fire erosion is usually viewed as a negative process affecting site resources and water quality (true enough), it is actually a dominant natural geomorphic process over the long term in the Sierra-Cascades, so the geologic context should be part of the discourse. Stand replacing wildfires in many instances caused by lack of management have an impact many times greater than all forms of land use combined.

Forest use and management alters the soil erosion budget of the forest. In the managed forest, road and trail prisms introduce a certain amount of permanently bare soil to the landscape, adding a source of chronic annual erosion. Timber harvest exposes additional bare soil, equipment compacts soil and reduces infiltration, and skid trails concentrate water flows; harvest-related erosion is usually localized, and short-lived as duff cover and understory vegetation can recover rather quickly, on the order of 2-5 years. Cattle and sheep grazing reduces soil cover in meadows and increases bank disturbance, particularly in meadows and riparian areas; grazing-related impacts are usually chronic and need to be managed.

In a managed forest, wildfires also continue as a major source of large amounts of erosion on an episodic basis. In a managed forest, roads and skid trails tend to magnify post-fire erosion when roads intercept overland and subsurface flow and concentrate post-fire, and when culverts plug and divert streams. Overall, roads and skid trails may increase the post-fire rill and gully erosion.

The soil erodibility on a skid trail is greater than in the areas between skid trails, and the erodibility following a wildfire is much greater than in an undisturbed forest (Robichaud et al. 1993).


The mass wasting regime can also be altered due to forest management. On terrain susceptible to mass wasting, roads and timber harvest have the potential to increase mass wasting and reactivate dormant landslide features.


Soil erosion is one of the major concerns in current forest management. Soil erosion reduces upland forest productivity. Sediment from eroding hillslopes adversely affects water quality in forest streams, impacting the viability of aquatic ecosystems and numerous endangered aquatic species. Currently, managers are seeking to minimize erosion by applying improved management practices for forest operations and fuel management. One of the questions managers are seeking to answer is whether frequent forest operations cause more or less erosion than less frequent wildfires (Elliot and Robichaud 2001).



In forests, soil erosion occurs from disturbances such as forest roads, timber harvesting, or fire. These disturbances have major affects on both the vegetation and the soil properties. Soil erodibility depends on both the surface cover and the soil texture (Elliot and Hall 1997). The soil erodibility on a skid trail is greater than in the areas between skid trails, and the erodibility following a wildfire is much greater than in an undisturbed forest (Robichaud et al. 1993).



Planned fuel reduction or timber projects results in lower long-term erosion rates than experienced following wildfires, which are ineveitable if fuel loads are not reduced (Elliot & Robichaud 2001).

  • Roads and Erosion.
Roads introduce a significant area of chronically bare soil and impervious ground to the forested landscape. The roads produce runoff from direct rainfall on cut-slope and road surface, and intercept hillslope runoff and subsurface storm flow. The concentrated flows erode the road surface and ditch. Where the concentrated flows are drained off to hillslopes, there can be further rill and gully erosion. Roads essentially introduce a new component of chronic annual erosion to the erosion budget of the forested landscape. Roads in some terrain also lead to an increase in mass wasting.

The erosion rate from road prisms depends on several factors including rainfall intensity, road surface, road maintenance, level of use, and design. Rainfall intensity varies across the Sierras, including by elevation, and east or west slope of the Sierra. (see Figure X – Map of rainfall intensity, USLE R factor). In areas where precipitation falls mainly as snow, rainfall and erosivity are lower.
[Insert map of R factor. Insert table of road erosion estimates]

Road maintenance has both positive and negative effects on erosion. Erosion increases in the short term following road grading (blading), but good road design, water control structures, and maintenance limits the concentration of water and greatly reduces erosion. Road maintenance was assessed by individual forests during the Forest Service 2010 watershed condition assessment, however the ratings were qualitative and subjective. Road surfacing with gravel can greatly reduce the road surface contribution to erosion [ref].

  • Wildfire and Erosion. [Episodic surface and rill erosion. Map of recent high severity fire and intersect with high intensity rainfall (R factor) to show where high post-fire erosion is probable. Reference – paper on erosion from infrequent but large events.]

In forests, soil erosion occurs from disturbances such as forest roads, timber harvesting, or fire. These disturbances have major affects on both the vegetation and the soil properties. Soil erodibility depends on both the surface cover and the soil texture (Elliot and Hall 1997). The soil erodibility on a skid trail is greater than in the areas between skid trails, and the erodibility following a wildfire is much greater than in an undisturbed forest (Robichaud et al. 1993). Planned fuel reduction or timber projects results in lower long-term erosion rates than experienced following wildfires, which are ineveitable if fuel loads are not reduced (Elliot & Robichaud 2001).

Post-fire erosion is a major part of the erosion budget in forest landscapes in the Sierras. Depending on fire intensity and frequency in the landscape, there are estimates that post-fire erosion may account for 30-70% of the overall sediment production (Moody and Martin, 2009). Where high severity fire and high intensity rainfall both occur, post-fire erosion will be a high proportion of total erosion.

Not every wildfire however results in significant erosion. Major determinants are the soil burn severity and residual soil cover. In high severity burned areas, soil cover is essentially reduced to zero, and soils are highly exposed to erosion. In moderate and low severity burned areas, the residual soil cover breaks up slope lengths and significantly limits erosion. The low severity of most prescribed fire makes a prescribed fire preferable to wildfire from the erosion perspective. For significant erosion to occur after wildfire, there must also be high intensity rainfall during the first few years of vegetative recovery. In areas of low intensity rainfall or where snowfall predominates over rainfall, post-fire erosion will be low. The erosion rate is dependent upon slope steepness, slope length, and soil erodibility.

In the aftermath of wildfires, roads and trails including skid trails compound post-fire erosion. Roads intercept the already high post-fire overland and subsurface flows, and further concentrate the flows. An additional mechanism for erosion occurs if a stream crossing culvert is plugged with woody debris. In the ideal situation, there is an armored dip to convey the overflow back to the stream. In other cases, the water flows across an unarmored road, erodes the road fill, and maintains its course. In a worse case, water diverts down an inside ditch and erodes a gully down the road. There is no regional data on the failure rate of stream crossings.

Skid trails, and trails of all types, can be relatively benign in the absence of fire, but significant causes of erosion after fire. A few years after a timber harvest or fuels treatment, skid trails are covered with duff and litter, only minor overland flow occurs on the trail, and the water is directed off the trail before it is too concentrated and infiltratres. After high severity fires, overland flow greatly increases, and trails of all sorts intercept the magnified overland flow, concentrate it, and release it to bare slopes, increasing the incidence of hillslope rills and gullies.

  • Mass Wasting
Mass wasting is a major contributor to the erosion budget in some terrains. Mass wasting depends on the geology, slope steepness, rainfall regime factors, soil development, and forest management. Where mass wasting is significant as a naturally occurring process, roads and timber harvest and stand replacing wildfire increase the amount of mass wasting. Roads are most often problematic when they cut through the toe of a stable, dormant landslide, causing reactivated movement in the wet season. With timber harvest, clearcut silviculture on steep terrain is most often problematic because root systems of entire stands are left to decompose; when roots lose tensile strength a dormant landslide can reactivate. There is a lag time between harvest and mass movement while root decomposition occurs, depending on species and size of trees, on the order of 5-12 years [ref?]. Partial-cut silviculture systems (thinning, individual tree selection) usually do not have this associated risk, especially with tap-rooting species on site.

Stand-replacing wildfire can have the same effects as clearcuts, for the same reason (lack of living tree root systems), with the same temporal lag effect; however, unlike management, the scale of fires and the patch sizes in fire severity mosaics have the potential to affect larger areas and even entire watersheds with accelerated mass wasting in susceptible terrain.

[Info about mass wasting at the regional scale. Reference – study on landslides at HJ Andrews. Forests can bring analysis down to Forest level. Use regional geology map that interprets landslide risk. Possibly intersect roads with landslide risk to identify at HUC 6 or 7 where cumulative road related landslide risk is high]

  • Meadow Erosion: Many if not most meadows in the Sierras have experienced some concentrated grazing in the last 150 years, especially prior to the establishment of the national forest system. There are numerous statements in historical documents of sometimes overgrazed conditions. The expected result would be loss of topsoil and riparian disturbance, with potential further effects on gullying, channel incision, and meadow stability.
There is no comprehensive regional data set on meadow condition and meadow soil conditions. However, there are a variety of data sets at the forest-level on meadows that include range condition, erosion and topsoil condition, gully and headcut occurrence, riparian vegetation condition, and bank conditions. [review of literature]

A special case of lost site productivity in meadows occurs when wet meadows become dry meadows. In the Sierras, many wet meadows have become drier after the streams flowing through the meadows have downcut channels from a few to many feet. As the water table drops, the meadows dry out, vegetation changes, and primary productivity falls. Forests have a variety of data on these conditions.

  • Erosion Summary:
From the soil productivity perspective, the most significant threat is the loss of nutrient rich topsoil. Areas of topsoil erosion could include post-fire surface and rill erosion from forested lands, erosion of skid trails especially post-fire, and topsoil erosion from meadows. Erosion from roads, stream channels/banks, and mass wasting are of lesser concern for site productivity, but certainly of importance because of water quality effects. [HAVE EROSION SUMMARY ABOVE, PRIOR TO DISCUSSION, NEEDED HERE?]
  • Organic Matter and Soil Fertility:
Conservation of surface and subsurface (soil) organic matter has conventionally been presumed to retain soil nutrients and facilitate nutrient cycling processes. Soil organic matter (SOM) is concentrated in the near-surface and declines with depth (in concentration, not necessarily in total content). Erosion is therefore a primary mechanism for SOM loss. SOM and nutrient losses may also occur by other mechanisms including volatilization of nutrients in high temperature fire, wind erosion of ash, and nutrient export in whole tree harvest.

Besides outright losses, nutrient availability may be reduced due to disruption of nutrient cycling, changes in soil pH, or addition of chemicals or materials that shift relative nutrient balances. Nutrients may be tied up in duff and litter layers as a result of fire suppression. Fuel management activities such as mastication rearrange woody residues as a surface mulch. Woody residues are relatively nutrient poor and carbon rich, so placing carbon stores in direct reach of soil microorganisms may induce a nitrogen deficiency for plants. This phenomenon is a current subject of research; it is hypothesized that effects are very near-surface, short-lived as soil microbes adjust and residues decompose, and effects are likely dependent upon residue particle size (specific surface area) and nutrient content.

Topsoil displacement can also rearrange SOM and impact productivity. Old "brushfield reclamation" projects involved windrowing of topsoil and brush roots, and planting conifers between the windrows. This later became a practice considered harmful to soil productivity, and was discontinued. However, many of these old plantations are now at an age where thinning and fuels reduction activities are desired. How to manage these areas is a subject of debate, as to whether restoration activities are warranted (respreading of windrows) and whether further impacts to SOM constitute cumulative effects for soils that are still recovering and rebuilding organic matter content.

Whole tree harvest:Nutrients flux by whole tree harvest and pile burning. (refs: concentration of nutrients in needles, twigs, 2) Zinke – distribution of P, 3) ?? – fire and volatilization of nutrients


  • Compaction:
There has been a history of concern for the effects of soil compaction on soil productivity, and there are a variety of impacts from compaction on soil strength, aeration, infiltration, water movement, water retention, and root growth. Regardless of the functional site processes involved, compaction is widely viewed as a degrading soil impact, negatively affecting soil productivity. There are numerous studies in the scientific literature documenting the negative effects of compaction of forest soils. However, systematic rigorous review of this body of literature (Powers, 1998) reveals most such studies classically focus on short-term seedling growth (1-5 years); they tend to be site specific and anecdotal; most studies do not recognize possible confounding factors, such as understory competition; and there are many other studies documenting conflicting results, showing better seedling growth on compacted sites. Thus, the classic literature on compaction is ambiguous, and broad generalizations are not demonstrable for widely ranging soils and sites.

Maintenance of soil productivity is a legal requirement for the USFS (NFMA 1976). USFS Research initiated the National Long-Term Soil Productivity Experiment (LTSP) in 1989 to directly investigate compaction on a wide range of forest soils, sites, forest types, and climatic zones (Powers, 2006). There are more than 100 site installations across the US and Canada, and to date hundreds of scientific publications have been published from this body of research, representing the world’s largest network and most rigorous science on the subject. Two landmark 10-year synthesis papers have been published looking at continent-wide results (Powers et al. 2005; Ponder et al. 2012); reference these papers for specifics on study design, methods, and wide-ranging results. Powers et al. (2005) was novel in demonstrating that productivity consequences of compaction may be negative, benign, or even beneficial for particular soils, depending on broad textural groups.

More pertinent to the Bio-Region, there are 12 LTSP sites in CA, all in the Sierra-Cascades mixed-conifer range. The southern-most 3 sites are on the Sierra NF. Results here indicate that compaction never had negative effects on conifer growth through year 10 (tree-only plots); plots with intermediate-severity compaction produced 5-93% more total biomass compared to no compaction, while severe compaction plots produced 1-102% more biomass. These positive-response results have been attributed to compaction causing an increase in soil water-holding capacity, in a Mediterranean climate where water is a major limiting factor in the annual growing season.

Results are more complex on plots with understory present (composed primarily of woody shrub and herbaceous species), allowed to grow unhindered along with planted trees. 4 of the Sierra Nevada sites had greater biomass production with severe compaction, while 5 of these sites had less biomass, indicating a negative-response to compaction. On sites that responded negatively, the biomass deficit was always attributed to the understory component, indicating that understory species are apparently more sensitive to compaction than conifer species. This may have important management implications depending on management objectives.

LTSP 15-20 year results to date (Zhang et al. unpublished) show precisely the same trends, although positive-response differences from compaction are declining, so there may yet be changing trends in the future of the study. It should be noted that differences in early growth rates do not necessarily translate to differences in fundamental soil productivity; real differences in productivity will become more apparent from measurement of periodic growth increment after sites have reached leaf-area carrying capacity, fully stressing the soil’s capacity to provide nutrient and water resources. Also noteworthy, soil bulk density has not significantly recovered from compaction on any of the sites through 15 years.

Hydrologic Function and Impacts

Soils have an important role in the water cycle, absorbing water, storing water, as a medium for flow to the ground water, as a medium for subsurface flow parallel to hillslopes, and as the bed for overland flow. Soils also retain water and release it to plants. The ability of soils to perform their hydrologic function is affected by management when roads and trails are compacted and decrease the infiltration of water, when traffic and fire remove the soil cover and runoff is more rapid, and when compaction alters the retention of water available to plants.

  • Roads, Skid Trails and Infiltration and Runoff.
Roads essentially replace areas of porous soil and high water infiltration capacity with impervious area. The loss in pervious soil area results in some overall decrease in infiltration, plant available water, and ground water recharge. Skid trails create areas of more or less compacted soil, soil that has lost its largest pores first, and soil area with less infiltration capacity and ground water recharge.

[how much area is affected, how much reduction in area with high saturated hydraulic conductivity, rate of recovery, references]

The significance of the reduction in infiltration will depend upon soil cover, rainfall intensity, the proportional amount of area compacted, the connectedness of the disturbed areas, and the rate of recovery. In general, skid trails will have minimal effect on runoff in areas where rainfall intensity is low, and if water is controlled and soil cover is in place. The soils next to these skid trails will normally have excess infiltration capacity and absorb the runoff. Recently used and bare skid trails have greater effects because raindrop impact seals the surface and further reduces infiltration, and the lack of cover and surface roughness facilitates greater flow velocity. Skid trails in burned areas have even greater effects because more water will run on to them, and the discharge will be to a burned hillslope.

  • Roads and Subsurface Stormflow Interception
In addition to their effects on infiltration and runoff, roads have the further effect of intercepting some subsurface lateral flows in cutslopes and redirecting them to the stream system, or otherwise impeding the shallow downslope movement of water through the soil.

  • Fire and Infiltration and Runoff.
Fire can significantly alter the hydrologic condition of hillslopes and the hydrologic function of soils depending on soil burn severity. High severity fire leads to severe loss of cover, exposure of soils to raindrop impact and surface sealing, often some level of water repellency, loss of surface storage, and reduction in surface roughness. The overall effect can be a large decrease in infiltration, an increase in the runoff, an increase in velocity of overland flow, and greatly increased susceptibility to sheet and rill erosion. When erosion and runoff pose a significant threat to soil productivity, natural resources, or infrastructure, the Forest Service Burned Area Emergency Response (BAER) program may treat slopes with mulch to lower the risk or loss. The effectiveness of such treatments depend somewhat on storm intensity during the recovery period.

Change in runoff coefficient. Change in Manning’s n or Darcy Weisbach.

The change in soil hydrologic condition in burned areas is temporary and recovers significantly in the first few years after a fire as the plant cover increases, soil porosity is restored, duff and litter cover increases, and water repellency fades. Soil hydrologic function in burned areas is generally considered almost fully recovered in about seven years. If no high intensity storm event occurs in those first few post-fire years, there may be no large runoff and erosion events or flood responses.
  • Grazing and Cover, Compaction, and Runoff
  • Compaction and Available Water Capacity
Soil compaction by the off road traffic of timber harvest and other equipment may have the effect of changing available water capacity. Much depends upon the initial pore-size distribution of a soil. Generally macropores (> 1mm diameter) function in water movement and aeration; mesopores ( mm diameter) function in water storage that is available to plants in the growing season; micropores ( mm diameter) store water that is held at higher tensions, which is generally considered unavailable to plants (although drought adapted species may be able to extract water at these higher tensions). Compaction affects macropores first, compressing them to mesopore size; thus infiltration and permeability may be reduced while water holding capacity may be increased. This is thought to be the mechanism for increased soil productivity with compaction on coarse-textured (sandy) soils in the LTSP Experiment (Powers et al. 2005). Additional compaction will continue to reduce macropores, and compress mesopores into micropores, which may adversely affect soil hydrologic function, and ultimately reduce water holding capacity. Managing the effects of compaction has conventionally been accomplished by limiting the amount of an area that is exposed to compaction by heavy equipment (e.g. < 15% aerial extent). Where compaction is viewed as unacceptable for a particular soil or site, remedial actions such as subsoiling may be applied as mitigation, realizing that such treatments are never 100% effective, and may have secondary effects on soil quality (e.g. subsoiling in decomposed granitics can cause an increased erosion risk).

Carbon Sequestration

Large amounts of carbon are stored in the forest floor (including litter and the soil O horizon) and in soil organic carbon coating mineral soil particles (soil organic matter, or SOM). These reservoirs contribute a significant amount to the total carbon sequestration in forest environments. In many ecosystems, below-ground carbon may equal or exceed all the carbon in the standing forest. Effects of forest management on belowground C pools is largely unknown and speculative, but this is currently a subject of intensive research on many fronts.

Heath et al. (2011) prepared estimates of carbon stocks on forestland of the United States, including stocks of forest floor and soil organic carbon by forest in the Sierra bio-region (Table x). However, these estimates of forest floor and soil organic carbon were not based on measured plot values (Smith et al. 2007). For the forest floor, the amounts were estimated by equations based on factors of region, forest type, and stand age. For soil organic carbon, estimates were based on the national STATSGO database, a coarse-scale general soil map.

Table X. Forest Floor and Soil Organic Carbon





Forest
Forest Floor (tonnes carbon per hectare)
Soil Organic Carbon (tonnes carbon per hectare)
Angeles
30.8
33.3
Cleveland
30.6
27.6
Eldorado
35.5
46.2
Inyo
28.2
34.0
Klamath
34.9
44.2
Lake Tahoe Basin
35.0
39.1
Lassen
31.7
44.0
Los Padres
27.7
29.1
Mendocino
32.3
38.3
Modoc
32.3
45.7
Plumas
33.5
45.4
San Bernadino
31.3
35.2
Sequoia
31.8
39.1
Shasta-Trinity
34.9
43.2
Sierra
34.1
41.5
Six Rivers
34.4
38.7
Stanislaus
33.8
43.3
Tahoe
31.8
44.9
FIADB 4.0, December 2009 as applied in Heath et al. 2011








There are available data for the bio-region that could be used to refine these estimates, including: data on the International Soil Carbon Network (www.soilcarb.net), soil data from Zinke et al. (1984), soil survey data from the national SSURGO soil survey database, data from forest soil surveys, plot data from the California Soil Vegetation Survey program.

  • Fire and Carbon in the Forest Floor and SOM. The sequestration of carbon in the duff and litter layer is more or less dynamic, subject to decomposition and fire. This storage is also subject to management, intentional or not. The intentional suppression of wildfire has the indirect effect of increasing forest duff and litter layer in areas where fire has been excluded. The amount of additional carbon or additional litter has not been assessed, but it might be assessed based on existing fire history data, interpretations of the departure from the natural fire return interval, and soil survey data.


The SOM is less susceptible to change, but SOM in the surface four inches can be reduced by high severity burn (Bormann et al. 2008). In the long term, and so long as the soil-forming factors remain constant, the SOM would be considered to be at equilibrium between storage and loss. Land use conversion or climate change and vegetative change or change in the fire regime could alter the SOM equilibrium.

A change in wildfire size or severity would have the potential to change the amount of carbon sequestered in duff and litter. Low and moderate severity fire leaves some of the forest floor charred but not combusted. High severity fire leaves almost no duff and litter remaining. Fires all have low, moderate, and high severity burned areas, but a shift in proportions would alter the carbon storage.

Buffering Capacity

There are not currently concerns for buffering capacity of forest soils in California. Fire and ash have temporary but short term effects on soil pH. Aerial deposition of nitrogen has increased in the Sierras due to auto exhaust, but N is generally a limiting nutrient in the Sierras and is also lost in fires, so there are not concerns for soil condition from this source (see Air section).

Inventory of Soil Improvement Needs

Forests have mapped some of their existing impairments and soil improvement needs. This may include locations where erosion is occurring, where topsoils were windrowed or piled during site preparation, where terrain is susceptible to landslides, where grazing is causing undesirable effects, or other improvement needs. This information is kept at the forest-level. There are no known regional patterns of soil impairment by critical loads, acidification, or invasive species impacts. Effects of past management (harvest) impacts could be crudely mapped, but post-activity condition and rates of natural soil recovery are often unknown, and assumptions must be made to model current condition of soils on a watershed, landscape, Forest, or Bio-Regional scale.


Anticipated Trend


There is a minimum of quantitative and statistically random measurement of soil conditions on which to base a trend assessment. Most soil condition data is collected at the project scale, and not aggregated either at the Forest or bioregional scale. However, there are trends in forest and soil management and use, and trends positive and negative in the drivers and stressors of soil condition. From these trends we may infer some trends in the effects on soil conditions.

Trends in forest management and use and stressors on soil condition include:

  • Timber/Silviculture/Fuels
    • o Decrease in board feet and acres of timber harvest
    • o Changes in slash piling that result in cleaner (less soil) in slash piles and less disturbance of soil
    • o Reduction in size of or cessation of clear-cutting (year?)
    • o Leadership intent to increase fuel treatment acres

  • Roads and Trails
    • o Cumulative reduction in road miles with ongoing decommissioning
    • o Cumulative increase in the proportion of roads that are storm-proofed
    • o Reduction in road maintenance funds
    • o OHV travel limitation to designated routes
    • o Increase in OHV activity
    • o Increase in restoration of OHV routes with state OHV grant funds
  • Wildfire
    • o Increase in acres burned
    • o Increase in acres burned at high severity
  • Watershed restoration
    • o Cumulative effects of improvement projects – eg. spreading windrowed topsoil, subsoiling of compacted areas
    • o Natural recovery from past disturbance
  • Grazing
    • o Stable trend in allotment acres


Soils Resource References

Bormann, B.T.; Homann, P.S.; Barbyshire, R.L.; Morrissette, B.A. 2008. Intense forest wildfire sharply reduces mineral soil C and N: the first direct evidence. Can. J. For. Res. 38: 2771-2783
Dahlgren, R.A., J.L. Boettinger, G.L. Huntington, and R.G. Amundson. 1997. Soil development along an elevational transect, western Sierra Nevada, California. Geoderma 78:207-236.
Elliot and Robichaud PR 2001, Comparing Erosion Risks from Forest Operations to Wildfire
Elliot, W. J., and D. E. Hall. 1997. Water Erosion Prediction Project (WEPP) forest applications
Fryjoff-Hung & Viers, 2012. Sierra Nevada Multi-Source Meadow Polygons Compilation (v 1.0), Center for Watershed Sciences, UC Davis. December 2012. http://meadows.ucdavis.edu/
Heath, Linda S.; Smith, James E.; Woodall, Christopher W.; Azuma, David L.; Waddell, Karen L. 2011. Carbon stocks on forestland of the United States, with emphasis on USDA Forest Service ownership. Ecosphere. 2(1): article 6. 21 p.
Moody, J.A.; Martin, D.A. 2009. Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States. International Journal of Wildland Fire. 18: 96-115.
NFMA 1976: National Forest Management Act of 1976 (16 U.S.C. 1600(note)). See http://www.fs.fed.us/emc/nfma/includes/NFMA1976.pdf
Ponder Jr. et al. 2012: Ponder Jr., F; Fleming, R.L.; Berch, S.; Busse, M.D.; Elioff, J.D.; Hazlett, P.W.; Kabzems, R.D.; Kranabetter, J.M.; Morris, D.M.; Page-Dumroese, D.; Palik, B.J.; Powers, R.F.; Sanchez, F.G.; Scott, D.A.; Stagg, R.H.; Stone, D.M.; Young, D.H.; Zhang, J.; Ludovici, K.H.; McKenney, D.W.; Mossa, D.S.; Sanborn, P.T.; Voldseth, R.A. 2012. Effects of organic matter removal, soil compaction, and vegetation control on 10th year biomass and foliar nutrition: LTSP continent-wide comparisons. Forest Ecology and Management 278 (2012) 35-54.
Powers et al. 1998: Powers, R.F.; Tiarks, A.E.; Boyle, J.R. 1998. Assessing Soil Quality: Practicable Standards for Sustainable Forest Productivity in the United States. In: Adams, M.B.; Bigham, J.M.; Kral, D.M.; Viney, M.K., eds. The Contribution of Soil Science to the Development of and Implementation of Criteria and Indicators of Sustainable Forest Management. Soil Science Society of America Special Publication Number 53.
Powers et al. 2005: Powers, R.F.; Scott, D.A.; Sanchez, F.G.; Voldseth, R.A.; Page-Dumroese, D.; Elioff, J.D.; Stone, D.M. 2005. The North American long-term soil productivity experiment: Findings from the first decade of research. Forest Ecology and Management 220 (2005) 31-50.
Powers 2006: Powers, R.F. 2006. Long-Term Soil Productivity: genesis of the concept and principles behind the program. Canadian Journal of Forest Research 36: 519-528 (2006).
Smith, James E.; Heath, Linda S.; Nichols, Michael C. 2007. U.S. forest carbon calculation tool: forest-land carbon stocks and net annual stock change. Revised. Gen. Tech. Rep. NRS-13. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 34 p. [DVD-ROM].

Robichaud, P. R., C. H. Luce and R. E. Brown. 1993. Variation among different surface conditions in timber harvest sites in the Southern Appalachians
Sundquist, E.T., Ackerman, K.V., Bliss, N.B., Kellndorfer, J.M., Reeves, M.C., and Rollins, M.G., 2009, Rapid assessment of U.S. forest and soil organic carbon storage and forest biomass carbon sequestration capacity: U.S. Geological Survey Open-File Report 2009–1283, 15 p., available at http://pubs.usgs.gov/of/2009/1283/.
Zhang et al. unpublished: Zhang, J.; Young, D.H.; Powers, R.F.; Busse, M.D.; Fiddler, G.O. unpublished. The LTSP Experiment: progress since “the 10-year paper” [work in progress from 15-20 year LTSP measurements], presented by D.H. Young at USFS Region 5 soil scientists workshop, Nevada City, CA 2011.
Zinke, P.J. 1983. Soils of the eastside pine type and their properties in relation to forest management. In: Management of the eastside pine type in northeastern California : proceedings of a symposium, June 15-17, 1982, Lassen College Forest Resource Center, Susanville, California / edited by Thomas F. Robson, Richard B. Standiford ; pp. 17-28
Zinke, P.J.; Stangenberger, A.G.; Post, W.M.; Emanuel, W.R.; Olson, J.S. 1984. Worldwide organic soil carbon and nitrogen data. ORNL/TM-8857. Oak Ridge National Laboratory, Oak Ridge, TN, 141 pp. Available at: http://cdiac.ornl.gov/ndps/ndp018.html (16 January, 2013)

Additional climate change/soil resource references to consider (reviewed in TACCIMO:http://goo.gl/Lg3Bn)):

Bradbury, D. C. & Firestone, M. K. (2012). Responses of redwood soil microbial community structure and N transformations to climate change. In R. B. Standiford, T. J. Weller, D. D. Piirto & J. D. Stuart tech. cords. Proceedings of the coast redwood forests in a changing California: a symposium for scientists and managers. General Technical Report PSW-GTR-238. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.

Guarin, A., & Taylor, A. (2005). Drought triggered tree mortality in mixed conifer forests in Yosemite national park, California, USA. Forest Ecology and Management, 28, 229-

Waldrop, M. P. & Firestone, M. K. (2006). Response of microbial community composition and function to soil change. Microbial Ecology, 52, 716 – 724. DOI: 10.1007/s00248-006-9103-3

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Water Resources


Please note that water resources are extensively covered in Chapter 8, please see refer to that chapter for additional information.

This section surveys available literature related to the effects of several major land-use activities on National Forests on water quality and compares their relative importance. The land-use activities considered include wildfires, vegetation management, roads, and livestock grazing. Sediment is a primary pollutant of concern for forest activities, so this summary focuses primarily on erosion and sediment.

Background

Effects of land uses on erosion and sedimentation can most usefully be evaluated through comparisons with long-term and spatially integrated information on water quality. This section presents four lines of evidence to establish the overall water-quality conditions on National Forests in the Sierra Nevada:
  1. Review of scientific literature on water quality conditions in large watersheds primarily in USFS management;
  2. Listings of impaired water bodies by the State Water Resources Control Board;
  3. Results of USFS monitoring of Best Management Practices to protect water quality;
  4. Reservoir sedimentation rates.

Based on published literature, the National Forests in California have generally provided a high level of protection for the headwaters of the State. A recent statewide survey found that streams in forested watersheds were in better condition than streams in watersheds in any other land use (Ode, 2007). Water quality of the Sacramento River and its tributaries, which drain primarily NFS lands, have generally good quality and support their beneficial uses (Domagalski and others, 2000). Sediment and nutrient loads from forested watersheds in the Sierra Nevada, including large areas within national forests, were found to be substantially lower than loads from downstream agricultural areas and significantly lower than average pollutant loads nationwide (Kratzer and Shelton, 1998). Ahearn and others (2005) compared water quality in the upper Consumnes River watershed, which is mostly national forest, to the more agricultural and heavily populated lower watershed, and found that “upland drainages tended to deliver dilute, clear waters to the lowlands, while lower elevation sub-watersheds produced more turbid waters with elevated levels of constituents” (p. 242).

The State Water Resources Control Board prepared 303(d) lists of impaired water bodies statewide in 2002, 2006, and 2010. Impaired water bodies are those that fail to support their designated beneficial uses owing to pollution by one or more contaminants. These lists specify which pollutants are responsible for the impairment, as well as the suspected source of the pollutants. Several water bodies in the Sierra Nevada were listed as impaired due to sediment related to silviculture and livestock grazing in 2002, 2006, and 2010 (Table 1).

Table 1: Sediment-impaired water bodies in the Sierra Nevada related to silviculture and livestock grazing
Source
2002
2006
2010
Silviculture
9
8
8
Livestock grazing
13
9
8




Two significant conclusions can be drawn from the data in Table 1. First, the number of water bodies considered to be impaired by the State is a small fraction of the hundreds of water bodies on NFS lands. The vast majority of water bodies on NFS lands is unimpaired and supports their designated beneficial uses. Second, the numbers of water bodies impaired due to silviculture and grazing have decreased slightly between 2002 and 2010, indicating that overall water quality on forested lands in the Sierra Nevada has improved during that period.

The USFS in Region 5 has used Best Management Practices (BMPs) to protect water quality for more than 30 years. BMPs for timber harvests, fuels, vegetation management, and prescribed fire in USFS Region 5 have been effective in preventing potential or actual adverse impacts to water quality more than 95% of the time in recent years (USDA Forest Service, Pacific Southwest Region, 2009). BMPs for roads have been effective 85% of the time, and BMPs for livestock grazing have been effective 81% of the time (USDA Forest Service, Pacific Southwest Region, 2009). Only 2% of BMP evaluations indicated significant adverse effects to water quality (USDA Forest Service, Pacific Southwest Region, 2009).
Measurements of long-term sediment accumulation in reservoirs offer a means of assessing sediment loads from forest lands. Reservoir storage capacities are usually measured prior to construction. Subsequent bathymetric surveys can be used to determine decreases in storage capacity resulting from deposition of sediment. Reservoir trap efficiencies vary based on reservoir shape and size and the size of the contributing drainage areas. Although trap efficiencies are generally less than 100%, they are high enough to consider reservoir sediment deposition equal to total sediment loads from contributing watersheds over the years between surveys.

The U.S. Geological Survey has reservoir sedimentation data for 16 reservoirs in or downstream of NFS lands in the Sierra Nevada (Table 2). These data are based on sequential surveys made for varying periods of time that included different climatic and land use conditions. Some reservoirs are within watersheds managed entirely as National Forests, but in other cases the reservoirs are downstream of both NFS and private lands. Despite these variable conditions, the results in Table 2 are useful in providing a broad overview of sedimentation rates on forested lands in the Sierra Nevada over timescales of years to decades.

Table 2: Reservoir sedimentation in the Sierra Nevada, from the USGS RESSED data base
[Sediment yields in ac-ft/yr/mi2were converted to tons/ac/yr assuming a sediment bulk density of 1.5 tons per cubic yard]
River
Reservoir
National Forest
Drainage area, mi2
Sedimen-tation
period
Decrease in capacity,
ac-ft
Sedimen-tation rate, ac-ft/yr
Sediment
yield,
ac-ft/yr/mi2
Sediment
yield,
tons/ac/yr
Little Butte Creek (Feather River)
Magalia
PNF
8.23
1918-1946
70
2.5
0.30
1.1
N. Yuba
Bullard’s Bar
TNF
479
1919-1939
2,607
130
0.27
1.0
Onion Creek
(American River)
Onion Creek no. 7
ENF
0.80
1958-1960
0.015
0.0075
0.009
0.03
Big Canyon Creek
Big Canyon
ENF
5.48
1934-1945
4
0.36
0.07
0.26
Bear River (Amador County)
Upper Bear River
ENF
28.2
1900-1946
22
0.48
0.017
0.06
Mokelumne
Pardee
ENF/STF
384
1929-1943
817
58.4
0.15
0.57
SF Stanislaus
Lyons Lake
STF
39.7
1930-1946
64
4.0
0.10
0.38
Tuolumne River
La Grange
STF/Yose-
Mite NP
1,501
1895-1905
1,264
126
0.08
0.30
Merced
Exchequer
Yosemite NP
1,022
1926-1946
3,354
168
0.16
0.60
NF San Joaquin
Crane Valley
SNF
52.7
1901-1946
382
8.49
0.16
0.60
Teakettle Creek (Kings River)
Teakettle No. 1
SNF
0.77
1938-1948 (overtopped by 1955)
0.21
0.02
0.03
0.11
Ten Mile Creek
Hume
SNF
24.1
1909-1946
27
1.59
0.07
0.26
Kings
Pine Flat
SNF
1,542
1952-1956
1,450
362.5
0.24
0.90
Kaweah
Terminus
SQF
560
1961-1967
2,500
417
0.74
2.80
Tule
Success Lake
SQF
393
1960-1967
2,550
364
0.93
3.52
Kern
Isabella
SQF
2,074
1953-1968
5,200
347
0.17
(higher rate between 1956 and 1968)
0.64

Annual sediment yields (Table 2) ranged over two orders of magnitude, from 0.03 to 3.52 tons per acre per year. The lowest reported sediment yield was for a very small drainage area for a very short period that did not include major storms. The highest sediment yields were reported for reservoirs in the southern Sierra Nevada for relatively short periods that spanned the large storms and floods of the mid-1960s.

Although the range of sediment yields reported in Table 2 is large, all reported sediment yields are relatively low, and are well within the range for forested lands in the western United States as reported by Patric and others (1984). The mean of 0.82 tons per acre per year is higher than the average of 0.165 reported by Patric and others (1984), but lower than the range of 2 to 5 tons per acre per year suggested as acceptable for agricultural lands (Wischmeier and Smith, 1978). Patric and others (1984) suggested that a sediment yield of 0.25 tons per acre per year would be a good estimate for undisturbed forest lands. Twelve of the 16 sedimentation rates reported in Table 2 for NFS lands in the Sierra Nevada are less than this estimate, although the reservoirs are located within areas of actively managed forests.

Unfortunately, no surveys have been reported since 1968. The lack of more recent bathymetric surveys is a substantial limitation in assessing effects of current land use practices on erosion and sediment transport on forest lands in the Sierra Nevada. New information that could be obtained through standard bathymetric surveying techniques or with newer airborne LiDAR measurements would be very helpful in evaluating the success of National Forests in controlling erosion and sedimentation.

RELATIVE EFFECTS OF WILDFIRES AND VEGETATION MANAGEMENT ON EROSION AND SEDIMENT TRANSPORT


Wildfires threaten forest resources and community safety in the Sierra Nevada. The size, frequency, and severity of wildfires in the Sierra Nevada have increased in recent years (Miller and others, 2009). Wildfires are therefore likely to pose a greater threat to water resources in the future, owing to expected changes in climate (Goode and others, 2012). Using vegetation management to reduce the amount of fuels available for wildfires has been effective in reducing fire severity (Safford and others, 2009; 2012). Vegetation management therefore offers an alternative to increasing fire severity in the Sierra Nevada.
Wildfires affect rates of soil erosion and sediment transport by removing protective vegetation and litter cover from forest soils, destroying roots that bind soil, removing woody debris that slows runoff and erosion, and reducing infiltration and increasing runoff owing to development of hydrophobic (water repellant) soils (Neary and others, 2005). Effects vary with fire severity, topography, geology, and climate. Severe fires that destroy a high proportion of vegetation, soil cover, and roots have the greatest potential to increase erosion, particularly if the fire is closely followed by significant precipitation or snowmelt (Benda and others, 2003; Bisson and others, 2003; Spencer and others, 2003). Post-wildfire erosion can significantly and adversely affect aquatic habitats if fire severity is high (Benda and others, 2003; Bisson and others, 2003; Spencer and others, 2003; Neary and others, 2005), and effects of modern fires under conditions of poor forest health are likely to be more detrimental than historical low-intensity fires (Rieman and others, 1997). Wildfires of high severity can adversely impact municipal water supplies (U.S. Geological Survey, 2012), and even low-intensity fires can have dramatic impacts on downstream riparian zones. Smoke and ash from fires also adversely impact aquatic habitats (Spencer and others, 2003). Post-fire erosion rates are generally highest in the first year after the fire, and decrease to pre-fire rates over the next several years (Neary and others, 2005; Mayor and others, 2007; Pierson and others, 2008).


In forests, soil erosion occurs from disturbances such as forest roads, timber harvesting, or fire. These disturbances have major affects on both the vegetation and the soil properties. Soil erodibility depends on both the surface cover and the soil texture (Elliot and Hall 1997). The soil erodibility on a skid trail is greater than in the areas between skid trails, and the erodibility following a wildfire is much greater than in an undisturbed forest (Robichaud et al. 1993). Planned fuel reduction or timber projects results in lower long-term erosion rates than experienced following wildfires, which are inevitable if fuel loads are not reduced (Elliot & Robichaud 2001).

Vegetation management treatments are implemented to reduce fire size, severity, and frequency. Vegetation management treatments involve both hand and mechanical disturbance of vegetation and soils as well as burning in some cases. Such treatments can increase erosion through removal of cover, compaction of soils, reductions in infiltration capacity, and increases in runoff. Adverse effects of vegetation management treatments, however, are generally much less severe than those of wildfires because:
  1. Vegetation management treatments are implemented at locations and at times that limit adverse effects, whereas wildfires frequently occur during extreme burning conditions and on steep slopes where post-fire erosion is high;
  2. Vegetation management treatments include implementation of Best Management Practices to limit adverse impacts to water quality;
  3. The overall intensity of disturbance to forest resources by wildfire is generally higher than that of vegetation management projects, which leave most soil cover and large trees intact.

Results of selected investigations described in published scientific literature for watersheds in the Sierra Nevada and in regions with similar topography, geology, climate, and vegetation are described briefly below. These studies provide some insight into the relative effects of wildfires and vegetation management on erosion and sediment transport.

Wildfires

Effects of wildfires on water quality have been extensively documented worldwide (Smith and others, 2011) but relatively few studies are specific to the Sierra Nevada. Wildfire effects on water quality can be reasonably expected to vary with topography, geology, fire severity, and post-fire precipitation.

The 2002 Gondola Fire near Lake Tahoe was affected by an intense rain and hail storm only 2 weeks after the fire was controlled. Erosion from the burned area ranged from 8,900 to 10,000 grams per square meter, or 1,800 to 6,700 grams per square meter per millimeter of rainfall (Carroll and others, 2007). For comparison, average annual suspended-sediment yields for tributaries to Lake Tahoe were reported to range from 0.7 to 67.9 grams per square meter per year (Nolan and Hill, 1991). The post-fire erosion rates observed at the Gondola Fire from a single rainstorm were therefore 131 to 14,286 times higher than long-term average annual suspended-sediment yields for recently unburned watersheds, which included a variety of land uses, including timber harvesting, roads, grazing, and residential construction.

Pierson and others (2008) monitored post-fire sediment yield for 3 years following a fire in northwestern Nevada and compared their results with sediment yield from an unburned control. They reported a cumulative sediment yield of 20,400 grams per square meter (6,800 grams per square meter per year on average) for the burned area, while the unburned control area had a cumulative sediment yield of 6 grams per square meter (2 grams per square meter per year on average). The sediment yield for the burned area was therefore 3,400 times higher than the sediment yield for the unburned area, indicating a very substantial increase caused by the fire. Fire effects decreased, but were still apparent 3 years after the fire.

In the first year following the Cerro Grande Fire in New Mexico, sediment delivery to a downstream reservoir was 140 times larger than pre-fire delivery. Delivery of ash and fine-grained sediment to the reservoir peaked within a year of the fire, while transport of coarser sediment did not approach pre-fire levels until the 5th year after the fire (Reneau and others, 2007).
A recent modeling study by Miller and others (2011) provided regional estimates for post-fire erosion across the western United States. For the Sierra Nevada, Miller and others (2011) estimated a mean post-fire erosion rate of 47 Mg/ha/yr (21 t/ac/yr), with a range of 0 to 2,100 Mg/ha/yr (0 to 937 t/ac/yr). The authors noted that predicted erosion was generally much less than measured values for watersheds with sediment yield information.

In other parts of the world with Mediterranean climates similar to that of California, researchers have reported substantial increases in post-fire erosion. For example, post-fire erosion rates in a semiarid forest in Spain increased by factors of 18.5 to 33.6 (Badia and others, 2008). In a mixed forest and agricultural area in Spain, post-fire sediment yields increased from 0.12 kilograms per hectare, or 0.012 grams per square meter (unburned) to 4,563 kilograms per hectare or 456 grams per square meter (burned), an increase by a factor of 38,025 (Mayor and others, 2007).

Wildfires, in addition to surficial erosion, can increase the number of debris flows and other landslides. For example, two large debris flows were observed on a single day in 2008 in separate recently-burnt watersheds (DeGraff and others, 2011). Post-fire debris-flow volumes have been found to be dependent on topographic gradients, extent of burned areas, and storm rainfall (Gartner and others, 2008; Cannon and others, 2009).

Vegetation Management

The scientific literature on the water-quality effects of vegetation management treatments is less extensive than the literature on wildfire effects. Effects vary with local conditions of topography, geology, climate, the scale of the study (plot vs. watershed) and particularly with the degree of implementation of Best Management Practices (BMPs) to prevent or reduce impacts of projects to water quality.

A comparison of plots affected by vegetation management treatments with untreated reference plots in the southern Sierra Nevada showed that rill formation on treated plots was minimal (rills are small erosional channels that form on hillslopes with low infiltration rates or high erodibility). The amount of bare soil on treated plots was not significantly different than the amount on reference plots (Berg and Azuma, 2010). Bare ground and rills are indicators of high rates of soil erosion, and these study results therefore indicate that the fuels reduction treatments did not substantially increase erosion in comparison to untreated control plots.

Hatchett and others (2006) studied runoff and erosion from plots subject to mastication and various other fuels reduction treatments, and found that under low-intensity rainfall, treated plots like undisturbed plots experienced no erosion. During high-intensity rainfall, the treated plots covered with wood chips had erosion rates 3.25 times higher than undisturbed plots. This increase is much smaller than most increases in erosion rates observed following wildfires.

Madrid and others (2006) studied effects of fuels reductions in forests in New Mexico. They reported sediment yields of 0.10 to 8.15 kilograms per hectare (0.01 to 0.82 grams per square meter) for treated plots as compared to sediment yields of 0.06 to 3.21 kilograms per hectare (0.006 to 0.32 grams per square meter) from untreated plots. They concluded that although sediment yields for treated plots were higher than sediment yields for untreated plots, the observed increases were small and “southwestern mixed conifer forest may be partially thinned without risk of significant increases in hillslope runoff and sediment yield (Madrid and others, 2006,p. 159).”

Vegetation management projects can have more substantial adverse effects if appropriate Best Management Practices (BMPs) are not followed. Best Management Practices are practices and techniques for control of nonpoint source pollution related to land uses such as timber harvest, roadbuilding, and grazing. Cram and others (2007) found that sediment yields increased by a factor of 22 following heavy mechanical operations on steep slopes in a southwestern conifer forest where USFS Region 5 BMPs were not implemented. However, Cram and others (2007) also found that light to moderate disturbance by mechanical harvesting did not significantly increase erosion rates even on steep slopes. The increase in erosion reported by Cram and others (2007) for heavy mechanical use on steep slopes is substantial, however, increases related to wildfires are often more extreme. More importantly, USFS Region 5 BMP 1.9 allows tractor logging only where the post-logging erosion hazard is expected to be low or moderate (USDA Forest Service, Pacific Southwest Region, 2011). Robichaud and others (2010) provide examples of BMPs effective in reducing road-related sediment delivery.

Comparison of sediment yields from areas affected by wildfires and vegetation management treatments

Both wildfires and vegetation management treatments have potential to increase erosion and sediment transport. The scientific literature indicates that the range of potential increases in erosion related to wildfires far exceeds the range for fuels treatments and other land uses, including roads (see the next section of this document, below). Sediment yields measured from burned areas in the Sierra Nevada and nearby areas have ranged from 6,800 grams per square meter per year (30 tons/ac/yr; Pierson and others, 2008) to 10,000 grams per square meter per year (44 tons/ac/yr; Carroll and others, 2007). Areas treated for fuels with properly implemented BMPs have much lower sediment yields. For example, the results of Madrid and others (2006) indicated sediment yields of 0.01 to 0.82 grams per square meter per year (0.0004 to 0.004 tons/ac/yr) following fuels treatments.

More recently, Elliott (2010) used typical erosion rates associated with forest land uses from the scientific literature and found that fuels reduction treatments with properly implemented BMPs can reduce long-term average annual watershed erosion rates from 0.45 megagrams per hectare per year(0.45 grams per square meter per year, or 0.20 tons/ac/yr) to 0.32 megagrams per hectare per year (0.32 grams per square meter per year, or 0.14 t/ac/yr) by reducing the size, severity, and frequency of fire. Elliott’s (2010) analysis included the effects of roads and wildfires as well as the direct effects of the fuels treatment activities. Therefore, Elliot (2010) provides recent scientific evidence that fuel treatments provide a net benefit for watersheds given the risk of severe erosion and sedimentation from wildfires.

FOREST ROADS

Forest roads are generally acknowledged to be one of the major sources of sediment pollution on NFS lands in California. Road decommissioning is the most effective approach to reducing road-related sediment delivery, but for roads that are needed for forest management and recreation, road maintenance, including stormproofing, is the primary means of controlling erosion. Declining budgets have reduced the ability of the National Forests in California to maintain and stormproof roads. This analysis was undertaken to estimate the amount of sediment potentially delivered from NFTS roads to streams on an average annual basis, and the potential for maintenance following Best Management Practices (BMPs) to reduce sediment delivery.

Approach

The basic approach taken for this analysis was to multiply road miles on NFS lands in Region 5 (from INFRA, provided by Regional Road Engineer Melissa Totheroh) by appropriate rates of road sediment production (erosion), in tons per mile. Owing to uncertainties inherent in extrapolating erosion rates determined from site-specific studies to large portions of the National Forest system, a range of erosion rates (low and high) was used to develop the estimated sediment loads. Erosion rates were taken from scientific literature where possible, and estimated based on professional judgment otherwise. Separate estimates were computed for road surface (including cutbank and fillslope) erosion, gully erosion, and landslide erosion. Estimates of sediment production were then adjusted for sediment delivery to stream channels, using information from literature (Coe, 2006) and professional judgment. Sediment delivery was estimated assuming that no BMPs were implemented to control drainage.
Although a substantial amount of information is available for forest road sediment transport, results of past studies vary in terms of geographic areas, timescales, spatial scales, prevailing weather, and BMP implementation. Most studies report sediment production rates, but some report sediment delivery (to streams) rates, which are always lower than production rates. Erosion rates must be expressed in units of mass per unit road length per year in order to be used to estimate average annual sediment loads based on road mileage. Results reported in other units were converted if possible. Results that did not specify the time period associated with the measured erosion could not be used. Erosion rates used for this analysis are summarized in Table 3 below.

Road erosion rates vary owing to differences in design, surfacing, width, and drainage features. Forest roads include 5 maintenance levels, ranging from infrequently maintained native-surface roads closed to all use to paved forest highways with high levels of traffic. However, the vast majority of road miles are in maintenance level 2. Roads in maintenance level 2 are generally native-surface roads that are infrequently graded, may be open to both standard high-clearance vehicles and OHVs, and are likely to be closed during winters. For the purposes of this analysis, all road miles were assumed to be comparable to maintenance level 2 because most of the erosion rates reported in the scientific literature are appropriate for ML 2 roads. Results of this analysis could be further refined in the future by developing separate erosion rates for other maintenance levels.

Table 3: Selected annual road sediment production (erosion) rates for the Sierra Nevada
Reference
Erosion process
Road erosion (tons/mi/yr)
MacDonald and Coe, 2010
Road surface
0.002 ot 42.4
Coe, 2006
Road surface
0.015 to 4.45
Cafferata and others, 2007
Road surface
7.42
MacDonald and others, 2004
Road surface
9.54
MacDonald and Coe, 2010
Landslide
66.3 to 283

Additionally, the following information was used in developing estimates for this analysis:
  1. Road hydrologic connectivity on well-maintained forest roads is 25% (Coe, 2006), but increases by 40% to 65% in the absence of engineering practices (BMPs) to control drainage and surfacing (Coe, 2006).
  2. Gully erosion constitutes about 43% of road-surface erosion (Coe, 2006).

Based on this information, low and high erosion rates per mile of road were estimated for National Forests in the Sierra Nevada, as shown in Table 4.

Table 4: Estimated average annual sediment production (erosion) rates for forest roads in the Sierra Nevada
Erosion process
Low rate (tons/mi/yr)
High rate (tons/mi/yr)
Road surface
0.002
40
Gully
0
16
Landslide
7
28

Results

Estimates of potential road-related sediment yields in the absence of BMPs were computed by multiplying road miles by road erosion rates (Table 4), summing erosion for all 3 processes (road surface, gully, and landslide), and dividing the totals by the number of NFS acres (government-owned acres only) on each National Forest (Table 5). “Low” estimated sediment yields range only from 0.01 to 0.02 tons per acre per year, with a mean of 0.01 tons per acre per year. “High” estimated deliveries range from 0.07 to 0.19 tons per acre per year, with a mean of 0.12 tons per acre per year. Total estimated road-related sediment delivery for the 10 Sierra Nevada National Forests ranged from 111,000 to 1.3 million tons per year.

Table 5: Potential road-related sediment yields for Sierra Nevada National Forests in the absence of BMPs designed to reduce hydrologic connectivity, based on Coe and MacDonald (2007)

National Forest
Road miles
National Forest acres
Low Road Sediment Yield, in tons/ac/yr
High Road Sediment Yield, in tons/ac/yr
Eldorado
2,067
683,953
0.02
0.19
Inyo
1,818
1,840,894
0.01
0.06
Lassen
2,340
1,070,344
0.01
0.14
Modoc
3,599
1,663,401
0.01
0.14
Plumas
3,145
1,176,005
0.01
0.17
Sequioa
1,402
1,144,235
0.01
0.08
Sierra
1,969
1,311,913
0.01
0.09
Stansilaus
2,271
898,121
0.01
0.16
Tahoe
2,383
871,495
0.01
0.17
Lake Tahoe Basin
174
154,000
0.01
0.07
Totals
21,169
10,814,361



The proportion of the delivered sediment that could be prevented from reaching streams through implementation of BMPs is roughly 60% (Weaver and others, 1995; Coe, 2006), and BMP effectiveness for NFS roads has been 85% in recent years (USDA Forest Service, 2009). Actual road-related sediment delivery on NFS lands can therefore be estimated by multiplying the sediment yields listed in Table 4 by 60% (0.60) and then dividing by 85% (0.85). On this basis, road-related sediment yields on NFS lands in the Sierra Nevada are estimated to range from 0.007 to 0.13 tons/ac/yr.

This range of estimated road-related sediment yields overlaps the low end of the range of reservoir sediment yields presented in Table 2. This comparison indicates that roads are likely to be substantial sources of sediment in some actively-managed forested watersheds with overall low sediment yields. However, this comparison also shows that road-related sediment cannot account for a majority of sediment from high-yield watersheds. Other sources of sediment therefore also need to be considered in planning effective programs to control sedimentation.

Road-related sediment yields (Table 5) are much lower than sediment yields associated with severe wildfires (see previous section). However, erosion from roads may result in chronically elevated concentrations of sediment that may be of importance for aquatic organisms (for example, Goode and others, 2012).

Restoration of Decommissioned or Closed Roads

Insert information on trends in restoration of decommissioned or closed roads


LIVESTOCK GRAZING

Livestock grazing is an authorized use of most NFS lands in the Sierra Nevada, but has potential to adversely affect water resources. Livestock frequently compact soil, remove vegetation, and deposit wastes in or near water bodies, resulting in reduced infiltration, increased runoff and erosion, and increased concentrations of sediment, nutrients, and bacteria in surface waters.

Grazing with high stocking rates and long seasons of use generally decreases infiltration, increases overland runoff, and increases surficial erosion (Kauffman and Krueger, 1984; Trimble and Mendel, 1995; Jones, 2000). Less intense grazing has much less significant effects (Trimble and Mendel, 1995).

Very few studies have reported sediment yields for pastures in the Sierra Nevada. Lewis and others (2006) reported that suspended-sediment yields in California oak woodland rangeland watersheds averaged 0.09 tons/acre/year, much less than sediment yields associated with wildfires but within the range of “high” sediment yields estimated for forest roads in Table 4 above.

Livestock grazing has probably contributed to channel incision in Sierra Nevada meadows, but the effects of grazing are very difficult to separate from those of other land uses such as construction of roads, railroads, and ditches, and climatic variability (Ratliff, 1985). Cattle have sufficient weight to compress meadow soils, which can destroy the natural meadow sod that protects meadows from erosion (Kleinfelder and others, 1992; Boschi and Baur, 2007). Many gullies in the meadows of the Sierra Nevada, however, did not develop until decades after livestock numbers peaked, suggesting that grazing was not necessarily the primary factor in widespread meadow erosion (Wood, 1975).

Studies of cattle exclosures on channel morphology have produced a range of results. For example, Knapp and Matthews (1996) reported that “current levels of livestock grazing are degrading the stream and riparian components of the study meadows to the detriment of golden trout populations (p. 805).” Kondolf (1993), in contrast, reported no significant differences in channel morphology within and outside of exclosures.

Livestock grazing allotments on NFS lands are often within wilderness areas used increasingly for public recreation. Livestock effects on surface-water quality are therefore a concern for public health. A number of recent studies have reported increased concentrations of coliform bacteria associated with livestock on NFS lands in the Sierra Nevada, including numerous concentrations above current regulatory standards (Derlet and others, 2004; Derlet and Carlson, 2006; Derlet and others, 2008; Derlet and others, 2012; Myers and Kane, 2011; Myers and Whited, 2012). In contrast, a study in progress by the USFS and UC Davis (Kromschroeder, 2012) found no nutrient concentrations in excess of regulatory nutrient standards and relatively few violations of regulatory standards for coliform bacteria.

Contamination of forest streams at levels significantly above State-established thresholds for recreational contact was shown to occur in three years of studies in the Stanislaus National Forest (Myers and Kane, 2011, Myers and Whited, 2012), but only after the seasonal arrival of livestock into study areas. Control areas without the presence of livestock showed no spike of fecal coliform levels or other elevation levels of pathogenic bacteria throughout the grazing season. Contamination of forest streams in areas with high levels of dispersed recreational uses such as hiking, camping, swimming, and other activities in or near water poses higher risk for low socio-economic recreational visitors who may not bring filters for use when drinking from streams that appear clear and safe. The Stanislalus Forest studies referenced were done fully consistent with State water sampling protocols. Due to the limited extent of water sampling, the study in progress by the USFS and UC Davis is not being done fully consistent with State water sampling protocols for determining violations of water quality standards, but the study does provide snapshot sampling results across a broad geographic area.

SUMMARY

Sediment yields from recently and severely burned areas are much higher than from unburned forests, including areas affected by vegetation management, forest roads, and livestock grazing (Table 6). Sediment delivery from burned areas is episodic, and decreases to post-fire levels within a few years. Sediment delivery from roads and pastures is relatively low, but persistent. Studies of fecal coliform bacteria related to livestock grazing on NFS lands have produced conflicting results.

Table 6: Sediment yields for selected land uses on NFS lands in the Sierra Nevada
Land use
Sediment yield, t/ac/yr
Background, from reservoir sedimentation
0.03 to 3.52
Wildfires (1 to 3 years postfire)
30 to 44
Vegetation management
0.0004 to 0.004
Forest roads (with typical BMPs)
0.07 to 0.13
Livestock grazing
0.09
Tables summarizing selected relevant scientific publications related to climate change and land-use effects on water quality on forested lands in the Sierra Nevada are provided as appendices following the References section:

A1: Climate change
A2: Wildfire and vegetation management
A3: Forest roads
A4: Livestock grazing

Water Resource Trend Information


The contribution of key watersheds, water resources and water within the plan area to use and enjoyment by the public, both consumptive including water withdrawals and diversions for agricultural, municipal, and commercial uses and non-consumptive including water storage for flood control, hydropower, and recreation.

The Organic Act of 1897 that established the National Forest system specified that one of two primary objectives of the National Forests was to “secure favorable conditions of water flow” from NFS lands. The Transfer Act of 1905 that created the USDA Forest Service as the agency responsible for managing the National Forests required the new agency to “see to it that the water, wood, and forage of the reserves (now Forests) are conserved and wisely used….” The Transfer Act also noted that “The continued prosperity of the agricultural, lumbering, mining, and livestock interests is directly dependent upon a permanent and accessible supply of water, wood, and forage…” An evaluation of the role of National Forests in providing water and protecting water quality is therefore a fundamental part of the bioregional assessment.

Identification of key watersheds
In this section, we present information on the importance of the major watersheds on NFS lands in the Sierra Nevada for water resources, including water supply, hydroelectric power production, fish and wildlife habitat, and recreation. Information from USFS and external sources was used for this summary.

Designated beneficial uses
Beneficial uses are the uses of water that are desired by human populations, whether they are existing or potential uses. Within the State of California, the nine Regional Water Quality Control Boards (Regional Boards) determine the beneficial uses, including existing, potential, and limited uses, for waters of the state within their respective regions. Beneficial uses are listed in the Basin Plans developed by the Regional Boards for the areas within their jurisdictions. Water quality standards are tied to established beneficial uses in Basin Plan objectives that are enforceable by the Regional Boards.

Two Regional Boards have jurisdiction over water quality on NFS lands in the Sierra Nevada. The Central Valley Water Quality Control Board has jurisdiction over the west slope of the range, and the Lahontan Regional Water Quality Control Board has jurisdiction over the east slope.

The Central Valley Regional Water Quality Control Board has developed two basin plans for its region. The Sacramento-San Joaquin Basin Plan includes the tributaries of the two major rivers that flow to San Francisco Bay, while the Tulare Lake Basin Plan covers the west slope of the extreme southern Sierra Nevada. The Lahontan Regional Water Quality Control Board has one basin plan that covers their entire region. The most common beneficial uses established for the major rivers flowing from NFS lands are listed in the tables below.

Table 1: Common beneficial uses established for major rivers flowing from NFS lands, Sacramento-San Joaquin Basin Plan

River
MUN
AGR
POW
REC-1
REC-2
WARM
COLD
MIGR
SPWN
WILD
Pit
X
X
X
X
X
X
X

X
X
Feather
X
X
X
X
X
X
X

X
X
Yuba
X
X
X
X
X
X
X

X
X
Bear
X
X
X
X
X
X
X
X
X
X
American
X
X
X
X
X
X
X

X
X
Consumnes
X
X
X
X
X
X
X

X
X
Mokelumne
X
X
X
X
X
X
X
X
X
X
Calaveras

X

X
X
X
X
X
X
X
Stanislaus
X
X
X
X
X
X
X

X
X
Tuolumne
X
X
X
X
X
X
X

X
X
Merced
X
X
X
X
X
X
X


X
San Joaquin
X
X
X
X
X
X
X

X
X

Table 2: Common beneficial uses established for major rivers flowing from NFS lands, Tulare Lake Basin Plan
River
MUN
AGR
POW
REC-1
REC-2
WARM
COLD
WILD
RARE
SPWN
Kings
X
X
X
X
X
X
X
X
X
X
Kaweah
X

X
X
X
X
X
X
X
X
Tule
X
X
X
X
X
X
X
X
X
X
Kern
X

X
X
X
X
X
X
X
X


Table 3: Common beneficial uses established for major rivers flowing from NFS lands, Lahontan Basin Plan
River
MUN
AGR
REC-1
REC-2
COMM
WARM
COLD
WILD
RARE
MIGR
SPWN
Susan
X
X
X
X
X
X
X
X
X
X
X
Truckee
X
X
X
X
X

X
X
X
X
X
Carson
X
X
X
X
X

X
X
X

X
Walker
X
X
X
X
X

X
X
X
X
X
Owens
X
X
X
X
X
X
X
X
X
X
X

As shown in Tables 1 to 3, most of the major streams draining NFS lands in the Sierra Nevada are, or could be, used for municipal and agricultural supplies, as well as for recreation and for fish and wildlife habitat. On the western slope, most streams are also used for hydropower production, but hydropower is not a major beneficial use on the eastern slope.

Watersheds supplying federal, state, and municipal water projects
Federal projects

Federal projects include projects operated by the Bureau of Reclamation (BOR, a part of the U.S. Department of the Interior) for water supply and projects operated by the U.S. Army Corps of Engineers (COE) for flood protection.

BOR projects have a statewide total capacity of 11 million acre-feet (MAF). A total of 7 MAF are delivered annually on average. This water provides irrigation for 3 million acres of farmland and domestic water supply for 2 million people. The largest BOR project is the Central Valley Project, with its dam and reservoir at Shasta Lake north of Redding. Shasta Lake impounds the Pit River, which originates within the Sierra Nevada planning assessment area on the Modoc National Forest, as well as several major streams that originate outside of the planning area. The major BOR facilities, and the rivers affected, are listed below:

Shasta Reservoir, Pit River
Englebright Reservoir, North Fork Yuba River
Folsom Reservoir, American River
New Melones Reservoir, Stanislaus River
Friant Dam, Millerton Lake, San Joaquin River
Pine Flat Reservoir, Kings River
Lake Kaweah, Kaweah River
Success Lake, Tule River

The COE operates Lake Isabella, a reservoir on the Kern River on the Sequoia National Forest. The COE also shares responsibility for managing several BOR reservoirs that are used for flood control as well as water supply.

State Water Project
The State Water Project (SWP) includes reservoirs and conveyances in the Feather River watershed. Total capacity of the SWP is 5.8 MAF, and average annual delivery is 3 MAF, of which, 70% goes to urban uses and 30% supports agricultural uses. About 600,000 irrigated acres are supported by the SWP, and about 20 million consumers rely on domestic water from the project.

Municipal Projects
Several municipal utilities use water from the Sierra Nevada National Forests. These include local mountain and foothill communities as well as more distant large urban populations. Several of the major municipal projects are described briefly below.

The Yuba County Water Agency (YCWA) operates 4 dams on the Yuba River with a total storage capacity of roughly 1 MAF. Annual deliveries average 310,000 acre-feet to irrigation districts. The YCWA also generates about 397 Mw of electricity annually through hydroelectric plants at its facilities.

The Placer County Water Agency (PCWA) serves 38,000 customers with water from the Yuba, Bear, and American Rivers. The PCWA has an extensive system of canals, reservoirs, storage tanks, and treatment plants. Untreated water is used for irrigation, and treated water is provided for domestic uses.

The Nevada Irrigation District (NID) uses water from the Yuba and Bear Rivers. The water is used for agriculture and domestic use. The NID storage system has a capacity of 280,380 acre-feet, and serves 25,400 customers.

The Eldorado Irrigation District (EID) diverts water from the South Fork of the American River for both agricultural and domestic uses. The EID has about 100,000 customers, and delivered 27,761 acre-feet in 2010. The EID has a total tank storage of 109,000,000 gallons.

The East Bay Municipal Utility District (EBMUD) serves customers in Alameda and Contra Costa Counties in the east Bay Area near San Francisco. Almost all of the water used by EBMUD is from the Mokelumne River downstream of the Eldorado and Stanislaus National Forests. Pardee Reservoir has a capacity of 197,950 acre-feet. Camanche Reservoir has a capacity of 417,120 acre-feet. The District serves 1.3 million customers and has water rights to 997 acre-feet per day, or 364,000 acre-feet per year.

The City and County of San Francisco diverts water from the Tuolumne River at Hetch Hetchy Reservoir to serve 2.6 million customers in San Francisco and other Bay Area cities. The storage capacity of Hetch Hetchy is 359,000 acre-feet. The watershed supplying Hetch Hetchy is mostly National Park lands, but includes the Cherry Creek watershed on the Stanislaus National Forest.

The Los Angeles Department of Water and Power (LADWP) diverts water from tributaries to Mono Lake and the Owens River. The LADWP storage system includes Lake Crowley and Grant Lake. The LADWP provides water for 4 million customers in the Los Angeles metropolitan areas as well as communities in the Owens Valley. The system delivers a total of roughly 295,000 acre-feet per year from east-slope Sierra Nevada watersheds.

Outstanding National Resource Waters
The State Water Resources Control Board (State Board) and the U.S. Environmental Protection Agency have designated only two Outstanding National Resources Waters in California, and both are within watersheds managed primarily as units of the National Forest System. The two designated waters are the California portion of Lake Tahoe and Mono Lake. This designation means that no degradation of water quality is allowed for these lakes.
Lake Tahoe is renowned for its great depth and water clarity, which, combined with its setting in the scenic east slope of the high Sierra Nevada, have made it a famous tourist attraction as well as a source for domestic water and habitat for fish and wildlife. However, owing to recent decreases in lake clarity, the lake is listed as impaired by the State Board and USEPA, and a Total Maximum Daily Load (TMDL) is being implemented to improve the quality of the lake’s water.
Mono Lake, also on the east side of the Sierra Nevada, is a stark contrast to Lake Tahoe, being located in a closed basin on the desert floor at the foot of the Sierra escarpment. Mono Lake provides critical migratory and seabird habitat, and has been at the center of a controversy over diversion of tributary streams by LADWP. The lake is currently in the process of refilling to a level designated in a legal settlement.

Watersheds supporting anadromous and native fisheries
Only 3 streams on NFS lands in the Sierra Nevada currently support anadromous fisheries (Kellett, Michael, USFS, personal commun., 2012). These streams are Deer, Antelope, and Mills Creeks, all on the Lassen National Forest. These streams support populations of Central Valley spring Chinook salmon, Central Valley fall Chinook salmon, and winter steelhead.

Many more streams supported anadromous fisheries in the past, but owing primarily to construction of dams, do not support those fisheries now. The State Water Resources Control Board has identified the streams listed in Table 4 below as potential habitat for anadromous fish. Many of the major rivers and creeks draining NFS lands in the Sierra Nevada are included. Streams with existing or potential habitat for nonanadromous fish are listed in Table 5.

Table 4: Streams with potential habitat for anadromous species identified as high priorities for development of in-stream flow standards in the Sierra Nevada by the State Water Resources Control Board
STREAM
SPECIES (potential)
NATIONAL FOREST
American River
Spring and fall Chinook salmon; steelhead; Sierra Nevada and Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Eldorado
Antelope Creek
Spring Chinook salmon; steelhead; Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Lassen
Battle Creek
Winter and Spring Chinook salmon; steelhead; green sturgeon; Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Lassen
Bear River
Spring Chinook salmon; steelhead; Sierra Nevada and Foothill yellow-legged frog;; Western pond turtle
Tahoe
Calaveras River
Fall Chinook salmon; steelhead; Sierra Nevada and Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Stanislaus
Clear Creek
Spring Chinook salmon; steelhead
Lassen
Consumnes River
Fall Chinook salmon; steelhead; Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Stanislaus
Cow Creek
Spring and fall Chinook salmon; steelhead; Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Plumas
Deer Creek
Fall Chinook salmon; steelhead; Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Lassen
Fall River
Winter and spring Chinook salmon; steelhead
Lassen
Hat Creek
Winter and spring Chinook salmon; steelhead
Lassen
Mill Creek
Spring Chinook salmon; steelhead; foothill yellow-legged frog; California red-legged frog; Western pond turtle
Lassen
Mokelumne River
Spring and fall Chinook salmon; steelhead; Sierra Nevada yellow-legged frog; California red-legged frog; Western pond turtle
Eldorado, Stanislaus
Pit River
Winter and spring Chinook salmon; steelhead
Modoc, Lassen
Upper San Joaquin River
Spring and fall Chinook salmon; steelhead; green sturgeon; Sierra Nevada and Foothill yellow-legged frog; California red-legged frog; Western pond turtle
Sierra
Stanislaus River
Spring and fall Chinook salmon; steelhead; Yosemite toad; Sierra Nevada yellow-legged frog; California red-legged frog; Western pond turtle
Stanislaus
Tuolumne River
Spring and fall Chinook salmon; steelhead; Yosemite toad; Sierra Nevada and foothill yellow-legged frog; California red-legged frog; Western pond turtle
Stanislaus
Yuba River
Spring Chinook salmon; steelhead
Tahoe


Table 5: Streams with potential habitat for non-anadromous species identified as high priorities for development of in-stream flow standards in the Sierra Nevada by the State Water Resources Control Board
STREAM
SPECIES (potential)
NATIONAL FOREST
Buckeye Creek
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog
Humboldt-Toiyabe (Region 4)
Hot Creek
Owens sucker; California floater freshwater mussel
Inyo
Independence Creek
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog
Inyo
Lee Vining Creek
Sierra Nevada yellow-legged frog; Yosemite toad; Mount Lyell salamander
Inyo
Little Truckee River
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog
Tahoe
Mammoth Creek
Owens sucker; California floater freshwater mussel
Inyo
Mill Creek
Sierra Nevada yellow-legged frog; Yosemite toad; Mount Lyell salamander
Inyo
Owens River (including tributaries)
Owens tui chub; Owens speckled dace; Owens sucker; Owens pupfish; Northern leopard frog; Sierra Nevada yellow-legged frog
Inyo
Pine Creek
Eagle Lake rainbow trout
Lassen
Reverse Creek
Sierra Nevada yellow-legged frog; Yosemite toad; Mount Lyell salamander
Inyo
Rush Creek
Sierra Nevada yellow-legged frog; Yosemite toad; Mount Lyell salamander
Inyo
Robinson Creek
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog
Inyo
Sagehen Creek
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog
Tahoe
Virginia Creek
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog; Yosemite toad
Humboldt-Toiyabe (Region 4)
East Walker River
Lahontan cutthroat trout; Sierra Nevada yellow-legged frog; Yosemite toad
Humboldt-Toiyabe (Region 4)

Wetlands
Wetlands are important for their hydrologic and geochemical functions and as fish and wildlife habitat. Wetlands include a wide variety of features, including palustrine and lacustrine marshes, swamps, meadows, bogs, and fens. In terms of area, meadows are the most important wetlands on NFS lands in the Sierra Nevada. The acres of meadows on the NFS administrative units in the Sierra Nevada are listed in Table 6 below (data are from the Sierra Nevada Framework Planning Amendment Environmental Impact Statement, 2001). As percentages of total National Forest area, meadows range over an order of magnitude, from 0.5% on the Plumas National Forest to 5% on the adjacent Lassen National Forest. Meadow distribution is affected by bedrock geology, geomorphic history (glaciation), and climate. Many meadows have been adversely impacted by historic land uses, and have lost some or all of their hydrologic and ecological functions owing to erosion by deep gullies (Ratliff, 1985) and erosion and compaction of topsoil. The USFS has worked for over 80 years to restore Sierran meadows .


Table 6: Meadows on National Forests in the Sierra Nevada
National Forest
Number of meadows
Total meadow area (acres)
Average meadow area (acres)
Total NFS land area (acres)
Percent of total land area in meadows
ENF
1,797
9,880
5.50
684,031
1.4%
INF
1,511
39,245
25.97
1,902,039
2.1%
LNF
1,585
53,836
33.97
1,070,344
5.0%
MDF
535
39,194
73.26
1,663,401
2.4%
PNF
219
5,787
26.42
1,176,005
0.5%
SQF
288
8,347
28.98
1,144,235
0.7%
SNF
634
9,748
15.38
1,311,913
0.7%
STF
1,854
12,947
6.98
898,121
1.4%
TNF
667
23,479
35.20
871,495
2.7%
LTBMU
2,523
18,835
7.47
191,000
9.9%
TOTAL
11,613
221,298

10,912,584
2.0%

Consumptive uses
In this section, we summarize available quantitative information on consumptive uses of water flowing on and from NFS lands in the Sierra Nevada based on information available in the 2009 update to the State Water Plan. Consumptive uses are those uses that do not return water to the water body from which the water was taken. The primary consumptive uses of water flowing from the Sierra Nevada are municipal water supplies and agricultural irrigation.

Surface Water
Statewide, municipal surface-water use totals about 9 MAF annually. Within the Mountain Counties region (Plumas to Sequoia Counties), where most of the Sierra Nevada National Forests are located, per capita water consumption is roughly 240 gallons per day, for a total of approximately 85,000 acre-feet of municipal and domestic use of surface water annually. The remainder of the 9 MAF is used downstream, primarily in the San Francisco Bay Area, the Central Valley, and in Southern California.
Average annual statewide agricultural surface-water use is about 34 MAF. Average annual agricultural use within the Mountain Counties region is about 255,000 acre-feet. The remainder of the 34 MAF is used downstream of the Mountain Counties, primarily in the Central Valley.

Groundwater
Groundwater provides about 40% of California’s total water supplies (Fram and Belitz, 2012), but is a relatively minor source of water in much of the Sierra Nevada. Most of the important groundwater basins in the range are in the volcanic terrain of the Feather River basin, according to the Mountain Counties Regional Report in the 2009 update of the State Water Plan (the Mountain Counties Region does not include Lassen County). Recharge in the Sierra Nevada helps supply Central Valley aquifers used for agriculture and municipal supplies. Groundwater provides about 5% of local water supply in the Sierra Nevada, limited to areas of fractured rock and small alluvial aquifers along streams. Most of this groundwater is used for domestic purposes. Although natural and artificial chemicals are found in Sierra Nevada groundwater, quality of groundwater in the Sierra Nevada is generally good (Fram and Belitz, 2012 a, b). Arsenic and uranium are the constituents of most concern in the Southern Sierra Nevada (Fram and Belitz, 2012b).

Nonconsumptive uses
Nonconsumptive uses are those uses of water that return water to the water body from which it was diverted, such as production of hydroelectricity. Uses that do not involve diversions, such as recreation and environmental flows for fish and wildlife habitat are also considered to be nonconsumptive.

Hydroelectricity
The delivery of water from the Sierra Nevada to municipalities and Irrigation use often starts high in the Sierra. Snowmelt is held in high elevation reservoirs, which provide storage for water that is used throughout the year for water uses including river and reservoir boating, swimming, and fishing. As the water is transported down to lower elevations, it commonly provides a source of energy to hydropower developments. Most nongovernmental hydropower projects are licensed to operate for 30-50 years by the Federal Energy Regulatory Commission (FERC). Small projects may have obtained an exemption from licensing, but still do have a footprint on the land, and can divert a large proportion of stream flows from small drainages.

There are currently 109 FERC licensed hydropower projects in California. Seventy six of those projects are located on NFS lands. An additional 139 FERC license exempt hydropower projects exist in California, with 27 on NFS lands. Altogether, there is a built capacity of nearly ten million megawatt hours with all of these projects, 96% of which is on NFS lands. Hydropower capacity of projects on the Sierra Nevada National Forests accounts for 92% of California’s total.

When a license reaches its expiration date, the license holder must apply to FERC for a renewed license to be issued to continue operation of that facility. At that time, FERC’s process for relicensing must be followed. The Forest Service in California has participated in the process for 42 renewed licenses in the past 15 years. Currently, since 2001, there are 23 new licenses being implemented, and 19 projects still in process.

During the relicensing process, the FS works collaboratively with the licensee, state and federal agencies, and stakeholders to determine conditions that are necessary for the protection, mitigation, and enhancement of forest resources in connection to the continued operation of the project for the next term. In order to determine which conditions are needed, intensive studies of the project’s effects on forest resources have been carried out by the licensees. Although there are documented effects from the diversion of water for these projects, the conditions of forest resources should improve over the next several years as the new licenses are implemented. Measures that are included in the new licenses include instream flows which seek to mimic a natural hydrograph in shape, timing, and to the extent possible magnitude. Special attention has been given to the life cycles of aquatic life within the river systems. Additional conditions address needs for plant and wildlife, fuels management, noxious weed management, and recreational resource needs.

Development of new projects has slowed down as most highly productive sites have been developed. However, there are currently nearly 30 potential projects in California which have applied for priority right to develop new hydropower facilities to be licensed, and are currently under investigation by the applicants and appropriate state and federal agencies.

Changes in precipitation type and patterns due to climate change have the potential to greatly effect hydropower production across the Sierra. As snowpack changes, the natural reservoir which it provides will be less affective in storing and metering water to downstream project reservoirs, likely causing a change in the effectiveness of the existing engineer designed layout of hydropower projects in the Sierra. The California Energy Commission (2012) estimates that hydropower production in the Sierra Nevada will decrease by 9% owing to warming temperatures and subsequent changes in streamflow. The Forest Service’s continued close connection to new licenses as they are implemented will be essential in order to ensure resource protection that has been carefully designed in the new license conditions.

Fish and wildlife
According to the 2009 update of the State Water Plan, annual environmental flows in California streams average 39 MAF. The section on key watersheds, above, provides information on streams that are existing and potential habitat for anadromous and non-anadromous fish species.
Recreation
The following streams are designated as Wild and Scenic by the federal or state government, or both (from the Mountain Counties Regional Report, State Water Plan 2009 update):
Wild and Scenic Rivers--Federal
Feather River, North and Middle Forks, 78 miles above Lake Oroville
North Fork American River, 38 miles east of Colfax
Tuolumne River, 83 miles above Don Pedro Reservoir
Merced River, 122 miles above Lake McClure

Wild and Scenic Rivers--State
South Yuba River, 39 miles above Englebright Lake
North Fork American River, 38 miles east of Colfax

The COE operates 3 recreational facilities at reservoirs on NFS lands in the Sierra Nevada: Englebright and Martis Creek Lakes on the TNF and Pine Flat Reservoir on the SNF. In addition, the COE operates 6 recreational facilities downstream of NFS lands in the Sierra Nevada.
DWR operates 4 recreational facilities in the Feather River watershed in or near the Plumas NF. The sites are located at Antelope, Frenchman, and Davis Lakes in the Feather River headwaters and at Lake Oroville.
Flood protection
The COE and the DWR are the primary agencies with responsibility for statewide flood control in California. Total flood storage capacity in the Sierra Nevada is roughly 14.4 MAF. Of this total, 2.2 MAF is in reservoirs operated by the COE, and 12.2 MAF is in reservoirs operated by cooperating agencies (Section 7 reservoirs).

The conditions and trends related to water use and enjoyment in the plan area and the broader landscape.

Appropriate management of natural resources requires an understanding of their current conditions and trends. For water in the Sierra Nevada, we evaluate in this section a number of indicators of water quantity, streamflow regimen, and quality.

Water yields from National Forest System (NFS) lands in the Sierra Nevada
An understanding of the importance and uses of water on and downstream of National Forests in the Sierra Nevada requires quantification of water supplies generated from runoff on NFS lands. Water yields are the amount of water delivered as streamflow per unit of contributing upstream drainage area over a convenient time period, generally one year. Water yields in this report are expressed as acre-feet of water per acre of watershed area per year, which is equivalent to feet of runoff per year. Precise estimates of water yields for individual National Forests are not possible owing to limited long-term monitoring stations located at or near National Forest boundaries, but adequate data for regional estimates have been collected. We reviewed two previous estimates of water yields for National Forests in the Sierra Nevada (Rector and MacDonald, 1986; Brown and Froemke, 2009) and developed a third independent set of estimates as a check.

Table 4: Average annual water yield from National Forests in the Sierra Nevada (from Rector and MacDonald, 1986)
[yield for Lake Tahoe Basin Management Unit is included in totals for Eldorado and Tahoe National Forests]
National Forest
Water Yield, acre-ft/year
Water Yield in acre-ft per acre per year
Modoc
566,000
0.3
Lassen
1,310,000
1.2
Plumas
2,470,000
2.1
Tahoe
2,010,000
2.4
Eldorado
1,440,000
2.1
Stanislaus
1,970,000
2.1
Sierra
2,560,000
1.9
Sequoia
734,000
0.6
Inyo
1,090,000
0.6
Total
14,150,000
--

Table 5: National Forest water yields from Brown and Froemke (2009)
National Forest
Water production, ac-ft/yr
NFS land area, ac
Water yield, ac-ft/yr/ac
Eldorado
1,146,960
604,000
1.90
Inyo
534,600
1,984,000
0.27
Lake Tahoe Basin
220,320
176,000
1.25
Lassen
1,220,670
1,151,000
1.06
Modoc
51,840
1,679,000
0.03
Plumas
1,646,730
1,202,000
1.37
Sequoia
1,765,800
1,114,000
1.59
Sierra
2,651,940
1,320,000
2.01
Stanislaus
2,522,340
898,000
2.81
Tahoe
1,789,290
825,000
2.17

Rector and MacDonald (1986) reported National Forest water yields (Table 4) that were computed using a variety of approaches that were not necessarily consistent or equally rigorous. The average annual water yield for the Sierra Nevada National Forests as estimated by Rector and MacDonald was 1.48 acre-feet per acre (or 1.48 feet per year).
The estimates provided by Brown and Froemke (2009; Table 5) are based on differences between regional estimates of precipitation and evapotranspiration, and are therefore affected by uncertainties associated with these estimates. Their estimates average 1.45 acre-feet per acre on an annual basis.

We calculated water yields for selected gaging stations operated by the U.S. Geological Survey, and included the most recent data available. For our estimates, we divided average annual streamflow, converted to acre-feet per year, by the contributing drainage area, in acres. This approach is very accurate for the drainage areas upstream of the gaging stations, but those areas generally do not correspond entirely to National Forest administrative boundaries. Our estimates for individual National Forests (Table 6), therefore, include uncertainty due to extrapolation of results from small to large watersheds on NFS lands and from areas of mixed ownership to watersheds entirely within the National Forest System.
The stations selected for this and other analyses in this chapter have relatively long periods of record, are located in or near and downstream of NFS lands, and are not substantially regulated or diverted. The flows measured at these stations can therefore be considered as representative of long-term water yields from managed NFS lands. One station, on the Merced River, is within Yosemite National Park, and was included to allow a comparison with flows from a watershed managed as a national park.



Table 6: Water yields calculated from average annual streamflow at selected USGS gaging stations on or near NFS lands
Stream
Administrative Unit
Drainage area, square miles
Period of streamflow record
Average annual water yield, ac-ft/ac/yr
Spanish Creek
Plumas National Forest
184
1934 to 2010
1.62
Sagehen Creek
Tahoe National Forest
10.5
1954 to 2010
1.29
Duncan Canyon
Eldorado National Forest
9.94
1961 to 2010
4.42
Merced River
Yosemite National Park
181
1916 to 2011
2.24
SF Kern River
Sequoia National Forest
530
1922 to 2010
0.27

The average water yield, excluding the Merced River that drains National Park lands, is 1.90 acre-feet per acre per year. This average is about 25% higher than the estimates determined by Rector and MacDonald (1986) and Brown and Froemke (2009), but is affected by the very high yield for Duncan Canyon, which is in an area of relatively high precipitation and low evapotranspiration. Given the uncertainties in all 3 sets of estimates, regional annual average water yield for NFS lands in the Sierra Nevada can be reasonably estimated to be 1.5 acre-feet per acre. The water yield for the Merced River in Yosemite National Park is higher than this average, but the reasons for and significance of this difference cannot be determined at present.

Dams and reservoirs
Dams and reservoirs are one of the two most significant impacts to streams in the Sierra Nevada (Kattleman, 1996; the other impact considered to be most important by Kattleman was hydraulic mining, discussed below). According to the Mountain Counties Regional Report in the 2009 update of the State Water Plan, a total of 76 reservoirs are located within the mountain counties (Plumas to Sequoia Counties). The reservoirs range in size from 0.0003 to 3.54 MAF, and total capacity of these reservoirs is 17.4 MAF.

Runoff regimen
Water availability for human uses in California is dependent on the total volume of water falling as precipitation but also on the timing of hydrologic processes such as snowmelt and streamflow. Annual precipitation and streamflow are useful measures for evaluating water resources, but the temporal distribution of streamflow is also important given the highly seasonal nature of rainfall and snowfall. High peak flows do not add substantially to water storage, and present hazards to life and property, whereas summer baseflows, although the lowest flows of the year, are critically important for human welfare and aquatic habitats.

Annual precipitation and streamflow
Annual amounts of precipitation and streamflow are fundamental to assessing water resources on the Sierra Nevada National Forests. In this section, we present records of precipitation and streamflow provided by the National Weather Service, DWR, and USGS to help in evaluating conditions and trends. It is important to note that global climate change is expected to affect temperature, and hence the ratio of snow to rain, more than the total amount of precipitation (California Department of Water Resources,
2008). Annual streamflow may remain relatively constant in the face of climatic change (Dettinger and others, 2004), but some researchers have suggested that higher temperatures will increase evapotranspiration and decrease annual flows (Null and others, 2010; California Energy Commission, 2012). All studies indicate early snowmelt and peak runoff in the Sierra Nevada (for example, Stewart and others, 2005; Andrews, 2012).


Figure 1: Quincy DWR precipitation in inches, 1934-2010 (PNF)

ch 8 bioregional water figure 1.JPG


Figure 2: Truckee DWR precipitation in inches, 1954-2010 (TNF)
ch 8 bioregional water figure 2.JPG



Figure 3: Annual precipitation in inches, DWR Tahoe City, 1961-2009
ch 8 bioregional water figure 3.JPG


Figure 4: Annual precipitation in inches, DWR YSV station, operated by NPS, 1916-2011
ch 8 bioregional water figure 4.JPG


Figure 5: Annual precipitation in inches at DWR station Kern Powerhouse 3, 1922-2010
ch 8 bioregional water figure 5.JPG

As shown in Figures 1 to 5, annual precipitation in the Sierra Nevada varies considerably at the five stations used for this analysis. At each station, maximum annual precipitation was roughly 5 to 6 times higher than minimum precipitation. No general trends are obvious from the graphs, but a statistical test of trend was not performed.

Figures 6 to 12, below, are double-mass curves (Searcy and Hardison, 1960) that plot cumulative annual streamflow on the vertical axis against cumulative annual precipitation on the horizontal axis. If relations between streamflow and precipitation remain constant, double-mass curves plot as straight lines. Deviations from straight lines indicate changes in the relation between streamflow and precipitation. A curve or bend to the right indicates less streamflow for each equivalent measure of precipitation, whereas a curve to the left indicates more streamflow. Double-mass curves do not provide information on the cause of any such changes, which might include increased evapotranspiration resulting from increased forest stand density, channel incision in wet meadows that depletes groundwater storage, or increased impervious areas resulting from soil compaction.

Figures 6 to 10 and 12 show double-mass curves for USGS gaging stations and nearby DWR rainfall stations on or near NFS lands. Figure 11 shows a double-mass curve for the Merced River in Yosemite National Park for comparison.


Figure 6: Spanish Creek, double-mass curve, 1934-2010 (near Plumas National Forest)
ch 8 bioregional water figure 6.JPG

Figure 7: Sagehen Creek, double-mass curve, 1954-2010 (Tahoe National Forest)
ch 8 bioregional water figure 7.JPG


Figure 8: Blackwood Creek, double-mass curve, 1961-2009 (Lake Tahoe Basin Management Unit)
ch 8 bioregional water figure 8.JPG

Figure 9: Trout Creek double-mass curve, 1961-2009 (Lake Tahoe Basin Management Unit)
ch 8 bioregional water figure 9.JPG


Figure 10: Duncan Creek, double-mass curve, 1961-2010 (Eldorado National Forest)
ch 8 bioregional water figure 10.JPG


Figure 11: Merced River, double-mass curve, 1916-2011 (Yosemite National Park)
ch 8 bioregional water figure 11.JPG


Figure 12: South Fork Kern River, double-mass curve, 1922-2010 (Sequoia National Forest)
ch 8 bioregional water figure 12.JPG

The double-mass curves for stations on or near NFS lands (Figures 6-10 and 12) all show subtle and alternating short-term trends in the past 50 years toward both slightly increased and decreased streamflow per inch of rainfall. The double-mass curve for the Merced River in Yosemite National Park (Figure 11) is noticeably straighter than the curves for the stations on NFS lands. This may be an artifact of the different land management activities in the parks and forests, or other factors may be responsible.


Peak flows
Major floods during the historic period in the Sierra Nevada occurred in 1861-62, 1906, 1909, 1955, 1964, 1986, 1997, and 2005. Based on these dates, the frequency of large floods may be increasing.

In Figures 13 to 16, peak flows at USGS gaging stations unaffected by regulation are plotted against time to provide a visual assessment of trends (Figure 15 for the Merced River is plotted using an arithmetic vertical axis to better display the plotted peak flows; all other figures use logarithmic vertical axes). These graphs do not suggest any systematic trends toward higher annual peak flows in the past 50 to 100 years.


Figure 13: Annual peak flows, Spanish Creek (near Plumas National Forest), 1934-2010, USGS data
ch 8 bioregional water figure 13.JPG


Figure 14: Annual peak flows, Duncan Canyon (Eldorado National Forest), 1961-2010, USGS data
ch 8 bioregional water figure 14.JPG


Figure 15: Annual peak flows, Merced River (Yosemite National Park), 1916-2011, USGS data
ch 8 bioregional water figure 15.JPG


Figure 16: Annual peak flows, South Fork Kern River (Sequoia National Forest), 1922-2010, USGS data
ch 8 bioregional water figure 16.JPG

Duration of baseflows
Baseflows are streamflows supplied by gradual discharge of groundwater and soil moisture to streams in periods between rainstorms or snowmelt periods. Baseflows are critical in California owing to the highly seasonal climate, in which almost all precipitation and snowmelt occurs between fall and late spring, and water demand for irrigation is highest during the summer.

Summer baseflows are likely to be affected by changing climate owing to warmer temperatures that reduce snowpack and advance snowmelt. Reduced snowmelt in reponse to climatic warming has already reduced regional groundwater recharge in the Sierra Nevada (Drexler and others, 2013), and is likely to continue to reduce recharge and summer baseflows in the future (Taylor and others, 2012).

Rough estimates of current baseflows were made by computing ratios of mean summer (July 1 to September 30) streamflows to mean annual streamflows for each year of record for 5 long-term USGS gaging stations on streams in the Sierra Nevada that are not regulated or diverted (Table 7, Figures 17 to 21). Average ratios for the 5 streams (Table 7) range substantially, from 0.10 for Duncan Canyon to 0.50 for the Merced River. Many factors may contribute to the wide range, including drainage basin size, bedrock geology, climate, aspect, land use history, and extent of meadows and other wetlands. Although substantial regional variation is apparent, no clear trends in the proportion of streamflow occurring during the summer months are obvious (Figures 17 to 21).

Table 7: Average ratios of average summer (July-September) streamflows to average annual flows for selected streams in the Sierra Nevada
Stream
Administrative Unit
Drainage area, square miles
Period of streamflow record
Average ratio, summer:annual streamflow
Spanish Creek
Plumas National Forest
184
1934 to 2010
0.15
Sagehen Creek
Tahoe National Forest
10.5
1954 to 2010
0.35
Duncan Canyon
Eldorado National Forest
9.94
1961 to 2010
0.10
Merced River
Yosemite National Park
181
1916 to 2011
0.50
SF Kern River
Sequoia National Forest
530
1922 to 2010
0.19



Figure 17: Spanish Creek (near Plumas National Forest), ratio of summer (July-September) to annual mean flows, 1934-2010
ch 8 bioregional water figure 17.JPG


Figure 18: Sagehen Creek (Tahoe National Forest), ratio of summer (July-September) to annual mean flows, 1954-2011
ch 8 bioregional water figure 18.JPG


Figure 19: Duncan Canyon (Eldorado National Forest), ratio of summer (July-September) to annual mean flows, 1961-2010
ch 8 bioregional water figure 19.JPG


Figure 20: Merced River (Yosemite National Park), ratio of summer (July-September) to annual mean flows, 1916-2011
ch 8 bioregional water figure 20.JPG


Figure 21: South Fork Kern River (Sequoia National Forest), ratio of summer (July-September) to annual mean flows, 1922-2010
ch 8 bioregional water figure 21.JPG



Water quality
The National Forests in California have generally provided a high level of protection for the Sierra Nevada headwaters. For example, a recent statewide survey found that streams in forested watersheds were in better condition than streams in watersheds in any other land use (Ode 2007). Water quality of the Sacramento River and its tributaries, which drain primarily NFS lands, have generally good quality and support their beneficial uses (Domagalski and others 2000). Sediment and nutrient loads from forested watersheds in the Sierra Nevada, including large areas within national forests, were found to be substantially lower than loads from downstream agricultural areas and significantly lower than average pollutant loads nationwide (Kratzer and Shelton 1998). Ahearn and others (2005) compared water quality in the upper Consumnes River watershed, which is mostly national forest, to the more agricultural and heavily populated lower watershed, and found that “upland drainages tended to deliver dilute, clear waters to the lowlands, while lower elevation sub-watersheds produced more turbid waters with elevated levels of constituents” (p. 242). Nevertheless, resource-management and protection activities on NFS lands have the potential to result in nonpoint source pollution of the State’s waters, and continual efforts are needed to maintain and improve water quality.



Watershed condition
A total of 774 6th-field subwatersheds were assessed on the 10 Sierra Nevada National Forests in 2010 with the USFS Watershed Condition Framework. The subwatersheds ranged in size from 8,058 to 236,289 acres (including NFS and non-NFS lands), with a mean of 23,025 acres. Of these subwatersheds, 490 (63%) were classified as “functioning properly,” 280 (36%) were classified as “functioning at risk,” and 4 (0.5%) were classified as “impaired function.”

The CALFire Forest and Range Assessment Program (FRAP) report evaluated watersheds for their value in providing water, based on surface water runoff, surface water storage, groundwater basins, and forest meadows. The Pit, North Fork Feather, East Branch North Fork Feather, Middle Fork Feather, North Fork and South Fork American, San Joaquin, and King River basins were rated as the watersheds with the highest water supply assets, all with composite scores of 100 of 100 possible points.

The FRAP report also evaluated threats to water supply within watersheds, based on impervious surfaces, future development, and climate change (snowpack change). The Truckee River was the only watershed in the Sierra Nevada that scored 100 of a possible 100 points for threats. The second highest composite threat score for a Sierra Nevada NFS watershed was 89.9 for the EB NF Feather River. Lake Tahoe was ranked third, with a composite score of 84.1. Threats to water quality were assessed, and of water bodies on NFS lands within Region 5 in the Sierra Nevada, only Lake Tahoe was listed as one of the “top” threatened watersheds.



Water quality impairments
Water quality in California is regulated by the State Water Resources Control Board and 9 Regional Water Quality Control Boards. The State and Regional Boards periodically assess the quality of waters under their jurisdiction and determine which water bodies fail to meet their designated beneficial uses, and are therefore impaired. The State Board prepared 303(d) lists of impaired waters statewide in 2002, 2006, and 2010. These lists specify which pollutants are responsible for the impairment, as well as the suspected source of the pollutants. The pollutant most commonly associated with activities on National Forests is sediment. The numbers of water bodies listed as impaired due to sediment related to silviculture and livestock grazing in 2002, 2006, and 2010 are listed in Table 8 below.

Table 8: Sediment-impaired water bodies in the Sierra Nevada related to silviculture and livestock grazing
Source
2002
2006
2010
Silviculture
9
8
8
Livestock grazing
13
9
8





Two significant conclusions can be drawn from the data in Table 8. First, the number of water bodies considered to be impaired by the State’s water quality regulatory agency is a small fraction of the hundreds of water bodies on NFS lands. The vast majority of water bodies on NFS lands is unimpaired and supports beneficial uses. Second, the numbers of water bodies impaired due to silviculture treatments and grazing have decreased slightly between 2002 and 2010, indicating that overall water quality on NFS lands has improved during that period.


Hydraulic mining and mercury contamination
Kattelmann (1996) considered hydraulic mining to be one of the two largest human-caused effects on streams in the Sierra Nevada (the other was water development infrastructure). Geologic sources of mercury in the Sierra Nevada are limited to relatively small areas of metamorphic rocks formed from ancient sea-floor volcanic rocks. However, historic gold mining introduced large quantities of mercury into streams of the Northern Sierra Nevada in the nineteenth century. Miners used mercury to amalgamate and recover gold during placer (alluvial), hard rock, and hydraulic mining. The greatest amounts of mercury were used at hydraulic mines.

Alpers and Hunerlach (2000) determined a relationship between intensity of historic hydraulic mining in the Northern Sierra Nevada and mercury contamination, expressed as the mass of mercury per mass of tissues in aquatic organisms. In order of increasing mercury concentration, the major rivers of the Northern Sierra Nevada were ranked:
  1. 1. American
  2. 2. Feather
  3. 3. North and Middle Yuba
  4. 4. South Yuba and Bear

These streams are all currently listed as impaired owing to excessive mercury concentrations.

The total amount of mercury lost to the environment from mining operations in the late nineteenth century in the Sierra Nevada may have been 3 to 8 million pounds or more (Alpers and Hunerlach, 2000). Most of this mercury probably remains in the river beds of the Sierra Nevada.

Reservoir sedimentation
Erosion and sedimentation are probably the most common water quality issues related to forest management. Unfortunately, very few records of annual sediment loads are available for streams on or near NFS lands in the Sierra Nevada.

Measurements of long-term sediment accumulation in reservoirs offer an alternative means of assessing sediment loads from forest lands. Reservoirs frequently have surveyed storage capacities at the time of their construction, and subsequent bathymetric surveys to determine decreases in storage capacity resulting from deposition of sediment. Reservoir trap efficiencies vary based on reservoir shape and size and the size of the contributing drainage areas. Although trap efficiencies are generally less than 100%, they are high enough to consider reservoir sediment deposition equal to total sediment loads from contributing watersheds over the years between surveys.

The USGS has reservoir sedimentation data for 16 reservoirs in or near and downstream of NFS lands in the Sierra Nevada (Table 9). These data are based on sequential surveys made for varying periods of time that included different climatic and land use conditions. Some reservoirs are within watersheds managed entirely as National Forests, but in other cases the reservoirs are downstream of both NFS and private lands. Despite these variable conditions, the results in Table 9 are useful in providing a broad overview of sedimentation rates on forested lands in the Sierra Nevada over timescales of years to decades.

Table 9: Reservoir sedimentation in the Sierra Nevada, from the USGS RESSED data base
[Sediment yields in ac-ft/yr/mi2were converted to tons/ac/yr assuming a sediment bulk density of 1.5 tons per cubic yard]

River
Reservoir
National Forest
Drainage area, mi2
Sedimen-tation
period
Decrease in capacity,
ac-ft
Sedimen-tation rate, ac-ft/yr
Sediment
yield,
ac-ft/yr/mi2
Sediment
yield,
tons/ac/yr
Little Butte Creek (Feather River)
Magalia
PNF
8.23
1918-1946
70
2.5
0.30
1.1
N. Yuba
Bullard’s Bar
TNF
479
1919-1939
2,607
130
0.27
1.0
Onion Creek
(American River)
Onion Creek no. 7
ENF
0.80
1958-1960
0.015
0.0075
0.009
0.03
Big Canyon Creek
Big Canyon
ENF
5.48
1934-1945
4
0.36
0.07
0.26
Bear River (Amador County)
Upper Bear River
ENF
28.2
1900-1946
22
0.48
0.017
0.06
Mokelumne
Pardee
ENF/STF
384
1929-1943
817
58.4
0.15
0.57
SF Stanislaus
Lyons Lake
STF
39.7
1930-1946
64
4.0
0.10
0.38
Tuolumne River
La Grange
STF/Yose-
Mite NP
1,501
1895-1905
1,264
126
0.08
0.30
Merced
Exchequer
Yosemite NP
1,022
1926-1946
3,354
168
0.16
0.60
NF San Joaquin
Crane Valley
SNF
52.7
1901-1946
382
8.49
0.16
0.60
Teakettle Creek (Kings River)
Teakettle No. 1
SNF
0.77
1938-1948 (overtopped by 1955)
0.21
0.02
0.03
0.11
Ten Mile Creek
Hume
SNF
24.1
1909-1946
27
1.59
0.07
0.26
Kings
Pine Flat
SNF
1,542
1952-1956
1,450
362.5
0.24
0.90
Kaweah
Terminus
SQF
560
1961-1967
2,500
417
0.74
2.80
Tule
Success Lake
SQF
393
1960-1967
2,550
364
0.93
3.52
Kern
Isabella
SQF
2,074
1953-1968
5,200
347
0.17
(higher rate between 1956 and 1968)
0.64

Annual sediment yields (Table 9) ranged over two orders of magnitude, from 0.03 to 3.52 tons per acre per year. The lowest reported sediment yield was for a very small drainage area for a very short period that did not include major storms. The highest sediment yields were reported for reservoirs in the southern Sierra Nevada for relatively short periods that spanned the large storms and floods of the mid-1960s.

Although the range of sediment yields reported in Table 9 is large, all reported sediment yields are relatively low, and are well within the range for forested lands in the western United States as reported by Patric and others (1984). The mean of 0.82 tons per acre per year is higher than the average of 0.165 reported by Patric and others (1984), but lower than the range of 2 to 5 tons per acre per year suggested as acceptable for agricultural lands (Wischmeier and Smith, 1978). Patric and others (1984) suggested that a sediment yield of 0.25 tons per acre per year would be a good estimate for undisturbed forest lands. Twelve of the 16 sedimentation rates reported in Table 9 for NFS lands in the Sierra Nevada are less than this estimate, although the reservoirs are located within areas of actively managed forests.

Unfortunately, no surveys have been reported since 1968. The lack of more recent bathymetric surveys is a substantial limitation in assessing effects of current land use practices on erosion and sediment transport on forest lands in the Sierra Nevada. New information that could be obtained through standard bathymetric surveying techniques or with newer airborne LiDAR measurements would be very helpful in evaluating the success of National Forests in controlling erosion and sedimentation.

Road-related sediment delivery
Forest roads have been frequently identified, with wildfires, as one of the most significant sources of sediment related to forest management in the western United States (McCashion and Rice, 1983; Cafferata and others, 2007; MacDonald and Coe, 2010). We therefore computed rough estimates of potential road-related sediment yields for the Sierra Nevada National Forests. We assumed for this analysis that Best Management Practices to reduce hydrologic connectivity of roads were not implemented (Coe, 2006) in order to estimate a “worst case scenario.”

The basic approach taken for this analysis was to multiply road miles on NFS lands in Region 5 (from INFRA, provided by Regional Road Engineer Melissa Totheroh) by appropriate rates of road sediment production (erosion), in tons per mile. Owing to uncertainties inherent in extrapolating erosion rates determined from site-specific studies to large portions of the National Forest system, a range of erosion rates (low and high) was used to develop the estimated sediment loads. Erosion rates were taken from scientific literature where possible (Table 10), and estimated based on professional judgment otherwise. Separate estimates were computed for road surface (including cutbank and fillslope) erosion, gully erosion, and landslide erosion. Estimates of sediment production were then adjusted for sediment delivery to stream channels, using information from literature (Coe, 2006) and professional judgment. Sediment delivery was estimated assuming that no BMPs were implemented to control drainage.

Table 10: Selected annual road sediment production (erosion) rates per road mile from published sources

Reference
Road erosion (tons/mi/yr)
MacDonald and Coe, 2010
0.002 ot 42.4
Coe, 2006
0.015 to 4.45
Cafferata and others, 2007
7.42
MacDonald and others, 2004
9.54

Additionally, the following information was used in developing estimates for this analysis:

  1. 1. Road hydrologic connectivity on well-maintained forest roads is 25% (Coe, 2006), but increases by 40% to 65% in the absence of engineering practices (BMPs) to control drainage and surfacing (Coe, 2006).
  2. 2. Gully erosion constitutes about 43% of road-surface erosion (Coe, 2006).

Based on this information, and using 10% of landslide erosion rates from the North Coast Ranges, low and high erosion rates were estimated, as shown in Table 11.

Table 11: Estimated average annual sediment production (erosion) rates per mile of forest road in the Sierra Nevada
Erosion process
Low rate (tons/mi/yr)
High rate (tons/mi/yr)
Road surface
0.002
40
Gully
0
16
Landslide
7
28

Estimates of potential road-related sediment yields in the absence of BMPs were computed by multiplying road miles by road erosion rates, summing erosion for all 3 processes (road surface, gully, and landslide), and dividing the totals by the number of NFS acres (government-owned acres only) on each National Forest (Table 12). “Low” estimated sediment yields range only from 0.01 to 0.02 tons per acre per year, with a mean of 0.01 tons per acre per year. “High” estimated deliveries range from 0.07 to 0.19 tons per acre per year, with a mean of 0.12 tons per acre per year. Total estimated road-related sediment delivery for the 10 Sierra Nevada National Forests ranged from 111,000 to 1.3 million tons per year.

Table 12: Potential road-related sediment yields for Sierra Nevada National Forests in the absence of BMPs designed to reduce hydrologic connectivity, based on Coe and MacDonald (2007)
National Forest
Road miles
National Forest acres
Low Road Sediment Yield, in tons/ac/yr
High Road Sediment Yield, in tons/ac/yr
Eldorado
2,067
683,953
0.02
0.19
Inyo
1,818
1,840,894
0.01
0.06
Lassen
2,340
1,070,344
0.01
0.14
Modoc
3,599
1,663,401
0.01
0.14
Plumas
3,145
1,176,005
0.01
0.17
Sequioa
1,402
1,144,235
0.01
0.08
Sierra
1,969
1,311,913
0.01
0.09
Stansilaus
2,271
898,121
0.01
0.16
Tahoe
2,383
871,495
0.01
0.17
Lake Tahoe Basin
174
154,000
0.01
0.07
Totals
21,169
10,814,361



The proportion of the delivered sediment that could be prevented from reaching streams through implementation of BMPs is roughly 60% (Weaver and others, 1995; Coe, 2006), and BMP effectiveness for NFS roads has been 85% in recent years (USDA Forest Service, 2009). Actual road-related sediment delivery on NFS lands can therefore be estimated by multiplying the sediment yields listed in Table 12 by 60% (0.60) and then dividing by 85% (0.85). On this basis, road-related sediment yields on NFS lands in the Sierra Nevada are estimated to range from 0.007 to 0.13 tons/ac/yr.

This range of estimated road-related sediment yields overlaps the low end of the range of reservoir sediment yields presented in Table 9. This comparison indicates that roads are likely to be substantial sources of sediment in some actively-managed forested watersheds with overall low sediment yields. However, this comparison also shows that road-related sediment cannot account for a majority of sediment from high-yield watersheds. Other sources of sediment therefore also need to be considered in planning effective programs to control sedimentation.

Contribution of water use and enjoyment of water to social and economic sustainability.
  1. A. Identification of users and any special/sensitive populations
  2. B. Locations where uses occur
INFRA—designated swimming areas, developed recreation sites
California Resources Agency 2009 State Water Plan:
http://www.waterplan.water.ca.gov/cwpu2009/index.cfm
  1. C. Current use levels and recent trends—check with Forest Rec Staff.
  2. D. Projected future trends in use given the possible influences of relevant drivers and stressors

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MacDonald, L., and Coe, D.B.R., 2004, Road sediment production and delivery: Processes and management (web page)

MacDonald, L.H., and Coe, D.B.R., 2010, Road sediment production and delivery: processes and management: available via internet at CalFIRE site.

MacDonald, L. H., Coe, D.B.R., and Litschert, S.E., 2004, Assessing cumulative watershed effects in the Central Sierra Nevada: hillslope measurements and catchment-scale modeling, in: Murphy, D. D. and Stine, P.A. (eds.), Proceedings of the Sierra Nevada Science Symposium; USDA Forest Service General Technical Report PSW-GTR-193, Albany, CA, 287 pp

McCashion, J.D., and Rice, R.M., 1983, Erosion on logging roads in Northwestern California: how much is avoidable? Journal of Forestry, p. 23-26.

Madrid, A., Fernald, A.G., Baker, T.T., and Vanleeuwen, D.M., 2006, Evaluation of silvicultural treatment effects on infiltration, runoff, sediment yield, and soil moisture in a mixed conifer New Mexico forest: Journal of Soil and Water Conservation 61(3):159-168.

Mayor, A.G., Bautista, S., Llovet, J., and Bellot, J., 2007, Post-fire hydrological and erosional responses of a Mediterranean landscape: Seven years of catchment-scale dynamics: Catena 71: 68-75.

Miller, J.D., Safford, H.D., Crimmins, M., and Thode, A.E., 2009, Quantitative evidence for increasing forest fire severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA: Ecosystems 12(1):16-32.

Miller, M.E., MacDonald, L.H., Robichaud, P.R., and Elliot, W.J., 2011, Predicting post-fire hillslope erosion in forest lands of the western United States: International Journal of Wildland Fire 20:982-999.

Myers, L., and Kane, J., 2011, The impact of summer cattle grazing on surface water quality in high elevation mountain meadows: Water Quality, Exposure and Health 3(1): 51-62.

Myers, L., and Whited, B., 2012, The impact of cattle grazing in high elevation Sierra Nevada mountain meadows over widely variable annual climatic conditions: Journal of Environmental Protection 3(28A): 823-837.

Neary, D. G.; Ryan, K.C.; DeBano, L.F. (eds.), 2005 (revised 2008), Wildland fire in ecosystems: effects of fire on soils and water. General Technical Report RMRS-GTR-42, Vol.4., Ogden, UT: USDA Forest Service, Rocky Mountain Research Station, 250 pp.

Nolan, K.M, and Hill, B.R., 1991, Suspended-sediment budgets for four drainage basins tributary to Lake Tahoe, California and Nevada, 1984-87: U.S. Geological Survey Water-Resources Investigations Report 91-4054, 40 pp., U.S. Geological Survey, Sacramento, CA.

Null SE, Viers JH, Mount JF (2010) Hydrologic Response and Watershed Sensitivity to Climate Warming in California's Sierra Nevada. PLoS ONE 5(4): e9932. doi:10.1371/journal.pone.0009932

Ode, P.R., 2007, Ecological condition assessment of California’s perennial wadeable streams: Report to the State Water Resources Control Board’s Non-Point Source Program: California Department of Fish and Game Aquatic, Bioassessment Laboratory, Rancho Cordova, CA.

Patric, J.H., Evans, J.O., and Helvey, J.D., 1984, Summary of sediment yield data from forested land in the United States: Journal of Forestry, Feb. 1984, p. 101-104.

Pierson, F.B., Robichaud, P.R., Moffet, C.A., Spaeth, K.E., Hardegree, S.P., Clark, P.E., and Williams, C.J., 2008, Fire effects on rangeland hydrology and erosion in a steep sagebrush-dominated landscape: Hydrological Processes 22: 2916-2929.

Ratliff, R., 1985, Meadows in the Sierra Nevada of California: state of knowledge: USDA Forest Service Pacific Southwest Forest and Range Experiment Station General Technical Report PSW-84, 52 pp.

Rector, J.R., and MacDonald, L.H., 1986, Water yield opportunities on National Forest lands in the Pacific Southwest Region: Proceedings of the California Watershed Management Conference, November 18-20, 1986, West Sacramento, CA, p. 68-73.

Reneau, S.L., Katzman, D., Kuyumjian, G.A., Lavine, A., and Malmon, D.V., 2007, Sediment delivery after a wildfire: Geology 35(2): 151-154.

Rieman, B., Lee, D., Chandler, G., and Myers, D., 1997, Does wildfire threaten extinction for salmonids? Responses of redband trout and bull trout following recent large fires on the Boise National Forest: Proceedings, Fire effects on rare and endangered species and habitats conference, November 13-16, 1995, IAWF, p. 47-57.

Robichaud, P. R., C. H. Luce and R. E. Brown. 1993. Variation among different surface conditions in timber harvest sites in the Southern Appalachians

Robichaud, P.R., MacDonald, L.H., and Foltz, R.B., 2010, Fuel management and erosion, Chapter 5 in Cumulative Watershed Effects of Fuel Management in the Western United States: USDA Forest Service RMRS-GTR-231, p. 79-99.

Safford, H.D., Schmidt, D.A., and Carlson, C.H., 2009, Effects of fuel treatments on fire severity in an area of wildland-urban interface, Angora Fire, Lake Tahoe Basin, California: Forest Ecology and Management 258:773-787.

Safford, H.D., Stevens, J.T., Merriam, K., Meyer, M.D., and Latimer, A.M., 2012, Fuel treatment effectiveness in California yellow pine and mixed conifer forests: Forest Ecology and Management 274:17-28.

Searcy, J.K. and Hardison, C.H., 1960, Double-mass curves: U.S. Geological Survey Water-Supply Paper 1541-B

Smith, H. G., Sheridan, G.J., Lane, P.N.J, Nyman, P., and Haydon, S., 2011, Wildfire effects on water quality in forest catchments: a review with implications for water supply: Journal of Hydrology, 396 (1-2): 170-192.

Spencer, C.N., Gabel, K.O., and Hauer, F.R., 2003, Wildfire effects on stream food webs and nutrient dynamics in Glacier National Park, USA: Forest Ecology and Management 178: 141-153.

Stewart, I.T., Cayan, D.R., and Dettinger, M.D., 2005, Changes toward earlier streamflow timing across the Western United States: Journal of Climate 18: 1136-1155.

Taylor, R.G., and others, 2012, Ground water and climate change: Nature Climate Change, MacMillan Publishers, 8 pp.

Trimble, S. W., and Mendel, A.C., 1995, The cow as a geomorphic agent: Geomorphology 13: 233-253.

USDA Forest Service, 2008, Land areas of the National Forest System: FS-383, 131 pp.

USDA Forest Service, Pacific Southwest Region, 2009, Water Quality Protection on National Forests in the Pacific Southwest
Region: Best Management Practices Evaluation Program, 2003-2007: Pacific Southwest Regional Office, Vallejo, CA, 28 pp.

USDA Forest Service, Pacific Southwest Region, 2011, Water Quality Management Handbook: Regional Supplement R5 FSH 2509.22-10-2011, 237 pp.

U.S. Geological Survey, 2012, Wildfire effects on source water quality--lessons from Four-Mile Canyon Fire and implications for drinking water treatment: USGS Fact Sheet 2012-3095, 4 pp.

Wischmeier, W.H. and Smith, D.D., 1978, Predicting Rainfall Erosion Losses: A Guide to Conservation Planning: Agriculture Handbook No. 537, USDA Science and Education Administration, US. Government Printing Office, Washington, DC, 58pp.

Wood, S.H., 1975, Holocene stratigraphy and chronology of mountain meadows, Sierra Nevada, California: USDA-Forest Service Earth Surface Monograph 4

APPENDICES


TABLE A1: REFERENCES FOR CLIMATE CHANGE EFFECTS ON WATER RESOURCES IN THE SIERRA NEVADA
REFERENCE
MAJOR FINDINGS
Andrews, E.D., 2012, Hydrology of the Sierra Nevada Network National Parks, Status and Trends, Natural Resource Report NPS/SIEN/NRR—2012/500, National Park Service, Fort Collins, CO, 192 pp.
A decreasing trend of the April-July/annual runoff ratio was found at half of the west slope gaging stations analyzed. In contrast, on the east slope of the Sierra Nevada, there is a generally increasing trend.
The most significant trends in streamflow magnitudewere increasing winter low flows. Further, at stations on the west slope of the Sierra, the center of mass and the snowmelt onset are occurring earlier in the year on average.
California Energy Commission, 2012, Water and energy sector vulnerability to climate warming in the Sierra Nevada: Simulating the regulated rivers of California’s west slope Sierra Nevada: CEC 500 2012 016, 71 pp.
Hydropower generation is likely to be reduced by 9 percent as a result of higher temperatures. Most reductions in hydropower generation will occur in the northern Sierra Nevada. A decrease in reservoir storage will result from warming that causes higher evapotranspiration and therefore less annual runoff.
Dettinger, M.D., Cayan, D.R., Meyer, M.K., and Jeton, A.E., 2004, Simulated hydrologic responses to climate variations and change in the Merced, Carson, and American River Basins, Sierra Nevada, California, 1900-2099:Climatic Change 62:283-317
Annual streamflow was predicted to be generally unaffected by warming temperatures, but snowmelt and peak streamflows are predicted to occur earlier in the year.
Drexler, J.Z., Knifong, D., Tuil, J., Flint, L.E., and Flint, A., 2013, Fens as whole-ecosystem gauges of groundwater recharge under climate change: Journal of Hydrology (in press).
Fens in the Sierra Nevada decreased in extent during the past several decades. These decreases were linked to changes in climate that have apparently reduced groundwater recharge.
Null SE, Viers JH, Mount JF (2010) Hydrologic Response and Watershed Sensitivity to Climate Warming in California's Sierra Nevada. PLoS ONE 5(4): e9932. doi:10.1371/journal.pone.0009932
Watersheds in the northern Sierra Nevada were found to be the most vulnerable to decreased mean annual flow, southern-central watersheds are most vulnerable to runoff timing changes, and the central portion of the range is most affected by longer periods with low flow conditions.
Stewart, I.T., Cayan, D.R., and Dettinger, M.D., 2005, Changes toward earlier streamflow timing across the Western United States: Journal of Climate 18: 1136-1155.
Spring snowmelt and streamflow peaks occur earlier in the year as a result of warming temperatures.
Taylor, R.G., and others, 2012, Ground water and climate change: Nature Climate Change, MacMillan Publishers, 8 pp.
“Aquifers in mountain valleys show shifts in the timing and magnitude of: (1) peak groundwater levels due to an earlier spring melt; and (2) low groundwater levels associated with longer and lower baseflow periods. Summer low flows in streams may be exacerbated by declining groundwater levels, so that stream flow becomes inadequate to meet domestic and agricultural water requirements and to maintain ecological functions such as in-stream habitats for fish and other aquatic species. The effects of receding alpine glaciers on groundwater systems are also not well understood, yet the long-term loss of glacial storage is estimated to reduce similarly summer baseflow.”

TABLE A2: EFFECTS OF WILDFIRES AND FUELS TREATMENTS ON EROSION, RUNOFF, AND WATER QUALITY IN THE WESTERN UNITED STATES
REFERENCE
MAJOR FINDINGS
  1. A. Wildfire effects on hillslope runoff and erosion
Benavides-Solorio, J., and MacDonald, L.H., 2001, Post-fire runoff and erosion from simulated rainfall on small plots, Colorado Front Range: Hydrological Processes 15(15):2931-2952.
This study included two wildfire sites and one prescribed fire site. Runoff increased only by 15-30%. Sediment yields from recent high-severity fires were 10 to 26 times higher than yields from unburned and low severity areas. Sediment yields from older high-severity burns about the same as unburned areas.
Carroll, E. M., Miller, W.W., Johnson, D.W., Saito, L.S., Qualls, R.G., and Walker, R.F., 2007, Spatial analysis of a high magnitude erosion event following a Sierran wildfire: Journal of Environmental Quality 36:1105-1111.
10.1 mm average erosion during a postfire storm on the 2002 Gondola Fire, South Lake Tahoe. Sediment yield of 1,800-6,700 g/m2/mm of rainfall was about 10,000 times greater than pre-fire erosion rates.
Johansen, M.P., Hakonson, T.E., and Breshears, D.D., 2001, Post-fire runoff and erosion from rainfall simulation: contrasting forests with shurblands and grasslands: Hydrological Processes 15:2953-2965.
Runoff from plots burned in a Ponderosa pine forest during the Cerro Grande Fire in New Mexico increased by a factor of 2. Sediment yield increased by a factor of 25.
Miller, M.A., MacDonald, L.H., Robichaud, P.R., and Elliot, W.J., 2011, Predicting post-fire hillslope erosion in forests lands of the western United States: International Journal of Wildland Fire 2001, 20: 982-999
Predicted median annual post-fire erosion rates were 0.1–2Mg/ha/year for most of the intermountain west, 10–40Mg/ha/year for wetter areas along the Pacific Coast, and up to 100Mg/ha/year for north-western California.
Moody, J.A., Martin, D.A., Haire, S.L., and Kinner, D.A., 2008, Linking runoff response to burn severity after a wildfire: Hydrological Processes 22: 2063-2074.
Fire effects on runoff/rainfall ratio depends on spatial distribution of burn severity, near-channel areas exert more influence than ridge areas.
Moody, J.A., and Martin, D.A., 2004, Wildfire impacts on reservoir sedimentation in the western United States: Proceedings of the Ninth International Symposium on River Sedimentation, October 18-21, 2004, Yichang, China, p. 1095-1102
Potential for postfire sediment deposition in reservoirs was found to be related more strongly to fire frequency, soil erodibility, channel slope, and rainfall intensity than to tectonic setting and underlying bedrock geology. Potential reservoir sedimentation rates were estimated to be high both for the tectonically active Coast and Transverse Ranges and the relatively stable Sierra Nevada.
Pierson, F.B., Robichaud, P.R., Moffet, C.A., Spaeth, K.E., Hardegree, S.P., Clark, P.E., and Williams, C.J., 2008, Fire effects on rangeland hydrology and erosion in a steep sagebrush-dominated landscape: Hydrological Processes 22: 2916-2929.
Burned area 3-year cumulative runoff was 298 L vs. 16 L on unburned control. Burned area 3-year cumulative sediment yield was 20,400 g/m2 vs. 6 g/m2 on unburned control.
Reneau, S.L., Katzman, D., Kuyumjian, G.A., Lavine, A., and Malmon, D.V., 2007, Sediment delivery after a wildfire: Geology 35(2): 151-154.
In the first year following the Cerro Grande Fire in New Mexico, sediment delivery to a downstream reservoir was 140 times larger than pre-fire delivery. Delivery of ash and fine-grained sediment to the reservoir peaked within a year of the fire, while transport of coarser sediment did not approach pre-fire levels until the 5th year after the fire.
  1. B. Wildfire effects on landslides and channel erosion and deposition
Benda, L., Miller, D., Bigelow, P., and Andras, D., 2003, Effects of post-wildfire erosion on channel environments, Boise River, Idaho: Forest Ecology and Management 178(2003):105-119.
Sediment eroded from burned forests in Idaho resulted in substantial changes to the morphology of major river channels. An increase in sediment supply resulting from wildfire followed by rainstorms aggraded an entire 4th order valley floor and rejuventated alluvial fans at tributary confluences.
DeGraff, J., Wagner, D., Gallegos, A., DeRose, M., Shannon, C., and Ellsworth, T., 2011, The remarkable occurrence of large rainfall-induced debris flows at two different locations on July 12, 2008, Southern Sierra Nevada, CA, USA: Landslides 8(2011):343-353.
Two very large debris flows in the southern Sierra Nevada occurred on July 12, 2008, on recently-burned watersheds. Wildfire appears to have been a factor in at least one of the debris flows.
  1. C. Wildfire effects on in-stream woody debris
Berg, N.H., Azuma, D., and Carlson, A., 2002, Effects of wildfire on in-channel woody debris in the Eastern Sierra Nevada, California: USDA Forest Service General Technical Report GTR-181, p. 49-63
Recruitment of large woody debris was higher in a burned watershed relative with an unburned control watershed within one year of a fire in the eastern Sierra Nevada. However, the burned watershed produced fewer debris jams owing to the generally smaller size of the remaining debris.
Bragg, D.C., 2000, Simulating catastrophic and individualistic large woody debris recruitment for a small riparian system: Ecology 81(5):1383-1394.
Catastrophic events such as wildfires increased the amount of large woody debris in small streams in Utah.
  1. D. Fuels treatment effects on hillslope runoff and erosion
Berg, N.H., and Azuma, D.L., 2010, Bare soil and rill formation following wildfires, fuel reduction treatments, and pine plantations in the Southern Sierra Nevada, USA: International Journal of Wildland Fire 2010: 478-489.
A plot study of wildfire and fuels treatments effect on rill and bare soil formation showed that wildfires increase both rilling and bare soil, but differences between burned and undisturbed reference plots disappear after 4 to 6 years. Rill formation on plots affected by fuels reduction treatments was minimal, and bare soil on plots within fuels treatments did not differ significantly from reference plots.
Cram, D.S., Baker, T.T., Fernald, A.G., Madrid, A., and Rummer, B., 2007, Mechanical thinning impacts on runoff, infiltration, and sediment yield following fuel reduction treatments in a southwestern dry mixed conifer forest: Journal of Soil and Water Conservation 62(5):359-366.
Heavy mechanical use on steep slopes resulted in fourfold increase in runoff and an increase in sediment yield by factor of 22.
Excerpt: “Significantly, the results of this study indicated light to moderate disturbance from mechanical operations did not significantly increase erosion over undisturbed control areas, even on steeper slopes.”
Elliot, W.J., 2010, Effects of forest biomass use on watershed processes in the Western United States: Western Journal of Applied Forestry 25(1):12-17.
Biomass removal can result in soil compaction and increased surface runoff on forested hillslopes. Implementation of appropriate Best Management Practices can mitigate these effects. Biomass removal can reduce erosion risks associated with wildfires.
Hatchett, B., Hogan, M.P., and Grismer, M.E., 2006, Mechanical mastication thins Lake Tahoe forest with few adverse impacts: California Agriculture 60(2): 77-82.
Mastication had little effect on soil compaction or erosion at an experimental site on the west shore of Lake Tahoe.
Loupe, T.M., Miller, W.W., Johnson, D.W., Sedinger, J.S., Carroll, E.M., Walker, R.F., Murphy, J.D., and Stein, C.M., 2009, Effects of mechanical harvest plus chipping and prescribed fire on Sierran runoff water quality: Journal of Environmental Quality 38(2):537-547.
Mechanical (CTL) thinning, chipping, and prescribed fire had minimal effects on nutrient concentrations in post-treatment runoff.
Madrid, A., Fernald, A.G., Baker, T.T., and Vanleeuwen, D.M., 2006, Evaluation of silvicultural treatment effects on infiltration, runoff, sediment yield, and soil moisture in a mixed conifer New Mexico forest: Journal of Soil and Water Conservation 61(3):159-168.
Partial thinning without burning in a New Mexico mixed-conifer forest did not significantly affect infiltration rates, runoff rates, or soil moisture. Sediment yield was very low in all cases.
  1. E. Fuels treatment effects on in-stream woody debris
Beche, L.A., Stephens, S.L., and Resh, V., 2005, Effects of prescribed fire on a Sierra Nevada (California, USA) stream and its riparian zone: Forest Ecology and Management 218(1-3): 37-59.
Prescribed fire had no effect on woody debris volume or recruitment.
Zelt, R.B., and Wohl, E.E., 2003, Channel and woody debris characteristics in adjacent burned and unburned watersheds a decade after wildfire, Park County, Wyoming: Geomorphology 57(3-4):217-233.
Frequency of in-channel large woody debris was lower in a burned watershed than in an adjacent unburned control, but debris jams were more common in the burned watershed.


TABLE A3: ROAD-RELATED SEDIMENT PRODUCTION IN THE SIERRA NEVADA

REFERENCE
MAJOR FINDINGS
Cafferata, P.H., Coe, D.B.R., and Harris, R.R., 2007, Water resource issues and solutions for forest roads in California: Proceedings of the American Institute of Hydrology 23(1-4):39-56.
Rock-surfaced roads produced 16 times less sediment than native surface roads. Grading resulting in doubling sediment production. Stream crossings were the most common point of sediment delivery from roads to streams. Road-related gullies produced about as much sediment as road surface erosion.
In the southern Sierra Nevada, native and mixed surface roads produced approximately three times the sediment as gravel surfaced roads. The estimated sediment delivery from roads ranged from less than 10 to as much as 50% of total watershed sediment yield.
Benda et al. (2003) produced a sediment budget for the Judd Creek watershed, a small tributary to Antelope Creek, which drains into the Sacramento River below Redding in the southern Cascade Range. No landslides were observed in this basin, where the average hillslope gradient is only 15 percent (Benda et al. 2003). Road-related erosion was estimated to produce only 3.5 percent of total estimated sediment yield, or an annual input of 9.4 Mg km-2 yr-1, while post-fire erosion (68 percent) and bank erosion/soil creep (28 percent) dominated long-term sediment production.
Coe, D.B.R., 2006, Sediment production and delivery from forest roads in the Sierra Nevada, California: MS thesis, Colorado State University, Fort Collins, CO, 117 p.
Sediment production rates from native surface roads were 12-25 times greater than from rocked roads. On average, recently-graded roads produced twice as much sediment per unit of storm erosivity as roads that had not been recently-graded. Twenty-five percent of the surveyed road length was connected to the channel network. Stream crossings accounted for 59% of the connected road segments, and gullying accounted for another 35% of the connected road segments.
MacDonald, L.H., and Coe, D.B.R., 2010, Road sediment production and delivery: processes and management: available via internet at CalFIRE site.
Unpaved roads can increase sediment production rates by more than an order of magnitude as a result of road surface erosion. Sediment delivery to streams occurs primarily at road-stream crossings and secondarily by road-induced gullies. The proportion of the road network that is connected to the stream network is primarily a function of mean annual precipitation, and is increased by about 40% in the absence of any engineered drainage structures.
Climate change can greatly increase road-induced landslides and road surface erosion by increasing the magnitude of large storm events and increasing the amount of rain relative
to snow.
Road surface erosion, the risk of road-induced landslides, and road sediment delivery can be greatly decreased by improved road designs and maintenance practices. Hence the greatest needs are to develop and provide land managers with the tools for identifying high-risk segments, and then to make the necessary improvements.
Stafford, A.K., 2011, Sediment production from hillslopes and forest roads in the southern Sierra Nevada, California: MS thesis, Colorado State University, Fort Collins, Colorado, 197 pp.
Mean hillslope sediment production in José Basin was 3.7 x 10-3 kg m-2 yr-1, which was similar to the value of 4.1 x 10-3 kg m-2 yr-1 in KREW. Native surface road segments in José Basin had a mean sediment production rate of 1.8 kg m-2 yr-1, and the estimated total sediment production from the 67 km of native surface roads is 680 metric tons per year. An estimated 30% of the native surface road length is connected to the stream network, indicating that up to 210 metric tons of sediment may be delivered to streams each year. Mean sediment production for the native surface road segments in the KREW watersheds was 0.13 kg m-2 yr-1, which was more than an order of magnitude lower than the mean value in José Basin, and road-stream connectivity was only 3%.
There was no significant difference in sediment production from native and gravel surface road segments in José Basin due to the high variability and the gravel segments still averaged 51% bare soil. The gravel surface segments had shorter drainage features than native surface segments, but 40% of the gravel roads were connected as they tended to be closer to streams. Graveled roads in the Providence Creek watersheds produced 0.16 kg m-2 yr-1, which was only 22% as much sediment as the native surface roads, and had 11% connectivity.
In José Basin grading initially decreased the mean segment length from 65 m to 41 m, but one year after grading 22% of the waterbars had failed, leading to a 15% increase in mean segment length. Graded road segments in José Basin produced eight and three times more sediment per unit area than ungraded segments in WY2008 and WY2009, respectively, and this can be attributed to extensive rilling. Sediment production rates decreased by 40-60% from the first to the second year after grading.


Table A4: Selected references on the effects of livestock grazing on water quality and channel geomorphology in the Sierra Nevada
REFERENCE
MAJOR FINDINGS
  1. A. Channel Geomorphology and Meadow Erosion
Cooke, R.U., and Reeves, R.W., 1976, Arroyos and environmental changes in the American Southwest, Oxford University Press, 213 pp.
The study area for this research includes meadows in southern and central coastal California that are similar to meadows in the southern Sierra Nevada. Its importance is primarily in showing that channel incision of alluvial valley deposits cannot be clearly linked to livestock grazing, and may be related to a combination of factors, including grazing and other land uses, climate change, and intrinsic geomorphic thresholds. This book cites most of the early “classic” geomorphology literature on the “arroyo problem” that is essentially the same as the “meadow instability problem” on Sierra Nevada National Forests.
Knapp, R.A., and Matthews, K.R., 1996, Livestock grazing, golden trout, and streams in the Golden Trout wilderness, California: impacts and management implications: North American Journal of Fisheries Management 16: 805-820.
The major conclusion of the study is that “current levels of livestock grazing are degrading the stream and riparian components of the study meadows to the detriment of golden trout populations (p. 805).” The study results show that canopy shading, stream depth, bank-full heights, and stream widths differed between stream reaches in and out of exclosures on the Kern Plateau, Inyo National Forest.
Kondolf, G.M., 1993, Lag in stream channel adjustment to livestock exclosure, White Mountains, California: Restoration Ecology 1(4): 226-230.
This study examined a stream channel on the Inyo NF where cattle had been excluded for 24 years. The study found that channel widths within and outside the exclosure were not significantly different.
Ratliff, R.D., 1985, Meadows in the Sierra Nevada of California: state of knowledge: USDA-Forest Service Pacific Southwest Forest and Range Experiment Station General Technical Report PSW-84, 52 pp.
Reviews scientific information relevant to Sierra Nevada meadows and attributes erosion to both natural processes and overgrazing.
Wood, S.H., 1975, Holocene stratigraphy and chronology of mountain meadows, Sierra Nevada, California: USDA-Forest Service Earth Surface Monograph 4, Pacific Southwest Region.
Documents the initiation of major gullies in meadows in the central and southern Sierra Nevada, showing that almost all gullies developed decades after peak livestock numbers.
  1. B. Nutrients, sediment, water temperature, and aquatic biota
Campbell, C.G., and Allen-Diaz, Barbara, 1997, Livestock grazing and riparian habitat water quality: an examination of oak woodland springs in the Sierra foothills of California: USDA Forest Service General Technical Report PSW-GTR-160, p. 339-346.
Intensity of grazing treatments was not significantly related to measured concentrations of nutrients, dissolved oxygen, water temperature, or pH.
Lewis, D.J., Singer, M.J., Dahlgren, R.A., and Tate, K.W., 2006, Nitrate and sediment fluxes from a California rangeland watershed: Journal of Environmental Quality 35:2202-2211.
This study presents results of a long-term water-quality monitoring effort on rangelands in the northern Sierra Nevada foothills. No relationships between grazing strategies or stocking rates and water quality are described.
Matthews, K.R., 1996, Diel movement and habitat use of California golden trout in the Golden Trout Wilderness, California: Transactions of the American Fisheries Society 125: 78-86.
No differences in water temperature, trout home ranges, or trout movements were observed between stream reaches within and outside of cattle exclosures.
  1. C. Wildlife
Allen-Diaz, Barbara, and Jackson, R.D., 2005, Herbaceous responses to livestock grazing in California oak woodlands: a review for habitat improvement and conservation potential: USDA Forest Service General Technical Report PSW-GTR-195, 18 pp.
This report reviews grazing impacts on wildlife habitat in oak woodlands, and concludes that grazing can improve habitat for species including burrowing owls and kit foxes.
Roche, L.M., Latimer, A.M., Eastburn, D.J., Tate, K.W., 2012, Cattle Grazing and Conservation of a Meadow-Dependent Amphibian Species in the Sierra Nevada: PLoS ONE 7(4): e35734. doi:10.1371/journal.pone.0035734
Yosemite toad breeding pool occupancy was positively related to meadow wetness, whereas cattle distribution was inversely related to wetness. Toads and cattle therefore were generally concentrated in different areas of meadows, based on hydrology. Low levels of grazing had no detectable effects on occupancy of pools by toads.
Roche, L.M., Allen-Diaz, B., Eastburn, D.J., and Tate, K.W., 2012, Cattle grazing and Yosemite toad (Bufo canorus Camp) breeding habitat in Sierra Nevada meadows: Rangeland Ecology and Management 65(1): 56-65.
Livestock exclusion was not observed to improve habitat conditions in breeding pools for Yosemite toads.
  1. D. Coliform bacteria
Derlet, R.W., Carlson, J.R., and Noponen, M.N., 2004, Coliform and pathologic bacteria in Sierra Nevada National Forest wilderness area lakes and streams: Wilderness and Environmental Medicine 15: 245-249.
Coliform bacteria in Sierra Nevada streams were found in higher concentrations in areas used for cattle grazing or human recreation.
Derlet, R.W., and Carlson, J.R., 2006, Coliform bacteria in Sierra Nevada wilderness lakes and streams: what is the impact of backpackers, pack animals, and cattle?: Wilderness and Environmental Medicine 17: 15-20.
Coliform bacteria concentrations were higher in samples of stream water obtained in areas used by cattle and pack stock compared to areas used only by backpackers.
Derlet, R.W., Ger, K.A., Richards, J.R., and Carlson, J.R., 2008, Risk factors for coliform bacteria in backcountry lakes and streams in the Sierra Nevada mountains: a 5-year study: Wilderness and Environmental Medicine 19: 82-90.
Coliform bacteria concentrations were higher in samples of stream water obtained in areas used by cattle and pack stock compared to areas used only by backpackers.
Derlet, R.W., Richards, J.R., Tanaka, L.L., Hayden, C., Ger, K.A., and Goldman, C.R., 2012, Impact of summer cattle grazing on the Sierra Nevada watershed: aquatic algae and bacteria: Journal of Environmental and Public Health, Volume 2012, 7 pp.
Periphytic algae and E. coli prevalence were compared among Sierra Nevada streams within grazed allotments, in recreational areas, and in remote areas with little or no livestock or human activities. Periphytic algae and E. coli were most prevalent in streams within grazed allotment, intermediate in streams within recreational use areas, and least prevalent in remote areas.
Myers, L., and Kane, J., 2011, The impact of summer cattle grazing on surface water quality in high elevation mountain meadows: Water Quality, Exposure and Health 3(1): 51-62.
Concentrations of total coliform, fecal colilform, and E. coli significantly increased compared to a ungrazed control stream during cattle grazing in samples collected from streams on the Stanislaus National Forest.
Myers, L., and Whited, B., 2012, The impact of cattle grazing in high elevation Sierra Nevada mountain meadows over widely variable annual climatic conditions: Journal of Environmental Protection 3(28A): 823-837.
During 3 years with varying climatic conditions, concentrations of total coliform, fecal coliform, and E. coli measured in stream samples increased significantly in comparison to ungrazed control streams during livestock grazing in the Sierra Nevada.
Rockwell, G.L., and Honeywell, P.D., 2004, Water-quality data for selected stream sites in Bridgeport Valley, Mono County, California, April 2000 to June 2003: U.S. Geological Survey Data Series 89, 35 pp.
This study of water quality includes data on fecal coliform concentrations at sites within and downstream of grazing allotments on the Humboldt-Toiyabe NF in California. Very few samples were collected at the sites farthest upstream, and these all showed very low FC concentrations with no exceedance of Regional Board objectives. FC concentrations increased at sites farther downstream, but still on NFS lands. These downstream sites were generally downstream of campgrounds as well as allotments. FC concentrations at these sites sometimes exceeded the Lahontan Regional Board objective of 20 CFU/100 mL, but did not exceed the EPA recommended level of 200 CFU/100 mL necessary for protection of the recreational contact beneficial use. FC concentrations above 200 CFU/100 mL were frequently found farther downstream, below private pastures.
Tate, K.W., Atwill, E.R., George, M.R., McDougald, N.K., and Larsen, R.E., 2000, Cryptosporidium parvum transport from cattle fecal deposits on California rangelands: Journal of Range Management 53(3):295-299.
Oocysts of Cryptosporidium parvum, a protozoan pathogen, were found to be transported from cattle feces into overland runoff for distances of up to 1 m. Transport of oocysts was related to topographic slope. The study did not determine if oocysts are transported for distances greater than 1 m.
Kromschroeder, L., 2012, Association of cattle grazing and recreation with water quality of grazing allotments in National Forests of northern California: MS thesis, UC Davis, Davis, CA, 54 pp.
Nutrient concentrations observed throughout the grazing-recreation season across the landscape were at least one order of magnitude below levels of ecological concern, and were similar to estimates for background water quality conditions in the region.
FIB concentrations peaked in August and September, coinciding with the greatest cattle/recreation activity and environmental conditions which promote microbial growth. Most samples met USEPA guidance for microbial water quality.
  1. E. Review and summary articles
Jones, Allison, 2000, Effects of cattle grazing on North American arid ecosystems: a quantitative review: Western North American Naturalist 60(2): 155-164.
A survey of studies in Western North America found that livestock grazing had adverse effects on soil erosion and infiltration, as well as other vegetative and habitat characteristics.
Trimble, S. W., and Mendel, A.C., 1995, The cow as a geomorphic agent: Geomorphology 13: 233-253.
Heavy grazing was reported to have significant effects on erosion and geomorphology, but moderate and light grazing had much less impact.

[snapshot: 4/9/2013 @0941]



Chapter 3

Bio-Region NF Composite Links
Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 - Water | Chapter 8 - Fish, Plants and Wildlife | Chapter 8 - Range | Chapter 8 - Timber | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Chapter 14 | Chapter 15

Chapter 3: Assessing System Drivers and Stressors

Table of Contents

Introduction

Changing climate, human populations, floods, and fires are all potent forces that drive or stress natural ecosystems, communities of people, and services we derive from wildlands. We call these drivers and stressors. We use drivers and stressors throughout the Bio-Regional Assessment to connect the dots. Drivers and stressors are repeating threads, and looking at them across boundaries helps describe the current condition and where we are headed on these forests.

What are Drivers and Stressors

  • Reference from 36 CFR 219.6(b):
    • o System drivers, including dominant ecological processes, disturbance regimes, and stressors, such as natural succession, wildland fire, invasive species, and climate change; and the ability of terrestrial and aquatic ecosystems on the plan area to adapt to change…”

  • How processes can be either or both a driver and stressor depending upon changes due to other processes or conditions
  • Why they come first
    • o Influence ecosystem conditions and human uses (services)

In this chapter, we should begin to talk about the changed evolutionary trajectory for Sierran forest ecosystems from a number of intersecting feedbacks. All of these drivers and stressors are interrelated. Loss of fire is the primary issue.

The discussion should be framed in the context of loss of native biodiversity, and then break out from there. Biodiversity can be thought of as a continuum of species, ranging from highly narrow niche dwellers that are rare, to common generalist species with a broad range of habitat tolerance. The more we homogenize the habitats that support each type or guild, the more the generalists will prosper.

Each stressor – coupled with the loss of keystone drivers/processes/species -- is related to the next: that is why there are feedback loops that punctuate or accelerate the losses. This needs to be the way this chapter is structured. The graphic illustration should show how anthropogenic factors have created feedbacks that accelerate a trajectory towards imbalance, or a loss of forest health, a forest out of synch with natural evolutionary processes.

SNEP Summary said:
“Activities occurring in the Sierra Nevada that pose the greatest indirect and direct threats to genetic diversity are those that break the chain of natural selection and adaptation” (p. 5-6, SNEP Summary).

This statement should form the starting point for looking at intersecting feedbacks and processes/drivers.

Chap3_BioRegion_01.jpg

Key Drivers and Stressors


Drivers

“Natural disturbance regimes; predominant climatic regimes; broad-scale disturbance regimes such as wildfire, wind, flooding, insects, and disease.

Natural vegetation succession including: human-caused changes in successional pathways that may maintain vegetation in an uncharacteristic age or size-class condition; scarcity and abundance of successional states relative to the reference period.”

Stressors

“Identify and characterize those that: directly and indirectly degrade or impair key ecosystem characteristics and ecological integrity; examples include invasive species impacts, loss of spatial connectivity, disruption of natural disturbance regimes, and influence of changing climate.

Consider: associated with irreversible conditions; not controllable through management that may affect conditions within the plan area, such as changing climate, changing land-use patterns adjacent to NFS units, water storage facilities, or hydropower facilities upstream or downstream from NFS units; stressors and threats to riparian conditions, such as changes in flow regime, hydrographic timing, water withdrawals and dewatering, channelization, invasive species, changes in sediment delivery to channel, herbivory, water temperatures or chemistry (such as heavy metals), wildfire and fuels.”

Selected for Bioregional Assessment


I. Anthropogenic Change
  • A. Climate Change
  • B. Logging
    • a. Simplification and Homogenization = Loss of Biological Diversity
      • 1. Altered fire regimes
      • 2. Altered Vegetation Composition
      • 3. Altered Vegetation Succession
      • 4. Altered Forest Structure and Composition
    • b. Roads
    • c. Invasive Species, pathogens
    • d. Pollution
  • C. Mining
  • D. Grazing
  • E. Development – Roads and Structures
  • F. Water Development (Dams, diversions)
  • G. Invasive Species
  • H. Insects/Pathogens
  • I. Pollution
II. Social Issues
  • A. Demographics
  • B. Demand services & Market influences
III. Abiotic, Natural Stressors (Since all living things have coevolved and coadapted to these natural, periodic stressors, we would not need to address them except in the context that they do interact with and amplify risks to species that are already on the threshold of extinction today)
  • A. Ambient Climate Change
  • B. Natural Fire (lightning)
  • C. Cyclic natural perturbations; stochastic events (earthquakes, landslides, flooding)


Current ConditionClimate


Terrestrial and Riparian Systems


Introduction
Climate is a fundamental process that strongly influences other drivers and stressors in the Sierra Nevada, including fire, invasive species, insects, pathogens, water development and diversion, aerial contaminants, and land use patterns. It is characterized primarily by regional temperature and precipitation (Figure 1), but also involves changes in humidity, atmospheric pressure, wind, cloudiness, and other meteorological variables. Changes in the timing and amount of one or more climatic variables directly influence many climate-related processes and patterns, such as snowpack distribution, drought, flooding, hydrologic flow, evapotranspiration, and extreme climatic events (e.g., heat waves, rain-on-snow events) (e.g., Figure 2). These climatic changes have numerous implications for the structure, function, and diversity of terrestrial and aquatic ecosystems in the Sierra Nevada.

Climate can be characterized according to both historic trends and projected future climate change. Historic temperature and precipitation trends in the Sierra Nevada are primarily based on regional climate station records from the past century. Although informative, these records are often incomplete (i.e., temporal data gaps), limited in temporal extent (most existing climate stations were established after the mid-20th century), and sparse in the upper elevations of the Sierra Nevada (relatively few stations exist >3,000 ft elevation). Consequently, historic trends have relied on the few long-term, reliable climate stations that have relatively uninterrupted climate data, with data gaps often filled using a physiographical sensitive statistical technique (e.g., Figure 1). In contrast to historic patterns, future climatic change is often projected from statistical or dynamical downscaled global climate models (GCMs). The spatial resolution of these models usually varies from 160 to 800 km per side for GCMs to 800 m to 50 km for downscaled models, although higher resolutions are available. Assumptions inherent to each alternative greenhouse gas emission scenario and GCM (based on the type of atmospheric general circulation model) influence model projections and performance. Therefore, the use of multiple GCMs or emission scenarios will often provide a more comprehensive outlook of the future effects of climate change within a region of interest.

In addition to projections in future climate, ecological response models may assess the response of species, habitats, or ecosystems to climate change. These models vary from qualitative conceptual models to quantitative niche-based (e.g., Maximum Entropy) and dynamic vegetation models (e.g., MC1; Figure 3). Model outputs may project changes in the climatic envelope of a wildlife species, distributional shifts of biomes, or changes in the amount of regional forest carbon. The variety of available ecological response models provides a suite of analysis tools to evaluate the vulnerability of key resources to climate change and climate-related stressors.

There is a consensus scientific view that “Reducing current sources of ecosystem stress (e.g., pollution, invasive species, habitat fragmentation, and extractive activities) is perhaps the most important and effective option for building ecosystem resilience” (Blate et al. 2009, p. 60).

  • Blate, G.M., Joyce, L. A., Littell, J. S., McNulty, S. G., Millar, C., Moser, S. C., Neilson, R. p., O’Halloran, K. and Peterson, D. L. 2009. Adapting to climate change in United States national forests. Unasylva 231/232 (60): 57-62.

Also see:
  • Thompson, I., Mackey, B., McNulty, S., Mosseler, A. 2009. Forest Resilience, Biodiversity, and Climate Change. A synthesis of the biodiversity/resilience/stability relationship in forest ecosystems. Secretariat of the Convention on Biological Diversity, Montreal. Technical Series no. 43, 67 pages.

Background

  • Safford et al. 2012. Chapter 3: Climate Change and the Relevance of Historic Forest Conditions in PSW-GTR-237 and Region 5 Climate Summaries for Sierra Nevada national forests (R5 Ecology Program)
  • California Climate Change Center Assessment Reports, California Energy Commission
  • Edwards and Redmond (2011) NPS Climate Assessment for the Sierra Nevada Network Parks
  • Das and Stephenson (2012) Appendix 22 in National Park Service Natural Resource Condition Assessment
  • Gonzalez (2012) NPS Climate Change Trends in the Southern Sierra Nevada
  • California Forest and Range Assessment (2010) Chapter 3.7: Climate Change

Key Indicators

Indicator
Measure
Source
Temperature (historical)
Monthly and annual average, minimum,
and maximum temperature (⁰F,⁰C)
Western Regional Climate Center (PRISM),
CA DWR California Data Exchange Center
Precipitation (historical)
Monthly and annual average precipitation,
Coefficient of variation in annual precipitation
(inches, mm)
Western Regional Climate Center (PRISM),
CA DWR California Data Exchange Center
Snowpack (historical)
Annual average Snow Water Equivalent
(SWE) (inches, mm)
NOAA National Operational Hydrologic
Remote Sensing Center, CA DWR
California Data Exchange Center
Drought (historical)
Palmer Z Index (short-term), Palmer Drought Index
(PDI; long-term), Palmer hydrological drought index
NOAA National Climatic Data
Center Palmer Indices
Projected Temperature
Annual and monthly average temperature (⁰F,⁰C)
MCI Model
Projected Precipitation
Annual and monthly average precipitation
(inches, mm)
MC1 Model
Projected
Snowpack
Annual average SWE (inches, mm)
MC1 Model

Summary of Current and Projected Future Condition

(from Safford et al. 2012)
  • Effects of climate change are already apparent in rising minimum temperatures, earlier snowpack melting, changing stream hydrology, and increased frequency of large, severe wildfires.
  • Tree mortality rates are increasing in lower and mid-elevation forests but may be decreasing for some subalpine species as well. Some animal species are changing their geographic ranges in response to climatic shifts.
  • Over the next century, average temperature is predicted to increase by 2 to 4 °F (1.1 to 2.2 °C) in the winter and 4 to 8 °F (2.2 to 4.4 °C) in the summer in the Sierra Nevada. Changes in precipitation are more difficult to model and may differ between northern and southern California. Models suggest that snowpack in the Sierra Nevada could decrease by 20 to 90 percent.
  • The annual summer drought in California may become more pronounced in its direct and indirect impacts on biota. Changing disturbance regimes (e.g., increases in fire frequency and burned area, and, in some forest types, fire severity) are likely to be the most significant influence on changes in vegetation types and distributions.
Chap3_BioRegion_02.jpg
Chap3_BioRegion_03.jpg
Differences in mean annual temperature (A), and mean annual precipitation (B) between the 1930s and 2000s, as derived by the PRISM climate model. Temperatures have risen across most of the Sierra Nevada (with some local areas of decrease), while precipitation has increased along most of the west slope. (Graphic courtesy of S. Dobrowksi, University of Montana).
Chap3_BioRegion_04.jpg
Trends in the amount of water contained in the snowpack (“snow water equivalent”) on April 1, for the period 1950–1997. Red circles indicate percentage of decrease in snow water; blue circles indicate increase in snow water. (Redrawn from Moser et al. 2009.)
Chap3_BioRegion_05.jpg
MC1 outputs for the Sierra Nevada (top graph) and Sierra Nevada Foothills (bottom graph) ecological sections, current vs. future projections of vegetation extent. These ecological sections include most of the Sierra Nevada west slope. See Safford et al. (2012) for figure details (Graphic developed using data from Lenihan et al. 2008.)

Chap3_BioRegion_06.jpg

References
  • Blate, G.M., Joyce, L. A., Littell, J. S., McNulty, S. G., Millar, C. i., Moser, S. C., Neilson, R. p., O’Halloran, K. and Peterson, D. L. 2009. Adapting to climate change in United States national forests. Unasylva 231/232 (60): 57-62.
  • Cayan, D. R., E.P. Maurer, M.D. Dettinger, M. Tyree, and K. Hayhoe. 2008. Climate change scenarios for the California region. Climate Change 87:S21-42.
  • Das, A.J., and N.L. Stephenson. 2012. Climatic Change. Appendix 22 in Sequoia and Kings Canyon National Park Natural Resources Condition Assessment. Natural Resource Report NPS/SEKI/NRR—2012/XXX. Three Rivers, CA.
  • Dettinger, M.D. 2005. From climate-change spaghetti to climate-change distributions for 21st century California. San Francisco Estuary and Watershed Science Vol. 3, Issue 1, (March 2005), Article 4. http://repositories.cdlib.org/jmie/sfews/vol3/iss1/art4
  • Dobrowski, S.Z., J.H. Thorne, J.A. Greenberg, H.D. Safford, A.R. Mynsberge, S.M. Crimmins, A.K. Swanson. 2011. Modeling plant ranges over 75 years of climate change in California, USA: temporal transferability and species traits. Ecological Monographs 81:241-257.
  • Edwards, L.M., and K.T. Redmond. 2011. Climate Assessment for the Sierra Nevada Network Parks. USDI National Park Service Natural Resource Report NPS/2011/NRR—2011/482. Fort Collins, CO.
  • Finch, D.M., ed. 2012. Climate change in grasslands, shrublands, and deserts of the interior American West: a review and needs assessment. USDA Forest Service RMRS-GTR-285. Fort Collins, CO.
  • Gonzalez, P. 2012. Climate Change Trends and Vulnerability to Biome Shifts in the Southern Sierra Nevada. USDI National Park Service Climate Change Responses Program Natural Resources Stewardship and Science Report. Washington, D.C.
  • Hayhoe, K., et al. (18 co-authors). 2004. Emissions pathways, climate change, and impacts on California. Proceedings of the National Academy of Sciences 101: 12422-12427.
  • Lawler, J.J., S.L. Shafer, S.L., D. White, P. Kareiva, E.P. Maurer, A.R. Blaustein, P.J. Bartlein. 2009. Projected climate-induced faunal change in the Western Hemisphere. Ecology 90:588–597.
  • Lenihan, J.M., R. Drapek, D. Bachelet and R.P. Neilson. 2003. Climate change effects on vegetation distribution, carbon, and fire in California. Ecological Applications 13: 1667-1681.
  • Lenihan, J.M., D. Bachelet, R.P. Neilson, and R. Drapek. 2008. Response of vegetation distribution, ecosystem productivity, and fire to climate change scenarios for California. Climate Change 87 (Suppl. 1): S215-S230.
  • Moser, S., G. Franco, S. Pittiglio, W. Chou, D. Cayan. 2009. The future is now: An update on climate change science impacts and response options for California. California Climate Change Center Report CEC-500-2008-071, May 2009. California Energy Commission, Sacramento, CA.
  • Pan, L., S. Chen, D. Cayan, M. Lin, Q. Hart, M. Zhang, Y. Liu, and J. Wang. 2010. Influences of climate change on California and Nevada regions revealed by a high-resolution dynamical downscaling study. Climate Dynamics 37:2005-2020.
  • Safford, H.D., M. North, and M.D. Meyer. 2012. Climate change and the relevance of historical forest conditions. Pages 27-41 in M. North, editor. Managing Sierra Nevada forests. General Technical Report PSW-GTR-237. USDA Forest Service Pacific Southwest Research Station, Albany, CA, USA.
  • Thompson, I., Mackey, B., McNulty, S., Mosseler, A. 2009. Forest Resilience, Biodiversity, and Climate Change. A synthesis of the biodiversity/resilience/stability relationship in forest ecosystems. Secretariat of the Convention on Biological Diversity, Montreal. Technical Series no. 43, 67 pages.


Climate – Aquatic Ecosystems


Climate change refers to the disruptive alterations of normal weather and climate patterns such that the thermal and hydrologic regimes of aquatic ecosystems function in a manner that is outside of the range of natural variability. These extreme alterations of climate are anticipated to cause disruptive changes in the composition of biological communities and the distribution of sensitive, declining and invasive species.

Background

  • Historical weather records, stream flow data, and modeling of atmospheric circulation patterns have shown clear indications that climate warming and drought in California and western North America are underway and becoming more severe (Barnett et al. 2008, Kalra et al., 2008; Meehl et al. 2009).
  • Regional climate forecasts generated for the next century suggest snow depletion will be most severe over the western and northern portions of the Sierra Nevada range and at lower elevations, but there is considerable variation across complex mountainous terrain (Knowles and Cayan 2004, Lundquist et al. 2008, Daly et al. 2009, Null et al. 2010).
  • Alterations in hydrograph pattern are thought to be important drivers of community structure in stream ecosystems, with predictable patterns setting a habitat template for population phenologies and the relative influence of abiotic and biotic forces in shaping the composition and type of species present (Poff and Ward 1989, Gasith and Resh 1999, Yarnell et al. 2010, Black et al. 2010).
  • Streams supporting high proportions of temperature- and flow-sensitive species will be most at risk of depletion of biodiversity under predicted climate change scenarios (Poff et al. 2010).
  • Extremes in variability are also a hallmark of changing climate, reducing the predictability of runoff volume and timing (Pagano and Garen 2005). This will change the budgeting of water in the state and the ecological integrity of stream ecosystems (Viers and Rheinheimer 2011).
  • The volume of snow lost, and related shift to earlier snow melt runoff and reduced late season flows have been modeled by the USGS climate laboratory using the variable infiltration capacity model (VIC; Liang et al. 1994, Wenger et al. 2010 show VIC is a useful habitat prediction tool).

‍‍‍Key Indicators‍‍‍

Indicator
Measure
Source
Predicted change in Water Availability
Percent change in April 1st Snow-water
Equivalence related to watershed characteristics
Data available for 165 reference watersheds in the
Sierra Nevada Province based on GIS analysis of
Variable Infiltration Capacity (VIC) model output
(USGS) from Dr. David Herbst, UC Sierra Nevada
Aquatic Research Laboratory and colleagues
Predicted change in Baseflow
Percent change in Cumulative Baseflow
Same as above
Predicted change in Baseflow
Percent change in Sept 30 baseflow
Same as above
Predicted change in runoff
Percent change in cumulative runoff
Same as above
Predicted change in runoff
Percent change in June 30th runoff
Same as above
Aquatic Macroinvertebrates Indicator Taxa
Thermal Tolerance values for most commonly
collected macroinvertebrate (aquatic MIS) taxa;
Other traits related to environmental tolerances of
hydrologic variation could also be developed
as indicator values.
Dr. David Herbst, SNARL, Mammoth Lakes, CA;
aquatic invertebrate taxa with associated temperature
data – these weighted-average values are preliminary
and could be refined with further analysis based on
existing data coming from SNARL data sets and the
USFS-supported climate change network

Summary of Current Conditions and Know or Anticipated


References

  • Barnett, T.P. and 11 others. 2008. Human induced changes in the hydrology of the Western United States. Science 319:1080-1083.
  • Black, B.A, J.B. Dunham, B.W., Blundon, M.F. Raggon, and D. Zima. 2010. Spatial variability in growth-increment chronologies of long-lived freshwater mussels: Implications for climate impacts and reconstructions. Ecoscience 17:240-250.
  • Daly, C., D.R. Conklin, and M.H. Unsworth. 2009. Local atmospheric decoupling in complex topography alters climate change impacts. International Journal of Climatology, doi:10.1002/joc
  • Gasith, A. and V.H. Resh. 1999. Streams in Mediterranean climate regions: abiotic influences and biotic responses to predictable seasonal events. Annual Review of Ecology and Systematics 30:51-81.
  • Kalra, A., T.C. Plechota, R. Davies, G.A. Tootle. 2008. Changes in U.S. stream flow and Western U.S. snowpack. Journal of Hydrologic Engineering 13:156-163.
  • Knowles, N. and D.R. Cayan. 2004. Elevational dependence of projected hydrologic changes iu the San Francisco estuary and watershed. Climate Change 62:319-336.
  • Liang, X., D.P. Lettenmaier, E.F. Wood, and S.J. Burges. 1994. A Simple hydrologically based model of land surface water and energy fluxes for GSMs. Journal of Geophysical Research 99:14415-14428.
  • Lundquist, J.D, N. Pepin, and C. Rochford. 2008. Automated algorithm for mapping regions of cold air pooling in complex terrain. Journal of Geophysical Research, doi:10.1029/2008JD009879
  • Meehl, G.A., C. Tibaldi, G. Walton, D. Easterling, and L. McDaniel. 2009. Relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S. Geophysical Research Letters doi:10.1029/2009GL040736
  • Null, S.E, J.H. Viers, and J.F. Mount. 2010. Hydrologic response and watershed sensitivity to climate warming in California’s Sierra Nevada. PLoS One doi:10.1371/journal.pone.0009932
  • Pagano, T., and D. Garen. 2005. A recent increase in Western U.S. streamflow variability and persistence. Journal of Hydrometeorology 6:173-179.
  • Poff, N.L., and J.V. Ward. 1989. Implications of streamflow variability and predictability for lotic community structure: a regional analysis of streamflow patterns. Canadian Journal of Fisheries and Aquatic Sciences 46:1805–1818.
  • Poff, N.L., M.I. Pyne, B.P. Bledsoe, C.C. Cuhaciyan, and D.M. Carlisle. 2010. Developing linkages between species traits and multiscaled environmental variation to explore vulnerability of stream benthic communities to climate change. Journal of the North American Benthological Society 29:1441-1458.
  • Viers, J.H. and D.E. Rheinheimer. 2011. Freshwater conservation options for a changing climate California’s Sierra Nevada. Marine and Freshwater Research 62:266-278.
  • Wenger, S.J., C.H. Luce, A.F. Hamlet, D.J. Isaak and H.M. Neville. 2010. Macroscale hydrologic modeling of ecologically relevant flow metrics. Water Resources Research 46: W09513, doi:10.1029/2009WR008839.
  • Yarnell, S.M., J.H. Viers, and J.F. Mount. 2010. Ecology and management of the spring snowmelt recession. BioScience 60:114-127.

Additional climate change/aquatic ecosystems references to consider (reviewed in TACCIMO: http://goo.gl/Lg3Bn)):
  • Barnett, T., Malone, R., Pennell, W., Stammer, D., Semtner, B., & Washington, W. 2004. The effects of climate change on water resources in the west: Introduction and overview. Climatic Change, 62, 1-11.
  • Basagic, H. J. & Fountain, A. G. (2011). Quantifying 20th century glacier change in the Sierra Nevada, California. Arctic, Antarctic, and Alpine Research, 43(3), 317-330.
  • Cayan, D., Tyree, M., Dettinger, M., Hidalgo, H., Das, T., Maurer, E., Bromirski,P.,Graham, N., & Flick, R. (2009). Climate change scenarios and sea level rise estimates for the California 2009 climate change scenarios assessment. California Energy Commission, PIER Energy-Related Environmental Research Program, CEC-500-2009-
  • Cayan, D. R., Maurer, E. P., Dettinger, M. D., Tyree, M. & Hayhoe, K. (2008). Climate change scenarios for the California region. Climatic Change, 87 (Suppl), S21-S42.
  • Christy, J. R., & Hnilo, J. J. (2010). Changes in snowfall in the southern Sierra Nevada of California since 1916. Energy & Environment, 21(3), 223-234.
  • Coats, R. (2010). Climate change in the Tahoe basin: regional trends, impacts and drivers. Climatic Change, 201, 435-466.
  • Coats, R., Costa-Cabral, M., Riverson, J., Reuter, J., Sahoo, G.,… & Wolfe, B. (2012). Projected 21st century trends in hydroclimatology of the Tahoe basin. Climatic Change, DOI 10.1007/s10584-012-0425-5.
  • Costa-Cabral, M., Roy, S. B., Maurer, E. P., Mills, W. B. & Chen, L. (2012). Snowpack and runoff response to climate change in Owens Valley and Mono Lake watersheds. Climatic Change, DOI 10.1007/s10584-012-0529-y
  • Dettinger, M. D., Cayan, D. R., Meyer, M. K., & Jeton, A. E. (2004). Simulated hydrologic responses to climate variations and change in the Merced, Carson, and American River basins, Sierra Nevada, California, 1900-2099. Climatic Change, 62, 283-317.
  • Dettinger, M. (2011). Climate change, atmospheric rivers, and floods in California - A multimodel analysis of storm frequency and magnitude changes. Journal of the American Water Resources Association, 47 (3), 514-523.
  • Dettinger, M., Hidalgo, H., Das, T., Cayan, D., & Knowles, N. (2009). Projections of potential flood regime changes in California. California Energy Commission, PIER Energy-Related Environmental Research Program, CEC-500-2009-050-F, 68pp.
  • Eheart, J. W. (1999). The effects of climate change and irrigation on criterion low streamflows used for determining total maximum daily loads. Journal of the American Water Resources Association, 35(6), 1365-1372.
  • Ficklin, D. L., Stewart, I. T. & Maurer, E. P. (2012). Projections of 21st century Sierra Nevada local hydrologic flow components using an ensemble of general circulation models. Journal of the American Water Resources Association, 48(6), 1104 – 1125.
  • Ficklin, D. L., Stewart, I. T. & Maurer, E. P. (2012). Effects of projected climate change on the hydrology in the Mono Lake Basin, California. Climatic Change, DOI 10.1007/s10584-012-0566-6
  • Hanak, E. & Lund, J. R. (2011). Adapting California’s water management to climate change. Climatic Change, 1-28. DOI 10.1007/s10584-011-0241-3
  • Hayhoe, K., Cayan, D., Field, C. B., Frumhoff, P.C., Maurer, E. P. … & Verville, J. H. (2004). Emissions pathways, climate change, and impacts on California. Proceedings of the National Academy of Sciences, 101 (34), 12422 – 12427.
  • Howat, I. M. & Tulaczyk, S. (2005). Climate sensitivity of spring snowpack in the Sierra Nevada. Journal of Geophysical Research, 110(F04021), 1 – 10.
  • Hunsaker, C. T., Whitaker, T. W. & Bales, R. C. (2012). Snowmelt runoff and water yield along elevation and temperature gradients in California’s southern Sierra Nevada. Journal of the American Water Resources Association, 48(4), 667 - 678. DOI: 10.1111/j.1752-1688.2012.00641.x
  • Jager, H. I., van Winkle, W., & Holcomb, B. D. (1999). Would hydrologic climate changes in Sierra Nevada streams influence trout persistence? Transactions of the American Fisheries Society, 128, 222-240.
  • Kim, J. (2005). A projection of the effects of the climate change induced by increased CO2 on extreme hydrologic events in the western U.S. Climatic Change, 68, 153 – 168.
  • Lutz, J. A., Van Wagtendonk, J. W., & Franklin, J. F. (2010). Climatic water deficit, tree species ranges, and climate change in Yosemite National Park. Journal of Biogeography, 37(5), 936-950.
  • Maurer, E.P. (2007). Uncertainty in hydrologic impacts of climate change in the Sierra Nevada, California, under two emissions scenarios. Climatic Change, 82, 309-325.
  • Mayer, T.D. & Naman, S.W. (2011). Streamflow response to climate as influenced by geology and elevation. Journal of the American Water Resources Association, 47(4), 724-738.
  • Meyers, E. M., Dobrowski, B., Tague, C. L. (2010). Climate Change Impacts on Flood Frequency, Intensity, and Timing May Affect Trout Species in Sagehen Creek, California. Transactions of the American Fisheries Society, 139 (6), 1657-1664.
  • Miller, N. L., Bashford, K. E., & Strem, E. (2003). Potential Impacts of Climate Change on California Hydrology. Journal of the American Water Resources Association, 1093-474x, 39(4), 771-784. doi: 10.1111/j.1752-1688.2003.tb04404.x
  • Mote, P. W., Hamlet, A. F., Clark, M. P., & Lettenmaier, D. P. (2005). Declining mountain snowpack western North America. American Meteorological Society, 86(1), 39-49.
  • Nelson, R. L. (2012). Assessing local planning to control groundwater depletion: California as a microsm of global issues. Water Resources Research, 48 (W01502), 1-14. doi:10.1029/2011WR010927
  • Null, S. E., Viers, J. H., Deas, M. L., Tanaka, S. K. & Mount, J. F. (2012). Stream temperature sensitivity to climate warming in California’s Sierra Nevada: impacts to coldwater habitat. Climatic Change, DOI 10.1007/s10584-012-0459-8
  • Pavelsky, T. M., Sobolowski, S., Kapnick, S. B. & Barnes, J. B. (2012). Changes in orographic precipitation patterns caused by a shift from snow to rain. Geophysical Research Letters, 39(L18706), 1 – 6. doi:10.1029/2012GL052741
  • Sadro, S. & Melack, J. M. (2012). The effect of an extreme rain event on the biogeochemistry and ecosystem metabolism of an oligotrophic high-elevation lake. Arctic, Antarctic, and Alpine Research, 44 (2), 222 – 234.
  • Sahoo, G. B. & Schladow, S. G. (2008). Impacts of climate change on lakes and reservoirs dynamics and restoration policies. Sustainability Science, 3, 189 – 199.
  • Sahoo, G. B., Schladow, S. G., Reuter, J. E., Coats, R., Dettinger, M., … & Costa-Cabral, M. (2012). The response of Lake Tahoe to climate change. Climatic Change, DOI 10.1007/s10584-012-0600-8.
  • Seavy, N. E., Gardali, T., Golet, G. H., Griggs, F. T., Howell, C. A., Kelsey, R., … & Weigand, J. F. (2009). Why climate change makes riparian restoration more important than ever: recommendations for practice and research. Ecological Restoration, 27(3), 330-338. doi: 10.3368/er.27.3.330
  • Shaw, M. R., Pendleton, L., Cameron, D., Morris, B., Bratman, G., Bachelet, D., Klausmeyer, K., MacKenzie, J., Conklin,D., Lenihan, J., Haunreiter, E., & Daly, C. (2009). The impact of climate change on California's ecosystem services. California Energy Commission Public Interest Energy Research (PIER) Program, CEC-500-2009-025-F.
  • Snyder, M. A., Sloan, L.C., & Bell, J. L. (2004). Modeled regional climate change in the hydrologic regions of California: A CO2 sensitivity study. Journal of the American Water Resources Association, 40 (3), 591 – 601.
  • Stewart, I. T. (2012). Connecting physical watershed characteristics to climate sensitivity for California mountain streams. Climatic Change, DOI 10.1007/s10584-012-
  • Tanaka, S. K., Zhu, T., Lund, J. R., Howitt, R. E., Jenkins, M. W., … & Ferreira, I. C. (2005). Climate warming and water management adaptation for California. Climatic Change, 76, 361 – 387. DOI: 10.1007/s10584-006-9079-5
  • Thompson, I., Mackey, B., McNulty, S., Mosseler, A. 2009. Forest resilience, biodiversity and climate change. A synthesis of biodiversity/resilience/stability relationships in forest ecosystems. Secretariat of the Convention on Biological Diversity, Montreal. Technical Series no. 43. 67 p.
  • Vicuna, S., Maurer, E. P., Joyce, B., Dracup, J. A., & Purkey, D. (2007). The sensitivity of California water resources to climate change scenarios. Journal of the American Water Resources Association, 43 (2), 482-498.
  • Vicuna, S., Leonardson, R., Hanemann, M. W., Dale, L. L. & Dracup, J. A. (2008). Climate change impacts on high elevation hydropower generation in California’s Sierra Nevada: a case study in the Upper American River. Climatic Change, 87 (Suppl 1), S123 – S137. DOI 10.1007/s10584-007-9365-x
  • Yates, D., Galbraith, H., Purkey, D., Huber-Lee, A., Sieber, J., West, J., Herrod-Julius, S., & Joyce, B. (2008). Climate warming, water storage, and Chinook salmon in California's Sacramento Valley. Climatic Change, 91, 335-350.

Current Condition – Social Change


Introduction

Note the bulk of this section will be filled in later, using information from Chapter 6. At this time, there is a brief summary from Chapter 6 included.

Summary of Current Condition

  • According to the Sierra Business Council (2007), population growth is considered to be the driving force of change throughout the Sierra Nevada. The population of the Sierra Nevada region grew by 27.6 percent between 2000 and 2010 to 3,261,939 people. This was much greater than the approximate 8 percent population growth at the state and national level. Some of this Region’s population growth is seen in the foothills, becoming part of the Sacramento metropolitan area, while there is also considerable population growth in remote, high mountain regions.
  • Internal growth has been accompanied by continued claims on the region’s resources from outside in California’s urban and agricultural areas
  • California’s population growth has been accompanied by increased land development, resulting in a loss of forests and rangelands. Low-density development poses a threat to the integrity of remaining forests and rangelands through the effects of fragmentation. The expansion of housing in the wildland-urban interface and housing development around public lands fragment natural land covers and often lead to additional development. Over 90 percent of housing units in the Sierra Nevada and Sierra Nevada Foothills regions were located in the WUI in 2000, and the WUI captured virtually all the net growth in housing units from 2000-2010.
  • A continuous influx of migrants from urban areas has been influencing the culture of many rural and traditionally resource-based communities in the Sierra Nevada. Newcomers are often less tied to natural resource production and more tied to scenic and rural qualities of the landscape, which can conflict with the views of long-time residents. Many newer residents are unfamiliar with the safety problems associated with building in certain locations. People living in high fire risk areas tend to be unduly optimistic about the degree of risk involved. California’s senior cohort is one of the fastest growing segments of the population and already the largest in the U.S. In the Sierra Nevada Region, the number of people 65 and older increased by 32.7 percent from 2000 to 2010, compared to 12.9 percent in California. The economic resources of these seniors are highly varied, and not all have the financial or physical means to prepare for home fire resilience on their own.
  • Population growth has led to increased competition for water among various uses within the Sierra Nevada, including instream flows for aquatic species, water recreation, extraction for hydropower, domestic uses, groundwater extraction, national forest sites, special use permit sites, and private inholdings.
  • Nationally, nature-based outdoor recreation between 2000 and 2009 increased in total number of participants as well as in number of activity days

Current Condition – Water Development


Driver/stressor: Aquatic habitat fragmentation

What is it? Habitat fragmentation is the loss of unity and cohesion and the splitting of habitat into isolated parts. Habitat fragmentation can result from physical, chemical or thermal barriers to species movements. The results of habitat fragmentation include isolation, loss of life history expression, reduced population genetic diversity, and increased vulnerability to disturbance and climate change.

Key Indicators

Indicator
Measure
Source
Dams
Length and distribution of habitat upstream of
impassable dams
California Passage Assessment Database (PAD);
SNDamFacilities_201024.gdb;
Cali_Dams.shp; National Hydrographic Dataset (NHD)
Diversions
Length and distribution of habitat upstream of
impassable diversions
California Passage Assessment Database (PAD);
SNDamFacilities_201024.gdb;
Cali_Dams.shp; National Hydrographic Dataset (NHD)
Diversions
Number and location of unscreened water diversions
State Water Resources Control Board database (EWRIM).
Dams & Diversions
Length and distribution of stream habitat with
altered hydrograph and/or water temperature
regimes downstream
NRIS AqS - Continuous H2O water temperature monitoring
data; FERC relicensing data – H2O temperature and
discharge data; USGS Gauge station data; California Data
Exchange Center (CDEC), National Hydrographic Dataset (NHD)
Barriers at road-stream crossings
Length and distribution of habitat upstream of
impassable road-stream crossing barriers
California Passage Assessment Database (PAD); NRIS
AqS – Passage Characterization; WCATT -




Summary of Current Condition by Indicator (or together)


Fragmentation by Water Development
Water development has and is an important part of the economy and social development in California. The Sierra Nevada provides a large proportion of the water for agriculture in the central Valley, and food from California is an important supply for the country as well as internationally. California also has a very large population of people and they depend upon water sources on national forest lands, including the Sierra Nevada. These uses have resulted in a highly developed and modified water system in the Sierra Nevada.

Chapter3_Water_07.jpg

Chapter3_Water_08.jpg

This has affected aquatic species, in particular fish and especially those that are anadromous and spend some of their life in the ocean, such as steelhead or salmon. Other fish that migrate or interbreed more locally, such as golden trout, may also be affected.

Ninety percent of historic salmon spawning and rearing habitat has been lost because of the physical barriers of dams. Anadromous eels have also been greatly restricted. Other species are affected by changes in the in-stream environment (changes in water temperature, daily and seasonal water flow fluctuations) such as insects (caddis flies), riparian plants that grow on recent floodplains (cottonwood, willows), and frogs. Biodiversity may be significantly decreased (e.g. Sanford and Hauer 1992, Victoria EPA 2004). However, dams can be operated to provide desirable temperature regimes directly downstream through selective withdrawal of water from varying reservoir depths (Stanford and Hauer 1992). Recent, large water developments have been limited and are carefully evaluated with FERC and NEPA. Notably, less closely managed are the extensive small hydro projects that started in the 1980’s that added considerably to the fragmentation of the aquatic ecosystems, particularly on smaller, headwater streams.

In riparian areas where water flow has been completely or nearly eliminated due to water development, riparian vegetation has nearly disappeared (Kattelman and Embury 1996). Ninety-three percent of studied watersheds in the bioregion have clear gaps in the riparian corridor-largely from road/railroad crossings, timber harvest, private lot clearing, livestock grazing, and dam/diversion dewatering (Kondolf et al. 1996).

Water development is administered at different levels. There are dams which are under the jurisdiction of the State of California, as depicted below in the map from the Department of Water Resources. Each of the black dots depict a dam managed by the state of California. The majority of these dams occur in the central and northern portions of the bioregion.

Ch3_Dams_In_CA_sm.jpg
Other water developments are under the jurisdiction of the Federal Energy Relicensing Commission. These projects include dams and diversions of water. These undergo periodic license review and revision, and the US Forest Service is only one party that participates in the revisions, namely for conditions that are related to mitigations.

Ch3_ExistingHydro_sm.jpg
The majority of the FERC projects are located below the boundaries or at the lower boundaries of the national forests, except for on the Plumas, Tahoe and Eldorado National Forests.

The map below of the historic and current range of Anadromous fish habitat, illustrates the impact of these water developments on continuity of water courses and species.

Ch3_AnadromousBarriers_sm.jpg

Examples of spatial patterns of fragmentation and the sources of the fragmentation were compiled in GIS by Michael Kellett, regional fish biologist. The following maps illustrate the current condition for the the Sequoia and Sierra National Forests.

Ch3_AquaticNetwork_sm.jpg

In this map, the lines represent water courses (rivers and streams). Dams are noted by black dots and waterfalls with stars. The waterfalls represent natural barriers to movement of species, such as migrating fish, and the dams are human-constructed. The changes in colors in the water courses represent where there is a break in the continuity. This example map shows that there are not many unbroken or connected water courses. This is because of extensive water development.

Fragmentation by Fire

Where populations have been constrained by habitat loss, fragmentation, and the expansion of exotic species, the probability for local extinctions linked to any disturbance has probably increased” (Rieman et al. 2003). If changes in fire patterns lead to larger, more severe disturbances than characteristic of at least the more recent evolutionary past for these species, the risks are compounded (i.e., fragmentation interacting with larger disturbances) (Dunham et al. 2003). Where these conditions coincide, the mitigation of extreme fires and their effects might benefit native fishes (Brown et al., 2001). On the other hand, research shows that higher severity fires can benefit native fishes. In a study in Montana, native bull and cutthroat trout tended to increase with higher fire severity, particularly where debris flows occurred. (Sestrich et al. 2011). Similarly, in ponderosa pine and Douglas-fir forests of Idaho at 5-10 years post-fire, levels of aquatic insects emerging from streams were two and a half times greater in high-severity fire areas compared to unburned mature/old forest, and bats were nearly 5 times more abundant in riparian areas with high-severity fire than in unburned mature/old forest. (Malison and Baxter 2010).

“Limited evidence suggests vulnerability of fish to fire is contingent upon the quality of affected habitats, the amount and distribution of habitat (habitat fragmentation), and habitat specificity of the species in question. Species with narrow habitat requirements in highly degraded and fragmented systems are likely to be most vulnerable to fire and fire-related disturbance.” (Dunham et al. 2003)

“Effective pre-fire management activities will address factors that may render fish populations more vulnerable to the effects of fire (e.g., habitat degradation, fragmentation, and nonnative species)” (Dunham et al. 2003).

“Proactive alternatives (pre-fire management) are most likely to have beneficial effects for fish, especially where habitat fragmentation and degradation have been identified as problems” (Dunham et al. 2003).

Fires can have substantial effects on streams and riparian systems and may threaten the persistence of some populations of fish, particularly those that are small and isolated (Rieman et al. 2003). Many fish populations are already depressed, small or isolated, and lack the resilience, diversity, or demographic support to rebound from disturbance (Rieman et al. 2003). According to Moyle and Williams (1990) and Moyle et al. (1996), many fish populations in the Sierra Nevada are restricted to small and often isolated remnants of a much larger and more continuous historical range.
Moyle et al. (1996) determined that only 18 (45%) of the 40 fishes native to the Sierra Nevada have stable or expanding populations. Furthermore, Moyle and Randall (1996) evaluated the biological health of 100 Sierra-Nevada watersheds and found that less than half (43%) were in good to excellent condition. Regardless of the quality of local habitats, populations that are small and isolated are vulnerable” (Rieman et al. 2003).

“The potential impact of postfire changes on small, isolated populations can be devastating” (Spina & Tormey 2000).

Remnant population networks and many of the remaining strongholds for native species are often found on public lands that now are key to the conservation of these species (Lee et al., 1997)” (Rieman et al. 2003).

“Small and isolated populations do face greater risks of extinction (Dunham et al., 1999; Rieman and Dunham, 2000; Dunham et al. 2003).”

“The influence of fire on persistence of native salmonid populations is highly variable. In some cases, local extinctions have been observed in response to fire, particularly in areas where populations of fishes have been isolated in small headwater streams” (Dunham et al. 2003).

References

  • Brown, K. D., A. A. Echelle, D. L. Propst, J. E. Brooks, andW. L. Fisher. 2001. Catastrophic wildfire and number of populations as factors influencing risk of extinction for gila trout. Western North American Naturalist 61:139–148.
  • Dunham, J. B., A. E. Rosenberger, C. H. Luce, and B. E. Rieman. 2007. Influences of wildfire and channel reorganization on spatial and temporal variation in stream temperature and the distribution of fish and amphibians. Ecosystems 10:335–346.
  • Moyle, P.B., Williams, J.E., 1990. Biodiversity loss in the temperate zone: decline of the native fish fauna of California. Conserv. Biol. 4(3), 275-284.
  • Moyle, P.B., Yoshiyama, R.M., Knapp, R.A., 1996. Status of fish and fisheries. Sierra Nevada Ecosystem Project: Final Report to Congress. Volume II. Centers for Water and Wildland Resources, University of California, Davis, pp. 953-973.
  • Moyle, P.B. and P.J. Randall. 1996. Biotic Integrity of Watersheds. Sierra Nevada Ecosystem Project: Final Report to Congress. Volume II. Centers for Water and Wildland Resources, University of California, Davis, pp. 975-983.
  • Rieman, B. E., D. Lee, G. Chandler, and D. Myers. 1997. Does wildfire threaten extinction for salmonids: responses of redband trout and bull trout following recent large fires on the Boise National Forest. Pages 47–57 in J. Greenlee, editor. Proceedings of the symposium on fire effects on threatened and endangered species and habitats. International Association of Wildland Fire, Fairfield, Washington.
  • Rieman, B.E., Dunham, J.B., 2000. Metapopulation and salmonids: a synthesis of life history patterns and empirical observations. Ecol. Freshw. Fish 9, 51-64.
  • Rieman, B. E., D. Lee, D. Burns, R. Gresswell, M. K. Young, R. Stowell, J. Rinne, and P. Howell. 2003. Status of native fishes in the western United States and issues for fire and fuels management. Forest Ecology and Management 178:197–211.
  • Spina, A.P., and Tormey, D.R., 2000. Postfire sediment deposition in geographically restricted steelhead habitat. N. Amer J. Fish. Manage. 20:562–569.


Water Development Introduction


Water development has occurred throughout the Sierra Nevada Bioregion. Water development is classified as either consumptive or non-consumptive. This section will cover water development classifications, water projects in the Sierra Nevada Bioregion, water assessments and measurement methods, and future trends.

Consumptive uses

In this section, we provide a summary of consumptive uses of water flowing on and from NFS lands in the Sierra Nevada based on information available in the 2009 update to the State Water Plan. Consumptive uses are those uses that do not return water to the water body from which the water was taken. The primary consumptive uses of water flowing from the Sierra Nevada are municipal water supplies and agricultural irrigation. [This entire section is lacking any discussion about the effects on aquatic species from water diversions and dams].

Reductions in flow are a significant stressor for aquatic species. Reductions in flow from dams and diversions are correlated with increased temperatures, increased sediment, increase in non-native plant invasions as well as increased numbers of non-native aquatic organisms. For example, “Stream-flow regimes are strong determinants of riparian vegetation structure, and hydrological alterations can drive dominance shifts to introduced species that have an adaptive suite of traits.”

  • Stromberg, J.C. et al. 2007. Altered stream-flow regimes and invasive plant species: the Tamarix case. Global Ecology and Biogeography, 16:381–393

... and slower water and higher temps are associated with lower native biodiversity and increased suitability for non-native fish and other aquatic organisms: “Although introduced species have been identified as a major cause of native fish declines, they often are as much a symptom of the decline as a cause. As a general rule, the more altered a stream or lake is by human disturbance, the more likely it is to become dominated by non-native species (Baltz and Moyle 1993)” (Moyle, Yoshiyama, and Knapp in SNEP 1996, Vol. 2, Ch. 33, pg. 964).

Surface Water

Statewide, municipal surface-water use totals about 9 million acre feet (MAF) annually. Within the Mountain Counties region (Plumas to Sequoia Counties), where most of the Sierra Nevada National Forests are located, per capita water consumption is roughly 240 gallons per day, for a total of approximately 85,000 acre-feet of municipal and domestic use of surface water annually. The remainder of the 9 MAF is used downstream, primarily in the San Francisco Bay Area, the Central Valley, and in Southern California.

Average annual statewide agricultural surface-water use is about 34 MAF. Average annual agricultural use within the Mountain Counties region is about 255,000 acre-feet. The remainder of the 34 MAF is used downstream of the Mountain Counties, primarily in the Central Valley.

Groundwater

Groundwater provides about 40% of California’s total water supplies (Fram and Belitz, 2012), but is a relatively minor source in much of the Sierra Nevada. Most of the important groundwater basins in the range are in the volcanic terrain of the Feather River Basin, according to the Mountain Counties Regional Report in the 2009 update of the State Water Plan (the Mountain Counties Region does not include Lassen County). Recharge in the Sierra Nevada helps supply Central Valley aquifers used for agriculture and municipal supplies. Groundwater provides about 5% of local water supply in the Sierra Nevada, limited to areas of fractured rock and small alluvial aquifers along streams. Most of this groundwater is used for domestic purposes. Although natural and artificial chemicals are found in Sierra Nevada groundwater, quality of groundwater in the Sierra Nevada is generally good (Fram and Belitz, 2012 a, b). Arsenic and uranium are the constituents of most concern in the Southern Sierra Nevada (Fram and Belitz, 2012b).

Federal Projects

Federal projects include those operated by the Bureau of Reclamation (BOR, a part of the U.S. Department of the Interior) for water supply and projects operated by the U.S. Army Corps of Engineers (COE) for flood protection.

BOR projects have a statewide total capacity of 11 million acre feet (MAF). A total of 7 MAF are delivered annually on average. This water provides irrigation for 3 million acres of farmland and domestic water supply for 2 million people. The largest BOR project is the Central Valley Project, with its dam and reservoir at Shasta Lake. Shasta Lake impounds the Pit River, which originates within the Sierra Nevada planning assessment area on the Modoc National Forest, as well as several major streams that originate outside of the planning area. The major BOR facilities, and the rivers affected, are listed below:
  • Shasta Reservoir, Pit River
  • Englebright Reservoir, North Fork Yuba River
  • Folsom Reservoir, American River
  • New Melones Reservoir, Stanislaus River
  • Friant Dam, Millerton Lake, San Joaquin River
  • Pine Flat Reservoir, Kings River
  • Lake Kaweah, Kaweah River
  • Success Lake, Tule River

The COE operates Lake Isabella, a reservoir on the Kern River on the Sequoia National Forest. The COE also shares responsibility for managing several BOR reservoirs that are used for flood control as well as water supply.

State Water Project

The State Water Project (SWP) includes reservoirs and conveyances in the Feather River watershed. Total capacity of the SWP is 5.8 MAF, and average annual delivery is 3 MAF, of which, 70% goes to urban uses and 30% supports agricultural uses. About 600,000 irrigated acres are supported by the SWP, and about 20 million consumers rely on domestic water from the project.

Municipal Projects

Several municipal utilities use water from the Sierra Nevada National Forests. These include local mountain and foothill communities, as well as more distant large urban populations. Several of the major municipal projects are described briefly below.

The Yuba County Water Agency (YCWA) operates 4 dams on the Yuba River with a total storage capacity of roughly 1 MAF. Annual deliveries average 310,000 acre-feet to irrigation districts. The YCWA also generates about 397 Mw of electricity annually through hydroelectric plants at its facilities.

The Placer County Water Agency (PCWA) serves 38,000 customers with water from the Yuba, Bear, and American Rivers. The PCWA has an extensive system of canals, reservoirs, storage tanks, and treatment plants. Untreated water is used for irrigation, and treated water is provided for domestic uses.

The Nevada Irrigation District (NID) uses water from the Yuba and Bear Rivers. The water is used for agriculture and domestic use. The NID storage system has a capacity of 280,380 acre-feet, and serves 25,400 customers.

The Eldorado Irrigation District (EID) diverts water from the South Fork of the American River for both agricultural and domestic uses. The EID has about 100,000 customers, and delivered 27,761 acre-feet in 2010. The EID has total tank storage of 109,000,000 gallons.

The East Bay Municipal Utility District (EBMUD) serves customers in Alameda and Contra Costa Counties in the east Bay Area near San Francisco. Almost all of the water used by EBMUD is from the Mokelumne River downstream of the Eldorado and Stanislaus National Forests. Pardee Reservoir has a capacity of 197,950 acre-feet. Camanche Reservoir has a capacity of 417,120 acre-feet. The District serves 1.3 million customers and has water rights to 997 acre-feet per day, or 364,000 acre-feet per year.

The City and County of San Francisco diverts water from the Tuolumne River at Hetch Hetchy Reservoir to serve 2.6 million customers in San Francisco and other Bay Area cities. The storage capacity of Hetch Hetchy is 359,000 acre-feet. The watershed supplying Hetch Hetchy is mostly National Park lands, but includes the Cherry Creek watershed on the Stanislaus National Forest.

The Los Angeles Department of Water and Power (LADWP) diverts water from tributaries to Mono Lake and the Owens River. The LADWP storage system includes Lake Crowley and Grant Lake. The LADWP provides water for 4 million customers in the Los Angeles metropolitan areas, as well as communities in the Owens Valley. The system delivers roughly 295,000 acre-feet per year from east-slope Sierra Nevada watersheds.

Non-consumptive Uses

Non-consumptive uses are those uses of water that return water to the water body from which it was diverted, such as hydroelectricity. Uses that do not involve diversions, such as recreation and environmental flows for fish and wildlife habitat are also considered to be non-consumptive.

The delivery of water from the Sierra Nevada to municipalities and Irrigation use often starts high in the Sierra. Snowmelt is held in high elevation reservoirs, which provide storage for water that is used throughout the year for water uses including river and reservoir boating, swimming, and fishing. As the water is transported to lower elevations, it provides a source of energy to hydropower developments. Most nongovernmental hydropower projects are licensed to operate for 30-50 years by the Federal Energy Regulatory Commission (FERC). Small projects may have obtained an exemption from licensing, but still do have a footprint on the land, and can divert a large proportion of stream flows from small drainages.

There are currently 109 FERC licensed hydropower projects in California. Seventy six of those projects are located on NFS lands. An additional 139 FERC license exempt hydropower projects exist in California, with 27 on NFS lands. Altogether, there is a built capacity of nearly ten million megawatt hours with all of these projects, 96% of which is on NFS lands. Hydropower capacity of projects on the Sierra Nevada National Forests accounts for 92% of California’s total.

When a license reaches its expiration date, the license holder must apply to FERC for a renewed license in order to continue operation of that facility. At that time, FERC’s process for relicensing must be followed. The Forest Service in California has participated in the process for 42 renewed licenses in the past 15 years. Currently, since 2001, there are 23 new licenses being implemented, and 19 projects still in process.

During the relicensing process, the FS works collaboratively with the licensee, state and federal agencies, and stakeholders to determine conditions that are necessary for the protection, mitigation, and enhancement of forest resources in connection to the continued operation of the project. In order to determine which conditions are needed, intensive studies of the project’s effects on forest resources have been carried out by the licensees. Although there are documented effects from the diversion of water for these projects, the conditions of forest resources should improve in future years as the new licenses are implemented. Measures that are included in the new licenses include instream flows, which seek to mimic a natural hydrograph in shape, timing, and to the extent possible magnitude. Special attention has been given to the life cycles of aquatic life within the river systems. Additional conditions address needs for plant and wildlife, fuels management, noxious weed management, and recreational resource needs.

Development of new projects has slowed down, as most highly productive sites have already been developed. However, there are currently nearly 30 potential projects in California which have applied for priority right to develop new hydropower facilities to be licensed, and are currently under investigation by the applicants and appropriate state and federal agencies.

Changes in precipitation type and patterns due to climate change have the potential to greatly effect hydropower production across the Sierra. As snowpack changes, the natural reservoir which it provides will be less affective in storing and metering water to downstream project reservoirs, likely causing a change in the effectiveness of the existing engineer-designed layout of hydropower projects in the Sierra. The Forest Service’s continued close connection to new licenses as they are implemented will be essential in order to ensure resource protection that has been carefully designed in the new license conditions.

Outstanding National Resource Waters

The State Water Resources Control Board (State Board) and the U.S. Environmental Protection Agency have designated only two Outstanding National Resources Waters in California, and both are within watersheds managed primarily as units of the National Forest System. The two designated waters are the California portion of Lake Tahoe and Mono Lake. This designation means that no degradation of water quality is allowed for these lakes.

Lake Tahoe is renowned for its great depth and water clarity, which, combined with its setting in the scenic east slope of the high Sierra Nevada, have made it a famous tourist attraction , as well as a source for domestic water and habitat for fish and wildlife. However, owing to recent decreases in lake clarity, the lake is listed as impaired by the State Board and USEPA, and a Total Maximum Daily Load (TMDL) is being implemented to improve the quality of the lake’s water.

Mono Lake, also on the east side of the Sierra Nevada, is a stark contrast to Lake Tahoe, being located in a closed basin on the desert floor at the foot of the Sierra escarpment. Mono Lake provides critical migratory and seabird habitat, and has been at the center of a controversy over diversion of tributary streams by LADWP. The lake is currently in the process of refilling to a level designated in a legal settlement.

Surface Drinking Water Assessment

The USDA Forest Service Forests to Faucets project uses GIS to model and map the continental United States land areas most important to surface drinking water, the role forests play in protecting these areas, and the extent to which these forests are threatened by development, insects and disease, and wildland fire.

The results of this assessment provide information that can identify areas of interest for protecting surface drinking water quality. The spatial dataset can be incorporated into broad-scale planning, such as the State Forest Action Plans, and can help identify areas for further local analysis. In addition it can be incorporated into existing decision support tools that currently lack spatial data on important areas for surface drinking water.

This project also sets the groundwork for identifying watersheds where a payment for watershed services (PWS) project may be an option for financing conservation and management on forest lands. On a macro scale, the Forests to Faucets data identifies areas that supply surface drinking water, have consumer demand for this water, and are facing significant development threats—all important criteria for successful PWS initiatives. In perhaps its most important role, this work can serve as an education tool to illustrate the link between forests and the provision of surface drinking water—a key watershed-based ecosystem service.

Ch3_ForestToFaucets_sm.jpg

A map displaying a model of surface drinking water importance across the United States. Much of the area covered by the Sierra Nevada Bioregion is modeled as having a high importance.

How Changes in Flow is Measured

State law requires water rights holders to monitor and report monthly diversions to the State Water Resources Control Board. On National Forest System lands, this is a responsibility of the USDA Forest Service (USFS). This note outlines several methods available to measure and record flows in ditches, pipes, and other conveyances. Methods range from very simple measurements that can be done with inexpensive equipment to sophisticated measurements using expensive state-of-the-art equipment. The selection of the appropriate method will depend mainly on the volume of flow to be measured and the resources available locally.

Flows are volumes of water per unit time, for example, gallons per minute or cubic feet per second. Flows are also equal to the velocity of water moving through a conveyance multiplied by the cross-sectional area of flow.

Techniques for Measuring Flow from Enclosed Pipes

Measuring pressurized flows in pipes generally requires a permanently installed in-line flow meter. Various types of meters are available (see the 2nd and 3rd web sites listed below). Such flow meters can be used with recording devices to produce continuous records of flow, or the meters can be read periodically to determine instantaneous flows that can be used to compute averages for various time periods.

If water is discharged from a full pipe, for example into a reservoir, a simple measurement technique can be used as described in the 1st web page listed below. The diameter of the pipe is measured, the area of the pipe is computed, and the ratio determined between the flow distance parallel to the pipe and the vertical fall of the flow as it exits the pipe. A simple equation is then used to compute the flow in gallons per minute.

Techniques for Measuring Flow from Open channels


This section will examine the various techniques used for measuring flow from open channels including volumetric, float, current meter, flumes and weirs, stage records, as well as rating curves and staff gages.

Volumetric measurements
The simplest and easiest measurements of open channel flows (or exit flows from pipes) are made using the volumetric approach. This method involves capturing all of the flow in a container of known volume and determining the time required to fill the container. The flow can then be easily computed as the volume of the container divided by the time required to fill it. Application of this method requires a location where the flowing water can be successfully intercepted with a container, for example, at a pipe outfall, a weir, or a small waterfall. The method is restricted to flows small enough to be contained in a bucket or other container. Accuracy of measurements depends primarily on the amount of time required to fill the container. Flow rates that fill the container rapidly will be measured less accurately than flow rates that require more time to fill the containers. As a general rule, fill times of less than 5 seconds are likely to result in poor measurements. Measurements should be repeated at least twice to compute an average. The web site provided below includes information on volumetric measurements as well as other types of measurements.

Float measurements
Float measurements are based on determining the mean flow velocity between two points at a known distance along the stream and multiplying by an average cross-section area as determined at the two end points. Float measurements can be used for low or high flows, as long as flow depths can be measured. Common problems with float measurements include floats being trapped by obstructions such as rocks or logs, and difficulty in determining when the float passes the downstream end point. These measurements are best made using a crew of 2 of more so that one person can remain at the downstream end point to determine the end time.

Chapter3_Water_02.jpg

A float measurement in progress on a suitable stream.
The general procedure for float measurements is as follows (see web site listed below for additional information):
  1. Measure a distance along the stream, roughly equivalent to 10 to 20 channel widths. Try to find a relatively uniform and straight reach without a lot of obstructions that might catch a float.
  2. Mark your upstream and downstream end points. If possible, stretch measuring tapes or taglines across the stream at both ends of the reach.
  3. Measure the width of the flow at both end points.
  4. Measure the depth of flow at roughly 5 points across the channel at both end points.
  5. Compute the cross sectional area at each end point as: Area = width x average depth.
  6. Compute the average of the two cross-sectional areas.
  7. Select a float. Anything that floats can work, but the best floats for this type of measurement are objects that float partially submerged and are less likely to be affected by wind. Often a useful float can be made from a water bottle partially full of water. You can tie some flagging to the bottle if necessary to increase visibility.
  8. Toss the float into the stream at mid-stream at least several feet upstream of your upstream end point.
  9. Time the float, beginning when it passes the upstream end point and ending when it passes the downstream end point. Do not use times if the float gets trapped in transit—instead, try again, using a smaller float, if necessary.
  10. Repeat, tossing the float close to the right bank and then the left bank.
  11. Compute the average transit time for the 3 measurements.
  12. Compute the velocity as the distance between end points divided by the average time and multiplied by a coefficient of 0.85 to convert surface velocity to average velocity.
  13. Compute the flow as the average velocity times the average area.

Current Meter Measurements
Current, or velocity, meter measurements involve using any of a variety of meters to determine the velocity of flow at a number of points across a stream cross section and determining the corresponding width and depth. The flow in each section is computed as the product of velocity, width, and depth. The flows for each section are then summed to determine the total streamflow. Measurements generally use either the mid-interval method, in which the velocity and depth at the mid-point of each section are assumed to represent the entire section, or the mean-interval method, in which the velocity and depth at each end of each section are averaged to determine the velocity and depth for the section. The two methods give equivalent results. Generally, a minimum of 20 sections is required for an accurate measurement, although a smaller number of sections may be used in narrow channels. Whenever possible, each section should include no more than 5% of the total flow, to minimize errors. See the web site below for more details.

Chapter3_Water_03.jpg


A velocity meter measurement in progress using a Marsh-McBirney meter. Note that the hydrographer is taking care not to impede flow by standing in the stream downstream of the meter.

Flumes and Weirs
Flumes and weirs are structures built or installed in channels to measure flows. Flumes are structures that confine the width of flows, while weirs are structures that impose rapid changes in channel bed elevation. Both flumes and weirs use the concept of critical flows to allow development of relatively simple exponential equations that can be used to convert the stage, or water level, at the upstream side of the flume or weir, to the discharge. Critical flow occurs when the flow velocity is equal to the speed at which a gravity wave propagates in water, which is also the square root of the acceleration of gravity multiplied by the water depth. Critical flows commonly occur at waterfalls and in other situations where flow accelerates or decelerates rapidly.

The most common type of flume used in the United States is the Parshall flume. Parshall flumes can be structures permanently installed in channels, or temporarily emplaced during measurements. Parshall flumes must be installed level, and the stage must be measured at two-thirds of the distance along the approach section. See the web site below for more detailed information.

Weirs can be of two types: broad-crested and sharp-crested. Sharp-crested weirs are weirs at which the flow falls freely and does not contact the downstream side of the weir. Sharp-crested weirs are generally most useful for smaller flows. At broad-crested weirs, the flow maintains contact with the downstream side of the weir. Broad-crested weirs can be used for larger flows. Both types of weirs use equations of the general form:

Q = a Hb wher Q is flow, H is the height of water above the bottom of the weir, and a and b are coefficients specific to the size and shape of the weir.

Chapter3_Water_04.jpg
A sharp-crested weir, from the upstream side. Note the stilling well with a stage recorder on the left of the weir.

Chapter3_Water_05.jpg
A broad-crested weir, from the downstream side. Note the stilling well on the left side of the photo.


Stage Recorders
A wide variety of data recorders can be used to continuously monitor water levels in streams, ditches, pipes, and reservoirs. Most of these recorders are manufactured to connect to pressure transducers that can be placed in the channel to measure the water level. Some types of recorders, such as the older Stevens paper chart recorders, require the use of a stilling well and counterweight. Information on most types of data recorders can be found on the internet.

Chapter3_Water_06.jpg
An electronic data recorder with a real-time satellite transmitter connected to a pressure transducer.


Rating curves and staff gages
Staff gages are simple numbered plates, or “rulers,” used to determine the water level (stage) at a stream gage relative to a datum (either sea level, or more commonly, an arbitrary datum). Measurements of stage are made at the same time as measurements of flow (discharge), and the pairs of stage-discharge measurements can be used to develop a stage-discharge rating curve. A rating curve represents the physical relations between water level and flow at a gaging location, and can be used to reliably estimate flow based on stage. This is of most importance when records of flow are determined from recorded stages. A complete discussion of stage-discharge rating curves is beyond the scope of this guidance, but more information is available at the web site below.

Projected Future Trends

As the human population of California grows, so too will demand for water, leading to greater diversion and de-watering within the Sierra Nevada riparian systems (Elmore et al. 2003). The synergistic impacts of declining water table depth, due to human demand, and increased climate variability, due to climate change, are likely to facilitate further invasion by non-native species (Elmore et al. 2003). More studies on natural range of variation in these traits will offer potential direction for management decision-making for riparian ecosystem sustainability.

Water Development Literature Cited



Current Condition – Fire

Summary

  • It is not desirable when a fire is burning toward a home. However, in much wildland of the western U.S. and the globe, fire has played a central role in shaping ecosystems. Both aspects of fire are important to understand. In this assessment, we examine different characteristics of fire which can have implications for wildland in areas we live in and use.
  • Since fires cross all administrative and ownership boundaries, it is important that there is close coordination between all of the responsible and impacted entities, not only in managing fires but also characterizing fire conditions and trends. An interagency working group has been formed to jointly address fire condition and trends. This includes: CALFire, Sierra Conservancy, US Forest Service, National Park Service, and the Bureau of Land Management. Not only does fire cross boundaries, but it is inefficient to have separate efforts and separate data sets. We are actively addressing this and have agreed upon characteristics of fire to assess, and sources of data. This will save money, time, and avoid duplication of effort.
  • Fire is an integral process in the Sierra Nevada, southern Cascades, and Modoc Plateau. It has occurred regularly for hundreds of thousands of years.
  • “It is not if fire will occur, but when and how”.
  • Most areas have missed at least four and up to 10 or more fire cycles.
  • After over 100 years of putting out fires (suppression), and vegetation and fuels have gotten denser and more continuous. Fires have become more difficult to suppress.
  • There has been a trend of increasing fire severity in the past 10 years alone. However, the total acreage burning annually is below historical levels and the amount of acreage burning at high-severity is likely well below historic levels (Stephens et al. 2007; Miller et al. 2012)
  • Recent changes in climate may be influencing fire patterns and are predicted to change in ways that would influence it more.
    • Under some scenarios, fires are predicted to increase in extent and severity. Under other scenarios (e.g., increased precipitation), fire may decrease.
    • Under some scenarios, precipitation is predicted to decrease, especially in the more mesic northern Sierra Nevada that would have a substantial effect on fire.
    • The California Department of Water Resources has noted a shift in seasonal patterns of precipitation (less late snow-April snowpack) that may be having a substantial effect on reduced fuel moisture and contributing to fires.

Introduction

When a fire is burning toward a house, it is not desirable. However, in many wildland of the western U.S. and the globe, fire has played a central role in shaping ecosystems. Both aspects of fire are important to understand. In this assessment, we examine different characteristics of fire which can have different implications for wildlands from areas we live and use. This dichotomy can make it difficult to assess fire in one section: it can be both a driver and a stressor. There are several ways we have addressed this dichotomy. First, we have focused on the impacts of fires to ecological integrity in Chapter 1, and on human uses and benefits in Chapter 7. In Chapter 7, the relationship between nature of fire and different ecosystem services is addressed, whether it is infrastructure, water, biodiversity, timber, or recreation. Whether or not ecological integrity or social and economic impacts of fire were addressed, there are some basic characteristics of fire that are commonly measured and reported. In this section we focus on these basic characteristics.

Since fires cross all administrative and ownership boundaries, it is important that there is close coordination between all of the responsible and impacted entities in not only managing fires but also characterizing fire conditions and trends. An interagency working group has been formed to jointly address fire condition and trends in an ongoing way. This includes: CALFire, Sierra Conservancy, US Forest Service, National Park Service, and the Bureau of Land Management. Not only does fire cross boundaries, but it is inefficient to have separate efforts and data sets. We are actively addressing this and have already agreed upon characteristics of fire to assess, and sources of data. This will save money, time, and avoid duplication of effort.

Fire ecologists use the concept of fire regimes to describe the unique characteristics of fires that occur in a given ecosystem. Individual fires can be described by attributes such as size, severity, type, etc. But fire as an ecosystem process is better characterized by the complex pattern of effects summed across multiple fires over long time periods. One difficulty with addressing any characteristic of fire is that there is a great deal of variation in the patterns, even within a single ecosystem, and they rarely follow a neat, “normal” distribution. In other words, the mean may be less informative than a description of the entire distribution (Sugihara et al. 1996). As humans, we tend to focus on one number to describe a component of a fire, such as mean fire return interval (average years between fire events); however, fire does not occur regularly every 10 or 20 or 100 years, as may be characterized by an average. In reality, the interval between fires can vary widely, and this variation is important, even though it is harder to characterize or think about (Sugihara et al. 2006). This variation is often referred to as the “historical range of variation (HRV)” when discussing characteristics of fires prior to Euro-American settlement. In Fire in California Ecosystems, Sugihara et al. (2006) developed a system for fire regime characteristics in terms of distributions. For example, the following figure from Sugihara et al. (2006) depicts hypothetical fire return interval distributions for three different types of fire regimes: short, medium and long. The distribution of the short return interval regime, typical of yellow pine systems, has a mode of less than ten years (i.e. most fires occur within ten years of the last one in a given location), but also shows that a range (variation) of 1 to 50 years is possible. This is critical to understand when characterizing both the influence of fire on ecosystem integrity and human uses, as well as how to plan and implement ecosystem restoration.

Ch3_FireIntroFireRegime.png
Hypothetical Fire Return Interval distributions for short, medium, and long fire regimes

Background

Much existing information is available on fire in the bio-region. Consequently, this assessment contains a concise summary of the available information, rather than a stand-alone science synthesis or analyses. The following were the primary sources for this assessment:

Summary of key sources used in assessment of current condition of fire.
Document or Website
Brief Description
Reference
Scientific literature review
Fire in California Ecosystems
Scientific text, published by UC Press, that encompasses fire regimes and effects , with summaries by major bioregions, including the Sierra Nevada, southern Cascades, Modoc Plateau and Great Basin and Mohave deserts on the Inyo.
Sugihara, N.G. et al. 2006. Fire in California Ecosystems. Univ. of California Press, Berkeley, CA.
Managing Sierra Nevada Forests
Scientific synthesis and implications on fire models and research on fuel treatment effectiveness & fire severity that can be used to plan for fuels reduction.
Collins, B.M. and S.L. Stephens. 2012. Chapter 1: Fire and Fuels Reduction. In: Managing Sierra Nevada Forests. PSW-GTR-237.
J. Forestry Publication
Review publication on incorporating fire into Forest Plan revision in the Sierra Nevada
North, Collins, and Stephens. 2012. Using Fire to Increase the Scale, Benefits, and Future Maintenance of Fuels Treatments. J. Forestry 110, 392-401
Interagency or Agency Fire Planning and Monitoring
California Forest and Range Assessment
Periodic assessment of fire and resources at risk for all lands in California. Using California specific data.
California’s Forests and Rangelands: 2010 Assessment. California Department of Forestry and Fire Protection. http://frap.fire.ca.gov/assessment2010.html
Landfire National Data and Assessment
National data library and program to facilitate national- and regional-level strategic planning.
LANDFIRE. (2007, January - last update).[Homepage of the LANDFIRE Project, U.S.
Department of Agriculture, Forest Service; U.S. Department of Interior], [Online]. Available:http://www.landfire.gov/index.php [2012, December 4, 2012].
Sierra Nevada Forest Plan Amendment (2001)
Analysis conducted for 2001 EIS document. Utilized California specific data (same as FRAP)

Fire Severity Monitoring Program
Remote sensing based (LANDSAT) annually updated monitoring of fire severity by USFS
Miller and others.

Fire as an Ecological Process
Fire as an ecological process is addressed primarily in Chapter 1 in the Ecological Integrity of Ecosystems. Much of the information is compiled and also cross-referenced here to ensure that this important topic is not overlooked.

Fire is an integral process in the Sierra Nevada, southern Cascades, and Modoc Plateau. It has occurred regularly for hundreds of thousands of years (Skinner and Chang 1996). It is characterized in terms of a “regime” that encompasses how often and regularly it occurs (frequency), how hot it burns (intensity), how much it influences living and non-living parts of the ecosystem (severity), and how it occurs across the landscape (spatial pattern) (Sugihara et al. 2006). It is a process that does not operate in a vacuum but is closely tied in both a “give” and “take” relationship with many other ecosystem processes and human uses, including vegetation, wildlife habitat, soils, hydrology, carbon cycling, insect populations, air quality and even climate. In 2006, Fire in California Ecosystems (Sugihara et al. 2006) summarized the current state of knowledge of fire regimes, both current and historic, and these interactions with other ecosystem processes and components.

According to the SNEP (1996) Fire and Fuels Summary, “Fire is a natural evolutionary force that has influenced Sierran ecosystems for millennia, influencing biodiversity, plant reproduction, vegetation development, insect outbreak and disease cycles, wildlife habitat relationships, soil functions and nutrient cycling, gene flow, selection, and ultimately, sustainability.“ SNEP goes on to report: "Timber harvest, through its effects on forest structure, local microclimate, and fuel accumulation, has increased fire severity more than any other recent human activity.”

Fire suppression that has created an ecosystem out of sync with its evolutionary history. SN forests are currently on a new evolutionary trajectory due to anthropogenic factors, the importance of which cannot be overemphasized.


Over one hundred years of fire suppression has changed the fundamental aspects of the structure and functioning of fire-adapted forests in the western United States (Webster and Halpren 2010). While the primary focus in the Sierra Nevada has been the larger, uncharacteristic fires of the recent past, little attention has been paid to the effects of the near complete absence of fire on millions of acres in the same Sierra Nevada Bio-region. There has been only scant study of the reintroduction and repeated use of fire in the restoration of forested landscapes measured as increases in biodiversity. Webster and Halpren used more than two decades of data from permanent plots in mixed conifer forests of Sequoia and Kings Canyon National Parks, California, to explore changes in plant diversity and abundance following reintroduction and repeated use of fire. Data on stand structure, fuel loading, fire severity and heterogeneity, and the richness and abundance of major growth forms were collected on 51 plots representing one of three treatments: control, first-entry burn, and second-entry burn. Understories showed distinct compositional changes over time in first- and second-entry burns. Burned plots supported more than twice as many species as controls 10 yr after treatment; first-entry plots showed a nearly threefold increase in richness by year 20. Burned plots supported four to five times as many shrub species as controls 5–10 yr after burning. Total plant cover (dominated by perennial forbs and shrubs) increased in first-entry plots, but did not differ from controls until 20 yr after treatment. Following second entry, cover did not change through final sampling (year 10). Nonnative species were rare, occurring in only three plots at low abundance. Higher severity fires led to greater numbers of species and to greater plant cover. Species richness was not correlated with burn heterogeneity. Long-term observations suggest that reintroduction of fire in previously unmanaged forests can gradually enhance the diversity and abundance of understory species. Repeated burning—necessary to achieve structural and fuel-reduction objectives—does not appear to have a detrimental effect on plant diversity and may enhance the distributions of species that are adversely affected by fire exclusion. If fire is to play an important role in restoration, however, it will need to be maintained as a frequent and spatially dynamic process on the landscape.

It is influenced by weather in the short-term and climate in the long-term (van Wagtendonk 2006, Minnich 2006). It is both influenced and influences vegetation patterns (Sugihara and Barbour 2006, van Wagtendonk and Fites-Kaufman 2006), Fites-Kaufman et al. 2006, North et al. 2009), and humans (Anderson 2006, Stephens and Sugihara 2006, Husari et al 2006, Thode et al. 2006, Ahuja et al. 2006, Klinger et al. 2006, and Sugihara et al. 2006). Fire, vegetation, and climate also influenced and are influenced by insects (Fettig 2012). Nutrient cycling, soil productivity, and carbon cycling processes are also are influenced and influence fire (Wohlgemuth et al. 2006). Planned fuel reduction or timber projects results in lower long-term erosion rates than experienced following wildfires, which are inevitable if fuel loads are not reduced (Elliot & Robichaud 2001).

Key Characteristics

There are many ways to characterize fire. Here, we have focused on key elements that are most important in both their influence on ecosystem integrity and humans, and our ability to influence them. These include: fire intensity and spread rate (how hot it burns, how fast it moves, and difficulty in management or suppression); severity or fire type (surface, mixed or moderate, crown); frequency; spatial patterns (extent and variability or “patchiness”); and overall fire regime characteristics.

Landfire (also known as Landscape Fire and Resource Management Planning Tool) is an interagency vegetation, fire, and fuel characteristics mapping program that provides a national, interagency database (Began 2004). FlamMap is a fire behavior prediction and assessment model that is widely used across the nation and in many other countries. It was produced by Dr. Mark Finney of the Missoula Fire Lab in 2006.

Summary of key sources used in assessment of current condition of fire.
Characteristic
Measures
Sources
Intensity
Potential fireline intensity (flamelength ft.), under 3 weather scenarios (moderate, high, extreme)
Fire behavior model (such as FLAMMAP)
using Landfire and California FRAP 2010 Threat Maps
Spread rate
Potential rate of spread (miles/hour), 3 weather scenarios
ibid
Fire Type
Surface, mixed (surface and passive crown), crown (active crown)
ibid
Wildland Urban Interface

California Forest and Range Assessment Program
Resistance to Control
3 weather scenarios
In development
Fuels and fuel accumulation rates

Remote sensing mapping from Landfire, FIA plots,
fire effects monitoring plots and research on fuel
accumulation rates.
Severity to vegetation & soils
Vegetation severity (Composite Burn Index [CBI] [Miller and Thode 2007; Miller et al 2009b]).
Soil severity (Parsons et al. 2010)
R5 Landscape fire effects monitoring program
USFS National Remote Sensing & Application Center
Spatial patterns
Complexity
High severity patch size
Fire Size
R5 Landscape fire effects monitoring program
Fire return interval
Fire Return Interval
Van de Water and Safford 2011
Fire deficit
Departure from expected fire extent and duration; includes estimates of severity, patch size, extent of fire
R5 Landscape fire effects monitoring program
Effects on ecological composition and structure (NOTE: this will be covered in Chapter 1 but is mentioned here)
Bird occupancy, plant species composition and abundance and/or size, soil cover
Data is highly varied in what is currently existing .
Most of the more detailed work is from research
\such as the fire surrogate research, fire effects
monitoring on federal and state lands, and opportunistic administrative studies or research on wildfires.
Existing information includes bioregional monitoring of birds, fire effects monitoring by NPS, USFS, CA State Parks, Research and administrative studies
Fire Suppression Costs
Cost per acre
See below
Fire Related Air Quality

See chapter 2 – more may be added here later
Fire and Biodiversity
Plant diversity and abundance
Webster and Halpren 2010 Sequoia-Kings Canyon National Park multiple burns effect on plant diversity and abundance.

Summary of Current Condition


Intensity

Intensity refers to how hot a fire burns (Pyne et al. 1996). It is measured in various ways but the most useful to visualize is flamelength (figure x). Flamelength is the length of a flame from the base to the tip. Firefighters use several basic categories to decide whether a fire can be suppressed or managed with handtools, heavy equipment (e.g. bulldozers), aircraft, or indirectly from a safe distance (p. 64 Pyne et al. 1966).
--Holling Chart ----Diagram of flamelength or picture

These categories in terms of flamelength (ft) are: less than 4 ft, 4-8 ft, 8-11 ft, and >11 feet.
We utilized FLAMMAP to simulate potential flamelength and fire type with the national LANDFIRE dataset. This dataset has been developed for national or regional scale applications. The assessment area overlaps with several of the LANDSAT regions, which results in some obvious differences in predicted fire behavior that are an artifact of different assumptions applied to the underlying remote sensing (LANDSAT) data used to depict fuels. These areas include the desert on the eastern portion of the Inyo National Forest, and the interface of many of the western portions of the assessment area with the California Central Valley. Additional analyses will be conducted in concert with other state (FRAP and Sierra Conservancy) and federal agencies, as well as more detailed analyses for the three southern Sierra Nevada forests (Inyo, Sierra and Sequoia) using more locally calibrated data sets. These analyses and data sets are not available at this time. The fire behavior simulations provide a reasonable depiction of overall fire patterns when compared with recent fires.

Under all but the most moderate weather and fuel moisture assumptions, flamelengths exceeding 8 feet and often 80 feet are regularly predicted. This agrees with what is often observed on fires. The greatest unknown is how often these conditions will occur in any one fire season or how many years in a decade. What is certain is that these conditions occur with regularity, at least every few years.

Modeled potential flamelength for four different fire weather and fuel moisture scenarios in the Sierra Nevada bioregion. The four weather and fuel moisture conditions are based upon those used by Scott and Burgan (2005) (see appendix x) and in general represent moderate to extreme fire weather conditions. The moderate conditions would occur during the earlier part of fire season in relatively wetter years, and the extreme fire weather is more typical later in the fire season when it is drier or windier. The more extreme conditions do not necessarily occur every year, but regularly several times every few years. The more extreme conditions may be becoming more common with recent changes in climate.

Predicted fire type, using a national remote-sensing based fuels layer (LANDSAT version 1.1.0 LANDSAT) for the bioregion. Four different weather and fuel moisture conditions were used, with assumptions from Scott and Burgan (2005).
FlameLength_Moist.jpg
FlameLength_ModDry.jpg
FlameLength_Dry.jpg
FlameLength_VeryDry.jpg
Spread Rate/Resistance to Control
In general, spread rate refers to how fast a fire moves. These data exist but are not summarized or mapped in a useable form yet.

Fire Type


How a fire spreads in a forest, whether on the ground, or up in the tops of trees or both, is described as the fire type. Three common categories used to describe fire type in forests are: surface, passive crown fire, and active crown fire, below. More rare, is independent crown fire. Independent crown fires are not thought to occur in the Sierra Nevada bioregion, and are not described here.
Surface Fire
Ch3_Fire-Surface_sm.jpg
Passive Crown Fire
Ch3_Fire-Passive_sm.jpg
Active Crown Fire
Ch3_Fire-Active_sm.jpg

The classification of fire type is very “forest-centric”. Categories apply well to forests but not necessarily to shrub, grass or herb-dominated vegetation. Fires are always classified as “surface” in these vegetation types, even though they vary in intensity and severity.

The type of fire is dependent upon several factors. One is the weather. If it is drier, and especially hotter, and windier, it is more likely to spread from the surface up into the crowns. Steepness of slope is another factor. Fire often spreads uphill, and when it does, the flames are leaning in the direction of the slope and tend to heat up or reach higher into the tree crowns up the slope. Last but not least, are the density, quantity and type of vegetation and fuels. The greater the quantity of fuels, the greater the heat produced at the surface, and the more likely that the upper crowns of trees get heated and ignite. In addition, the more continuous the branches, foliage or vegetation is from the surface up to the tops of the trees, the more likely a fire will spread up the “ladder” from the surface to the tops of the tree crowns.
The Mediterranean climate in the Sierra Nevada, and drier Great Basin portion of the bioregion has typically been characterized by dry, hot summers conducive to intense fire. Historically, frequent or moderately frequent fires swept through the landscape, keeping forests more open or patchy, with lower levels of litter on the ground. With fire suppression, especially in the relatively productive west slopes of the bioregion, substantial accumulations of live and dead vegetation have developed. This has resulted in conditions where fires are more intense, but they are also more likely to spread up into the crowns of many trees.

Predicted fire type for much of the bioregion under the dry and very dry conditions is either passive or active crown fire (figure x). There is a moderate level of uncertainty in modeling the difference between the two types of crown fire. Consequently, it is less important to distinguish the two and more important to note that either or both occur regularly every several of years.

It also means that it is not possible to readily distinguish between passive crown fires where some individual trees or small patches or clumps may burn in the crowns, from those where most or all of the trees burn in crowns under moderate or moderate dry conditions. This distinction can only be made with more site specific observations, modeling and evaluations that fire experts make at a given location.

A crown fire can be a scary thing when it is heading for a town or where people are. It may result in negative impacts to important wildlife habitat but can also result in the creation of important wildlife habitat (e.g., black-backed woodpecker habitat). Fire can and does provide within stand variation in structure that is associated with quality foraging habitat for many forest species, including the California spotted owl and the fisher. Both mechanical treatment and carefully applied higher intensity and severity fire are useful tools for forest restoration where it is denser and has a higher proportion of shade tolerant species than desired.

Resistance to Control

The term “resistance to control” refers to the relative difficulty of constructing and holding a fire control line. Resistance to control is affected by steepness of terrain, fuel loading, accessibility to the area, the type of fireline being constructed (i.e. hand or bulldozer) and all aspects of fire behavior (rate of spread, intensity, and fire type). Fires are more difficult to control in steeper terrain, with higher fuel loading and poor access. The effect of fire behavior depends on the fuel type. Grass fires typically move very fast, with a high rate of spread, but are generally easier to control than forest fires. Fires in forest or chaparral that have higher intensity are more difficult to control. Because there are so many factors involved, it is more difficult to map and assess. It has not been determined if a separate analysis on resistance to control will be conducted or if the analysis will be limited to the fuels and fire behavior factors.

Fuels and fuel accumulation rates

Landscape patterns of fuels and vegetation are available from a national program, LANDFIRE.
http://www.landfire.gov/
LANDFIRE (also known as Landscape Fire and Resource Management Planning Tools) is an interagency vegetation, fire, and fuel characteristics mapping program, sponsored by the United States Department of the Interior (DOI) and the United States Department of Agriculture, Forest Service. LANDFIRE produces a comprehensive, consistent, scientifically credible suite of spatial data layers for the entire United States. The program is a longrange initiative to periodically update data to sustain the value of the original project investment, and to ensure the timeliness, quality, and improvement of data products into the future.

Fuel accumulation rates, in particular surface fuels, are more difficult to obtain. However, there are several sources of information in the bioregion that are comprehensive and long-term. One source is monitoring from permanent plots installed on National Park Service, US Forest Service and California State Park lands (refer to website….xxx). There is also some more limited research (van Wagtendonk and Sydoriak 1987, van Wagtendonk and Moore2010, Vaillant et al. 2013).


  • van Wagtendonk, J. W., & Moore, P. E. (2010). Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA.Forest Ecology and Management, 259(10), 2122-2132.
  • van Wagtendonk, J. W., & Sydoriak, C. A. (1987, April). Fuel accumulation rates after prescribed fires in Yosemite National Park. In Ninth Conf. on fire and forest meteorology, Am. Meteor. Soc., San Diego, CA (pp. 101-105).

Wildland Urban Interface

Wildland Urban Interface, or WUI, is where homes or buildings for businesses, infrastructure for power, recreation or communication and transportation, is adjacent to or intermixed with wildland vegetation. This is important to consider for several reasons. First, people do not want their homes or businesses to be impacted by high severity wildfire. Second, since humans cause a high proportion of fires, particularly at low elevations, the proximity is important for fire suppression and fuel treatment planning. Finally, it affects planning for fuel treatments and costs of suppression. When communities are at risk, different fire suppression strategies are used and these are usually more costly. For fuel treatment strategies, more care needs to be taken with intensive mechanical treatment, which some people are uncomfortable with, or prescribed fire, which is more difficult operationally and limits the size of fires that can be applied.

The combination of accumulated vegetation and fuels in the wildlands and increased population in communities adjacent and intermixed with them throughout the western US is recognized by many to be a contribution to increasing threats to communities as well as increased fire management costs throughout the western US (California Forest and Range Assessment 2010, Toman and others 2012, Cohesive Strategy 2013, Ecological Restoration Intstitute 2013). A large portion of the bioregion has WUI throughout, or at the edges, particularly long the western boundary and along major transportation corridors (i.e. highways 80, 50, 49, 70, 395). The map below depicts the general location of WUI within the bioregion and is based upon information from the California Forest and Range Assessment Program (2010).

Ch3_FRAP_WUI_sm.jpg

There are several key findings in recent major reports including the interagency National Cohesive Wildland Fire Management Strategy (2013), a special report on The Efficacy of Hazardous Fuel Treatments (2013), and a literature review on Social Science at the Wildland-Urban Interface (2013). One is that an all lands approach is necessary to effectively address fire in the WUI, to plan for fire resilient wildlands and fire-adapted communities. Second, communities and agencies at all levels need to work together to accomplish any plans. Goals and performance measures established in the National Cohesive Fire Plan include:
  1. Restore and maintain fire resilient landscapes;
  2. Achieve fire-adapted communities; and
  3. Coordinate safe, effective, and efficient risk-based wildfire management responses.

For the WUI, specifically: reduce risk of wildfire impacts to communities; jurisdictions assess level of risk and establish roles and responsibilities for mitigating both the threat and consequences of wildfire; and effectiveness of mitigation activities are monitoring, collected and shared.

A review of available information on the current status of community wildfire protection plans, adjacent wildland fire plans, and recent and on-going treatments to restore fire resilient wildlands and fire-adapted communities showed that there is no comprehensive source of information. Each agency has their own data system and format to track projects. This includes separate databases housed by individual federal and state agencies, as well as counties, communities and fire safe councils. The individual data systems emphasize the location and type of restoration or hazard reduction treatments, and not the pre- or post-treatment fuel conditions necessary to assess potential fire behavior (intensity, speed, and severity). The major state and federal agencies are starting to coordinate sharing data through the California Biodiversity Council, but it is unclear how long it will take to implement coordinated data in the WUI. There are individual coordinated efforts, such as all lands, project level mapping by the Plumas County Fire Safe Council, but there is not a comprehensive, consistent effort.

One broad-scale approach that the Cohesive Fire Strategy provided initial examples and analysis of was a probabilistic assessment of wildfire risk (Cohesive Strategy, p. 16 2013). In this national risk assessment, the Sierra Nevada mountain range was identified as one of the highest risk areas in the country (Cohesive Strategy, p. 17, 2013). In the bioregion, increased fire resilience of wildlands will support increased resilience of communities.

Assessing the condition and trends in potential fire and fire effects in the WUI is not simple. Within the and directly adjacent to homes and other WUI infrastructure, the potential fire behavior, such as intensity and speed of fire (rate of spread) in relation to the ability of fire crews to put out fires is important. Also important and more complex to characterize is the potential fire behavior in the adjacent wildlands where fires develop intensity or “heat” and can spread into the WUI. How far out this zone occurs and how it is best characterized is subject to different interpretations depending upon the nature of the vegetation, landscape topography and preference of wildland management approaches.

Some research based on modeling showed that reducing fuels in forest stands near residential structures was effective in reducing potential damage to structures but would result in higher ecological impacts (i.e. loss of large wildlife trees) (Ager et al. 2010). When fuel treatments were located several miles away from the structures in the wildlands, there were also substantial reductions in fire probability and fire intensity (flamelength) around structures as well as decreased impacts to large wildlife trees.

Within the WUI, conditions reflecting effectiveness of fire suppression by firefighters was jointly characterized by an interagency group, including the US Forest Service, CALfire, US Department of Interior (Bureau of Land Management) and others. This is depicted in the table below for forested and chaparral types. For grassland and sagebrush fuel types, the speed of fire, or rate of spread, is also important and is in the process of being classified.

The fire resilience rating varies with both potential flamelength, which is a function of the amount of fuel to burn (or density and quantity of live and dead vegetation), and the steepness of the slope. Fire intensity or heat output is magnified on steeper slopes, since it burns uphill at a faster rate, and the flames tend to lean over and be closer to the surface.

Table x. Fire resilience ratings for the WUI for forest and chaparral landscapes. (Grassland and sagebrush are in progress and incorporate rate of spread)

Fire Resilience Rating

Topography (% slope)
Flamelength (feet)
<30%
>30%
<4’ (suppressed by firefighters)
Very resilient
4-8’ (need equipment to suppress)
Resilient
Moderately resilient
8-12’
Moderately resilient
Low resilience
12-20’
Low resilience
Very low resilience
>20’
Very low resilience

Initial attempts to display the WUI fire resilience conditions were deemed inadequate at the bioregional scale because of the lack of complete information on fuel conditions in the WUI. There are numerous different organizations, agencies and communities that assess and treat fuel conditions in the WUI. An integrated approach, such as piloted by the Plumas County Fire Safe Council, to spatially track conditions and projects in the WUI is required before an accurate assessment of conditions in the WUI can be conducted. The Plumas Fire Safe Council compiled a geographic database of project boundaries in the WUI including those completed by the Plumas County Fire Safe Council, the US Forest Service, the US Natural Resource Conservation Service (which funds grants to reduce fuels in private lands in the WUI), US Bureau of Land Management, and private timber companies. The compilation of project boundaries is one step in the right direction to permit an assessment of fire conditions and trends in the WUI. The next steps would be to include individual treatment unit boundaries and the fuel conditions before and after treatment.

The second aspect or scale of potential fire behavior in the WUI is based upon the potential fire behavior in the landscape that surrounds the WUI. Fires that start in or directly adjacent to the WUI, behave in a manner that reflects those fuel conditions in that immediate area. If the fuels are sparse, then fire intensity is limited and fire spread is limited. If the fuels are heavy and continuous, then fire intensity is greater and spread is greater. Many fires start farther out in wildlands, initially away from WUI’s but then spread towards them, such as the Chips fire last year(2012) on the Plumas and Lassen National Forests. This fire started in the Feather River Canyon, in a sparsely populated area and spread initially through steep, unroaded areas on the Plumas National Forest. After a number of days, it progressed toward the communities around Lake Almanor. The fuel conditions and topography of the surrounding wildland areas can influence how fast a fire spreads toward a WUI, how difficult it is to suppress or manage, and how many embers it generates that can travel ahead of the main body of the fire and ignite fuels or structures in the WUI. The wildland fire resilience layer described above, provides some assessment of this where it was based on fire behavior but less so, where it was based on departure in fire return interval. The assessment of this wildland zone adjacent to the WUI will be addressed in more detail in the forest-scale assessments.

References

  • Canton-Thompson, J., Gebert, K. M., Thompson, B., Jones, G., Calkin, D., & Donovan, G. (2008). External human factors in incident management team decisionmaking and their effect on large fire suppression expenditures. Journal of Forestry, 106(8), 416-424.
  • Calkin, D. E., Gebert, K. M., Jones, J. G., & Neilson, R. P. (2005). Forest Service large fire area burned and suppression expenditure trends, 1970-2002. Journal of Forestry, 103(4), 179-183.

“Fire Threat”

The California Forest and Range Assessment Program developed an integrated “fire threat” map that includes fire frequency and potential fire behavior (flamelength and firetype), figure below. There are many ways to integrate aspects of fire into one that represents where fire that is most likely to be difficult to control and have more severe effects.

In recent decades, there have been several areas that have experienced numerous fires, often large and with considerable crown or high severity fire. This includes the northern subregion (Plumas north) and the eastern subregion. Other areas with repeated or particularly large, high severity fires have included the westside of the Stanislaus and the Sequoia National Forests. In other areas, the term “threat” is difficult to apply to the high probability of fire. One major exception is the eastern half of the Sequoia National Forest, where the bulk of the fires occur at higher elevations in drier ecosystems where “managed fires” have resulted in numerous fires with effects that fall within the natural range of variability (need to cite Ewell and Reiner, and Fites et al. ).
Ch3_FM_CrownMoist_sm.jpg
Ch3_FM_CrownModDry_sm.jpg
Ch3_FM_CrownDry_sm.jpg
Ch3_FM_CrownVeryDry_sm.jpg

Severity

Fire severity was summarized from the USFS Region 5 Fire Monitoring Program (Miller and Safford 2008). It is updated annually, but information from 2012 fires has not been fully processed, and includes data from 1984, when the earliest fires were assessed for severity to 2011. There are different ways to measure severity. For this assessment, the overall “CBI” index, which incorporates changes to LANDSAT remote sensing data was utilized. While some information on soil and water conditions may be reflected, vegetation is the primary ecosystem component assessed.

Chap3_Fire_04.jpg
Low severity effects to vegetation
Chap3_Fire_05.jpg
Very high severity fire effects to vegetation
Half to 2/3 of the areas burned since 1984 have been classified as moderate to high severity. Individual fires may have predominately high severity or low severity (examples from sequoia kern plateau). The montane zone, comprised of ponderosa (or Jeffrey) pine and mixed conifer forests, have the highest overall severity levels in all bioregions. Mostly, it exceeds 60% of the areas burned. This may be an underestimate, since the maps are made one year following the fires and it may take several years for larger trees to die following a fire, depending upon the weather in years following a fire and how much of the crown was consumed.

Severity of fires on Forest Service lands in the bioregion from 1984 to 2011, based upon remote sensing based monitoring (CBI index) (Miller and Safford, 2008). Data were aggregated by broad ecological zones; major ecosystem changes with elevation and precipitation.
Chap3_Fire_31.jpg
Chap3_Fire_32.jpg
Chap3_Fire_33.jpg
Chap3_Fire_34.jpg
Chap3_Fire_35.jpg


Total area burned and by severity classes on Forest Service lands in the bioregion from 1984 to 2011, based upon remote sensing based monitoring (CBI index) (Miller and Safford, 2008). Data were aggregated by broad ecological zones; major ecosystem changes with elevation and precipitation (described in Chapter 1). Subregions and ecological zones were described in Chapter 1. Subregions are based on north-south and east-west variation in precipitation, dominant vegetation and geology/topography. Subregions include the following administrative units: north/westside- Lassen and Plumas National Forests; Central-Tahoe, Eldorado, Stanislaus and west shore of Lake Tahoe Basin; southwest- Sierra and Sequoia National Forests (including Kern Plateau on the Sequoia is unique in character); northeast – Modoc, and eastern portions of the Lassen, Plumas, Tahoe and Lake Tahoe Basin; southeast- Inyo National Forest.


High Severity
Moderate Severity
Low Severity
Un- changed



Subregion and Ecological Zone
Total Burned
Not Burned
Total Acres




North-westside
195,052
207,958
245,108
159,482
807,864
2,864,339
3,672,203
Foothill
67,311
98,800
97,183
99,404
362,697
772,085
1,134,782
Montane
102,453
84,713
117,840
44,310
349,579
1,429,966
1,779,545
Upper Montane
25,163
24,352
29,954
15,755
95,224
640,609
735,833
Subalpine/Alpine
125
93
131
14
363
21,677
22,040
Central
153,618
180,072
160,376
56,360
550,538
5,792,054
6,342,592
Foothill
75,379
98,060
76,451
30,157
280,047
2,680,098
2,960,145
Montane
73,119
74,463
74,187
21,705
243,475
1,696,659
1,940,134
Upper Montane
5,120
7,549
9,738
4,498
27,017
1,048,991
1,076,007
Subalpine/Alpine





366,306
366,306
South-west (& Kern Plateau)
131,082
140,550
126,950
69,789
468,406
4,827,985
5,296,391
Foothill
46,608
47,848
39,999
27,164
161,619
2,250,155
2,411,774
Montane
70,352
74,866
52,703
20,826
218,748
1,147,398
1,366,146
Upper Montane
14,036
17,517
32,802
18,462
82,837
673,189
756,026
Subalpine/Alpine
82
317
1,445
3,334
5,192
757,209
762,401


Subregion and Ecological Zone
High Severity
Moderate Severity
Low Severity
Un- changed



East North
190,166
146,606
108,135
62,911
508,213
7,494,220
8,002,433
Foothill
17,540
18,922
16,658
11,553
64,673
1,319,281
1,383,955
Montane
140,585
100,493
71,739
37,613
350,651
4,931,783
5,282,434
Upper Montane
29,664
24,285
16,813
11,034
81,854
633,493
715,347
Subalpine/Alpine
776
1,510
1,569
510
4,365
93,425
97,790
Sagebrush/Pinyon Juniper
1,602
1,395
1,356
2,200
6,670
516,238
522,907
East South
159,684
93,729
69,112
42,618
365,160
6,188,922
6,554,082
Foothill
1
0
1
0
3
13
16
Montane
89,193
44,819
24,284
17,689
176,003
1,846,091
2,022,094
Upper Montane
43,014
39,559
37,026
18,987
138,586
1,584,137
1,722,723
Subalpine/Alpine
86
164
162
133
545
467,922
468,467
Sagebrush/Pinyon-Juniper
27,389
9,186
7,640
5,808
50,023
2,290,759
2,340,782
Grand Total
829,601
768,915
709,681
391,160
2,700,181
27,167,519
29,867,701

Published research has established that wildfires have become larger and large fires more frequent across the western United States since the 1970’s (Calkin et al. 2005, Westerling et al. 2006). In 2009, Miller et al. (2009) published the first paper that showed an increasing trend in the percentage of high-severity for a large (60%) sample of area burned 1984-2006 within the Sierra Nevada Forest Plan Amendment (SNFPA) area. With completion of historical severity data assessments, an update of an assessment of trends was recently completed using a comprehensive catalogue of fires >200 ac from 1984-2010 (Miller and Safford 2012). Stratifying the severity data for fires on Forest Service managed lands with Landfire’s Biophysical Settings (BpS) potential vegetation data (see Spatial Patterns section below for a description of BpS) Miller and Safford (2012) found a statistically significant increasing trend in both percentage and area of high severity per year in yellow pine/mixed conifer forests. The following two figures, taken from Miller and Safford (2012) portray the trends in percentage and area of high-severity fire per year for yellow pine/mixed conifer forests in fires >200 ac between 1984 and 2010. Miller and Safford (2012) used a time series modeling approach commonly used for building predictive models to identify the trends. As part of the modeling approach any linear trend must first be identified and removed from the data. The two figures below show the time series model for entire 27 year period and the linear trend lines for seven time series models beginning in 1984 and ending in the years 2004-2010; the trend lines did not fundamentally change for the seven time series.

Ch3_FireSevTrend_sm.jpg
Ch3_FireSevTrendHa_sm.jpg

Miller and Safford (2012) also found that the number of fires larger than 1000 ac per year that burned in at least one of the three major forest types in the study area has increased since the 1950’s, which is generally considered to be advent of the modern fire suppression era. The following figure from Miller and Safford (2012) shows that the last 17 years (1994-2010) was the longest period with at least one large fire every year since 1950. The second longest period was 8 years (1968 through 1975). Five of those 8 years had only 1 or 2 large fires, whereas the longer 17 year period only had 3 years with only 1 or 2 large fires. Miller and Safford (2012) also found that the percentage of high severity per fire during 1984-2010 was significantly greater in fires >1000 ac than in small fires (200-1000 ac). Extrapolating that relationship over the longer 1950-2010 period, it is not hard to see why the trends in percentage and area of high severity per year increased. More years with large fires over the 1950-2010 period in the Sierra Nevada bioregion are consistent with observed increases in the number of large fires across the western US, and predictions of more large fires in California due to climate change (Westerling et al. 2006; Lenihan et al. 2008).

Ch3_FireNumTrend_sm.jpg

Spatial Patterns


Assessing whether the extent, severity and high severity patch size within contemporary fires are within the historical range of variability is a difficult task. Issues associated with those types of assessments can lead to some uncertainty: 1) historical forest and fire reconstruction studies can never achieve a broad spatial coverage due to the labor intensive data collection methods (tree rings, fire scars), 2) historical fire size reconstructions are inherently incomplete because some data (recording trees) are lost from fire and decomposition, and 3) there are very few reference sites with intact fire regimes due to the long-established policy of fire exclusion and other forest management practices. While historical conditions can serve to inform and provide context for management direction, the comparison of contemporary to historical patterns may not be entirely relevant due to changing climate conditions. Therefore there is not a perfect method for assessing which factors are contributing to the current range of fire effects relative to pre-settlement conditions. However, comparisons to contemporary reference sites that exhibit the most intact (i.e. least influenced by human decisions) can provide some insight into contemporary fire patterns (Meyer et al. 2010). In the Sierra Nevada bioregion, one such comparison that could be made is between lands managed by the Forest Service and National Park Service (NPS). Although policies of both agencies have allowed the use of naturally ignited wildland fires for resource benefits since the late 1960s and early 1970s, implementation has varied between the two agencies. The national parks in the Sierra Nevada were subjected to fire exclusion policies similar to Forest Service prior to the early 1970s. But since then the national parks have allowed extensive use of managed wildfires from natural ignitions. In contrast, the Forest Service in the Sierra Nevada bioregion still suppresses almost all wildfires, except for some that occur in higher elevation wilderness areas, primarily in the southern Sierra Nevada forests. In addition, NPS lands have not had extensive timber harvesting or livestock grazing since the parks were established at the beginning of the 20th century. Therefore, NPS lands have the potential to at least partially serve as contemporary reference forests



A recent study by Miller et al. (2012) used fire perimeters and satellite-derived estimates of fire severity to compare fire statistics (fire size, percent high-severity and high-severity patch size) for wildfires that occurred in Yosemite National Park to lands managed by the Forest Service in the Sierra Nevada, Southern Cascades, and Modoc Plateau. The following figure from their paper shows how Miller et al. divided Forest Service lands into three regions for comparing fire statistics to Yosemite NP: Cascade-Modoc, westside, and eastside. The study looked at all fires larger than 200 ac that occurred 1984–2009, represented by the red polygons in the figure below.

Ch3_FirePatterns_MillerStudy01.png


When characterizing fire regime characteristics over broad scales it makes most sense to stratify with vegetation data that describe the geographic distribution of forest types independently of their seral stage (Rollins 2009, Van de Water and Safford 2011). Miller et al. (2012) therefore used the LANDFIRE-generated Biophysical Settings (BpS) potential natural vegetation (PNV) layer to stratify their fire severity data. The BpS data describe the vegetation that could occur at a physical location based upon the site’s biophysical environment (climate, soils and topography; see Rollins 2009). The following figure depicts the distribution of the three major forest types as mapped by BpS within the bioregion: mixed conifer, yellow pine and red fir.

Ch3_FirePatterns_LandfireBPS.png

Miller et al. (2012) found that high severity patch size was smaller, and percent high-severity, regardless of forest type, was less in Yosemite NP than on Forest Service lands. The following figure from Miller et al. (2012) shows comparisons of the percentage of high-severity per fire sliced two ways; top are results by forest type, bottom are results by region. Bars labeled with different small letters indicate values are significantly different (labels: CM = Cascade-Modoc, E = Eastside, W = Westside, Y = Yosemite National Park; MC = mixed conifer, YP = yellow pine, RF = red fir.)

Ch3_FirePatterns_MillerStudy03.png


Note: additional synthesis of scientific literature on conditions and trends in spatial patterns of fire by major vegetation type throughout the bioregion is in the final stages of completion by the USFS Region 5 Ecology Program as part of a Natural Range of Variability summary. These summaries include: plant composition; vegetation structure; historic fire, wind, flooding, and tectonic regimes; and future trends, including invasive plant species. There is very little scientific information on spatial patterns of fires and severity, particularly in relation to the natural range of variability.

Fire Frequency/Return Interval and Fire Deficits


One of the most commonly studied and measured aspects of fire is the frequency with which it occurs, or the interval between fires for any size area considered (Agee 1996). This is because at least some of the evidence of fire is recorded in tree ring scars. Dendrochronology, particularly comparisons of multiple trees across various areas, can be used to date the year a fire occurred and sometimes the season (Stokes and Smiley 1996, Cook et al. 1990, Fule et al. 2003). There have been several comprehensive syntheses of historic and current fire frequencies or return intervals in the Sierra Nevada bioregion (Skinner and Chang 1996, van Wagtendonk and Fites-Kaufman 2006, Skinner and Taylor 1996, Reigel et al. 1996, Stephens et al. 2007, Van de Water and Safford 2011). There are several key aspects and implications of these scientific works.

First, the “prehistoric” (pre 1800) area burned in California overall was estimated to be vastly greater than current patterns (Stephens et al. 2007). These changes have not been uniform. Vegetation types where fires burned most frequently in the past, such as yellow pine or mixed-conifer, have undergone the sharpest decline. Subalpine forests, where fires were historically less frequent, due to the patchier and sparse vegetation and shorter fire season, have undergone fewer changes. These vegetation-specific spatial patterns were estimated by Van der water and Safford (2011) in the form of fire return interval departure (FRID) models based upon existing vegetation maps (Figure x). Although, there are uncertainties associated with using current vegetation to estimate departures with historic fire the estimated patterns are very useful in providing a broad-scale view of changes in fire. The findings agree with Stephens et al. (2007) with the greatest departures occurring in lower and mid-elevation forests and wildlands.


Ch3_FRID_sm.jpg


This shift in fire has had a profound effect on the amount and continuity of fuels throughout the bioregion (van Wagtendonk and Fites-Kaufman 2006). In many drier forested ecosystems in the western US, frequent fire played a key role in regulating forest density and surface fuel accumulation. Although much of the bioregion has seasonally dry weather, overall it is productive and vegetation grows and accumulates annually. Decomposition by fungi is slowed by dry conditions. The combination of these factors lead to very high accumulations of fuels.

Probability

There are several different sources of fire occurrence data and ways that it is compiled to produce estimates of the likelihood or probability of fire. The National Fire Program Analysis (FPA) http://www.forestsandrangelands.gov/FPA/index.shtml produces national level modeled fire probability. Burn probability raster data are generated using the large fire simulator - FSim - developed FPA. FSim uses historical weather data and current LANDFIRE land-cover data for discrete geographical areas (Fire Planning Units - FPUs) and simulates fires in these FPUs. Using these simulated fires, an overall burn probability and marginal burn probabilities at four fire intensities (flame lengths) are produced by FSim for each 270m pixel in the FPU. FSim also produces burn probabilities for six flame length classes.


external image BioRegA_FPA2012BP.jpg
The Western Wildland Environmental Threat Assessment Center (WWETAC) has a map browser to view FSim output data on an Interactive Map at http://www.fs.fed.us/wwetac/wflc/

The State of California Forest and Range Assessment Program compiles fire occurrence data and uses it to create a fire rotation map. NEED TO DEFINE MORE—in DISCUSSIONS WITH FRAP AND OTHERS. These data provide a snapshot based on fires that have occurred recently and in the past on where fires are most likely to occur and spread (Figure x).

Overall, there is a moderate to high probability of fire occurrence in much of the Sierra Nevada. The probability is greatest at low elevations and decreases with increasing elevation. This likely reflects not only a longer fire season but also the greater prevalence of humans. People cause over half of the fires (USDA 2001: Vol. 2, p. 250). At lower elevations (<4000 feet), humans cause more than half of the ignitions. Below 3000 feet, humans cause more than 80% of the ignitions. This is also reflected in the acres burned (USDA 2001: Vol.2, p 249), with the majority of acres burned in human caused fires.

Both the lowest elevations on the westside and eastside of the bioregion have the highest probability of fire. On the eastside in particular, this is partly a reflection of the grassland or sagebrush/grass dominated ecosystems in some areas. Not only are these ecosystems very dry, grass also ignites very readily.

Chap3_Fire_37.jpg
Map of fire rotation from the California Forest and Range Assessment Program. [Need to add detail from FRAP on years of data used etc]

Condition Class
Condition class was devised to integrate changes in fire characteristics (e.g. fire frequency, fire severity, and size etc.) with changes in vegetation and effects on vegetation and ecosystems (e.g. soils, vegetation, wildlife).
Condition Class
Fire Regime Status
(current compared to historic)
Key Ecosystem Component Implications
Class 1
Within natural (historic range
Vegetation is intact and functioning within the natural (historical range)
Class 2
Moderately altered from natural range
Fire frequency has departed by one or more return intervals. Vegetation and fuels have been moderately altered.
Class 3
Substantially altered from historic range
Fire frequencies have departed from natural range by multiple fire return intervals. Dramatic changes in fire size, intensity, severity and landscape patterns have occurred.

Fire regime conditions classes are pre-dominantly classes 2 or 3 throughout most of the bioregion, whether in the south, central, north, east or west (Figure x). This is because historically, fire was prevalent in the bioregion, albeit at different frequencies, intensities and spatial extents, but firefighters have been successful at suppressing most fires (van Wagtendonk and Fites-Kaufman 2006).

Proportion of area (%) in different condition class ratings (see table above) by National Forest from LANDFIRE in 2008.
Chap3_Fire_38.jpg
Chap3_Fire_39.jpg
Chap3_Fire_40.jpg

References (incomplete)

  • Berg, N.H. and Azuma, D.L. 2010. Bare soil and rill formation following wildfires, fuel reduction treatments, and pine plantations in the southern Sierra Nevada, California, USA. International Journal of Wildland Fire 19(4): 478-489.
  • Calkin, D.E., K.M. Gebert, J.G. Jones, and R.P. Neilson. 2005. Forest Service large fire area burned and suppression expenditure trends, 1970–2002. Journal of Forestry 103: 179-183.
  • Eliott, W.J and P.r. Robichaud. 2001. Comparing erosion risks from forest operations to wildfire. In: Schiess, Peter; Krogstad, Finn, eds. Proceedings of the International Mountain Logging and 11th Pacific Northwest Skyline Symposium: 2001 - a forest engineering odyssey. Seattle, WA : College of Forest Ressources, University of Washington and International Union of Forestry Research Organizations: 78-89 Available at http://www.treesearch.fs.fed.us/pubs/23559
  • Hann, W.J. and D. J. Strohm. 2003. Fire Regime Condition Class and Associated Data for Fire and Fuels Planning: Methods and Applications. In: USDA Forest Service Proceedings RMRS-P-29. 2003.
  • LANDFIRE. 2007, January (last update).[Homepage of the LANDFIRE Project, U.S. Department of Agriculture, Forest Service; U.S. Department of Interior], [Online]. Available: http://www.landfire.gov/index.php [2012, December 4, 2012].
  • Lenihan, J., D. Bachelet, R. Neilson, and R. Drapek. 2008. Response of vegetation distribution, ecosystem productivity, and fire to climate change scenarios for California. Climatic Change 87: S215-S230.
  • Lutz, J., van Wagtendonk, J., Thode, A., Miller, J. and Franklin, J. 2009. Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA. International Journal of Wildland Fire 18: 765-774.
  • Meyer, C.B., D.H. Knight, and G.K. Dillon. 2010. Use of the historic range of variability to evaluate ecosystem sustainability. Pages 251-261 in: R.A. Reck, editor. Climate Change and Sustainable Development. Volume Linton Atlantic Books, Ltd., Urbana, IL.
  • Miller, J.D. and Thode, A.E. 2007. Quantifying burn severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR). Remote Sensing of Environment 109(1): 66-80.
  • Miller, J.D. and Safford, H.D. 2008. Sierra Nevada Fire Severity Monitoring: 1984-2004. USDA Forest Service, Pacific Southwest Region, Vallejo, CA. R5-TP-027: 102pp.
  • Miller, J.D., Safford, H.D., Crimmins, M.A. and Thode, A.E. 2009a. Quantitative evidence for increasing forest fire severity in the Sierra Nevada and southern Cascade Mountains, California and Nevada, USA. Ecosystems 12(1): 16-32.
  • Miller, J.D., Knapp, E.E., Key, C.H., Skinner, C.N., Isbell, C.J., Creasy, R.M. and Sherlock, J.W. 2009b. Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada and Klamath Mountains, California, USA. Remote Sensing of Environment 113(3): 645-656.
  • Miller, J.D., and Safford, H.D. 2012. Trends in wildfire severity 1984-2010 in the Sierra Nevada, Modoc Plateau, and southern Cascades, California, USA. Fire Ecology 8(3): 41-57.
  • Miller, J.D., Collins, B.M., Lutz, J.A., Stephens, S.L., van Wagtendonk, J.W. and Yasuda, D.A. 2012. Differences in wildfires among ecoregions and land management agencies in the Sierra Nevada region, California, USA. Ecosphere 3(9): art80.
  • Parsons, A., Robichaud, P.R., Lewis, S.A., Napper, C. and Clark, J.T. 2010. Field guide for mapping post-fire soil burn severity. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. General Technical Report. RMRS-GTR-243: 49pp.
  • Rollins, M.G. 2009. LANDFIRE: a nationally consistent vegetation, wildland fire, and fuel assessment. International Journal of Wildland Fire 18: 235-249.
  • Scott, J. 1998. Fuel reduction in residential and scenic forests: A comparison of three treatments in a western Montana ponderosa pine stand. USDA Forest Service, Rocky Mountain Research Station, Research Paper. RMRS-RP-5.
  • Sugihara, N., J. van Wagtendonk, J. Fites-Kaufman. 2006. Chapter 4. Fire as an Ecological Process. In Fire in California Ecosystems. Edited by: N. Sugihara, J. van Wagtendonk, J. Fites-Kaufman, A. Thode, and K. Shaffer. UC Press, Berkeley, CA. pp. 103-134.
  • Thode, A.E., van Wagtendonk, J.W., Miller, J.D. and Quinn, J.F. 2011. Quantifying the fire regime distributions for severity in Yosemite National Park, California, USA. International Journal of Wildland Fire 20(2): 223-239.
  • Van de Water and H.D. Safford. 2011. A summary of fire frequency estimates for California vegetation before Euro-American Settlement. Fire Ecology (7) 3: 26-58.
  • Webster, K. M., and C. B. Halpern. 2010. Long-term vegetation responses to reintroduction and repeated use of fire in mixed-conifer forests of the Sierra Nevada. Ecosphere 1(5):art9. doi:10.1890/ES10-00018.1
  • Westerling, A.L., H.G. Hidalgo, D.R. Craven, and T.W. Swetnam. 2006. Warming and earlier spring increase Western U.S. forest wildfire activity. Science 313: 940-943.Thode, A.E. (2005). Quantifying the Fire Regime Attributes of Severity and Spatial Complexity Using Field and Imagery Data. Davis, CA, University of California. PhD.

Effects on ecological composition and structure

(NOTE: this will be covered in Chapter 1 but is mentioned here)

Existing data is highly varied . Most of the more detailed work is from research, such as the fire surrogate research, fire effects monitoring on federal and state lands, and opportunistic administrative studies or research on wildfires. Existing information includes bioregional monitoring of birds, fire effects monitoring by NPS, USFS, CA State Parks, Research and administrative studies. These data include: bird occupancy, plant species composition and abundance and/or size, soil cover. Some of this information is currently being compiled by the Regional USFS Ecology program as part of their Natural Range of Variability Assessment. In addition, there are some comprehensive literature reviews available in the text “Fire in California Ecosystems” (2006), monitoring reports by the National Park Service (http://www.nps.gov/fire/wildland-fire/learning-center/fire-in-depth/fire-effects-monitoring.cfm) and US Forest Service (http://www.fs.fed.us/adaptivemanagement/pub_reports/JFS_vaillant2.shtml), and Point Rey Bird Observatory (http://data.prbo.org/apps/snamin/index.php?page=bioreg-home-page). In addition, as part of a Joint Fire Science project, there are several publications in progress by Forest Service researchers and other scientists (http://www.fs.fed.us/adaptivemanagement/pub_reports/JFS_vaillant2.shtml and http://www.firescience.gov/JFSP_advanced_search_results_detail.cfm?jdbid=%24%26Z/8W%20%20%20%0a)

In the Sierra Nevada, there is a pressing need to understand the nexus of silvicultural practices, wildfire, and fuels treatments in order to maintain forest ecosystems that are ecologically diverse and resilient. Land managers need more information about the suitability of habitat created through fire suppression, fuel treatments, and wildfire and post-wildfire management to ensure the goals of maintaining biological diversity are achieved. In order to fully understand the effects of fire and develop a strategy for managing for fire and after it ecological monitoring of a suite of focal species is advised. Bioregional monitoring such as is being conducted through the Management Indicator Species program as well as strategic adaptive management based monitoring of individual fires is critical to guiding a strategy for managing for this most important of ecological processes in the Sierra Nevada.

While the size of fires and their severity have increased in recent years, the total acreage burning annually is still far below pre-european levels seen previous centuries (Stephens et al. 2007). Even with this increase in high severity fire in the last 30 years the amount of acreage burning at high severity is likely still well below historic levels. The difference being these acres are all now clumped in a few large fires spread across the region vs. in small patches spread through the vast acreage that burned annually. Areas that burn at high severity provide critical habitat for a vast array of wildlife species, including a number of species that are rare and/or declining in the Sierra Nevada (Burnett et al. 2011, Seavy et al. 2012).

See also Fire Resilience in Chapter on Ecosystem Services


Ecological Role of Fire


The ecological role of fire as a process has been discussed in Chapter 1 in the section on Ecological Integrity of Ecosystems, in both the Terrestrial and also the Riparian subsections. Some of the information below is similar to that content, but because of the fundamental role of fire in ecosystems in the bioregion, it is also covered here.

While it is often described as a “disturbance”, but in Fire in California Ecosystems, Sugihara et al. (2006) deleted that word from the entire text and extensively described how integral fire is as an ecosystem process in the bioregion. Fire is an integral process in the Sierra Nevada, southern Cascades, and Modoc Plateau. It has occurred regularly for hundreds of thousands of years (Skinner and Chang 1996). It is a process that does not operate in a vacuum but is closely tied in both a “give” and “take” relationship with many other ecosystem processes and human uses, including vegetation, wildlife habitat, soils, hydrology, carbon cycling, insect populations, air quality and even climate. It is characterized in terms of a “regime” that encompasses how often and regularly it occurs (frequency), how hot it burns (intensity), how much it influences living and non-living parts of the ecosystem (severity), and how it occurs across the landscape (spatial pattern) (Sugihara et al. 2006). As vegetation and weather changes with elevation or precipitation, the range of fire regime characteristics change. For example, at the highest elevations, with predominately rocky soils and short growing seasons, subalpine and alpine ecosystems, the fire regime is characterized by small fires, with irregular frequency (depending on lightening patterns), and varied severity (van Wagtendonk and Fites-Kaufman 2006). At lower elevations, in the ponderosa pine or mixed conifer dominated forests, fire season was and is longer were more frequent, larger and dominated by low and moderate severity effects. The regularity, intensity (how hot) and severity (amount of tree mortality) varies with density of the vegetation and dryness or temperature of the growing season. Forests that receive more rain and snow, such as the west slopes of the northern Sierras have different patterns than the drier ones east of the crest or on west slopes in the southern Sierras (van Wagtendonk and Fites-Kaufman 2006).Fundamentally, fire shaped vegetation variation, including what kinds of plants and trees, how dense they were and how they were arranged in the landscape, within a watershed, and within patches. As Barbour et al. 1993 so eloquently stated:

“In California, vegetation is the meeting place of fire and ecosystems. The plants are the fuel and fire is the driver of vegetation change. Fire and vegetation are often so interactive that they can scarcely be considered separately from each other.”

Prior to extensive fire suppression in the mid 1900’s, fires were frequent, larger, and mostly low or mixed severity (van Wagtendonk and Fites-Kaufman 2006; Safford 2013). Recurrent fire kept tree and other plant density lower or patchier, so that when dry summer or windy fall conditions occurred, fire swept through with fewer effects (i.e. less large tree kill) than what we see now. It invigorated browse for wildlife (Shaffer and Laudenslayer 2006). It kept levels of insects in acorns low for better deer and bear browse (Lake and Long 2013). It recycled nutrients, fertilizing soils. It created diverse riparian plant communities (Webster and Halpern 2010), dominated by deciduous shrubs (i.e. willow and dogwood) and trees (aspen and cottonwood) that are important for many songbirds, insects, and litter inputs into the stream foodwebs. Native Americans lived with fire and through traditional ecological management, utilized it for many life-sustaining purposes, such as: enhancing straight growing shrub stems with no insects to make better baskets; improving game forage or plant vigor for food sources; reducing habitat for disease spreading ticks; and clearing around living areas or travel routes (Anderson 2006; Lake and Long 2013).

Very large patches of high severity fire can change ecological function of old forest ecosystems, killing most or all large, old trees across large areas, and breaking connectivity (Franklin and Fites-Kaufman 1996) of canopied forests for cover and travel of wide-ranging species such as the fisher (Zielinski 2013; Keanne 2013). Other species, such as the black-backed woodpecker are drawn to these freshly burned sites with their high prevalence of snags. Other birds (i.e. mountain quail, calliope hummingbird, flycatchers or warblers) increase or are drawn here by the vigorous growth of shrubs or hardwood trees, stimulated to sprout by fire (PRBO 2012). Songbirds and the black-backed woodpecker also use other habitats and it is likely that previous, highly variable, fine-scale patchiness from varying fire was equally used. The California spotted owl has a more variable and complex response. Some level of fire may not change reproduction or occupancy of owls and can increase rodent populations that provide food. It is uncertain how much and what kind of fire has specific effects. For plants, there are varied effects and many more unknowns.

A large number of plants are adapted and often enhanced and sometimes dependent upon fire for successful survival and reproduction (van Wagtendonk and Fites-Kaufman 2006, Webster and Halpern 2010). Fire can enhance survival and persistence for sprouting species, particularly when they complete with conifers, such as aspen. Others may be less common or have lower flowering now because of a lack of fire that can stimulate flowering in some (Fites-Kaufman et al. 2006), such as the rare Calachortes clavatus or uncommon bearded penstemon. Many plants in the bioregion have underground tubers or rhizomes that store food and energy that are buried deep below the surface allowing them to stay below high fire temperatures on the surface.

According to the recent report, A National Cohesive Wildland Fire Manaagment Strategy (2013), the current fire regime of the Sierra Nevada mountain range is not providing for sustainability of ecological processes and structure (p. 31). The historical burn rate was approximately 800,000 acres per year on average and currently it is 70,000 acres per year on average. In contrast, the Great Basin, has seen increases in average burned area, particularly where annual grasses (cheatgrass) have replaced native sagebrush ecosystems (p. 29). .

There are several different ways to assess current condition and trends in the ecological role of fire. One is to assess the “resilience” to fire in the current fire conditions that occur today. The second is to assess the time since fire. Fire resilience is a way of capturing what the effects of fires that may burn during any time of the year, but in particular in the peak of summer and fall fire seasons. Resilient ecosystems, would have effects that are within the presumed natural range of variability (see Chapter 1) but more importantly the primary ecosystem components (structure and composition), and processes (provision of habitat, connectivity, carbon cycling, hydrologic functions) would be intact within a reasonable degree, and ecosystem services would still be provided within some acceptable range. Defining what is resilient in terms of these characteristics is subject to interpretation and can only be broadly characterized at this time and with the next phase of forest plan revision, can be more definitively described when desired conditions are defined. The other means of characterizing current conditions of the ecological role of fire is to assess the time since last fire. This measure is more important for ecosystems that have had a sharp reduction in the frequency of fire compared to historic conditions, such that some ecosystem components of composition and structure may be reduced with the absence of fire. At this time, we have focused on fire resilience.


Ecological Role of Fire: Time Since Last Fire


The time since fire will be included in the forest scale assessments, since it will involve assembly of more detailed information on the location and timing of prescribed and managed fires, as well as uncontrolled wildfires.

Fire Resilience

In order to conditions and trends in fire resiliency across the bioregion, two different approaches were applied fire return interval departure, and fire resiliency index across watersheds. For both, the purpose was to define resilience in terms of sustaining ecological integrity, the primary intent of the new planning rule.

First, available “fire return interval departure” (FRID) maps were used (Van de Water and Safford 2011). The FRID approach compares reconstructed, historic average years between fires with current fire return intervals. This serves to provide an overall view of ecological “fire deficit”, where many fire cycles have been missed with associated ecological consequences. Some of these fire deficits were already discussed and more are described in the ecological integrity section that follows. The map displays the departure in terms of the percent of fire cycles that were missed (difference in average now compared to average historic) or where fires are more frequent. In general, there are large fire deficits in the lower elevation forests and few changes in subalpine or higher reaches of the upper montane forests. Other areas, namely desert and sagebrush stepplands where cheatgrass invasions are extensive, have a trend of increasing fires over what occurred historically.

For the second approach, a fire resiliency index was calculated for large areas reflecting differences in current potentials for high, moderate or low severity (to vegetation) fires. Fire in the forests was assessed with potential fire type developed with LANDFIRE data (Rollins 2009). There were two categories applied. Forest “surface” fire,; it occurs mostly in the understory. Crown fire burns into the tops or crowns of individual or clumps of trees, or entire forests. Predicting the type of fire depends upon the weather conditions that are input into the model and the detail of information available for the live and dead vegetation (fuels). At the bioregional scale, potential fire behavior provide a useful gauge of overall fire effects to vegetation or communities (FRAP 2010). For non-forested types, we used the Departure from Fire Return Interval Index (Van de Water and Safford 2011).

Fire effects to ecological integrity are far less important at the individual forest stand, animal or plant location or meadow. Ecological integrity is most influenced by fire effects at landscape scales, across areas where large fires occur and fire regimes are characteristic. More importantly, current , more uniform and dense, andscape vegetation makes development of large intense fires more likely. Once a fire gets started in the drier part of the summer or fall, it often covers thousands of acres in days or hundreds of acres in short bursts of crown fire . These fire runs are often very difficult to “attack” directly in a safe or effective manner, and therefore, the consequences must be evaluated in larger areas. We used readily available, large watershed basin boundaries to delineate large landscapes. For a first approximation of ecological resilience, we defined four different levels based largely on the likely degree of effect on wildlife habitat (e.g. spotted owls) and old forest, and to some degree on natural range of variability (NRV). We did not use only NRV because at this time, conditions are far removed from them in terms of fire regime, and even a modest shift back toward that level of resiliency would benefit ecological integrity and is more feasible in a short period of time. The planning rule specifically provides for using ecological integrity based on measures other than NRV where this is the case.

These were not meant to represent desired conditions but rather broad, relative differences in fire effects. The levels were developed for broad landscapes (“ecological zones”, Chapter 1, WIKI) defined by dominant vegetation and climate including: foothill, dry montane, mesic montane, upper montane, subalpine, and eastside pinyon-juniper. Within these landscapes, forested areas (i.e. pine, mixed-conifer, red fir) were rated by broad levels of fire types as shown in the table below. For other types, where the potential fire models are less useful for ecological effects, the FRID data were used (i.e. chaparral, sagebrush, desert, foothill oak woodland).



Resilience Rating


rating
High Resilience (1)
Moderate Resilience (2)
Low Resilience (3)
Very Low Resilience (4)
Vegetation type
Ratio of Surface: Crown (% of large area)
Ponderosa pine; Jeffrey pine; eastside pine; eastside mixed conifer
>75%:<25%
50-75:25-50
25-50:50-75
<25%:>75%
Douglas-fir and mixed conifer or mixed conifer hardwood; white fir; foothill oak woodland (>40% tree cover)
>60%:<40%
40-60:40-60
20-40:60-80
<20:>80
Red fir; subalpine; lodgepole pine; Foothill pine-oak
>50:<50

25-50:50-75
<25:>75

Fire Interval Departure (FRID)
Chaparral; live oak, sage; other non-forest types
<33% departure (+ or -)

33-66% departure (+ or -)
>66% departure (+ or -)

Resilience was also rated differently around communities and infrastructure (wildland urban interface, or WUI), based on fire behavior standards for firefighting based on an interagency fire assessment group (state and federal). This is described more in Chapter 3 on the WIKI, and the results in the following section on social and economic sustainability. This was in a relatively narrow band is largely masked in the wildland resiliency ratings.

Resilience is greatest at the highest elevations, predominately in the subalpine and alpine dominated wildernesses in the south. Resilience is lowest in the drier montane (east and west of the crest), especially in the north, where elevations are overall lower. Fire resilience affects the integrity of many species, particularly those that are limited in distribution or impacted by large, severe fires. Nearly half of the Critical Aquatic Refugues (CARS), 2/3 of the goshawk and fisher locations, and more than 80% of the spotted owl and pine marten sites are in landscapes with a low to very low fire resilience. This means that during a typical fire season, in the drier, hotter portions, fires are likely to be large with a high proportion of large patches of high severity fire, which threatens the forest conditions upon which these resources depend.

Ch3_FireResilienceEcozones_sm.jpg

Fire resilience, ranging from 0 or 1, which is highly resilient, to 3 or 4, which denotes low to very low resilience, varies across the bioregion (figure x). Resilience is greatest at the highest elevations, predominately in the subalpine and alpine dominated wildernesses in the south. Resilience is lowest in the drier montane (east and west of the crest), especially in the north, where elevations are overall lower.
ires

The implications of these broad ecological resilience levels to different components of biodiversity from Critical Aquatic Refuges (CARS), to spotted owl, goshawk and forest carnivore locations is widespread (figure x). Nearly half of the CARS, 2/3 of the goshawk and fisher locations, and more than 80% of the spotted owl and pine marten sites are in landscapes with a low to very low fire resilience. This means that during a typical fire season, in the drier, hotter portions, fires are likely to be large with a high proportion of large patches of high severity fire.

Ch3_FireResilience_Wildlife_sm.jpg

The pattern of the trends in fire in different parts of the bioregion has implications for connectivity and the distribution of species, such as the spotted owl. There has been a disproportionately high concentration of owl sites affected by high severity fire in the northern Sierra Nevada and southern Cascades (figure x). This is primarily the result of several large fires that burned under very hot, dry and sometimes windy conditions in steep terrain (e.g. Moonlight and Chips fires). Early seral species, such as birds, respond favorably to these fires (Chapter 1, WIKI: Hanson and North 2008, Tarbill 2010, Siegel et al. 2012, PRBO). However, more distributed, smaller large severity patches would provide better connectivity across the bioregion, than several large, high severity patches in limited portions of the bioregion. Thus, the pattern of a few, high severity fires, do not contribute as much to connectivity for early seral species and are detrimental to connectivity for late seral species.


Fire (from a wildlife perspective)

Fire’s role as driver or stressor can be viewed through multiple lenses. One primary lens is wildlife because their response to fire reflects the evolutionary relationship between fire and ecology and also provides insights into the contemporary aspects of fire. For example, while some recent fires have been characterized as too large or as containing too high a percentage of high-severity fire (e.g., McNally Fire, Moonlight Fire), these same fires can be characterized as ecologically beneficial (and necessary from an evolutionary perspective) in light of data regarding wildlife use of the post-fire landscape. In regard to the McNally Fire, one study (Buchalski et al. 2013) found that most phonic groups of bats showed higher activity in areas burned with moderate to high-severity. (See also Malison and Baxter 2010, finding greater bat activity was observed in high-severity burned riparian habitat within mixed-confer forest than at unburned areas of similar habitat in central Idaho). Similarly, in the McNally area, California spotted owls were found to be preferentially selecting high-severity fire areas for foraging. (Bond et al. 2009). In the Moonlight Fire area, researchers explained that “[i]t is clear from our first year of monitoring three burned areas [Cub, Moonlight and Storrie Fires] that post-fire habitat, especially high severity areas, are an important component of the Sierra Nevada ecosystem.” (Burnett et al. 2010). They also found that “[o]nce the amount of the plot that was high severity was over 60% the density of cavity nests increased substantially,” and that “more total species were detected in the Moonlight fire which covers a much smaller geographic area and had far fewer sampling locations than the [unburned] green forest.” (Burnett et al. 2010). Moreover, while the Forest Service has characterized the Moonlight Fire as detrimental to spotted owls, the impacts of the extensive salvage logging directly adjacent to the PACs were not accounted for. In general as well, it is important to keep in mind that post-fire areas that are manipulated by salvage logging and/or by reforestation efforts are, from an ecological perspective, no longer valuable as post-fire areas; rather post-fire salvage logging and reforestation substantially reduce, and often locally eliminate, wildlife species strongly associated with the forest habitat created by high-severity fire patches. (Burnett et al. 2012, Hutto 1995, Hutto 2008, Seavy et al. 2012, Siegel et al. 2012, 2013).

Time since fire provides important insights into the continuum of use of post-fire areas over time by different species. Black-backed woodpeckers, for example, are well known to require areas with very high snag densities immediately post-fire – e.g., mature forest that has very recently experienced higher-severity fire, and has not been salvage logged (Hanson and North 2008, Hutto 1995, 2008, Saab et al. 2009, Seavey et al. 2012, Siegel et al. 2010, 2011, 2012, 2013). However, “while some snag associated species (e.g. black-backed woodpecker) decline five or six years after a fire [and move on to find more recent fire areas], [species] associated with understory plant communities take [the woodpeckers’] place resulting in similar avian diversity three and eleven years after fire (e.g. Moonlight and Storrie).” (Burnett et al. 2012). Burnett et al. 2012 also noted that “there is a five year lag before dense shrub habitats form that maximize densities of species such as Fox Sparrow, Dusky Flycatcher, and MacGillivray’s Warbler. These species have shown substantial increases in abundance in the Moonlight fire each year since 2009 but shrub nesting species are still more abundant in the eleven year post-burn Storrie fire. This suggests early successional shrub habitats in burned areas provide high quality habitat for shrub dependent species well beyond a decade after fire.” (Burnett et al. 2012). Raphael et al. 1987 found that at 25 years after high-severity fire, total bird abundance was slightly higher in snag forest than in unburned old forest in eastside mixed-conifer forest of the northern Sierra Nevada; and bird species richness was 40% higher in snag forest habitat. In earlier post-fire years, woodpeckers were more abundant in snag forest, but were similar to unburned by 25 years post-fire, while flycatchers and species associated with shrubs continued to increase to 25 years post-fire. (Raphael et al. 1987). In ponderosa pine and Douglas-fir forests of Idaho at 5-10 years post-fire, levels of aquatic insects emerging from streams were two and a half times greater in high-severity fire areas than in unburned mature/old forest, and bats were nearly 5 times more abundant in riparian areas with high-severity fire than in unburned mature/old forest. (Malison and Baxter 2010). Schieck and Song 2006 found that bird species richness increased up to 30 years after high-severity fire, then decreased in mid-successional forest [31-75 years old], and increased again in late-successional forest [>75 years]).

Even areas that burn at high-severity and then, shortly therafter, burn again at high-severity, can be ecologically valuable. Donato et al. 2009 found that a high-severity re-burn [high-severity fire occurring 15 years after a previous high-severity fire] had the highest plant species richness and total plant cover, relative to high-severity fire alone [no re-burn] and unburned mature/old forest; and the high-severity fire re-burn area had over 1,000 seedlings/saplings per hectare of natural conifer regeneration. Fontaine et al. 2009 found that bird species richness was not significantly different between high-severity re-burn, high-severity burn alone, and unburned old-growth forest, but was numerically highest in areas burned once by high-severity fire 17-18 years earlier, and in high-severity re-burn areas. Total bird abundance was higher in the high-severity fire area, at 17-18 years post-fire, than in the unburned old-growth forest [Figs. 3a and 3b]. (Fontaine et al. 2009).

Mixed-Severity Fire Across Forest Types
High-severity fire is an important component of not only fir and lodgepole pine forest, but also of mixed-conifer forests in the Sierra region (e.g., Collins and Stephens 2010). Although it is now well accepted that high-severity fire is a key component of the landscape and a disturbance that numerous wildlife species rely upon either directly or indirectly, there is scientific debate as to what is the acceptable range of high-severity percentage in any given fire or fires, and there is still debate as to what is the appropriate size for high-severity patches within a fire.

Contrary to past assumptions (e.g., the 2004 Sierra Nevada Framework), considerable data and research exists that indicates that mixed-severity fire: a) is not limited to true fir and lodgepole pine and is instead also a natural condition in ponderosa-pine/Jeffrey-pine and mixed-conifer forest, b) generally dominated pre-fire suppression fire regimes in these forest types, and c) can include a significant proportion of high-severity fire including occasional large high-severity fire patches hundreds or thousands of acres in size. (Baker 2006, Baker 2012, Baker et al. 2007, Beaty and Taylor 2001, Bekker and Taylor 2001, Bekker and Taylor 2010, Brown et al. 1999, Collins and Stephens 2010, Colombaroli and Gavin 2010, Hessburg et al. 2007, Iniguez et al. 2009, Klenner et al. 2008, Leiberg 1897, 1899a, 1899b, 1899c, 1900a, 1900b, 1900c, 1902, 1903, 1904a, 1904b, Nagel and Taylor 2005, Sherriff and Veblen 2007, Shinneman and Baker 1997, Show and Kotok, 1924, 1925, Stephenson et al. 1991, Taylor 2002, USFS 1910-1912, Whitlock et al. 2008, 2010, Williams and Baker 2010, 2011, 2012a, 2012b, Wills and Stuart 1994).
For example, Baker 2012 found that in dry mixed-conifer forests of the eastside of the southern Cascades in Oregon, historic fire was 24% low-severity, 50% mixed-severity, and 26% high-severity [Table 5].) The Baker 2012 paper, as well as the recent Williams and Baker studies (2012a, 2012b), have been criticized for their methodology and for not being specific to the Sierras. However, no similar landscape level effort has been conducted for the Sierras – in other words, there is no other study or studies for the Sierra that can claim to have answered the questions that the Williams and Baker methodology (see Williams and Baker 2011) is designed to answer. Moreover, in the regions where the Baker and the Williams and Baker studies do exist, the same assumptions that prevail in the Sierras had prevailed in those areas as well – i.e., the assumption that low-severity fire heavily dominated and maintained forests that were mostly open and parklike. (Williams and Baker. 2010, Williams and Baker 2011, Williams and Baker 2012a, 2012b). Further, the Williams and Baker 2012 study was based on over 13,000 records from surveyors across about 4 million acres of land in three states and these records are as good or better than the kinds of data other studies reply upon, and the accuracy and validity of the survey data were validated in an extensive scientific trial (Williams and Baker 2011). Finally, the tree-ring data that others rely upon are very spatially limited and are generally from small, isolated studies totaling at most thousands of acres, not millions of acres.

Data that do exist for the Sierra/southern Cascades region of California are telling as well. Beaty and Taylor 2001, in the western slope of the southern Cascades in California, found that historic fire severity in mixed-conifer forests was predominantly moderate- and high-severity, except in mesic canyon bottoms, where moderate- and high-severity fire comprised 40.4% of fire effects [Table 7]. Bekker and Taylor 2001, another study in the western slope of the southern Cascades in California, found historic fire severity to be predominantly high-severity in their study area [Fig. 2F]. Bekker and Taylor 2010, in mixed-conifer forests of the southern Cascades, found reconstructed fire severity to be dominated by high-severity fire effects, including high-severity fire patches over 2,000 acres in size [Tables I and II]. Leiberg 1902, which contains information from the central and northern Sierra Nevada, found high-severity fire patches over 5,000 acres in size in mixed-conifer forest that had not been logged previously during the 19th century, prior to fire suppression. Show and Kotok 1924, in ponderosa pine and mixed-conifer/pine forests of the Sierra Nevada, found that high-severity crown fires, though infrequent on any particular area, “may extend over a few hundred acres” in patches [p. 31; see also Plate V, Fig. 2, Plate VII, Fig. 2, Plate VIII, Plate IX, Figs. 1 and 2, and Plate X, Fig. 1], with some early-successional areas resulting from high-severity fire patches covering 5,000 acres in size or more [pp. 42-43]. Within unlogged areas, the authors noted many large early-successional habitat patches, dominated by montane chaparral and young, regenerating conifer forest, and explained that such areas were the result of past severe fire because: a) patches of mature/old forest and individual surviving trees were found interspersed within these areas, and were found adjacent to these areas, indicating past forest; b) snags and stumps of fallen snags, as well as downed logs from fallen snags, were abundant in these areas; c) the species of chaparral found growing in these areas are known to sprout abundantly following severe fire; and d) natural conifer regeneration was found on most of the area [p. 42], often growing through complete chaparral cover [p. 43].Show and Kotok 1925 found that within the ponderosa pine and mixed-conifer/pine belt of the Sierra Nevada, 1 acre out of every 7 on average was dominated by montane chaparral and young regenerating conifer forest following high-severity fire [Footnote 2, and Figs. 4 and 5]; and on one national forest 215,000 acres out of 660,000 was early-successional habitat from severe fire [p. 17].) Forest Service Timber Survey Field Notes from 1910-1912 show that surveys were conducted within primary forest to evaluate timber production potential in 16.2-ha (40-acre) plots within each 259.1-ha (640-acre) section in ponderosa pine and mixed-conifer forest on the westside of the Stanislaus National Forest, using one or more 1.62-ha transect per plot. The surveyors noted that surveys for individual tree size, density and species were not conducted in areas that had experienced high-severity fire sufficiently recently such that the regenerating areas did not yet contain significant merchantable sawtimber. Surveyors also noted that the dominant vegetation cover across the majority of many 259.1-ha sections was montane chaparral and young conifer regeneration following high-severity fire. For example (from a typical township in the data set): a) T1S, R18E, Section 9 (“Severe fire went through [this section] years ago and killed most of the trees and land was reverted to brush”, noting “several large dense sapling stands” and noting that merchantable timber existed on only four of sixteen 16.2-ha plots in the section); b) T1S, R18E, Section 14 (“Fires have killed most of timber and most of section has reverted to brush”); c) T1S, R18E, Section 15 (same); d) T1S, R18E, Section 23 (“Most of timber on section has been killed by fires which occurred many years ago”); T1S, R18E, Section 21 (“Old fires killed most of timber on this section and most of area is now brushland”.)

In regard to patch size, burned patches have been found to conform to a power law size distribution that is scale invariant and applies to any fire regime. Small patches are more numerous, but large patches cover much of the area. The implication is that large patches will be found in any analysis that evaluates a large area and it is necessary to study a large area to adequately encompass large patches. As a result, studies done over large areas of the Sierra Nevada, such as Leiberg’s, are most useful for documenting the large patches. Conversely, studies of relatively small areas or small fires may or may not intersect large patches depending on how and where they are located with respect to those patches. Thus, while there are studies that have evaluated relatively small areas within the Sierra landscape which found no large stand-replacing fire patches, this does not negate the occurrence of large patches outside the boundaries of these study areas.

Existing data and research also suggest that Sierra forests were historically structurally complex, with a high degree of heterogeneity from natural disturbance, in terms of chaparral patch extent, stand structure, density, and species composition—including stands dominated by fir and cedar with dense understories as a significant part of the mix in both ponderosa-pine/Jeffrey-pine and mixed-conifer forests. Baker 2012 found that historic mixed-conifer forests contained some open and park-like areas, but such areas were a minority. Rather, overall, the area was dominated by denser forests with substantial shrub cover and understory conifer density—small trees comprised over 50% of all trees on over 72% of the forest. (see also Duren et al. 2012.) Leiberg 1902 found that, in mixed-conifer forests in the central and northern Sierra Nevada, while some of the areas were open and parklike stands dominated by ponderosa pine, Jeffrey pine, and sugar pine, the majority were dominated by white fir, incense-cedar, and Douglas-fir, especially on north-facing slopes and on lower slopes of subwatersheds; such areas were predominantly described as dense, often with “heavy underbrush” from past mixed-severity fire. Natural heterogeneity, resulting from fire, often involved dense stands of old forest adjacent to snag forest patches of standing fire-killed trees and montane chaparral with regenerating young conifers: “All the slopes of Duncan Canyon from its head down show the same marks of fire—dead timber, dense undergrowth, stretches of chaparral, thin lines of trees or small groups rising out of the brush, and heavy blocks of forest surrounded by chaparral.” [p. 171]) Similarly, the USDA 1910-1912 Timber Survey Field Notes found that historic ponderosa pine and mixed-conifer forests of the central/southern Sierra Nevada [western slope] varied widely in stand density and composition; open and park-like pine-dominated stands comprised a significant portion of the lower montane and foothill zones, but dense stands dominated by fir and cedar, and by small/medium-sized trees, dominated much of the middle montane zone (It should be noted that the old-growth forests chosen for study by Scholl and Taylor 2010 and Collins et al. 2011 comprised only a very small portion of the 1910-1912 Stanislaus data set.)

Current rates of high-severity fire (rotation intervals) in the Sierra Nevada and southern Cascades are likely lower (longer rotation intervals) than historic rates, indicating less high-severity fire overall. Miller et al. 2012 found that the current high-severity fire rotation interval in the Sierra Nevada management region overall is over 800 years. The authors recommended increasing high-severity fire amounts [i.e., decreasing rotation intervals] in the Cascades-Modoc region and on the western slope of the Sierra Nevada, where the current high-severity fire rotation is 859 to 4650 years [Table 3]. The authors noted that “high-severity rotations may be too long in most Cascade-Modoc and westside NF locations, especially in comparison to Yosemite . . . .”

Due to the lack of fire (compared to historic levels) in the Sierra region, it is sometimes assumed that when fire does finally enter an area again, that area will be more likely to burn at high-severity due to the missed intervals. However, research has found that forest areas that have missed the largest number of fire return intervals in California’s forests are burning predominantly at low/moderate-severity levels, and are not experiencing higher fire severity than areas that have missed fewer fire return intervals. (Miller et al. 2012b, Odion and Hanson 2008, Odion et al. 2010, van Wagtendonk et al. 2012). This is important because it means that missed fire return intervals are not a reliable indicator of how a forest will burn when fire does again enter a given area.

References

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  • Leiberg, J.B. 1899b. Present condition of the forested areas in northern Idaho outside the limits of the Priest River Forest Reserve and north of the Clearwater River. USDI Geological Survey, Nineteenth Annual Report, Part V. Forest Reserves, pp. 373–386. US Government Printing Office, Washington, DC.
  • Leiberg, J.B. 1899c. Priest River Forest Reserve. USDI Geological Survey, Nineteenth Annual Report, Part V. Forest Reserves, pp. 217–252. US Government Printing Office, Washington, DC.
  • Leiberg, J.B. 1900a. Bitterroot Forest Reserve. USDI Geological Survey, Twentieth Annual Report to the Secretary of the Interior, 1898–99, Part V. Forest Reserves, pp. 317–410. US Government Printing Office, Washington, DC.
  • Leiberg, J.B. 1900b. Sandpoint quadrangle, Idaho. USDI Geological Survey, Twenty-first Annual Report, Part V. Forest Reserves, pp. 583–595. US Government Printing Office, Washington, DC.
  • Leiberg, J. B. 1900c. Cascade Range Forest Reserve, Oregon, from township 28 south to township 37 south, inclusive; together with the Ashland Forest Reserve and adjacent forest regions from township 28 south to township 41 south, inclusive, and from range 2 west to range 14 east, Willamette Meridian, inclusive. U.S. Geological Survey Annual Report 21(V):209-498.
  • Leiberg, J. B. 1902. Forest conditions in the northern Sierra Nevada, California. USDI Geological Survey, Professional Paper No. 8. U.S. Government Printing Office, Washington, D.C.
  • Leiberg, J. B. 1903. Southern part of Cascade Range Forest Reserve. Pages 229–289 in H. D. Langille, F. G. Plummer, A. Dodwell, T. F. Rixon, and J. B. Leiberg, editors. Forest conditions in the Cascade Range Forest Reserve, Oregon. Professional Paper No. 9. U.S. Geological Survey, U.S. Government Printing Office, Washington, D.C., USA.
  • Leiberg, J.B. 1904a. Forest conditions in the Absaroka division of the Yellowstone Forest Reserve, Montana. USDI Geological Survey Professional Paper No. 29, US Government Printing Office, Washington, DC.
  • Leiberg, J.B. 1904b. Forest conditions in the Little Belt Mountains Forest Reserve, Montana, and the Little Belt Mountains quadrangle. USDI Geological Survey Professional Paper No. 30, US Government Printing Office, Washington, DC.
  • Malison, R.L., and C.V. Baxter. 2010. The fire pulse: wildfire stimulates flux of aquatic prey to terrestrial habitats driving increases in riparian consumers. Canadian Journal of Fisheries and Aquatic Sciences 67: 570-579.
  • Miller, J.D., B.M. Collins, J.A. Lutz, S.L. Stephens, J.W. van Wagtendonk, and D.A. Yasuda. 2012. Differences in wildfires among ecoregions and land management agencies in the Sierra Nevada region, California, USA. Ecosphere 3: Article 80
  • Nagel, T.A. and Taylor, A.H. 2005. Fire and persistence of montane chaparral in mixed conifer forest landscapes in the northern Sierra Nevada, Lake Tahoe Basin, California, USA. J. Torrey Bot. Soc.132: 442-457.
  • Odion, D.C., E.J. Frost, J.R. Strittholt, H. Jiang, D.A. DellaSala, and M.A. Moritz. 2004. Patterns of fire severity and forest conditions in the Klamath Mountains, northwestern California. Conservation Biology 18: 927-936.
  • Odion, D.C., and C.T. Hanson. 2008. Fire severity in the Sierra Nevada revisited: conclusions robust to further analysis. Ecosystems 11: 12-15.
  • Odion, D. C., M. A. Moritz, and D. A. DellaSala. 2010. Alternative community states maintained by fire in the Klamath Mountains, USA. Journal of Ecology, doi: 10.1111/j.1365-2745.2009.01597.x.
  • Raphael, M.G., M.L. Morrison, and M.P. Yoder-Williams. 1987. Breeding bird populations during twenty-five years of postfire succession in the Sierra Nevada. The Condor 89:614 -626.
  • Russell, W. H., J. McBride, and R. Rowntree. Revegetation after four stand-replacing fires in the Tahoe Basin. Madrono 45: 40-46
  • Saab, V.A., R.E. Russell, and J.G. Dudley. 2009. Nest-site selection by cavity-nesting birds in relation to postfire salvage logging. Forest Ecology and Management 257:151–159.
  • Schieck, J., and S.J. Song. 2006. Changes in bird communities throughout succession following fire and harvest in boreal forests of western North America: literature review and meta-analyses. Canadian Journal of Forest Research 36: 1299-1318.
  • Seavy, N.E., R.D. Burnett, and P.J. Taille. 2012. Black-backed woodpecker nest-tree preference in burned forests of the Sierra Nevada, California. Wildlife Society Bulletin 36: 722-728.
  • Sestrich, C.M., T.E. McMahon, and M.K. Young. 2011. Influence of fire on native and nonnative salmonid populations and habitat in a western Montana basin. Transactions of the American Fisheries Society 140: 136-146
  • Sherriff, R. L., and T. T. Veblen. 2007. A spatially explicit reconstruction of historical fire occurrence in the Ponderosa pine zone of the Colorado Front Range. Ecosystems 9:1342-1347.
  • Shinneman D.J. and W.L. Baker, 1997. Nonequilibrium dynamics between catastrophic disturbances and old-growth forests in ponderosa pine landscapes of the Black Hills. Conservation Biology11: 1276-1288.
  • Show, S.B. and Kotok, E.I. 1924. The role of fire in California pine forests. United States Department of Agriculture Bulletin 1294, Washington, D.C.
  • Show, S.B. and Kotok, E.I. 1925. Fire and the forest (California pine region). United States Department of Agriculture Department Circular 358, Washington, D.C.
  • Siegel, R. B., R. L. Wilkerson, and D. L. Mauer. 2008. Black-backed Woodpecker (Picoides arcticus) surveys on Sierra Nevada national forests: 2008 pilot study. The Institute for Bird Populations, Point Reyes, CA.
  • Siegel, R.B., J.F. Saracco, and R.L. Wilkerson. 2010. Management Indicator Species (MIS) surveys on Sierra Nevada national forests: Black-backed Woodpecker. 2009 Annual Report. The Institute for Bird Populations, Point Reyes, CA.
  • Siegel, R.B., M.W. Tingley, and R.L. Wilkerson. 2011. Black-backed Woodpecker MIS surveys on Sierra Nevada national forests: 2010 Annual Report. A report in fulfillment of U.S. Forest Service Agreement No. 08-CS-11052005-201, Modification #2; U.S. Forest Service Pacific Southwest Region, Vallejo, CA.
  • Siegel, R.B., M.W. Tingley, R.L. Wilkerson, and M.L. Bond. 2012. Assessing home rangesize and habitat needs of Black-backed Woodpeckers in California: 2011 Interim Report. Institute for Bird Populations. A report in fulfillment of U.S. Forest Service Agreement No. 08-CS-11052005-201, Modification 3; U.S. Forest Service, Pacific Southwest Region, Vallejo, CA.
  • Siegel, R. B., M. W. Tingley, R. L. Wilkerson, M. L. Bond, and C. A. Howell. 2013. Assessing home range size and habitat needs of Black-backed Woodpeckers in California: Report for the 2011 and 2012 field seasons. Report to USFS Pacific Southwest Region. The Institute for Bird Populations, Point Reyes Station, CA.
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Comment: This chapter describes fire and fire behavior from the point of view of fire suppression. This chapter should be discussion in detail of the role of the drivers and shapers of SN forest ecosystems. Fire should be described in its evolutionary context as the primary shaper of SN biodiversity and plant succession; demonstrating the need for getting fire restored to the SN landscape. This is the place to describe the evidence for fire adaptation build into the SN ecosystem. Here is where the document needs to build the scientific basis for restoring fire. This section should be describing all the ways that fire shapes the ecosystem up and down the food chain, and describing in detail the cascading effects of lack of fire (diseases; increased high intensity fire; loss of species and the domino effect of such losses). This chapter should be building a case for more prescribed fire and more wildland use fire.


See additional sections above on ecological role of fire and fire resilience. See also Chapter 1, Ecological Integrity and subsection on fire as an ecological process.


References

  • Collins, B. M., Everett, R. G., & Stephens, S. L. 2011. Impacts of fire exclusion and recent managed fire on forest structure in old growth Sierra Nevada mixed-conifer forests. Ecosphere, 2(4), Article 5, 1-14.
  • Stephens, S. L., Martin, R. E., and Clinton, N. E. 2007. Prehistoric fire area and emissions from California’s forests, woodlands, shurblands, and grasslands. Forest Ecology and Management 251(3): 205-216.
  • North, M., Stine, P., O’Hara, K., Zielinski, W., and Stephens, S. 2009. An Ecosystem Management Strategy for Sierran Mixed-Conifer Forests. Gen. Tech. Rep. PWS-GTR-220. Albany, California: U. S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.
  • North, Malcolm, ed. 2012. Managing Sierra Nevada Forests. Gen. Tech. Rep. PSW-GTR-237. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 184 p.
  • North, M., Collins, M., and Stephens, S. North, M., Collins, M., and Stephens, S. 2012. Using fire to increase the scale, benefits, and future maintenance of fuels treatments. J. For. 110(7):392–401
  • Silvas-Bellanca, K. 2011. Ecological Burning in the Sierra Nevada: Actions to Achieve Restoration http://www.sierraforestlegacy.org/Resources/Conservation/FireForestEcology/FireScienceResearch/FuelsManagement/FM-SFLFireWhitePaper2011.pdf
  • Webster, K. M., & Halpern, C. B. 2010. Long-term vegetation responses to reintroduction and repeated use of fire in mixed-conifer forests of the Sierra Nevada. Ecosphere, 1(5), Article 9.

Trends in Number of Fires and Acres Burned 1993-2012


This trend analysis covers nine National Forests and 1 Management Unit in the Sierra Nevada and Southern Cascades bioregion. This encompasses the Eldorado, Inyo, Lassen, Modoc, Plumas, Sequoia, Sierra, Stanislaus, Tahoe National Forests, and Lake Tahoe Basin Management Unit.
“The number and extent of wildfires in the western United States each season are driven by natural factors such as fuel availability, temperature, precipitation, wind, humidity, and the location of lightning strikes, as well as anthropogenic factors. It is well known that climate fluctuations significantly affect these natural factors, and thus the severity of the western wildfire season, at a variety of temporal and spatial scales.” (Westerling et al. 2002). The size of fires is also influenced by the number, type, and location of both initial and extended attack suppression resources.

Although there is variability from year to year, the long term trends for this bioregion in the number of fires and total acres burned over the past 20 years indicate:
  • Ø While the number of fires is decreasing, the total acres burned are increasing.


Chap3_Fire_07.jpg

A review of the fires under 300 acres (fire size class A, B, C, and D) for the bioregion has the following trend:

  • Ø There is a decrease in both the number of fires and acres burned.

Chap3_Fire_08.jpg


A review of the fires over 300 acres (fire size class E, F, and G) for the bioregion has the following trend:

  • Ø There is an increase in both the number of fires and acres burned. This is attributable to the 2008 fire season which saw the highest number of fires and acres burned in the past 20 years. When the 2008 data is removed, the number of fires decrease slightly, and acres burned have a flat line trend.

Chap3_Fire_09.jpg

Trends in Acres Burned and Emergency Suppression Expenditures 2005-2012


Fire suppression expenditure data was analyzed for the years 2005-2012. During that 7 year period the total acres burned increased, once again attributed to the record setting 2008 fire season. However, the suppression expenditures exhibit a downward trend.

Chap3_Fire_10.jpg
A very similar trend emerges when comparing fire suppression expenditures to acres burned for fires greater than 300 acres in size (fire size class E, F, and G). While the acres burned trend increased, the suppression expenditures also exhibit a downward trend.

Chap3_Fire_11.jpg
Suppression expenditures per acre for the bioregion also exhibit a downward trend. This trend was also noted in the research paper “Forest Service Large Fire Area Burned and Suppression Expenditure Trends, 1970–2002” (Calkin et al. 2005) which analyzed all USDA Forest Service data from 1970-2002.

Chap3_Fire_12.jpg

References

  • Calkin, D.E., K. Gebert, J.G. Jones, AND R.P. Neilson. 2005. Forest Service Large Fire Area Burned and Suppression Expenditure Trends, 1970–2002. Journal of Forestry. 181.
  • Westerling, A.L., A. Gershunov, T.J. Brown, D.R. Cayan, and M.D. Dettinger. 2003. Climate and wildfire in the Western United States. Bull. Am. Meteorol. Soc. 84(5):595.

Trends in Climate-Fire Interactions


Climate warming is expected to increase wildfire activity in the western U.S. over the next century (Flannigan et al. 2000, Westerling et al. 2006, Miller et al. 2008). Forecasting into the future beyond very short-term is difficult. Looking backward at the fire and climate record provides a frame of reference for future expectations. In the past decade a variety of research has been conducted assessing the historic correlation of climate variables such as precipitation with wildfire activity. Most of these studies involve dendrochronological techniques and fires scar time series reconstructions (Norman and Taylor, 2003,Taylor and Beaty, 2005, Kitzberger et al. 2007, Vaillant and Stephens, 2009). Historically, years with widespread drought have been shown to have widespread fires (Kitzberger et al. 2007, Taylor et al., 2008, Trouet et al., 2006). In some regions, such as the Sierra Nevada and the Southwest (SW), wet years preceded years with the most widespread fire synchrony (Kitzberger et al. 2007, Taylor and Beaty, 2005). Taylor and others (2008) did not find this in Southern Cascades, nor did Kitzberger and others (2007) in the Pacific Northwest (PNW). Projecting future expectations in terms of fire- climate relationships over the next 20 years may be especially useful for ongoing and upcoming forest plan revisions. Opportunistic strategies employing maximum flexibility will have the highest probability of success in meeting fuels and restoration objectives.

Climate systems and their relationships with natural processes, like wildfire, are complex interacting forces that are not easily separated. As stated above, variability in precipitation and drought appear to be major drivers of wildfire activity across the western U.S. Here, we discuss three major contributors to precipitation patterns to the Sierra Nevada region: El Niño- Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and the Atlantic Multi-decadal Oscillation (AMO). All three of these phenomena are indices of sea surface temperature (SST) anomalies, represented as positive (warm) and negative (cool) phases. They can interact with each other, causing moderating or synergistic effects (Kitzberger et al., 2007, McCabe et al., 2004). There are many other ocean-atmospheric patterns and teleconnections that may impact fire-climate relationships, such as the Pacific–North American teleconnection (PNA), Southern Oscillation Index (SOI), among others. For brevity and simplicity, here we explore only ENSO, PDO, and AMO.

ENSO is affected by SST in the Pacific Ocean off the west coast of South America. A complete cycle lasts from two to a few years, each phase lasting from 9 to 24 months. The positive ENSO phase is known as El Niño, and the negative phase La Niña. ENSO extremes have been associated with extreme drought and flooding. El Niño is associated with wet and warm weather in the southwest and cool dry weather in the Pacific Northwest (Taylor et al, 2008). La Niña produces opposite effect. As of February 2013, ENSO neutral conditions prevail and are expected to continue through the spring (http://www.cpc.ncep.noaa.gov/) (Figure 1).

Chap3_Fire_13.jpg
Weekly sea surface temperature anomalies associated with ENSO. From: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstweek_c.gif

SST anomalies in the northern Pacific Ocean above 20o N influence the PDO index, and phase changes occur roughly every 20 years (Kitzberger et al., 2007). Positive PDO is associated with wet weather in the Southwest and warm dry weather in the Pacific Northwest (Trouet et al., 2006, Taylor et al., 2008). Negative PDO conditions are generally opposite the positive phase. The PDO recently went to the negative phase.

Chap3_Fire_14.jpg
Pacific Decadal Oscillation SST anomalies from: http://www.ncdc.noaa.gov/teleconnections/pdo/

AMO occurs in the North Atlantic Ocean on about a 60 year phase length. A positive AMO is associated with increased frequency of widespread droughts. However, when the AMO is negative, dry conditions often prevail in the Pacific Northwest (Kitzberger et al, 2007). The AMO is currently in the warm phase, since the mid-late 1990s .


Chap3_Fire_15.jpg
Atlantic Multidecadal Oscillation annual SST anomalies from: http://www.intellicast.com/Community/Content.aspx?a=127

Potential Fire-Climate Interaction Impacts to the Bioregion

The positive phase of the AMO is expected to persist through the next 20 year planning period (McCabe et al. 2004). This supports the likelihood of increased frequency of widespread droughts in the U.S., including some parts of the West. However, drought conditions might be moderated by the negative PDO phase (McCabe et al 2004). McCabe and others (2004) further state that when both the AMO and PDO are positive, there is elevated potential for droughts similar to those experienced in the 1930s. Additionally, the current positive AMO may indicate widespread fire synchrony in the West in the coming decades (Kitzberger et al. 2007).
ENSO contributes to a see saw pattern of precipitation variability pivoting around 40o north (Dettinger et al., 1998). This creates asynchronies in fire activity between the SW and PNW (Trouet et al., 2006, Taylor et al., 2008). Southern portions of the bioregion are most likely to share synchrony with the SW, while northern portions of the bioregion can be expected to synchronize more with the PNW.

Positive AMO and negative PDO we are currently experiencing may lead to widespread fire synchrony in the SW, and this may impact the southern portion of the bioregion in a similar fashion, depending on how the pattern is set up in relation to the dipole around the north-central portion of the region (~40-45o N). For the northern portion of the bioregion, the negative PDO may moderate the effects of the positive AMO. However, when the PDO shifts phases again, the northern portion should be expected to synchronize with the PNW and fire activity may increase. Couple these with shorter-term precipitation fluctuation associated with ENSO, and fire activity may exhibit even more extremes depending on alignment of the multiple factors.

Climate shifts due to ENSO and PDO may be evident in the weather record. Figures 4, 5, and 6 show a time series for annual precipitation and for maximum and minimum temperatures (respectively) for four hydrologic units in the Sierra Nevada Bioregion. Precipitation patterns (Figure 4) appear to be fairly stable but with high interannual variability, possibly due to ENSO. Maximum temperatures (Figure 5) show fluctuations over decades, most notably an apparent downward trend over the last decade, consistent with the PDO phase change to negative. Minimum temperatures (Figure 6) are consistently on an upward trend, although some hydrologic unit time series appear to indicate declines over the last few years (North Lahontan and North Mojave-Mono Lake). Rising minimum temperatures increase rain: snow ratios, produce longer fire seasons, and earlier soil and fuels drying.

Annual precipitation time series for four of the hydrologic units associated with Portions of the Sierra Nevada Bioreigion. From WestMap: http://www.cefa.dri.edu/Westmap/Westmap_home.php

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Annual maximum temperature time series for four of the hydrologic units associated with Portions of the Sierra Nevada Bioreigion. From WestMap: http://www.cefa.dri.edu/Westmap/Westmap_home.php
Chap3_Fire_17.jpg

Annual minimum temperature time series for four of the hydrologic units associated with Portions of the Sierra Nevada Bioreigion. From WestMap: http://www.cefa.dri.edu/Westmap/Westmap_home.php

Chap3_Fire_18.jpg

It is clear that warm weather and dry conditions are important factors contributing to elevated fire activity in the West. The coincidence of drought and warm weather varies over time and geographic area, and these variations are strongly influenced by climate patterns of varying temporal periodicity. Forecasting climate variability based on these climate phenomena is challenging, since the phases of each differ in length, and other factors undoubtedly contribute to the challenge of forecasting. However, the current positive AMO and negative PDO provide a level of forecasting confidence for the next decade. Monitoring ENSO conditions is critical for seasonal assessments for fire planning.

In order to monitor ENSO and utilize forecasts for planning and scheduling treatments, the Climate Prediction Center provides discussions and predicted ENSO conditions at: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html. A useful standardized index for examining the historic ENSO pattern is the multivariate ENSO index (MEI). Using principal components analysis and clustering, MEI relates a variety of Pacific Ocean variables (Figure 8). MEI shows that warm events are more dominant since 1976. This shift in ENSO climate has increased the frequency of cold and wet seasons in the southwest, and increased the frequency of drought in the pacific northwest. Brown and Betancourt (2000) attribute this shift with a surge of tree recruitment in the southwest, and a pulse of tree mortality in the pacific northwest.

An index of six observed variables (such as pressure, air and sea-surface temperatures, winds, cloudiness) over the tropical Pacific is used to monitor the coupled ocean-atmosphere phenomenon known as the El Ni ño-Southern Oscillation (ENSO). Areas with large positive values of the index (large red spikes) depict the "El Niño" warm phase of the ENSO phenomenon. [From the NOAA Climate Diagnostics Center]

Chap3_Fire_19.jpg


Other tools that may assist treatment scheduling include precipitation probability graphs, figure below, that users can create at the Western Regional Climate Center (WRCC) website (http://www.wrcc.dri.edu/cgi-bin/PCPNdur_form.pl?).

Precipitation probability for less than or equal to 0.10 inch of precipitation over 5, 10, and 30 day period at Groveland Ranger Station, California. Graph produced at Western Regional Climate Center website (http://www.wrcc.dri.edu/cgi-bin/PCPNdur_form.pl?).

Chap3_Fire_20.jpg

Climate variation can hinder or aid in fuels treatment and or fire management. Knowledge of past, present and future climate conditions is essential to managers seeking to protect communities and resources and to restore ecosystem processes. Strategies need to be flexible and opportunistic to take advantage of favorable conditions when they occur, or to shift efforts to other treatments or areas when conditions are not suitable. Shown here are just a few of the readily available tools that can assist in planning, scheduling, and implementing fuel and fire treatments. To see in depth descriptions of these and other climate and smoke management related tools, see Brown and Betancourt (2000). The WRCC provides Information specific to climate in the Western U.S. (http://www.wrcc.dri.edu) and for information related specifically to fire and ecosystem management see the Program for Climate, Ecosystem and Fire Applications (http://www.dri.edu/ASC/CEFA).

Trends in Fire Occurrence and Probability

In progress


The quantitative measures for the extent of salvage logging and plantations in the forest is not addressed anywhere in this document or fire section. There needs to be a discussion about their role in contributing to fire hazard and fuel loading; their role in homogenizing forest ecosystems (see SNEP, eg: “The primary impact of 150 years of forestry on middle-elevation conifer forests has been to simplify structure (including large trees, snags, woody debris of large diameter, canopies of multiple heights and closures, and complex spatial mosaics of vegetation), and presumably function, of these forests.” (SNEP, Summary, pg. 6). These descriptions of complex forests apply to fire hazard as well, because fire behaves differently in complex forests, leaving the post-fire landscape more complex as well. Fire in homogenized habitats results in increasing the conditions facilitating further homogenization: this is a feedback loop. When salvage logging and plantation establishment is added on, the condition is further exacerbated. The cumulative impact of these intersecting stressors needs to be addressed.


SEE:

  • David Lindenmayer, Philip Burton, and Jerry Franklin (Island Press, 2008). Salvage Logging and Its Ecological Consequences.
  • Swanson, M.E. et al. 2010. The forgotten stage of forest succession: early-successional ecosystems on forest sites. Frontiers Ecol Environ 9(2): 117–125.\


Summary of Trends in Fire and Associated Uncertainty

There have been a notable number of very large, high severity fires in the western U.S. in the past several decades (Westerling et al. 2006). There is also evidence that both total area and the area in high severity fire in the Sierra Nevada bioregion in yellow pine and mixed conifer forests are increasing (Miller et al. 2009), although the amount and severity of fire in any one year is widely varying. Miller et al. (2009) did not find significant changes in fire severity in red fir forests.

While the size of fires and their severity have increased in recent years, the total acreage burning annually is still far below pre-european levels estimated in the previous centuries based on dendrochronology and other historical records (Stephens et al. 2007). What is notable in the changes in high severity fire, particularly in the yellow pine and mixed conifer forests, is that these acres are all now clumped in a few large fires spread across the region vs. in small patches spread through the vast acreage that burned annually. Although there can be undesirable ecological and human effects associated with large fires with extensive patches of high severity fire, not all effects are negative. Areas that burn at high severity provide critical habitat for a vast array of wildlife species, including a number of species that are rare and/or declining in the Sierra Nevada (Burnett et al. 2011, Seavy et al. 2012).


Attributing what causes changes in fire is more difficult than measuring and analyzing the changes (Holmes et al. 2008, Westerling et al. 2006). The two most commonly attributed causes to increases in area burned or fire severity are changes in vegetation/fuels amount and distribution and climate or fire season weather (Westerling et al. 2006). The only constant aspect of climate is that it is always changing. In the recent century and into the immediate future, there have been well documented trends of warming, sometimes drying, and in the Sierra Nevada bioregion, especially early spring snowmelt (Westerling et al. 2006, Westerling and Bryant 2008). These result in longer fire seasons, drier fuels, and in general conditions more conducive to fire ignition and spread. At the same time, there have been documented increases in vegetation density, continuity, and overall fuel loading in many lower and mid-elevation forests in the bioregion (McKelvey et al. 1996, van Wagtendonk and Fites-Kaufman 2006). Both of these factors likely contribute to increased fire area and also increased severity. Increases in area burned have been linked with climate change in historic records, based on dendrochronology, when fuel loads were lower and patchier (Swetnam and Baisan 2002). Current, greater, fuel conditions, may make landscapes more sensitive to climatic changes (Westerling et al. 2006). Most importantly, in considering the ecological, resource value, and human effects of fire, the higher fuel conditions lead to more uniformly severe fires than are typically desirable.

The Sierra Nevada and northeastern California have been noted as one of the particularly vulnerable areas in the western US to the likelihood of future fire increases (Westerling and Bryant 2008). There are uncertainties associated with predicting what kinds of climate changes will occur in the future. If current trends in earlier spring snowmelt persist, as predicted by numerous models and studies, then there are related predictions that this may result in more ignitions turning into fires from lightning alone, according to a study in Yosemite National Park (Lutz et al. 2008). Lutz et al. (2008) also predict greater fire severity, consistent with trends in the last few decades observed by Miller et al. (2009).

On the other hand, if conditions become warmer and wetter as a result of climate change, as predicted in some studies, then a decrease in fire may occur (Gonzalez et al. 2010; Hamlet at el. 2007; Krawchuk et al. 2009; Liu et al. 2010; McKenzie et al. 2004; Mote 2003)

Some climate vulnerability assessments currently being conducted suggest that upper montane red fir forests may be more vulnerable. Whether this will result in increasing trends of fire severity is unknown.
There is always some level of uncertainty with how much, where and what kind of fire will occur in any one year. This makes predicting trends into the future difficult at best. Trends in the recent past provide some insight, but are no guarantee that the future will follow these trends closely. Trends in fire could continue on the same upward course on the average and with greater swings in extremes, or the trends could increase or decrease in rate.

Element
Drivers/Stressors Affecting
Trend
Uncertainty in Trend
Sources
Fire size
Climate, vegetation succession, increase in population
Increase in extremes
moderate
Brown et al. 2004; Miller et al. 2009
Area burned
ibid
increase
moderate
Westerling et al. 2006;
Area burned at high severity
Climate, vegetation succession
increase
moderate
Miller et al. 2009; Lutz et al. 2009;
Fire season intensity (Energy Release Component) and length
Climate change
increase
moderate
Westerling et al. 2006, Lutz et al. 2009; Brown et al. 2004
Effects of fire to Wildland Urban Interface (potential property damage)
Increasing fire season, severity, and population growth
Increase, particularly in northern Sierra Nevada
moderate
Westerling and Bryant 2008

Restoration Pace and Scale

Restoration to lessen fire threat to wildland urban interfaces, reduce large, high severity fires, or to reintroduce low to moderate severity fire all entail addressing far more acres than are currently managed (Collins and Skinner 2013: Science Synthesis Chapter 4.1). North et al. (2012) estimated that current treatment rates (including wildfires of all severities) is at a rate less than 20% of what burned historically. This strongly suggests that both the pace and scale needs to be increased to affect change in fire resilience.

Currently a small fraction, less than 5%, of the landscape is treated. This has not been effective in restoring forests so that when intense fires burn through during the hottest and driest, or windiest weather, habitat and ecological integrity is maintained. While strategically placed fuel treatment zones reduce fire intensity and spread, and improve effectiveness of firefighting, they only affect a small part of the landscape. Reduction of forest density and increasing forest patchiness or “heterogeneity” across more of the landscape in the lower and middle elevations will be needed to effectively change fire intensity and tree kill to levels that provide for ecological integrity. Fire prediction models do not account for the more extreme, explosive fires that are becoming more common (Brown et al. 2004, Westerling et al. 2006, Westerling and Bryant 2008, Westerling and Bryant 2008)). One tool is currently in development by Westerling and others as part of a USDA research grant. It links the probability of very large, very severe fires with changing climate and proportion of the landscape in fire resilient states (condition classes – Barrett et al. 2010) (Westerling, personal communication).

Social, economic and ecological issues all play a role in determining the scope and pace of restoration of fire resilience. Controversy around smoke (Bytnerowicz et al. 2013: Science Synthesis Chapter 8); ecological effects of different types, locations and extents of treatments to owls (Keane 2013: Science Synthesis Chapter 7.2), and forest carnivores (Zielinski 2013: Science Synthesis Chapter 7.1); and likelihood to affect change with different treatment objectives and configurations (Collins and Skinner 2013; Science Synthesis Chapter 4.1; North 2013 2013; Science Synthesis Chapter 2). Institutional capacities and fire policy also influence the type, pace and scale of restoration. In the past decades, there has been cooperation of federal and state fire management and forest management agencies to jointly address fire management issues. Changes in the patterns of fire to increasingly large, high severity fires, in proximity of wildland urban interfaces has made shifting practices on the ground to match policy difficult (Caulkin et al. 2005). Climate trends will increase the need for restoration. The Sierra Nevada and northeastern California have been noted as one of the particularly vulnerable areas in the western US to the likelihood of future fire increases (Westerling and Bryant 2008). Current, greater, fuel conditions, may make landscapes more sensitive to climatic changes (Westerling et al. 2006).

References


  • Brown, T. J., Hall, B. L., & Westerling, A. L. 2004. The impact of twenty-first century climate change on wildland fire danger in the western United States: an applications perspective. Climatic Change, 62(1), 365-388.
  • Gonzalez, P., R.P. Neilson, J.M. Lenihan, and R.J. Drapek. 2010. Global patterns in the vulnerability of ecosystems to vegetation shifts due to climate change. Global Change and Biogeography 19:755-768
  • Hamlet, A.F., P.W. Mote, M.P. Clark, D.P. Lettenmaier. 2007. Twentieth-century trends in runoff, evapotranspiration, and soil moisture in the western United States. Journal of Climate 20:1468-1486.
  • Holmes, T. P., Huggett, R. J., & Westerling, A. L. 2008. Statistical analysis of large wildfires. The Economics of Forest Disturbances, 59-77
  • Krawchuk, M.A., M.A. Moritz, M. Parisien, J. Van Dorn, and K. Hayhoe. 2009. Global pyrogeography: the current and future distribution of wildfire. PloS ONE 4: e5102.
  • Liu, Y., J. Stanturf, and S. Goodrick. 2010. Trends in global wildfire potential in a changing climate. Forest Ecology and Management 259:685-697.
  • Lutz, J. A., van Wagtendonk, J. W., Thode, A. E., Miller, J. D., & Franklin, J. F. 2009. Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA. International Journal of Wildland Fire, 18(7), 765-774.
  • McKenzie, D., Z. Gedalof, D.L. Peterson, and P. Mote. 2004. Climatic change, wildfire, and conservation. Conservation Biology 18: 890-902.
  • Mote, P.W. 2003. Trends in temperature and precipitation in the Pacific Northwest during the twentieth century. Northwest Science 77:271–282.
  • Swetnam, T. W., & Baisan, C. H. 2002. 6. Tree-Ring Reconstructions of Fire and Climate History in the Sierra Nevada and Southwestern United States. Fire and Climatic Change in Temperate Ecosystems of the Western Americas, 160, 158.
  • Westerling, A. L., & Bryant, B. P. 2008. Climate change and wildfire in California. Climatic Change, 87, 231-249.
  • Westerling, A. L., Hidalgo, H. G., Cayan, D. R., & Swetnam, T. W. 2006. Warming and earlier spring increase western US forest wildfire activity.Science, 313(5789), 940-943.



References (incomplete)

  • Agee, J. 1996. Fire ecology of Pacific Northwest forests. Island Press.
  • Berg, N.H. and Azuma, D.L. 2010. Bare soil and rill formation following wildfires, fuel reduction treatments, and pine plantations in the southern Sierra Nevada, California, USA. International Journal of Wildland Fire 19(4): 478-489.
  • Burnett, R.D. M. Preston, and N. Seavy. 2012. Plumas-Lassen Administrative Study 2011 Post-fire Avian Monitoring Report. http://data.prbo.org/apps/snamin/uploads/images/fire/PRBO%20PLAS%202011%20Post%20Fire%20Report.pdf
  • Cook, E. R., & Kairiukstis, L. A. (Eds.). 1990. Methods of dendrochronology: applications in the environmental sciences. Springer.
  • Fulé, P. Z., Heinlein, T. A., Covington, W. W., & Moore, M. M. 2003. Assessing fire regimes on Grand Canyon landscapes with fire-scar and fire-record data. International Journal of Wildland Fire, 12(2), 129-145.
  • Hann, W.J. and D. J. Strohm. 2003. Fire Regime Condition Class and Associated Data for Fire and Fuels Planning: Methods and Applications. In: USDA Forest Service Proceedings RMRS-P-29. 2003.
  • LANDFIRE. 2007, January. (last update).[Homepage of the LANDFIRE Project, U.S. Department of Agriculture, Forest Service; U.S. Department of Interior], [Online]. Available: http://www.landfire.gov/index.php [2012, December 4, 2012].
  • Lutz, J., van Wagtendonk, J., Thode, A., Miller, J. and Franklin, J. 2009. Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA. International Journal of Wildland Fire 18: 765-774.
  • Miller, J.D. and Thode, A.E. 2007. Quantifying burn severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR). Remote Sensing of Environment 109(1): 66-80.
  • Miller, J.D. and Safford, H.D. 2008. Sierra Nevada Fire Severity Monitoring: 1984-2004. USDA Forest Service, Pacific Southwest Region, Vallejo, CA. R5-TP-027: 102pp.
  • Miller, J.D., Safford, H.D., Crimmins, M.A. and Thode, A.E. 2009a. Quantitative evidence for increasing forest fire severity in the Sierra Nevada and southern Cascade Mountains, California and Nevada, USA. Ecosystems 12(1): 16-32.
  • Miller, J.D., Knapp, E.E., Key, C.H., Skinner, C.N., Isbell, C.J., Creasy, R.M. and Sherlock, J.W. 2009b. Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire severity in the Sierra Nevada and Klamath Mountains, California, USA. Remote Sensing of Environment 113(3): 645-656.
  • Miller, J.D. and Safford, H.D. 2012. Trends in wildfire severity 1984-2010 in the Sierra Nevada, Modoc Plateau, and southern Cascades, California, USA. Fire Ecology in press.
  • Miller, J.D., Collins, B.M., Lutz, J.A., Stephens, S.L., van Wagtendonk, J.W. and Yasuda, D.A. 2012. Differences in wildfires among ecoregions and land management agencies in the Sierra Nevada region, California, USA. Ecosphere 3(9): art80.
  • Parsons, A., Robichaud, P.R., Lewis, S.A., Napper, C. and Clark, J.T. 2010. Field guide for mapping post-fire soil burn severity. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. General Technical Report. RMRS-GTR-243: 49pp.
  • Seavy, N., R. Burnett, and P. Taillie. 2012. Black-backed woodpecker nest-tree preference in burned forests of the Sierra Nevada, California. Wildlife Society Bulletin 36:722-728.
  • Stokes, M. A., & Smiley, T. L. 1996. An introduction to tree-ring dating. University of Arizona Press.
  • Thode, A.E. 2005. Quantifying the Fire Regime Attributes of Severity and Spatial Complexity Using Field and Imagery Data. Davis, CA, University of California. PhD.
  • Scott, J. 1998. Fuel reduction in residential and scenic forests: A comparison of three treatments in a western Montana ponderosa pine stand. USDA Forest Service, Rocky Mountain Research Station, Research Paper. RMRS-RP-5.
  • Sugihara, N., J. van Wagtendonk, J. Fites-Kaufman. 2006. Chapter 4. Fire as an Ecological Process. In Fire in California Ecosystems. Edited by: N. Sugihara, J. van Wagtendonk, J. Fites-Kaufman, A. Thode, and K. Shaffer. UC Press, Berkeley, CA. pp. 103-134.
  • Thode, A.E., van Wagtendonk, J.W., Miller, J.D. and Quinn, J.F. 2011. Quantifying the fire regime distributions for severity in Yosemite National Park, California, USA. International Journal of Wildland Fire 20(2): 223-239.
  • Van de Water and H.D. Safford. 2011. A summary of fire frequency estimates for California vegetation before Euro-American Settlement. Fire Ecology (7) 3: 26-58.
  • Safford, H. D., Miller, J., Schmidt, D., Roath, B., & Parsons, A. 2008. BAER soil burn severity maps do not measure fire effects to vegetation: a comment on Odion and Hanson (2006). Ecosystems, 11(1), 1-11.
  • Van de Water, K. M., & Safford, H. D. 2011. A summary of fire frequency estimates for California vegetation before Euro-American settlement. Fire Ecology, 7(3), 26-58.

Additional climate change/fire references to consider (reviewed in TACCIMO: **http://goo.gl/Lg3Bn**)):

  • Beaty, R. M. & Taylor, A. H. 2008. Fire history and the structure and dynamics of a mixed forest landscape in the northern Sierra Nevada, Lake Tahoe Basin, California, USA. Forest Ecology and Management, 225, 707 – 719.
  • Bryant, B. & Westerling, A. \2009. Potential effects of climate change on residential wildfire risk in California. California Energy Commission Public Interest Energy Research Program , CEC-500-2009-048-F, 1-30.
  • Cayan, D., Luers,A. L., Hanemann, M., Franco, G., & Croes, B. 2006. Scenarios of climate change in California: An overview. California Energy Commission, PIER Energy-Related Environmental Research Program, CEC-500-2005-186-SF, 53pp.
  • Collins, B. M. & Stephens, S. L. 2012. Fire and fuels reduction. In M. North, Malcolm, ed. Managing Sierra Nevada forests. General Technical Report PSW-GTR-237. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research
  • Fried, J. S., Torn, M. S. & Mills, E. 2004. The impact of climate change on wildfire severity: A regional forecast for Northern California. Climatic Change, 64, 169 – 191.
  • Gardali, T., Howell, C. A., Seavy, N. E. Shuford, W. D. & Stralberg, D. 2011. Projected effects of climate change in California: Ecoregional summaries emphasizing consequences for wildlife, Version 1.0. Petaluma, CA: PRBO Conservation Science. 68pp. http://data.prbo.org/apps/bssc/climatechange
  • Holmes, K. A., Veblen, K. E., Young, T. P. & Berry, A. M. 2008. California oaks and fire: A review and case study. In A. Merenlender, D. McCreary & K. L. Purcell, Kathryn L., tech. eds. Proceedings of the sixth California oak symposium: today's challenges, tomorrow's opportunities. General Technical Report PSW-GTR-217. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.
  • Hurteau, M., & North, M. 2008. Mixed-conifer understory response to climate change, nitrogen, and fire. Global Change Biology, 14. doi:10.1111/j.1365-2486.2008.01584.x
  • Karl, T. R., Melillo, J. M., & Peterson, T. C. 2009. Global climate change impacts in the United States. New York, NY, USA: Cambridge University Press.
  • Lawson, D. M., Regan, H. M., Zedlers, P. H., & Franklin, J. 2010. Cumulative effects of land use, altered fire regime and climate change on persistence of Ceanothus verrucosus, a rare, fire-dependent plant species. Global Change Biology, 16, 2518-2529. doi: 10.1111/j.1365-2486.2009.02143.x
  • Lenihan, J. M., Bachelet, D., Neilson, R. P., & Drapek, R. 2008. Response of vegetation distribution, ecosystem productivity, and fire to climate change scenarios for California. Climatic Change, 87 (Suppl. 1), S215-S230.
  • Lenihan, J. M., Drapek, R., Bachelet, D., & Neilson, R. P. 2003. Climate change effects on vegetation distribution, carbon, and fire in California. Ecological Applications, 13(6), 1667-1681.
  • Lenihan, J. M., Bachelet, D., Drapek, R., & Neilson, R. P. 2006. The response of vegetation distribution, ecosystem productivity, and fire in California to future climate scenarios simulated by the MC1 dynamic vegetation model. California Energy Commission, PIER Energy-Related Environmental Research Program, CEC-500-2005-191-SF, 25pp.
  • McKenzie, D., Gedalof, Z., Peterson, D. L., & Mote, P. 2004. Climatic change, wildfire, and conservation. Conservation Biology, 18(4), 890-902.
  • Miller, C. & Urban, D. L. 1999. Forest pattern, fire, and climatic change in the Sierra Nevada. Ecosystems, 2, 76-87.
  • Running, S. W. 2006. Is global warming causing more, larger wildfires? Science, 313, 927-928.
  • Taylor, A. H., & Beaty, R. M. 2005. Climatic influences on fire regimes in Northern Sierra Nevada mountains, Lake Tahoe Basin, Nevada, USA. Journal of Biogeography, 32, 425-438.
  • Westerling, A. L., Bryant, B. P., Preisler, H. K., Holmes, T. P., Hidalgo, H. G., Das, T., & Shrestha, S. R. 2009. Climate change, growth, and California wildfire. California Energy Commission Public Interest Energy Research (PIER) Program, CEC-500-2009-
  • Westerling, A. L. & Bryant, B. P. 2008. Climate change and wildfire in California. Climatic Change, 87 (Suppl 1), S231- S249.
  • Westerling, A. L., Cayan, D. R., Brown, T. J., Hall, B. L. & Riddle, L. G. 2004. Climate, Santa Ana winds and autumn wildfires in southern California. EOS, 85(31), 289 – 300.
  • Wiedinmyer, C., & Hurteau, M. D. 2010. Prescribed fire as a means of reducing forest carbon emissions in the Western United States. Environ. Sci. Technology, 44(6), 1926-1932.
  • Winford, E. M. & Gaither, J. C. 2012. Carbon outcomes from fuels treatment and bioenergy production in a Sierra Nevada forest. Forest Ecology and Management, 282, 1 – 9.

References
  • Brown, T.J., and J.L. Betancourt, 2000. Effect of climate variability and forecasting on fuel treatment schedules in the western U.S. Proceedings Joint Fire Science Conference and Workshop, Vol. II , Boise, ID, 15-17 June 1999, University of Idaho and the International Association of Wildland Fire, 167-172.
  • Dettinger, M.D., D.R. Cayan, H.F. Diaz, and D.M. Meko. 1998. North–South Precipitation Patterns in Western North America on Interannual-to-Decadal Timescales. Journal of Climate; Volume 11, Issue 12 pp. 3095-3111.
  • M.D. Flannigan, B.J. Stocks, and B.M. Wotton. 2000. Climate change and forest fires. The Science of the Total Environment, Vol. 262, 221-229.
  • Kitzberger, T., P.M. Brown, E. K. Heyerdahl, T.W. Swetnam, and T.T. Veblen. 2007. Contingent Pacific–Atlantic Ocean influence on multicentury wildfire synchrony over western North America. PNAS; Vol. 104, no. 2, pp 543-548.
  • McCabe, G.J., M.A. Palecki, and J.L. Betancourt. 2004. Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States. PNAS; Vol. 101, no.12, pp 4136-4141.
  • Miller, J. D., H. D. Safford, M. Crimmins, and A. E. Thode. 2008. Quantitative Evidence for Increasing Forest Fire Severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA. Ecosystems, Volume 12, Issue 1, pp 16-32.
  • Norman, S.P., and A. H. Taylor. 2003. Tropical and north Pacific teleconnections influence fire regimes in pine-dominated forests of north-eastern California, USA. Journal of Biogeography; 30, 1081–1092.
  • Taylor, A.H., and R. M. Beaty. 2003. Climatic influences on fire regimes in the northern Sierra Nevada mountains, Lake Tahoe Basin, Nevada, USA. Journal of Biogeography; 32, 425–438.
  • Taylor, A. H., D, V. Trouet, and C. N. Skinner. 2008. Climatic influences on fire regimes in montane forests of the southern Cascades, California, USA. International Journal of Wildland Fire, 17, 60–71.
  • Trouet, V. ,A. H. Taylor, A.M. Carleton, and C.N. Skinner. 2008. Fire-climate interactions in forests of the American Pacific coast. Geophysical Research Letters, Vol. 33.
  • Vaillant, N.M., and S.L. Stephens. 2009. Fire history of a lower elevation Jeffrey pine-mixed conifer forest in the eastern Sierra Nevada, California, USA. Fire Ecology 5(3): 4-19.
  • Westerling, A. L., H.G. Hidalgo,D.R. Cayan, and T.W. Swetnam. 2006. Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity. Science Vol. 313, 940.


[UFS1]prboburnett1Yesterday 3:14 pm
i believe this is incorrect - the chips fire only burned at about 20% high severity based on initial post fire survey.
Reply
This is based upon the immediate post-fire rapid surveys that reflect needs to remediate soils and potential erosion. See Safford et al. 2008. Fire effects to vegetation are typically mapped after one year. Dr. Jo Ann Fites-Kaufman was present during much of the fire and personally made extensive field observations of immediate post-fire effects to vegetation. Areas that burned at high to moderate intensity had a high proportion of the trees of all sizes where the needles were consumed. This makes it virtually unlikely that they will survive. Areas where needles were scorched and remain on the tree, have varying likelihoods of recovering or surviving depending upon the species and environmental conditions—i.e. soil moisture following the fire.



Current Condition – Insects and Pathogens


Summary

Forest insects and diseases are important disturbance agents in the Sierras, affecting forest structure and composition, nutrient recycling, creation of wildlife habitat, and soil development.

Annual aerial surveys of tree mortality have mapped over 1.3 million affected acres in the ten Sierran National Forests in the last five years. The most important groups in terms of impacts are the bark and engraver beetles, defoliators, Heterobasidion root disease, mistletoes, and white pine blister rust. Only the last of these is non-native.
Trees stressed by drought, increased competition, or other disturbances are most vulnerable to attack from insects and diseases. Often it’s the net effect of multiple agents that leads to tree mortality.

At the landscape scale, insects and diseases tend to be inconspicuous except when biotic and abiotic conditions are conducive of outbreaks. The two most important such conditions are overstocking and drought. The climate over most of the Sierras is expected to get drier in the future, which could lead to profound impacts from insects and diseases unless other sources of tree stress (overstocking; increased fire intensity) are alleviated.

Large areas within the Sierras are showing symptoms of insect and disease outbreaks. The National Insect and Disease Risk Map estimates that over 1.49 million acres are at risk of losing >25% of the standing volume over the next 15 years.

We can also look at the role of insects and fungi in shaping the types of diverse forest snag structure that provides homes for dozens of Sierran forest wildlife species. For example, the pileated woodpecker is a keystone species, a primary cavity excavator, that creates habitat for more than two dozen forest species and secondary cavity nesters (individuals that use cavities but do not create them) (Raphael and White 1984, McClelland and McClelland 1999, Bonar 2001, Aubry and Raley 2002). They also facilitate heart-rot through their excavating and foraging activities and are the primary architects of snag development (Aubry and Raley 2002).

Pileated woodpeckers require extensive forests containing large mature diseased trees and snags, dense forests, and a forest floor littered with decaying wood (e.g. Bull 1975, Schroeder 1982). Ideal habitat provides a relatively humid environment (such as streamsides) that can promote fungal decay and sustain the ant, termite, and beetle populations on which these birds feed. Pileated woodpeckers primarily eat carpenter ants excavated from dead or decayed sap- or heartwood (Bull et al. 1986) but they also eat a variety of beetles and other insects and smaller amounts of plant foods (less than 30 percent) (Beal 1911 in Zeiner et al.1988).

Research in Eastern Oregon found that canopy reduction from natural causes (insect outbreaks) did not affect pileated woodpecker density, as long as extensive logging and fuel reduction had not occurred (Bull et al. 2007). The cavities produced by pileateds are used by fisher, marten, numerous owl species, prey for owl (northern flying squirrel for example), marten, and many other mammals and birds.

Mistletoe, considered a forest pest by forest pathologists, produces berries that are highly sought after food for a variety of birds and mammals, and the brooms provide nesting habitat for a many different birds and mammals, including spotted owls.

Need to add information about the needs of black backed woodpeckers for recently burned forests, and the rich food sources provided by insects that are attracted to forest fires. We get a different outlook about the role of insects and fungi when we think about the ecology of the forest, and are not just thinking about growing trees for lumber production.

References:


  • Coleman, D.C. and P. Hendrix (eds.). 2000. Invertebrates as Webmasters in Ecosystems. CABI Publishing, Wallingford, Oxon, U.K.
  • Mattson, W.J. and N.D. Addy. 1975. Phytophagous insects as regulators of forest primary production. Science 190:515-522.
  • Romme, W.H., D.H. Knight, and J.B. Yavitt. 1986. Mountain pine beetle outbreaks in the Rocky Mountains: Regulators of primary productivity? American Naturalist 127:484-494.
  • Schowalter, T.D. 2000. Insect ecology: An ecosystem approach. Academic Press, San Diego CA.
  • Schupp, E.W. 1988. Seed and early seedling predation in the forest understory and in treefall gaps. Oikos 51:71-7.

Current Condition

The desired state of forest health, in relation to insects and diseases, is the condition in which these agents do not threaten ecosystem structure and function and/or management goals and objectives. Many of the forest ecosystems in the Sierra Nevada are showing serious symptoms of forest health decline. In many areas, fire exclusion, grazing, and logging activities, have combined with environmental and ecosystem changes to create overly dense stands, a loss of age diversity, and an altered mix of vegetation. This alteration of conditions has resulted in an increase in susceptibility to insects, pathogens and weather-induced stresses. Bark and engraver beetles, defoliators, root diseases, mistletoes and an introduced fungus which causes white pine blister rust are important forest insects and diseases throughout the Sierra Nevada range. Ecosystems which are presently outside their natural range of variability may be less resilient to diseases, and attacks by insects.

Historically, the most significant widespread effect on vegetation has been conifer mortality associated with bark beetles and severe moisture stress. Conifer mortality tends to increase when annual precipitation is less than about 80% of normal. Trees stressed by inadequate moisture levels have their normal defense systems weakened to the point that they are highly susceptible to attack by bark, engraver and woodboring beetles. High levels of conifer mortality have frequently been recorded in association with extreme or protracted dought in the Sierra Nevada range (http://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fsbdev3_046696, http://caforestpestcouncil.org/meetings-reports/).

The bark and engraver beetles operating in forested ecosystems are native and have coevolved with their host species. These disturbance agents are generally inconspicuous except during periods when their damage becomes readily apparent over large areas. Bark beetles and engraver beetles are fairly host specific which assists in determining the cause of tree mortality. Red and white fir mortality is associated with attacks by the fir engraver beetle (Scolytus ventralis). Mountain pine beetle (Dendroctonus ponderosae) attacks 5 needle pines, lodgepole and ponderosa pine. Western pine beetle (Dendroctonus brevicomis) attacks ponderosa pine and attacks and Jeffrey pine beetle (Dendroctonus jeffreyi) attacks Jeffrey pine.

Over 1.3 million forested acres in the Sierra Nevada range have experienced some level of tree mortality caused by bark beetles over the past 5 years (http://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fsbdev3_046696) (Table ? and Figure ?). The highest numbers of acres with mortality have been attributed to fir engraver beetle and mountain pine beetle. Effects resulting from bark beetle-caused tree mortality can include openings that vary in size, fewer trees/acre, reduced canopy closure, increase in standing dead and down woody material, increase in fuel load, increase in decomposition and nutrient cycling, increase/decrease in species diversity, and changes in forest structure and species composition. The importance or significance of these effects depends on their severity and extent and ultimately how they affect ecosystem structure and function and specific management goals and objectives.

Number of acres with tree mortality caused by bark beetles for Sierra Nevada forests (2008-2012). Source: Forest Health Protection, Aerial Detection Survey program.
National Forest
Number of acres with some level of tree mortality
Eldorado NF
63,268
Inyo NF
41,156
Lassen NF
319,005
Modoc NF
188,824
Plumas NF
200,709
Sequoia NF
143,018
Sierra NF
158,842
Stanislaus NF
96,054
Tahoe NF
136,929
Lake Tahoe Basin Mgmt Unit
22,562
TOTAL
1,370,367

Defoliating insects are exceeded only by bark beetles in importance as forest insect pests. Douglas-fir tussock moth (Orgyia pseudotsugata), black oak leaf miner (Eriocraniella aurosparsella), the Modoc budworm (Choristoneura viridis) and sawflies (Neodiprion sp.) have been recorded as causing widespread defoliation – and sometimes tree mortality - in the Sierra Nevada range.

Heterobasidion root disease (Heterobasidionsp.)is one of the most important conifer diseases in the Sierra Nevada. Current estimates indicate that the disease infests about 2 million acres of commercial forest land in California resulting in an annual volume loss of 19 million cubic feet (reference). In recreation areas, Heterobasidion root disease-infected trees can be extremely hazardous, causing death or injury to visitors, and damage to property. Ecologically, this root disease decays wood in the butt and roots of trees and recycles nutrients. It can createstand openings and alter forest structure, composition, and succession, thus providing enhanced diversity and improved wildlife habitat for certain species. Comment: Need to draw the link between Heterobasidion and production of snags, cavities, food, and habitat.

Approximately 1.4 million acres of ponderosa pine and Jeffrey pines and 600,000 acres of true fir in California are infected with Heterobasidion sp. H. irregular in incense-cedar and H. occidentale in true fir can cause problems in recreational areas. It had typically been thought that ponderosa and Jeffrey pines were usually killed by the disease before their root systems were extensively decayed and that incense-cedar and true fir usually had extensive decay in the roots before these trees die and could fail while still alive, however, it has recently become apparent that even healthy-appearing pine trees can fail from root decay. Since 2010 on the Lassen National Forest, several apparently healthy mature pine trees blew over in four different areas. Each tree had Heterobasidion-like decay in the roots. All of the trees were in recreation areas or administrative sites where root damage could have provided and entry court for the disease.

Dwarf mistletoes (Arceuthobium spp.) are considered among the most serious forest disease agents in many of the western states and are widespread in the Sierra Nevada range. They are also important food plants, and provide nesting and roosting sites for a variety of birds and mammals. They are a major cause of growth loss and reduced vigor with the degree of growth reduction dependent upon the intensity of infection and the location of the mistletoe in the tree. Dwarf mistletoes can kill trees directly, but it is more common for dwarf mistletoes in conjunction with bark beetles and woodborers to cause the death of heavily infected hosts. Thus mistletoe can contribute to reversing the significant snag deficit occurring in Sierra Nevada forests.

White pine blister rust (Cronartium ribicola) has been devastating to sugar pine since the disease entered northern California around 1930. Although the spread of blister rust in the Sierra Nevada range has been slow and erratic, infections have been reported over the entire range of sugar pine, except for a few isolated populations. All age and size classes of sugar pines are highly vulnerable to the disease, which can eventually result in direct mortality of infestation by mountain pine beetle. This rust also occurs on other five-needle pine species in the Sierra Nevada. In addition, numerous other insects and diseases also affect trees in Sierra Nevada forests (http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_046410.pdf) causing decline, dieback and/or mortality.

Natural Range of Variability/ Trends

Susceptibility of forests to future tree mortality caused by insects and diseases was assessed nationally in 2012 resulting in the National Insect and Disease Risk Map (NIDRM) (http://www.fs.fed.us/foresthealth/technology/nidrm.shtml). The NIDRM was driven by several models used to predict how individual tree species would react to various mortality agents. The models were developed using the interactions of predicted agent behavior and known forest parameters. The most widely used forest parameters for NIDRM were stand basal area, stand density index, and quadratic mean tree diameter. Risk of mortality is defined as the expectation that 25% or more of the standing live volume greater than 1” DBH will die over the next 15 years. In Sierra Nevada forests over 3.5 million acres were determined to be susceptible to high levels of insect and disease-caused mortality based on the 2012 NIDRM (Figure ?).

Continuous (across state and regional borders, coast to coast) vegetation layers were developed for use in the National Insect and Disease Risk Map. Species-specific models were developed that were optimized for each tree species at 30-meter resolution, by utilizing a series of independent variables such as spectral signatures, climate, terrain, soil indices, and many others to predict an individual tree species parameter, such as presence/absence, BA, or SDI (Krist et al. 2013). These species models were developed by analyzing known locations (FIA plots) of tree species, identifying the values of independent variables at those locations, utilizing statistical software to create a model for each tree species, and then applying those models across the landscape to generate species layers. These 30-meter layers were resampled to 240-meter for inclusion in the risk modeling process.

Some issues with the specific host (vegetation) layers have been identified in Region 5. One such issue occurs in areas where similar species, such as ponderosa and Jeffrey pines coexist. The spectral signatures of the species are so similar that the species specific models may not be accurate where the species mix. One known area where this error occurs is on the Lassen National Forest. We hope to rectify this and other vegetation layer issues in the next iteration of species and risk modeling.

Vegetation layers that exist at the Forest or District level may be more accurate than those used in the NIDRM, therefore local validation is highly recommended prior to use of these data in planning efforts. These products were generated for use in a national product, and anomalies at a local rather than a landscape scale may become apparent. Local users of the data should also be aware of the scale. A 30-meter pixel is 0.22 acres; each pixel provides a value for SDI, BA, etc, which may be located anywhere within that area.


Acres determined to be susceptible to high levels of mortality should be surveyed for opportunities for treatment, primarily thinning to reduce stand density, if they occur where higher levels of mortality will affect the ability to meet land management objectives and goals. In general, higher levels of tree mortality may be acceptable on general forest land and in remote or wilderness areas, whereas preventing tree mortality would be preferred in campgrounds, around homes, structures, utility lines, evacuation corridors, and in areas highly susceptible to wildfire. Depending on the stand structure and density, treatments designed to meet fuels treatments alone may not reduce susceptibility to bark beetle-caused mortality. An integrated approach to determining treatment areas, residual tree density, and residual species composition will allow for strategic placement of treatment areas and afford the ability to meet multiple resource objectives with one entry.

Climate

A pattern of decreasing precipitation or changes in the form of the precipitation (e.g. rain instead of snow) may reduce the growth & vigor of vegetation, thereby increasing the susceptibility to mortality caused by insects and diseases. There is abundant evidence that bark beetle caused tree mortality dramatically increases in the Sierra Nevada during extreme or protracted drought periods (http://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fsbdev3_046696, http://caforestpestcouncil.org/meetings-reports/). If droughts become more frequent, of greater intensity, or are more protracted in the future, high levels of bark beetle-caused tree mortality should be expected. In addition, bark beetle population success is influenced directly by temperature effects on insect development (Powell and Logan 2005). Some bark beetle species may be able to complete additional generations in a year and timing of beetle emergence and flight periods may be altered. Stand density and host species composition are also important factors in determining drought effects. Although all stands become increasingly stressed as the drought persists, tree mortality is typically higher in denser stands. Those species less tolerant of drought are likely to be attacked by bark beetles first, followed by attacks to more drought tolerant species.

Most plant pathogens are strongly influenced by environmental conditions and vigor of the host (Kliejunas et al. 2009). Climate change will directly affect the pathogen, the host, and the interaction between them, resulting in disease impacts (Brasier 2005, Burdon et al. 2006). Root pathogens such as Heterobasidion sp.are more aggressive when hosts are stressed, so its incidence and spread could increase (Kliejunas et al. 2009) under future climate regimes. Mistletoes currently play a significant role in tree mortality when trees are stressed by drought and other agents. Surveys in California indicated that trees infected with dwarf mistletoe were the first to die during drought (Byler 1978). If droughts become more frequent, of greater intensity, or are more protracted in the future, mistletoes will continue to cause mortality, be a predisposing factor to attack by bark beetles, and may also expand their range (Kliejunas et al. 2009). Although stem rusts (Cronartium sp.) can adapt to a wide range of environmental conditions, their tolerances are unknown. Under changing climates, the incidence of rusts will be determined chiefly by host distribution. Typically, rusts increase in intensity and distribution in “wave years” during which the weather is especially favorable for sporulation, dispersal, and infection. As climate changes, the frequency of such waves years is expected to change (Kliejunas et al. 2009).

Areas (in red) determined to be susceptible to high levels (>25% of the standing volume) of insect and disease-caused mortality based on the 2012 NIDRM (Source: Meghan Woods, Forest Health Protection). SierraNevada_NIDRM2012.png

Number of acres at risk to >25% of the standing volume to die from insects and diseases over the next 15 years for Sierra Nevada forests.
Sources: http://www.fs.fed.us/foresthealth/technology/nidrm.shtml, http://www.fs.fed.us/foresthealth/technology/pdfs/CA_Workbook_2007.pdf
National Forest
Number of acres at risk to >25% of the standing volume to die over the next 15 years.
Eldorado NF
159,555
Inyo NF
299,525
Lassen NF
703,579
Modoc NF
672,807
Plumas NF
322,255
Sequoia NF
287,455
Sierra NF
469,328
Stanislaus NF
228,131
Tahoe NF
333,016
Lake Tahoe Basin Mgmt Unit
101,099
TOTAL
3,576,750

Key Indicators

Indicator
Agents
Measures
Source
Acres, %, or number of trees affected by native insects and diseases
bark/engraver beetles;
defoliating insects;
root diseases; mistletoes; needle diseases; rusts; cankers
Number of dead trees;
number of defoliated trees;
% infected trees
Aerial surveys; ground surveys; FHP evaluations; CAIDA; FIA data; pertinent literature and reports.
Acres, %, or number of trees affected by abiotic processes (non-fire)
Weather related; ozone

Aerial surveys; ground surveys; FHP evaluations; CAIDA; FIA data; pertinent literature and reports.
Acres, %, or number of trees affected by invasive insects and diseases
White pine blister rust;
% infected trees
Aerial surveys; ground surveys; FHP evaluations; CAIDA: FIA data; pertinent literature and reports.
Acres susceptible to native insects and diseases
(overall risk, % host BA loss, % total BA loss)
bark/engraver beetles
Douglas-fir tussock moth
Heterobasidion sp.
Total SDI, % host, host, QMD, drought frequency
Position index, drainage index, % host, host QMD
Annual temp., annual precip., soil moisture regime, host QMD, % host, host BA, total BA; annual relative humidity
NIDRM pertinent literature and reports.
Acres susceptible to invasive insects and diseases
White pine blister rust; goldspotted oak borer; sudden oak death
Criteria per NIDRM
NIDRM; host range maps; pertinent literature and reports.

Bark Beetles
Native bark beetles are a major cause of tree mortality in the Sierra Nevada. When, where, and the extent to which they cause tree mortality is typically influenced by forest stand conditions and weather patterns. A dramatic increase in the number of dead trees follows one to several years of inadequate precipitation. The more severe and prolonged the drought, the greater the number of dead trees. Dense stands are particularly susceptible to bark beetle attacks due to stress caused by increased competition for limited resources. Stressed trees are suitable host material for bark beetles; their successful colonization results in increased beetle populations and higher levels of tree mortality. Pine bark and engraver beetle-caused mortality occurs primarily in small groups of trees, whereas mortality caused by the fir engraver beetle usually occurs as single trees scattered over several hundred acres. Successful attacks by pine bark beetles almost always result in tree mortality. Successful attacks by the fir engraver can result in top-kill, branch kill, patch kills along the bole and/or whole tree mortality. In general, bark beetle-caused tree mortality occurs in stands with high tree density, however during periods of protracted drought, mortality may be expected to occur in less dense stands as well.

Bark beetles spend most of their lives beneath the bark of their host and are only exposed to outside environments when they mature and disperse to find new hosts. For most conifer species, there is at least one bark beetle that is capable of killing the tree under the right conditions. Bark beetles are fairly opportunistic and usually require their hosts to be under some form of physiological stress for colonization to be successful. Some of the typical agents of stress in addition to drought include defoliating insects, various tree diseases that weaken hosts, or a number of abiotic agents (air pollution, fire, wind damage, mechanical injury, etc.) which lower tree defenses. Populations of bark beetles can fluctuate dramatically from year to year depending on the degree to which stress agents are operating in the forest. Available food source (i.e. the availability of stressed trees) is the ultimate regulator of bark beetle populations.

Defoliating Insects

Defoliating insects are exceeded only by bark beetles in importance as forest insect pests. The larvae feed on and in the needles of conifers and leaves of broadleaf trees, thus depriving trees the ability to photosynthesize and transpire water. In some cases, the entire tree may be defoliated in a short period of time, and thus killed. Where defoliation is not so severe, top, branch, twig, bud and cone damage may occur. Growth, both height and diameter, may also be reduced. These weakened trees may become susceptible to bark beetle attack or attack from other destructive pests. Most forest defoliators are in the orders Lepidoptera (butterflies, moths, loopers, case bearers, needle miners) and Hymenoptera (sawflies). Some species may cause localized outbreaks that last for a year or two, while others may cause extensive outbreaks of a decade or more in duration.

Root Diseases

Root diseases are extremely important natural disturbance agents in Sierra Nevada forest ecosystems. Root disease organisms kill host cambium, decay wood, plug water conducting tissue, or cause some combination of these effects. Tree death resulting directly from root disease occurs when trees with decayed roots are wind thrown, or caused by bark beetles that attack the weakened trees. Some root pathogens are favored by conditions associated with low host vigor.

Others are able to cause infection regardless of tree condition. Some are quite host specific, while others have large host lists. Susceptibility to root disease pathogens also often varies with host age or with geographic location.
Root diseases exert profound influences on forest structure, composition, function, and yield. Root diseases are important gap formers, creating openings in the forest of varied sizes, depending upon the pathogen(s) and hosts present. They also influence tree species composition by selectively killing some species and allowing others to survive. Stocking levels may be reduced in discrete areas or across the stand depending on the distribution of inoculum and the tree species present. Species diversity may increase or decrease depending upon location. Root diseases influence structure by reducing the likelihood that some trees will achieve large sizes, or at the very least, by slowing the process.

Root diseases kill trees creating snags that are extremely important for wildlife habitat. The very nature of the decay associated with some root pathogens, though, would suggest that many disease-caused snags will remain standing for only a short period of time relative to trees killed by other pathogens or insects. Root diseases create considerable down woody material that is important for wildlife habitat, soil water holding capacity, and nutrient cycling.

Heterobasidion sp. infect a wide range of woody plants. Trees suffering from root rot are markedly less able to absorb and translocate sufficient water. During periods of drought, trees with decayed roots are more likely to die, usually as a result of bark beetle attacks. Affected trees are also more vulnerable to windthrow. In true firs, the fungus causes root and butt decay more often than mortality, at least in larger trees. This may result in windthrow and increased susceptibility to engraver beetle attack. Potential impacts of the disease include: increased susceptibility of infected trees to attack by bark beetles, mortality of infected trees, and the loss of site productivity. In recreation areas, depletion of vegetative cover, loss of aesthetic views and increased probability of tree failure. In recreation areas, Heterobasidion-infected trees can be extremely hazardous, causing death or injury to visitors, and damage to property.

Black stain root disease is caused by the fungus Leptographium wageneri. In California, the fungus has three host specific strains that infect either ponderosa and Jeffrey pine, singleleaf pinyon pine, or Douglas-fir. Black stain root disease is usually found in areas where there has been significant site disturbance or substantial amounts of tree injury, especially in stands after pre-commercial thinning, along roads, skid trails and landings, on sites with drought-stressed, waterlogged, or compacted soils, or where rotary blade brush cutters have been used to clear roadsides. Certain characteristics are related to black stain root disease in ponderosa pine in the central Sierra Nevada range. For pines, stands are usually densely stocked and are either pure or predominantly ponderosa pine. Infections in Douglas-fir are more scattered, but occur more often in the lower elevations of the host range. The largest and most rapidly expanding disease centers are often in cool, low-lying sites with high soil moisture levels in the spring. In recent years, black stain root disease has been detected in many new areas, often causing locally severe damage and incidence appears to be steadily increasing. Bark beetle-caused mortality of trees that are weakened by L. wageneri in these areas can be significant during periods of drought.

Mistletoes
The parasitic flowering plants commonly known as mistletoes are found in the Sierra Nevada range. Two genera of mistletoes are native: Phoradendron (true mistletoes) and Arceuthobium (dwarf mistletoes). The true mistletoes grow on both conifers and broadleaf trees; the dwarf mistletoes grow only on conifers. Male and female flowers are produced on separate plants in both genera. True mistletoes are large woody plants with mature shoots more than 2 feet long and 2 inches or more in diameter. Foliage is leafy or scaly. In contrast, dwarf mistletoes are small plants, with mature shoots less than 8 inches long and 0.2 inches in diameter. The shoots are non-woody, segmented and have scale-like leaves. Seeds produced in oval-shaped bicolor fruit are forcibly released when ripe. Although both mistletoes are damaging parasites of trees, by far the greatest timber loss in coniferous forests of the western United States is attributed to dwarf mistletoes. Billions of board feet of lumber are lost each year as a result of growth reduction and mortality. They also cause serious damage to trees in high-value, high-use forest recreational areas. However, they are key habitat features for species like the fisher and therefore serve an essential ecological role.

Other diseases

Cytospora canker is a damaging, canker inducing fungus that is most damaging on red fir. Usually it infects dwarf mistletoe-swollen branches. It is common to find over 70% of red fir trees showing a fairly high level of infection (Mortensen Thesis).

The Elytroderma deformans fungus can cause a needle disease of ponderosa and Jeffrey pine which reduces the photosynthetic capacity of infected trees. These infections can also become systemic in the vascular tissue of stems and boles and cause the infected branches and stems to become very convoluted, form witches brooms or die. Elytroderma deformans is a very common disease in the Sierra Nevada range, but usually overlooked until weather conditions incite an outbreak.

[Comment: Life cycles, relationships to logging activities, and ecological roles of the above pests and pathogens are largely absent from this discusion].

Abiotic Agents

Drought can be a local problem when plants are growing in soil with a low moisture holding capacity, or can be more widespread when insufficient precipitation occurs. Reduced moisture availability increases the susceptibility of plants to injury and mortality caused by insects and diseases. Ozone damage is especially likely to occur in forests located near some of the passes and the western flanks of the Southern Sierra due to polluted air from areas with high vehicular traffic. Ozone affected trees are less vigorous and are more easily affected by other diseases and bark beetles. The application of de-icing salt along roads can lead to needle tip dieback of adjacent conifers. Symptoms are usually evident within 100 feet of the road on the down slope side, although this distance may increase along drainages. Most herbicide injury is a result of improper application. Injury is usually found along roads, rights of way, fuel breaks, dwellings, or other areas where herbicides are often used. See (http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_046410.pdf) for additional information.

Fire can outright kill trees, cause injuries that result in eventual mortality, or can cause injured trees to be more susceptible to bark beetles and woodborers, thus also resulting in tree mortality.

A fire-injured trees susceptibility to bark beetles is determined by the amount of injury and the tree’s response, the time of year fire occurs, populations of bark beetles within the vicinity, and pre- and post-fire weather patterns (Gibson and Negron 2007). In addition, bark beetle-caused tree mortality may result in changes to fuels complexes and fire behavior during and following beetle outbreaks.

Severe winterstorms cause tree injury in the forms of windthrow, breakage, or stem deformations from snow loading. Green slash or injured live trees can be highly attractive to engraver and bark beetles.

Invasive insects and diseases

The most damaging conifer rust in California, white pine blister rust (WPBR), was introduced to the west coast of North America in 1910 on eastern white pine seedlings grown in France and continues to pose a serious threat to the regeneration and management of sugar pine in California. Because of its impacts on ecosystem diversity, it is also becoming a concern in high elevation western white pine, whitebark pine, foxtail pine, bristlecone pine, and limber pine. The rust has spread through most of the Sierras. WPBR infects needles of the five-needle (white pines) and spreads into branches and sometimes into the main stem. WPBR can infect even the healthiest of trees. For some trees, infection only means a slowing of the growth rate; for many others, however, infection leads to a protracted death. This disease readily kills seedlings and also can result in reduced cone production, thus negatively affecting regeneration.

Sudden oak death caused by Phytophthora ramorum is presently limited to coastal counties in California and Curry County in Oregon. Distribution within those counties is variable. The disease has also been found in nursery stock in various parts of California and other states. It has not been detected in the Sierra Nevada range although known hosts are widespread. It was first identified in the 1990’s killing oaks and tanoaks along the central coast of California. It has been spreading north and south since then and has had an ever expanding host range including hardwoods, conifers, and understory shrubs, ferns and herbaceous plants. Phytophthora ramorum is a quarantined pest resulting in restrictions on the movement of host material out of the zone of infestation both to uninfected parts of the state and to other states and countries. Infections by P. ramorum occur on leaves, branches, shoots, and stems. Leaf spotting, needle dieback, tip dieback, and bleeding stem lesions can be found. Symptoms vary significantly by host.

Goldspotted oak borer (GSOB) Agrilus auroguttatuss, was first detected in California (San Diego County) in 2004 during a trap survey for invasive tree pests. In 2008, this borer was linked to elevated levels of oak mortality ongoing in San Diego County since 2002. Its existence in California may date back to as early as 1996, based on examinations of previously killed oaks. GSOB is native to Arizona and Mexico and was likely introduced into southern California via infested oak firewood. It is a serious pest of coast live oak, Quercus agrifolia, canyon live oak, Q. chrysolepis and California black oak, Q. kelloggii in California and has killed thousands of trees. GSOB-killed oaks were only found in San Diego County as recently as 2012, but a single infested tree was found in Riverside County in late 2012. It is expected that the area of infestation will expand and tree mortality will increase due to adult flight from infested trees and new infestations initiated by beetles emerging from transported infested firewood. Thousands of oak trees in the Sierra Nevada range are susceptible to this invasive beetle.

Natural Range of Variability/ Trends

With the exception of a few introduced insects and pathogens, forests in the Sierra Nevada have the same insect and disease associates they had 150 years ago. Although records are non-existent, the difference between then and now is likely a change of scale of the interactions between insects, pathogens, and their hosts, in both spatially and temporally. Although large insect outbreaks are known to have occurred historically, the landscape patterns of vegetation often resulted in disturbances that were brief and spatially confined.

Tree species composition, tree densities, and tree size and distribution, however, are significantly different now than they were over a century ago Currently, many of the forest ecosystems in the Sierra Nevada range are highly susceptible to serious forest health threats. Fire exclusion and past grazing and logging activities are compounded with environmental and ecosystem successional changes creating overly dense stands, loss of age diversity, and an altered mix of tree species.

Some insects and pathogens have evolved relations of mutual benefit to themselves and the ecosystem. Others are opportunistic on injured or stressed trees, shrubs, or herbs. Most act in beneficial processes such as pollination, wildlife habitat creation, water and nutrient absorption by plants, nutrient cycling, soil development and moisture retention, reduction of large plant residues and detritus, or biological control of other organisms. All species play a role in ecosystem processes; relatively few species capitalize on changes in vegetation conditions over large areas and provide significant disturbance to landscapes. Most disturbances caused by insects and pathogens produce heterogeneous and patchy effects. Insect or disease-caused patches of mortality create small gaps that are an integral component of forest development.

Interactions of key drivers and stressors

Frequently, more than one causal factor contributes to tree mortality, and certain sets of factors are commonly found in association with one another. Phytophagous (plant eating) insects and tree pathogens are often close associates in forests and, usually a forest will be influenced by a number of different diseases and insects concurrently. One organism may affect a tree and weaken it, predisposing it to attack by another, or one organism may actually introduce another organism into the host. In addition, abiotic factors frequently function as stressors, predisposing trees to mortality caused by biotic agents.

A pattern of decreasing precipitation or changes in the form of the precipitation (e.g. rain instead of snow) may reduce the growth & vigor of vegetation, thereby increasing the susceptibility to mortality caused by insects and diseases. There is abundant evidence that bark beetle caused tree mortality dramatically increases in the Sierra Nevada during extreme or protracted drought periods (http://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fsbdev3_046696, http://caforestpestcouncil.org/meetings-reports/). If droughts become more frequent, of greater intensity, or are more protracted in the future, high levels of bark beetle-caused tree mortality should be expected. In addition, bark beetle population success is influenced directly by temperature effects on insect development (Powell and Logan 2005). Some bark beetle species may be able to complete additional generations in a year and timing of beetle emergence and flight periods may be altered. Stand density and host species composition are also important factors in determining drought effects. Although all stands become increasingly stressed as the drought persists, tree mortality is typically higher in denser stands. Those species less tolerant of drought are likely to be attacked by bark beetles first, followed by attacks to more drought tolerant species.

Most plant pathogens are strongly influenced by environmental conditions and vigor of the host (Kliejunas et al. 2009). Climate change will directly affect the pathogen, the host, and the interaction between them, resulting in disease impacts (Brasier 2005, Burdon et al. 2006). Root pathogens such as Heterobasidion sp.are more aggressive when hosts are stressed, so its incidence and spread could increase (Kliejunas et al. 2009) under future climate regimes. Mistletoes currently play a significant role in tree mortality when trees are stressed by drought and other agents. Surveys in California indicated that trees infected with dwarf mistletoe were the first to die during drought (Byler 1978). If droughts become more frequent, of greater intensity, or are more protracted in the future, mistletoes will continue to cause mortality, be a predisposing factor to attack by bark beetles, and may also expand their range (Kliejunas et al. 2009). Although stem rusts (Cronartium sp.) can adapt to a wide range of environmental conditions, their tolerances are unknown. Under changing climates, the incidence of rusts will be determined chiefly by host distribution. Typically, rusts increase in intensity and distribution in “wave years” during which the weather is especially favorable for sporulation, dispersal, and infection. As climate changes, the frequency of such waves years is expected to change (Kliejunas et al. 2009).

Interactions between bark beetles and fire are complex. In the long run, reintroducing fire to fire-adapted western forest ecosystems will favor species and plant communities that are better adapted to these ecosystems. In the short term fire can damage residual trees to the extent that they become more susceptible to bark beetle attacks and in some cases can lead to increased bark beetle activity for one to two seasons following the fire.

References

  • Aerial Detection Survey Program. U.S.D.A. Forest Service, R5, Forest Health Protection. (http://www.fs.usda.gov/detail/r5/forest-grasslandhealth/?cid=fsbdev3_046696
  • Brasier, C.M. 2005. Climate change and tree health. Proceedings, trees in a changing climate conference.
  • Burdon, J.J., P.H. Thrall and L. Ericson. 2006. The current and future dynamics of disease in plant communities. Annual Review of Phytopathology. 44: 19-39.
  • Byler, J.W. 1978. The pest damage inventory in California. In: Scharpf, R.F. and J.R. Parmeter, tech. coords. Proceedings of the symposium on dwarf mistletoe control through forest management. Gen. Tech. Rep. PSW-031. Berkeley, CA. U.S.D.A. Forest Service, Pacific Southwest Research Station. Pgs. 162-171.
  • California Forest Pest Conditions Reports, 1961-2011. An annual report published by the California Forest Pest Council (http://caforestpestcouncil.org/meetings-reports/).
  • California Insect and Disease Training Manual, XXXX. U.S.D.A. Forest Service, R5, Forest Health Protection and the California Department of Forestry and Fire Protection. (http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_046410.pdf)
  • DeMars Jr. and B. H. Roettgering. 1982. Forest Insect and Disease Leaflet 1. U.S.D.A. Forest Service. 8 p.
  • Ferrell, G.T. 1991. Fir engraver. Forest Insect and Disease Leaflet 13. U.S.D.A. Forest Service. 8 p.
  • Fettig, C.J. 2012. Forest health and bark beetles. In: North, Malcolm, ed. Managing Sierra Nevada forests. Gen. Tech. Rep. PSW-GTR-237. U.S.D.A. Forest Service, Pacific Southwest Research Station. Pgs. 13-22.
  • Gibson, K., S. Kegley and B. Bentz. 2009. Mountain pine beetle. Forest Insect and Disease Leaflet 2. U.S.D.A. Forest Service. 12 p.
  • Gibson, K. and J.F. Negron. 2009. Fire and bark beetle interactions. In: Hayes, J. L.; Lundquist, J. E., comps. The Western Bark Beetle Research Group: A unique collaboration with Forest Health Protection: Proceedings of a symposium at the 2007 Society of American Foresters conference. Gen. Tech. Rep. PNW-GTR-784. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 51-70
  • Hessburg, P.F., D. J. Goheen, and R. V. Bega. 1995. Black stain root disease of conifers. Forest Insect and Disease Leaflet 13. U.S.D.A. Forest Service. 8 p.
  • Kliejunas, J.T., B. W. Geils, J. M. Glaeser, E.M. Goheen, P. Hennon, K. Mee_sook, H. Kope, J. Stone, R. Sturrock and S.J. Frankel. 2009. Review of literaature on climate change and forest diseases of western North America. Gen. Tech. Rep. PSW-GTR-225. Albany, CA. U.S.D.A. Forest Service, Pacific Southwest Research Station. 54 p.
  • Krist Jr., F.J., F.J. Sapio and B.M. Tkacz. 2007. Mapping risk from forest insects and diseases. U.S.D.A. Forest Service, Forest Health Protection, Forest Health Technology Enterprise Team. FHTET-2007-06. http://www.fs.fed.us/foresthealth/technology/nidrm.shtml,
  • Miller, D.R., J.W. Kimmey and M.E. Fowler. 1959. White pine blister rust. Forest Pest Leaflet 145. U.S.D.A. Forest Service. 9 p.
  • Mortensen L.A. 2011. Spatial and ecological analysis of red fir decline in California using FIA data. M.S. Thesis. Oregon State University. 96 p. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/21828/MortensonLeifA2011.pdf?sequence=1
  • Page, W.G. and M.J. Jenkins. 2007. Mountain pine beetle induces changes to selected lodgepole pine fuel complexes within the Intermountain Region. Forest Science. 53: 507-518.
  • Powell, J.A. and J.A. Logan. 2005. Insect seasonaility: circle map analysis of temperature-driven life cycles. Theoretical Population Biology. 67: 161-179.
  • Scharpf, R.F. technical coordinator.1993. Diseases of Pacific Coast Conifers. U.S.D.A. Handbook 521. 199 p.
  • Schmitt, C.L., J.R. Parmeter and J.T. Kliejunas. 2000. Annosus root disease of western conifers. Forest Insect and Disease Leaflet 172. U.S.D.A. Forest Service. 9 p.
  • Smith, S.L., R.R. Borys and P.J. Shea. 2009. Jeffrey pine beetle. Forest Insect and Disease Leaflet 11. U.S.D.A. Forest Service. 8 p.

Additional insects & pathogens references to consider (reviewed in TACCIMO: http://goo.gl/Lg3Bn)):

  • Millar, C. I., Westfall, R. D., Delany, D. L., Bokach, M. J., Flint, A. L. & Flint, L. E. 2012. Forest mortality in high-elevation whitebark pine (Pinus albicaulis) forests of eastern California, USA; influence of environmental context, bark beetles, climatic water deficit, and warming. Canadian Journal of Forest Research, 42, 749 – 765.
  • Sturrock, R. N., Frankel, S. J., Brown, A. V., Hennon, P. E., Kliejunas, J. T., Lewis, K. J., … Woods, A. J. 2011. Climate change and forest diseases. Plant Pathology, 60, 133-149. doi: 10.1111/j.1365-3059.2010.02406.x
  • Trumble, J. T. & Butler, C. D. 2009. Climate change will exacerbate California's insect est problems. California Agriculture, 63 (2), 73-78.
  • Venette, R. C. & Cohen, S. D. 2006. Potential climatic suitability for establishment of Phytophthora ramorum within the contiguous United States. Forest Ecology and Management, 231, 18 – 26.
  • Ziter, C., Robinson, E. A. & Newman, J. A. 2012. Climate change and voltinism in Californian insect pest species: sensitivity to location, scenario and climate model choice. Global Change Biology, doi: 10.1111/j.1365-2486.2012.02748.x


Current Condition – Non-native Invasive Plants


Introduction

Invasive species are among the most significant environmental and economic threats facing our Nation’s forest, grassland, and aquatic ecosystems. They endanger native species and threaten ecosystem services and resources including clean water, recreational opportunities, sustained production of wood products, carbon sequestration, wildlife habitat, livestock forage production, and human health and safety. Adverse effects from invasive plant species can be exacerbated by interactions with fire, native pests, weather events, human actions, and environmental change. Invasive species cause billions of dollars in damage each year (Pimentel et al. 2005, Holmes et al.2009, Kovacs et al. 2010, Aukema et al. 2011). In 2010, The Nature Conservancy estimated damage from invasive species worldwide totaled more than $1.4 trillion – five percent of the global economy (Pimentel et al. 2001). However, in all fairness it must be acknowledged that these costs include the costs of crop agricultural pest losses from introduced insect pests, which are very high because of pesticide applications. Further, these figures don't include the costs to the environment from intentional introduction of non-native wildlife, including livestock cattle in mountain meadows, for example. The methodology used to created these figures may have an agricultural and economic bias.

Accelerated global trade and transportation have facilitated increased movement of non-native invasive plants across continents irrespective of geographical boundaries. Increasing numbers of people living in, accessing, and using forests and grasslands have accelerated the spread of non-native invasive plants onto these public lands. When plants that evolved in one region of the globe are moved by humans to another region, some species flourish at the expense of native vegetation and the wildlife that feeds on it. Invasives can affect ecosystem processes such as hydrologic integrity, fire regimes, and soil chemistry. Non-native invasive plants have a competitive advantage because they are no longer controlled by their natural predators, and they are adapted to conditions of chronic disturbance. In many instances, native species have been eliminated, habitats have been altered, and seed banks have been depleted, leaving the door open to establishment of generalist non-native plant invaders. They can quickly spread out of control.

There are numerous feedback loops that favor invasive species establishment and spread: disturbance of soil; loss of topsoil (eg, loss of mycorrhizal symbionts needed by most Calif. native species for successful establishment); changes in hydrological regimes (dams/diversions) that favor non-native or generalist species; soil compaction; loss of duff and canopy that help to suppress establishment of generalist species; suppression of fire (many native spp are fire obligate); loss of native seed bank (a variety of causes which intersect and are punctuated in feedback); deposition of nitrogen from burning fossil fuels, and other chemicals which alter native soil chemistry and favor non-native generalists.

In California, approximately 3% of the plant species growing in the wild are considered highly invasive, but they inhabit a much greater proportion of the landscape. The California Invasive Plant Council (Cal-IPC) focuses on plant species that impact natural areas, sometimes referred to as “wildland weeds.” The California Department of Food and Agriculture (CDFA) maintains a list of “noxious weeds” that are subject to regulation or quarantine by county agricultural departments. Noxious weeds are typically agricultural pests, though many also have impacts on natural areas and the two lists overlap considerably.

Recent economic issues have caused CDFA to eliminate all state funding for the noxious weed program, resulting in the loss of personnel, including all CDFA invasive plant biologists. This loss of funding as well as the continuing economic downturn has resulted in a cascading negative effect to integrated pest management programs conducted at the county level throughout the state. Forest Service invasive plant funding to the national forests in California has never been high. These economic factors will continue to result in a loss of capacity to directly manage non-native invasive plants at the forest and local levels. Although no studies have been done on range expansion specific to California, monitoring has shown that untreated populations of noxious weeds in the Western US can be expected to expand at a rate of approximately 10-15% annually (Asher and Dewey 2005).

Managing non-native invasive plants requires an integrated approach (referred to as integrated pest management) that combines prevention, research, education, monitoring, and treatments. Prevention is a key aspect, and is the least expensive, both economically and ecologically.

With limited funds and workforce, prioritization of treatments is a key consideration. In California, the USFS has been working with several cooperators to develop a computer-based prioritization tool that can be used at a landscape level to establish priorities for treating known populations of non-native invasive plants. This model is currently being developed into a user-friendly web-based application.

In general terms, non-native invasive plant spread at the local level is tied to how the forest is used. Fuel reduction, minerals extraction, livestock grazing, recreation, and other management activities all have the potential to move them from one place to another. Another component of non-native invasive plant spread involves the ability of these species to become established. Areas that are disturbed and/or have reductions in soil and canopy cover have increased risk of non-native invasive plant establishment. Without requirements to help prevent non-native invasive plant introduction these disturbed areas also have increased risk of introduction.

Key Indicators

Indicator
Measure
Source
Species Status
CDFA noxious or Cal-IPC wildland weed
CDFA nox weed list at http://www.cdfa.ca.gov/plant/ipc/weedinfo/winfo_list-pestrating.htm
Cal-IPC wildland weed list at http://www.cal-ipc.org/ip/inventory/index.php
Statewide current extent
Known mapped occurrences and Quads known to be infested
CalWeedMapper (http://calweedmapper.calflora.org/). This online mapping tool documents efforts made over the last few years to combine known mapped occurrence data in the CalFlora database and expert local knowledge on infestations within 1:24000 quadrangle throughout the state. This has been combined into the CalWeedMapper website.
Management Status
Managed or unmanaged
CalWeedMapper (http://calweedmapper.calflora.org/). By Quad, experts assessed whether species were being managed or not, and if so, was management resulting in a change in species extent.
Species Impacts
Ecological Impact Ratings
The Plant Assessment Forms (PAF) for all species in Cal-IPC’s wildland weed inventory are located at http://www.cal-ipc.org/ip/inventory/weedlist.php. These PAFs provide any known information by species on ecological impacts in California. Ecological Impact is one of three major criteria for rating. Other information is at the Fire Effects Information System website: http://www.fs.fed.us/database/feis/plants/weed/weedpage.html.
Possibility of expansion (region-wide)
Geographical extent of possible habitat expansion in California under current climate and forecasted future climate change scenarios
For geographical extent under current and future climates, CalWeedMapper (http://calweedmapper.calflora.org/).
Possibility of expansion (locally)
Acres of recently disturbed areas (wildfire, logging, landslides, road construction, etc). Changes in canopy cover and soil cover. Location of nearby invasive plants.
For localized disturbance, various existing data layers (e.g., recent fire perimeters, transportation system, trails system). For location of nearby invasives, the USFS invasive plant inventory.

Summary of Current Condition

  • There are currently over 200 species of plants considered to be invasive by the California Invasive Plant Council. Although new introductions to the state are not very common, still one or two new species of potentially non-native invasive plants are discovered each year. Not all of these species are problematic in the Sierra Nevada bio-region.
  • With very few exceptions, most invasive plant distributions in the forested lands of California, although locally extensive and impacting, are not found in great densities throughout the Sierra Nevada. Non-native invasive plants that could be considered exceptions are yellow star thistle in the foothills and along major east-west highway corridors and invasive annual grasses (cheat grass, medusahead, etc.) on the eastside of the Sierra Nevada Range. The highest elevations (subalpine, alpine zones) are still relatively free on invasive non-native plants.
  • Local populations are having impacts to processes and systems, including degrading wildlife habitat, increasing sediment transport into streams, affecting recreation use, and changing fire regimes.
  • Cal-IPC recently published a report on priority species for the Sierra Nevada ecoregion, listing 15 species considered as high priority for management ecoregion wide: Russian knapweed, musk thistle, spotted knapweed, yellow starthistle, rush skeletonweed, stinkwort, Scotch thistle, Dyer’s woad, brooms (Scotch, French, Spanish), red sesbania, giant reed, and toadflaxes (Dalmatian, yellow). Over time, priorities will change as new species are found in a particular area.
  • A coordinated multi-agency and multi-year integrated pest management effort to contain yellow star thistle at the lower elevations of the Sierra Nevada Range has resulted in restricting the expansion of this species, although current losses in funding threaten to negate these gains.
  • When considered as a whole across the Sierra Nevada Range, the amount of acres treated annually is not keeping up with expansion of known populations, discovery of unknown populations, and new introductions.
  • Future climate change has variable effects on species distribution, as would be expected. Range expansions as well as range restrictions will occur depending on the species and the part of the state considered. A warming climate in the western part of the United States will often lead to an upward elevational migration of plant species. Rapid changes in climate may cause a loss of native plant species from the lower elevations if they cannot migrate upward and establish fast enough. Stressed communities with fewer native plant species are then more available for the invasion and establishment of nonnative invasive plants.
  • Wildfires with moderate to severe burn intensities in the Sierra Nevada often result in rapid expansion of nearby non-native invasive plant populations.

References

  • Asher, J. and Dewey, S. 2005. Estimated annual rates of weed spread on western federal wildlands. Federal Interagency Committee for Management of Noxious and Exotic Weeds (FICMNEW).
  • California Invasive Plant Council (Cal-IPC). 2011. Prioritizing Regional Response to Invasive Plants in the Sierra Nevada. Cal-IPC Publication 2011-1. California Invasive Plant Council, Berkeley, CA. Avaialble: www.cal-ipc.org.

Additional climate change/invasive species references to consider (reviewed in TACCIMO: http://goo.gl/Lg3Bn)):

  • Concilio, A. L., Loik, M. E. & Belnap, J. 2013. Global change effects on Bromus tectorum L. (Poaceae) at its high-elevation range margin. Global Change Biology, 19,
  • Dukes, J. S., Chiarello, N. R., Loarie, S. R., & Field, C. B. 2011. Strong response of an invasive plant species (Centaurea solstitialis L.) to global environmental changes. Ecological Applications, 21 (6), 1887-1894.
  • Rahel, F. J., & Olden, J. D. 2008. Assessing the Effects of Climate Change on Aquatic Invasive Species. Conservation Biology, 22(3), 521–533. doi: 10.1111/j.1523-1739.2008.00950.x
  • Sandel, B. & Dangremond, E. M. 2012. Climate change and the invasion of California by grasses. Global Change Biology, 18, 277-289.

Current Condition – Vegetation Succession



Comment: This section would benefit from data to support the statements. For example, it would be useful to provide data to support the conclusion that high severity wildfires have results in shrubfields that are outside the natural range of variability in terms of patch size or extent. Also, it would be useful to illustrate how harvest practices (past nad present ) have resulted in the loss of large tree attributes (both dead and live trees) on the landscape. this section should also be better integrated with the insects/disease section. It is still not clear what, in terms of mortality rates as a result of insects and disease, what can be reasonably considered outside the range of variability. The mistletoe and bugs provide habitat structure and food for key species. If the assessment can help clarify what is out of range for these process, then one can assess where and how to manage to reduce the "stress" and maintain the "process."


Introduction
The existing condition of Sierra Nevada vegetation is largely the result of multiple anthropogenic and climatic influences. Contemporary literature commonly describes large changes in tree stocking levels and arrangements, as well as a shift in species composition. A limited number of datasets and publications verify this overall change. Of particular value is the work of forester A. E. Wieslander. His 1930’s survey of California vegetation, called the Vegetation Type Mapping Project has provided what may be the most detailed set of vegetation mapping and plot-level data available for the Sierra Nevada.

The vegetation of the Sierra Nevada trends toward high levels of heterogeneity in all dimensions. At landscape scales, the pattern of vegetation varies by both latitude and by elevation. This scale permits reasonably accurate descriptive generalizations. At larger scales, landform, slope, and aspect drive fine-scale variations that consistently defy accurate generalizations. Nevertheless, the following portrays useful characterizations that can provide starting points for more detailed discussions. Compendium level information is provided in published resources such as the Sierra Nevada Ecosystem Project 1996, Sugihara, N., J. et al. 2006, and Fites-Kaufman, Jo Ann, et al.2007.

Like all mountain ranges, elevation change, with related temperature and precipitation effects, drives vegetation development. In the case of the Sierra Nevada, with its prevailing north-south alignment, the additional effect of the west- to east-driving jet stream creates a relatively productive west slope. The east slope, however, exists in a rain shadow. The westside, with higher levels of precipitation and warmer temperatures, is capable of supporting a more diverse set of plant communities, as compared to the drier and colder eastside environment.

While vegetation patterns have never been static, the most notable changes observed today are likely associated with the relatively short-term influences of successful fire suppression and wood product harvesting. Multiple other influences exist as well. Climatic influences, especially a changing temperature regime, further modify any human-related effects and may be regarded as the controlling influence. For example, increasing temperatures, which affect fuel moisture and plant moisture stress levels, eventually result in landscape-level fire effects and plant species diversity and composition.

The history of successful fire suppression, while generally meeting the objectives of limiting the extent of adverse wildfire effects, allowed for the successful establishment of vegetation that would have otherwise been consumed by fires. A substantial increase in shade-tolerant conifers, typified by white fir and incense cedar, was then able to ‘fill in’ the relatively open forests, reducing the variation of what was once a mosaic of variable tree sizes and arrangements into an increasingly uniform landscape.

In addition, the harvesting of trees, to meet societal demands for wood products, led to widespread changes in tree size distribution and species composition. High demand for lumber products, combined with technological and economic considerations, resulted in a focus on the removal of the larger trees, especially the relatively high-value pines. The new forests that resulted from these activities contain increased tree numbers, but fewer pines. While the number and extent of large trees increase with each growing season, additional decades of growth are required before forests could begin to resemble earlier conditions.

Vegetation development is affected by multiple drivers and stressors. Purposeful human activities can set the stage for specific trends; however the effects of wildfire can redirect them, as can the overarching influence of climate. The following sections describe the general characteristics of key vegetation elements, their current status, and the apparent trends, given assumptions of the future environment.

Element
Drivers/Stressors Affecting
Trend
Uncertainty in Trend
Sources
Vegetation Density




Trees/Acre




Canopy Cover




Structural Elements




Large Trees




Snags




Down Trees




Heterogeneity




Landscape Scale




Patch Scale




Tree Neighborhood




Species Composition




Shade Tolerance




Large trees





Current conditions
Much of the discussion relating to forest vegetation currently relates to the size, density, and arrangement of vegetation, species presence or absence, and the suitability of forests as habitat for specific wildlife species.

Vegetation Density

Substantial acreages of today’s forests can be described as overly dense. As described above, natural regeneration occurring over substantial acreages, without any management activity to modify numbers of trees, results, as would be expected, in substantial acreages of dense forest. This density has led to conditions commonly recognized as hazardous, in a fire behavior context. They are also recognized as ‘at risk’ of substantial mortality during multi-year droughts, when bark beetle- and pathogen-related mortality can reach above average levels over extensive acreages.

A notable exception to the broad generalization of overly dense and adversely affected by successful fire suppression is the higher elevation forest in the upper montane and subalpine zone, where longer fire-free time periods and more moderate fire behavior has allowed today’s forests to more closely resemble earlier forests.

More recent disturbances, primarily stand-replacement wildfire, have changed large areas into landscapes characterized by early seral vegetation. Colonization of these fires, by seedling trees, both planted and by seed, has been slow and limited. Significant portions of these landscapes are now dominated by resprouting trees and woody shrubs.

While conifer forests are the dominant plant community, woody shrubs, meadows, and grass/forb communities are present throughout. Highly variable in size, they exist both within and adjacent to forested areas. Like the forests they frequently coexist with, successful fire suppression has led to changes in their extent and composition. The increasing density and extent of forest, with the resultant decreases in light penetration, has reduced these communities.

Conversely, the recent large, stand-replacement wildfire patches have resulted in expansive shrub fields, likely larger in size than during recent centuries. Additionally, when affected by fire, meadows, both dry and wet, have regained some of their former extent.

Throughout the elevational gradient, both deciduous and evergreen hardwoods comingle with associated communities. After disturbance, their ability to resprout or recolonize by seed, they commonly maintain or expand their extent. If overtopped by taller, denser forests, they decline and, in some cases, die. Both California black oak and quaking aspen are common examples of tree species that have been adversely affected by the increase in tree density.

Featured Forest Elements

As described above, a significant influence affecting today’s forests was the earlier widespread removal of large trees to meet society’s needs. This, combined with fire-related mortality, reduced the population and distribution of larger trees over the landscape.

The desire to reestablish a well-distributed population of large conifers was formalized over 20 years ago. Insect/pathogen- and wildfire-related mortality of these featured trees has likely reduced the effectiveness of this focus.

Coincident with the focus on retaining larger trees, the retention of dead trees increased. Both standing and fallen, they provide for wildlife habitat as well as a related set of biological goals. The removal of danger, or hazard, trees has continued, affecting roadside, trail, and recreational development sites. Likewise, limited salvage of dead/dying trees, post-wildfire, continues.

Heterogeneity

The absence of wildfire effects, during the decades of effective fire suppression, allowed for large numbers of seedlings to persist and develop into the medium and large trees that exist today. As compared to evidence of historic forest structure, site-to-site conditions are more uniform. Primarily due to the age of most modern forests, sufficient time has not yet allowed for the development of higher levels of tree-scale horizontal and vertical variation.

Beyond the tree neighborhood scale, the widespread nature of the early 20th century logging provided for large contiguous areas of uniformly-aged forest. Evidence of historic disturbance patterns apprears to have commonly yielded higher levels of variation within landscapes.

Species Composition

The species composition of today’s forest is explained by a wide variety of circumstances. In addition to the effects of the proximity of post-disturbance, seed-bearing trees, the level of continued establishment of largely shade-tolerant trees created the mixture present today.

Forests originating by natural regeneration will be populated by, initially, resprouting species, like the California black oak, or other species capably of resprouting after disturbance. Residual or adjacent conifers added to the new forest as seed levels and favorable germination sites allowed. In the case of forests affected by early 20th century logging, preferential removal of the more highly-valued pines sometimes resulted in increased proportions of true fir and/or incense-cedar. In other cases, where smaller pines were retained, the new forests contained significant numbers of pine. As railroad logging trended toward mid-century, removals were increasingly selective and limited.

Further affecting the status of today’s species composition is the range of shade tolerance among the variety of species existing within the bounds of Sierra Nevada forests. While the presence of sexually mature individuals is essential, the ability to successfully establish is the first real test. After establishment, growth rates within the immediate environment control the pathway toward long-term persistence. While the germane tree species can be classified by shade tolerance, this ability exists along a gradient and is further affected by the specific light environment being considered. Nevertheless, the pines thrive in higher levels of sunlight. In contrast, true fir, also capable of thriving in sunlight, is better adapted to lower light environments and can persist for decades in shade-dominated microenvironments which would lead to mortality for pine. This capability explains both the ability of true fir, and other shade-tolerant species, to eventually replace shrub fields and the presence of a fir understory beneath upper canopy pines.

Trends
The trajectory for future conditions of Sierra Nevada forests is, in general, inferred by today’s conditions, but is subject to much uncertainty. While plant growth rates certainly affect the annual development of future structure and composition, the likelihood of disturbance cannot be minimized. Disturbance agents, like wildfire can swiftly nullify current development trends. Likewise, seasonal precipitation, combined with evapotranspiration demands, influence the effects of pathogens and insects on trees ad other vegetation. The following segment discusses the likely trends for selected aspects of the vegetation succession story.
Vegetation Density
With regard to forest trees, the effect of annual growth is to incrementally move toward the biological limitations defined by site capacity. In broad terms, forests with low to moderate stocking will continue to increase in that pattern, adding in both height and diameter, with low levels of potential mortality. Conversely, the existing high density forests will inch forward in tree size, increasing competition levels, with resultant potential for increases in density-related mortality.
In the context of tree neighborhoods, intertree competition between adjacent trees is expected to increase. Depending on the specific arrangement of trees, this effect may be limited to small groups of trees or much higher numbers. Above and belowground competition for sunlight and soil moisture, respectively, can reduce tree vigor.
Forests originating from natural regeneration, with little or no influence from wildfire, are the forests now focused on for key wildlife habitat and fuel reduction. High densities of moderately-sized conifers, with varied levels of older and larger trees left during the earlier harvests, are now at or near peak stocking levels and are increasingly susceptible to insect- or pathogen-related mortality. In additional, given the high tree density and the development of multiple canopy layers, wildfire effects can trend toward stand-replacement at scales not common in the historic record.

Older planted forests, some now exceeding 60 years in age, are relatively uniform in size and distribution. Species composition, reflective of both earlier market preferences and of nursery capabilities, is dominated by pine, but frequently includes various other species, originating from adjacent trees. Oaks, resprouting from the root system after the earlier disturbance or persisting despite it, exist within the matrix of planted conifers. In some cases, now limited in crown expansion by adjacent conifers, are in decline. These young forests are now strongly influenced by high levels of intertree competition, with bark beetle-related mortality evident at highly variable levels.
More recently planted forests, are commonly multi-species forests, with more variable spacing and arrangement. These early seral forests include higher levels of grass, forbs, and woody shrubs. With the development of crown competition, levels of these associated plants trend downward. Commonly, in the second decade, intertree competition becomes increasingly important. Excepting areas of low tree density, or where tree thinning management actions have occured, annual tree growth begins to accumulate to the point where the previously described stress elements become important.

Background mortality rates have increased over time. Regional warming, with related increases in water deficits, may be the dominant contributor to the increases in tree mortality rates (van Mantgem et al, 2009). The figure below, illustrates increasing rates of annual mortality for five different variables.

Modeled trends in tree mortality rates for (A) regions, (B) elevational class, (C) stem diameter class, (D) genus, and (E) historical fire return interval class.
Chapter3_Vege_01.jpg

In a study located in Yosemite National Park, “co-occurring periods of high spring and summer temperatures and low annual and seasonal precipitation triggered high tree mortality. However, mortality was not simply associated with dry years. Statistically significant associations between low moisture and high tree mortality were only found for multi-year periods. This indicates that although any annual drought may be severe, elevated tree mortality is mainly associated with dry conditions over extended periods.” (Guarín and Taylor, 2005).

Multi-year drought is an historical norm for California (Israel, 1995). Tree mortality rates are increasing and all sizes are included. Large numbers of studies have consistently indicated that lower levels of tree stocking result in lower levels of tree mortality (references). It is unknown how much lower stocking levels need to be to minimize the loss of key habitat values associated with large, old trees.

Featured Forest Elements

Areas that have not yet been affected by stand-replacement wildfire, provide widespread century-old forest that continues to increase in size and density. Typical growth rates, in the absence of significant disturbance events, will steadily increase the population size of large trees. Unknowns regarding the effects of wildfires and pathogen- or insect-related mortality reduce the predictive certainty of trend information.
Climate changes that place additional transpirational demands on trees, especially in dense tree neighborhoods, will be at risk of higher levels of mortality. The number and extent of this is currently unknown.
Populations levels of standing or fallen dead trees will likely increase, due to both wildfire and pathogen- or insect-related mortality.

Heterogeneity Trend

In the absence of treatment effects, mortality will lead to increases in horizontal heterogeneity. Changes in vertical heterogeneity may be less noticeable, as some evidence exists for mortality effects that cover the full range of tree heights.

Modern silvicultural treatments, with inherent objectives of increasing tree spacing variation, will add to background effects.

Areas affected by low-moderate severity wildfire will also exhibit increases in both horizontal and vertical heterogeneity. Areas affected by stand-replacement wildfire are likely to be, initially, dominated by relatively uniform vegetation responses, but will increase in heterogeneity as trees become reestablished. Purposeful reforestation actions can be designed to rebuild desired heterogeneity levels.

Species Composition Trend

Silvicultural treatments, incorporating actions designed to alter species composition, can provide for increases. In existing stands, species preferences would allow for shifts in growing space that facilitate the development of desired species. Reforestation practices can be designed to achieve similar goals by planting a wide variety of species.

In the absence of purposeful actions, species composition changes will be affected, primarily, by wildfire. Low to moderate severity would likely kill a portion of the shade-tolerant species now developing in many forest stands.
Trends in undisturbed stands may likely be relatively stable, as new and favorable sites for new seedling germination would likely be minimal. Individual or group mortality would create new sites, but the extent of significant species shifts is unknown.

Need to describe and include data on extent of plantations where native understory has been either reduced or eliminated....skipping the early successional stages that are the foundation of forest food web and contributing to loss of biological and structural diversity, and contributing to uncharacteristic natural fire behavior. Significance is documented in a couple of references, eg.,

  • Lindenmayer, D.B., P. Burton, and J. Franklin. 2008. Salvage Logging and Its Ecological Consequences. Island Press.
  • Swanson, M.E. et al. 2010. The forgotten stage of forest succession: early-successional ecosystems on forest sites. Frontiers Ecol Environ 9(2):117-125

Conclusion
Variation in elevation and latitude, combined with soil productivity, provide for an extensive range in structure and composition. Historical land usage has led to increases in density and stand-scale uniformity. The relatively recent trend in wildfire size and related tree mortality is the most significant factor affecting vegetation succession. A warming climate is implicated in mortality rate increases, affecting the redevelopment of historic conditions. Future vegetation is trending toward higher density levels, potentially leading to even higher levels of wildfire or pathogen- or insect-related mortality.

References

  • Alejandro Guarín, Alan H. Taylor. 2005. Drought triggered tree mortality in mixed conifer forests in Yosemite National Park, California, USA. Forest Ecology and Management, 218: 229–244.
  • Fites-Kaufman, Jo Ann, et al. 2007. "Montane and Subalpine Vegetation of the Sierra Nevada and Cascade Ranges." Terrestrial vegetation of California XX:456.
  • James H. Thorne, Brian J. Morgan, and Jeffery A. Kennedy. 2008. Vegetation Change Over Sixty Years In the Central Sierra Nevada, California, USA Madroño 55 (3): 223- 237
  • Morris Israel and Jay R. Lund, 1995, Recent California Water Transfers: Implications for Water Management, Natural Resources Journal, 35: 1-32.
  • North, Malcolm; Stine, Peter; O’Hara, Kevin; Zielinski, William; Stephens, Scott. 2009. An ecosystem management strategy for Sierran mixed-conifer forests. Gen. Tech. Rep. PSW-GTR-220. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 49 p.
  • Sierra Nevada Ecosystem Project, 1996. Final Report to Congress, vol. 1, Assessment Summaries and Management, Chapter 1, Sierra Nevada Ecosystems (Davis: University of California, Centers for Water and Wildland resources, 1996)
  • Sugihara, N., J. van Wagtendonk, J. Fites-Kaufman. 2006. Chapter 12. Sierra Nevada Bioregion. In Fire in California Ecosystems. Edited by: N. Sugihara, J. van Wagtendonk, J. Fites-Kaufman, A. Thode, and K. Shaffer. UC Press, Berkeley, CA. pp. 264-294.


Interactions of key drivers and stressors & implications for provision of ecosystem services


Interactions (and Feedbacks)

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Positive
Negative

Fire-Climate-Succession-Insects-Economics

The effects of rising cost of fire management both directly to the agencies responsible for managing fire and indirectly to communities or businesses affected and taxpayers who ultimately foot the bill is one of the most important interactions to address. Despite repeated efforts of responsible agencies to ………It is not straightforward or simple, despite the importance. Air quality is also affected because of smoke that can have direct effects to human health but also are important to quantify in terms of carbon emissions. This topic will be a focus of the next stage of the assessment on trends. We welcome input on sources of information that will be useful for this discussion. There is a fire group on the Our Forest Place website that is one excellent place to provide your input.
References

[snapshot: 4/9/2013 @0945]



Chapter 4

Bio-Region NF Composite Links
Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 - Water | Chapter 8 - Fish, Plants and Wildlife | Chapter 8 - Range | Chapter 8 - Timber | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Chapter 14 | Chapter 15
Sierra Nevada Bio-region
Chapter 4: Carbon Stock Conditions and Trends

Figures
Figure 1. Flows of carbon from the atmosphere to the forest and back. Carbon is stored mostly in live and dead wood as forests grow
Figure 2. Post-fire forest C recovery over time showing Total Carbon that includes the decomposition of trees killed by fire (Dead Wood), tree regeneration (Trees), and soil (Soil)

Figure 3. Projected Carbon Sequestration Capability under a range of management scenarios
Figure 4. Process Emissions less Carbon Stored in Floor Structure Components and Assemblies


Tables
Table 1. Carbon statistics for NFS lands, by national forest, in 2004 - 2006

Table 2. California public forestlands storage and emissions


Executive Summary


Forests have the potential to substantially mitigate the climate effects of increasing atmospheric CO2 concentrations by removing carbon from the atmosphere and storing it as biomass. Worldwide, forests offset about a third of global CO2 emissions from fossil fuel combustion. U.S. forests offset about 10-20% of U.S fossil fuel emissions.

Available information suggests that carbon stocks of the Sierra Nevada Assessment Forests have been increasing over the last several decades. These forests currently store approximately 1,442 Tg C (teragrams carbon) and represent approximately 7% percent of total National Forest System carbon stocks. Wood products harvested from these Forests store an additional XXX Pending from Stockman million metric tons of carbon. Bioenergy produced by these forests have offset an estimated XXX Pending from Stockman metric tons.

Recent Forest Inventory and Analysis plot data indicates that overall, Assessment area forests are sequestering carbon. However, reserved forest lands are emitting carbon while non-reserved areas are still sequestering carbon. Reference pending FIA data analysis. The overall future trajectory of carbon stocks on the assessment area is projected to increase for the next several decades though at a diminishing level due to, declining growth rates of maturing forest stands, the extent and severity of future fires, declines in the rate of tree regeneration after disturbances, tree mortality caused by bark beetles and other forest insects, the spread of root diseases, and potential changes in forest productivity. Projected changes in regional climate may exacerbate many of these change agents and thus reduce the carbon stocks on the assessment area.

Forest management activities that reduce the potential for uncharacteristically large and severe natural disturbances, promote rapid forest regeneration after disturbances, and build forest stand resistance to potential drought and insect and disease attacks may reduce some of these potential risks to forest carbon stocks. However, these activities may not be significantly meaningful in achieving system wide carbon stocks and can cause substantial negative impacts to wildlife habitat.

Introduction


Carbon storage is an important attribute of forest ecosystems. Management of forest systems can substantially affect the total forest carbon stocks, and changes. One of the goals of the 2010-2015 USDA Strategic Plan is to ensure national forests and private working lands are conserved, restored, and made resilient to climate change. The USFS roadmap for responding to climate change identified assessing and managing carbon stocks and change as a major element of its plan. Forests, shrublands and meadow lands exchange carbon with the atmosphere through photosynthesis and respiration. Photosynthesis converts carbon dioxide into sugars used to grow leaves, stems, woody materials, and roots. Forests release carbon dioxide to the atmosphere as a result of respiration and decay of dead wood, litter, and organic matter in soils. Balances of exchange and storage are influenced by multiple factors. Forests release some stored carbon to the atmosphere through decomposition of dead trees and vegetation caused by fires, insects and pathogens, drought related moisture tress, high wind events. Timber harvesting ,thinning and fuel hazard reduction activities remove carbon from the forest, although some of it is stored in wood products or used to produce energy – displacing fossil fuel use (Ryan et al. 2010) (Figure 1).

Forests have a substantial influence on global climate by removing CO2 from the atmosphere and storing carbon as biomass. From 1990 to 2006, terrestrial vegetation absorbed approximately one third of the annual global carbon emissions from fossil fuel combustion and land use change (Bonan 2008; Canadell et al. 2007a; Denman et al. 2007). Keeping forest systems healthy and productive helps maintain the feedback of carbon between the atmosphere and terrestrial ecosystems.


Carbon01.JPG
Figure 1. Flows of carbon from the atmosphere to the forest and back. Carbon is stored mostly in live and dead wood as forests grow (adapted from Ryan and Law. 2005. Biogeochemistry. 73:3-27).

The rate of forest carbon gains and losses, and total forest carbon stocks, vary over a forest’s life cycle. When forests are disturbed by fire, harvest, insect outbreaks, and other perturbations, forest carbon stocks will usually recover fully over the life-cycle of the forest (Kashian et al. 2006). Thus, over time, the net carbon change is often zero. This is an important attribute of healthy, functioning forest systems. Short term emissions of carbon from fire, harvest, insect outbreaks and other perturbations are eventually reabsorbed. Figure 2 below (McKinley et al. 2011) depicts a theoretical balance and recovery of carbon for a forest disturbed by fire.

carbon02.JPG
Figure 2. Post-fire forest C recovery over time showing Total Carbon that includes the decomposition of trees killed by fire (Dead Wood), tree regeneration (Trees), and soil (Soil).

Over large areas of forest comprised of a multitude of stands of different ages, carbon storage and sequestration rates are more stable because stands are in different stages of recovery from disturbance, with some stands providing a carbon “sink”, while others act as net “sources” releasing more greenhouse gases than they sequester (Ryan et al. 2010). Changes in the frequency or severity of disturbance regimes over large areas compared to the historical baseline can increase or lower the average carbon stocks in forests over time (Kashian et al. 2006, Smithwick et al. 2007, McKinley et al. 2011). Over time, these processes can significantly affect the amount of CO2 in the atmosphere, and thus global climate (McKinley et al. 2011, Bonan 2008, Canadell et al. 2007; Denman et al. 2007; Sabine et al. 2004).
Most studies estimate that the terrestrial biosphere is currently a net sink, removing more carbon from the atmosphere than it is emitting, and thus mitigating the effects of CO2 emissions from fossil fuel combustion and land use change (Denman et al. 2007, Le Quéré et al. 2009). Forests are the dominant contributors to the terrestrial ecosystem carbon sink, removing about 2.4 billion metric tons of CO2 per year from the atmosphere from 1990 to 2007, offsetting about one third of global CO2 emissions from fossil fuel combustion (Pan et al. 2011)

While still acting as a net carbon sink, Sierra forests are likely adding carbon presently in a way that diminishes their resiliency to climate change and uncharacteristically severe fire. Much of the carbon now accumulating in these forests is being added in the form of small trees that act as ladder fuels. Previous to the regime of fire suppression that started about a century ago, the accumulation of small trees was kept in check by frequently returning natural or anthropogenic fire. Such a regime needs to be restored to the Sierra ecosystem. One area that needs further study is the accumulation of biochar that results from from fire, particularly mixed-severity fire (McElligott, K. et al. 2011) (mostly low-severity, but with some moderate and high-severity patchiness), which may be an important carbon store in itself that not only stores oxidation resistant carbon but also contributes to the nutrient and hydrological cycles. (See also: Lehmann, J., et al. 2006.)

It is clear that forests currently play a key role in mitigating global CO2 emissions, and thus the rate of climate change (Nabuurs et al. 2007). However, the future of this ecosystem service is uncertain. Conversion of forests to non-forest, particularly in the tropics, and the potential effects of climate changes on forests raise questions about the future strength of the global forest carbon sink, and whether it may convert to an additional source of carbon to the atmosphere.

CA Assembly Bill 32 (AB, 32)

The Global Warming Solutions Act (AB 32) was signed into law in 2006 by Governor Schwarzenegger. This groundbreaking legislation requires California to reduce greenhouse gas emissions to 1990 levels by 2020 and by Executive Order, roll back emissions to 80% of 1990 levels by 2020.These goals will be achieved through capping greenhouse emitting sectors (manufacturing, energy production, transportation etc.) and issuing emissions allowances that will achieve these greenhouse gas reductions. In analyzing greenhouse gas balances in CA, the California Air Resources Board (CARB) Scoping Plan (CARB 2008) determined the Forest Sector was a net carbon sink. For implementation of the AB32, the forest sector was assigned an annual target of 5.2 Tg of carbon per year through 2020. This was to be achieved through sustainable management practices, including reducing the risk of catastrophic wildfire, and the avoidance or mitigation of land-use changes that reduce carbon storage. The Scoping plan states that “The federal government must also use its regulatory authority to, at a minimum, maintain current carbon sequestration levels for land under its jurisdiction in California”. Though non-binding, federal lands have an important role to play. The integrity of federal forest lands as a carbon sink or emission source will directly affect California’s greenhouses balances.

The balance of this chapter summarizes the best available scientific information on the carbon stocks and fluxes of the Assessment area. It provides estimates of existing carbon pools of the forest sector, including live and dead above ground biomass, soil carbon, and harvested wood products. These estimates are derived from local data collected during soil surveys, systematic forest inventory (the Forest inventory and Analysis Program), and forest harvest records.

Current Carbon Stocks


Carbon stocks and accounting can be performed in multiple ways. The United States adopted standard accounting and reporting protocols for forests and forest products, adapted from the U.S. Department of Energy (DOE) 1605(b) methodology -Technical Guidelines for Voluntary Reporting of Greenhouse Gas Program, Ch. 1. These forest carbon estimates included live trees, understory vegetation, standing dead trees, forest floor, down dead wood, soil carbon, harvested wood in use, and landfilled wood products (EPA 2004).

Forestlands

Forestlands are defined here as being composed of at least 10% cover by live trees of any size, including land that formerly had such tree cover and that will naturally or artificially be regenerated (Smith et al.2004). A nationwide study of estimates of forestland live tree, understory vegetation, standing dead tree, forest floor, down dead wood, soil carbon stocks was conducted by Heath et al. (2011), using ground-based datasets from the USFS Forest Inventory and Analysis program, and summarized data by NFS region and forest. These estimates did not include harvested wood in use or landfilled wood products. Of the pools included, all NFS lands were found to contain an average of 192 Mg C/ha on 60.4 million ha, and to sequester about a net 150 Tg CO2/yr. Of the nine NFS Regions analyzed, the Pacific Southwest region is one of the top four in terms of forest carbon stock (Mg C/ha). Table 1 shows forestland carbon stocks within the Assessment area. Forest carbon density is generally greatest in the central subregion of the assessment analysis area, and lowest in the eastern subregion. These patterns can be attributed generally to climatic patterns that affect ecosystem productivity, and, in turn carbon storage.

Table 1. Carbon statistics for NFS lands, by national forest, in 2004 - 2006. (Heath et al.)
Subregion
National Forest
Forest carbon density(Mg C/ha)
Forest area (1000 ha)
Total forest C +/- 95% CI as percentage of mean (Tg)
Aboveground live tree C density(Mg C/ha)
Central
Eldorado
281.9
232
65+/-20
135.4
South, East
Inyo
138.9
456
63+/-15
52.6
South, East
LTBMU
200.5
75
15+/-49
86
North, East
Modoc
142.9
517
74+/-15
38.8
North
Plumas
252.2
454
114+/-13
116.5
South
Sequoia
203.6
393
80+/-17
88.6
Central
Sierra
244.3
455
111+/-14
115.5
South
Stanislaus
235.3
320
75+/-18
106.5
Central
Tahoe
242.1
327
79+/-17
111.1
North
Lassen
213.9
420
90+/-15
91.2

Forest Products

Placeholder for Keith Stockman’s (RMRS) assessment of R5 harvest, products, current condition

Shrublands

The above table does not represent carbon stocks associated with shrublands or meadow systems. Meyer (2012) summarized findings regarding carbon storage in cold desert shrublands. The deep rooting systems and high root to shoot ratios of these ecosystems results in large carbon reserves, despite the fact that productivity in these areas is low compared to most forested lands, and that their role in the carbon cycle is assumed to be minor. Soil carbon dominates the terrestrial carbon pool, exceeding carbon stocks held in plant biomass nearly five-fold (Janzen, 2004). Hunt et al. (2004) found that sagebrush shrub lands in Wyoming are carbon sinks, gaining 30 g/cm/yr, in comparison to mixed grass prairie, which had a net ecosystem exchange rate for carbon of zero.

One of the greatest threats to cold desert shrub land is invasion by cheat grass, due to both an increase in fire frequency, and a lower root to shoot ratio for cheat grass as compared to native shrubs and grasses. Meyer (2012) reports that, as of 2006, total biomass C loss as a result of conversion to cheat grass in sagebrush steppe was 27-58 Tg, and 2 Tg in salt desert shrublands. Meyer concludes that shrubland management techniques may provide mitigation measures for improved carbon storage in the western US.

Meadows

Similar to shrublands, meadows may play a significant role in the carbon cycle, primarily due to their extensive belowground biomass. In addition, the role of meadows in the carbon cycle is magnified because they are typically associated with greater soil moisture compared to surrounding landscapes, and soil moisture is correlated to greater ecosystem productivity and respiration (Norton et al., 2006). Finally, human uses that are concentrated in meadows, such as grazing and water diversion, may impact soil carbon in these systems.
Norton et al. (2006) found that carbon storage was positively correlated to soil moisture in montane and subalpine Sierra Nevada meadows. They also found that meadows in properly functioning conditions (USFS definitions) store more soil carbon than degraded meadows, suggesting that stream restoration projects may increase carbon storage in Sierra Nevada meadows. Interactions between grazing and soil carbon storage were more complex. Grazing effects on soil moisture and carbon:nitrogen ratios overshadowed direct impacts to the carbon pool itself. However, a study on the influence of grazing on soil carbon storage in the high elevation meadows of the Tibetan Plateau, found that grazing did cause a loss of soil carbon storage, and resulted in a conversion of alpine meadows from carbon sinks to carbon sources (Sun et al., 2011).
Shaw and Harte (2001) investigated the potential effects of climate change on the carbon cycle in high elevation meadows in Colorado. They found that decomposition in a subalpine meadow-sagebrush ecosystem was limited by moisture in dry sites, and by temperature in mesic sites. Based on these findings, it would be expected that decomposition rates would increase in a warming climate for sites with adequate moisture, thereby reducing carbon storage. However, in dry sites, warming temperatures would be expected to have little influence on carbon storage.

Projected Trends in Forest Carbon Stocks


Overview
Management of forest systems can substantially affect the total forest carbon stocks, and changes. One of the goals of the 2010-2015 USDA Strategic Plan (USDA 2010) is to ensure national forests and private working lands are conserved, restored, and made resilient to climate change. The USFS roadmap for responding to climate change (USDA FS 2010a) identified assessing and managing carbon stocks and change as a major element of its plan. The future of the terrestrial carbon sink of western U.S. forests is uncertain due to the uncertainty associated with the multiple interacting factors that influence carbon stocks and fluxes (Lenihan et al. 2008a; Ryan et al. 2008; King et al. 2007; Pacala et al. 2007; Birdsey et al. 2007). These factors include: climate variability and change; potential positive effects of increased atmospheric CO2 concentrations on plant productivity; frequency, duration and severity of moisture stress; changes in the rate and severity of natural disturbances; and land management practices (Canadell et al. 2007; Smithwick et al. 2008; Hyvonen et al. 2007).

Projected climate changes for the region suggest that relatively high-elevation forests may increase in productivity and carbon sequestration, whereas these processes may decline in low elevation forests and mid-elevation forests with south and southwesterly aspects. Potential increases in the frequency and size of high severity fires, bark beetle outbreaks and root disease occurrence or severity could also have a significant impact on the carbon budgets of these forests over the 21st century. Extensive high severity fires, large scale tree mortality from bark beetles, and productivity losses due to root diseases could convert the Assessment area Forests from a net carbon sink to a carbon source for several decades (Kurz et al. 2008a; Kurz et al. 2008b; Bond-Lamberty et al. 2007). These influences are discussed in more detail below.

Climate Variability
Across the southwestern United States (California, Nevada, Utah, Arizona, Colorado, and New Mexico), temperatures since 1950 are reported to be the warmest in the past 600 years, with average daily temperatures in the most recent decade (2001 – 2010) being higher than any other decade since 1901 (Overpeck et al. 2012). Likewise, the spatial extent of drought from 2001 – 2010 covered the second largest area observed for any decade since 1901, and total streamflows in the four major drainages of the Southwest (Sacramento/San Joaquin, Upper Colorado, Rio Grande, and Great Basin) fell 5 percent to 37 percent below the 20th century averages during the 2001 – 2010 decade (Overpeck et al. 2012).

In the Sierra Nevada, warming temperatures since the 1980s are generally attributed to increasing nighttime minimum temperatures across the region; however, different elevations have experienced a range of temperature changes. For example, the annual number of days with below-freezing temperatures in higher elevations is decreasing, whereas the number of extreme heat days at lower elevations is increasing (Safford et al. 2012). Changing temperatures combined with elevation differences influence the type of precipitation received in the Sierra Nevada, which in turn greatly impacts regional hydrology and fire vulnerability.

Observations show an increase in the proportion of precipitation falling as rain instead of snow since the 1980s (Safford et al. 2012, Harpold et al. 2012); this change has manifested in spring snowpack decreases of at least 70 percent across the lower elevations of the northern Sierra Nevada, a trend that has not yet been observed in the higher elevation southern Sierra Nevada. By 2002, snowmelt was beginning 5 to 30 days earlier than what was typical in 1948, and peak streamflows were occurring 5 to 15 days earlier. These changes have, in effect, extended the fire season in the Sierra Nevada, particularly in low- to mid-elevation conifer forests (Safford et al. 2012). These changes are a primary concern for forest and water resource managers across the synthesis region and will effect forest health, productivity and integrity of forest carbon stocks.

Disturbance from Fire, Insects and Disease
A longer fire season, associated with earlier drying and more cured fuels, has resulted in increases in the size and intensity of wildfires across the Western United States in general and the Sierra Nevada and southern Cascades specifically (Westerling et al. 2006, Miller et al. 2012, Safford et al. 2012, Miller and Safford 2013). Scientists report increasing frequency and extent of wildfires, along with the increasing occurrence of uncharacteristically severe wildfire in the synthesis area (Lenihan et al. 2003, Miller et al. 2012, Miller and Safford 2012, Miller et al. 2009, Westerling et al. 2011) (see Fire and Fuels chapter (4.1)). In addition, climate-driven projections suggest that forests will become more susceptible to insect attack and disease (Evangelista et al. 2011, Sturrock et al. 2011), and a complex interaction of climate change, drought, altered fire regimes, and air pollution pose threats to forest resilience (see Air Quality chapter (8.0)). Research has already documented increased rates of insect attack, disease, and mortality in many Western forests that could portend vulnerability to substantial changes in forest structure, composition, and function (van Mantgem et al. 2009).

It is important to keep in mind, however, that even if an increasing trend of larger, more severe wildfire exists (some scientists have challenged this finding for the Sierra Nevada region), that trend can be beneficial to forests by helping to restore critical forest conditions (such as complex early seral forest). (See, e.g., Hanson and North 2008, Hutto 2008, Bond et al. 2009, Donato et al. 2009, Saab et al. 2009, Swanson et al. 2010, Burnett et al. 2011, Siegel et al. 2011, Donato et al. 2012, Seavy et al. 2012, Siegel et al. 2012, Buchalski et al. 2013, Siegel et al. 2013). Similarly, increased insect attack, disease, and mortality can all help restore important forest conditions for wildlife (such as resting sites, den sites, and nesting sites). Moreover, while some studies have found an increasing likelihood of fire due to climate change based on their modeling projections, a number of other studies and climate models predict decreasing fire activity—even as temperatures increase—due to increasing precipitation, including summer precipitation and changes in vegetation (McKenzie et al. 2004, Hamlet et al. 2007, Krawchuk et al. 2009, Gonzalez et al. 2010, Liu et al. 2010, Crimmins et al. 2011).

Climate Model Projections
Modeling experiments based on projected changes in climate, but not land use, suggest that the future strength of the forest carbon sink is very sensitive to the degree of change in climate, particularly precipitation, and fire regimes (Bachelet et al. 2001, Lenihan et al. 2008a; Lenihan et al. 2008b). If precipitation increases and temperature increases are small or moderate, net ecosystem productivity and carbon stocks are expected to increase. Conversely, if climate changes result in decreased precipitation and soil moisture during the growing season, net ecosystem productivity is expected to decline due to drought stress, and may result in a net carbon source to the atmosphere (Lenihan et al. 2008a; Lenihan et al. 2008b). Increasing concentrations of atmospheric CO2 may moderate these impacts by enhancing vegetation productivity and water use efficiency (Bachelet et al. 2001; Joyce and Nungesser 2000; Lenihan 2008a; Lenihan 2008b), at least up to a point where nutrient limitations and increasing temperatures overwhelm the beneficial effects of CO2 concentrations (Fishlin et al. 2007). Increases in annual area burned may further reduce net ecosystem productivity and carbon stocks despite the potentially positive effects of increasing CO2 concentrations (Lenihan et al. 2008a; Lenihan 2008b).

Long-term projections of regional net carbon balances depend upon assumptions about the future vegetation composition of currently forested areas (Canadell et al. 2008; Kashian et al. 2006). In coming decades, climatically suitable habitat for many tree species may shift from their current locations (Rehfeldt et al. 2006). Some models suggest that changes in climatically suitable habitat combined with amplified disturbance regimes may result in some forests of the Assessment area converting to non-forest vegetation (Westerling et al. 2012). However, there is considerable uncertainty regarding the effects of climate change on the composition of forest vegetation. These uncertainties in future forest composition and structure contribute to the uncertainty in long-term projections of forest carbon stocks and flux, and regional net carbon balances (Smithwick et al. 2008; Rhemtulla et al. 2009).

Model simulations estimate that from 1951–2000 in California’s forest, shrublands and grasslands there was an increase of 7% in the net primary productivity (NPP), mainly due to CO2 fertilization, and there was an increased in heterotrophic respiration of 5%, mainly due to increased forest soil carbon and temperature (Liu et al. 2011).

Net ecosystem productivity is very sensitive to changes in temperature, precipitation, soil moisture and other climate characteristics (Angert et al. 2005, Paio et al. 2009; Paio et al. 2008. All global climate models project surface temperature warming in the Assessment area. Average annual temperatures are expected to increase by +1.5°F to 5.9°F by the 2040s depending on the rate of GHG emissions. These projected temperature increases exceed observed 20th century year-to-year variability.

Several dynamic general vegetation models developed over the last decade have used climate and biogeochemical cycle data, and vegetation distribution and growth models to estimate trends in ecosystem distribution and carbon stocks. Aber (2001) provided a review of the earlier generation of these models, which have become more robust in recent years (Bachelet et al., 2004; Gonzalez et al., 2010; Lenihan et al., 2008). Lenihan et al. (2008) used a dynamic general vegetation model known as MC1, which estimated ecosystem productivity and resolution over past, current, and future time intervals, at the highest resolution available to date for California. Under all scenarios, vegetation types were found to migrate upward in elevation to habitat more suitable in terms of temperature. Models with differing precipitation scenarios produced were contrasted. Wetter conditions were expected to result in expansion of forests, whereas drier conditions were correlated to expansion of grasslands.
Regardless of precipitation scenario, these models predict a continued increase in mean carbon storage across California. The complex interactions of changing fire regime, changes in aboveground to belowground biomass, and plant-level ecophysiological responses to climate were considered. Geospatial datasets from this study are publicly available, and were summarized by Bioregional Assessment subregions in Table X, which compares carbon storage from the late 20th to the late 21st centuries. The data indicate that responses are highly dependent on the modeled climate projections, with the greatest increase in carbon storage predicted for the eastern sub region, probably as a result of greater belowground carbon storage. The greatest carbon losses were noted in forested regions that are anticipated to migrate upward, and potentially be replaced by less productive ecosystems.

Table X-Carbon storage from the late 20th century to the late 21st century

Numerous assessments have been conducted projecting future trends in carbon sequestration. Shaw et al. (2009) projected carbon sequestration of aboveground biomass decreases in all of the model-emission scenarios. Models project a decline in biomass because of a loss of conifer forests due to drought stress and because there will be significant fire loss as temperature increases and humidity decreases. Model-emission scenarios showed that the spatial pattern of carbon storage of aboveground carbon stocks changes drastically across California by the end of the century. Emission scenarios showed the following model projections: for the northwest an increase in carbon stocks under warm, wet climate conditions; for the eastern Sierra a significant loss in aboveground live carbon stocks; and carbon storage increases in live trees statewide (Shaw et al. 2009).

Robards et al. 2010 modeled growth and emissions of California Public forestlands over the next 10 years. Annual net carbon sequestration rates were estimated to be nearly 7MMTc after accounting for carbon stock reductions from insects and disease, wildfire and harvested wood products. Insect and disease mortality accounting for 34% reductions, wildfire accounting for slightly over 11% reductions, harvested wood accounting for .78% reductions.

Table 2 California public forestlands storage and emissions (Robards, 2010)

Source
Type
C (tonnes)
CO2e
Growth
Storage
-12,660,007
-46,462,226
Model Mortality
Emission
4,319,121
15,851,175
Wildfire
Emission
1,415.436
5,194,651
Harvest (merchantable)
Emission
40,703
149,379
Harvest (non-merchantable
Emission
57,008
209,219
Wood Products (in-use)
Pool
-28,039
-102,905
Wood Products (landfill)
Pool
-3,513
-12,894
Net

-6,859,292
-25,173,600

The California Energy Commission (CEC) commissioned a study of forest carbon in California that estimated that 7.5 Tc of Carbon per year were sequestered (Brown et al. 2004)

Goines et al 2009 conducted an assessment of carbon sequestration capabilities of the national forests in California over the next 100 years. The assessment analyzed forest growth, disturbance and management options under a range of management scenarios for national forests in CA. The analysis concluded that under current forest management activities, over the next 4-6 decades, California national forests will accumulate carbon at a higher rate than carbon will be lost although at a decreasing rate because of increased carbon loss through disturbances such as wildfire, insect and disease related pest mortality and inter-tree competition. However, at some point in the mid-21st century, carbon losses from wildfire, disease and other disturbances will exceed growth and national forests in California will become net emitter of carbon.

Figure 3. Projected Carbon Sequestration Capability under a range of management scenarios

Ch4_Tab3.png

Real Time Inventory Data

Real time carbon trend data is captured for the assessment area by Fried et al (under development for release) in the remeasurement of Forest Inventory and Analysis plots in California over this last decade. These measurements found that overall, forest lands in California are sequestering carbon, however, forests held and managed in a reserve status (wilderness, roadless areas) have become net emitters of carbon due primarily to mortality from fires, insect and disease mortality. Lands in non-reserve status are still sequestering carbon, however when the measurements are broken down by national forest boundaries there is significant variability. While most national forest units are still sequestering carbon, others have become become net emitters to fires and insect and disease mortality.

Harvested wood Products and Biomass utilization
Utilization of woody biomass for production of wood products as a substitute for more greenhouse gas intensive materials (e.g., steel and cement) for construction, and as a source of energy production have the potential to provide substantial global carbon benefits (Nabuurs et al. 2007). The assessment area has contributed substantial timber and volumes of biomass to bioenergy facilities since the 1980’s. Stockman et al evaluated the assessment areas contributions to harvested wood products and bioenergy sectors over the history of national forest system management.

Future contributions will depend upon management practices and energy policies in California. At regional and local scales, limited and declining capacity in the wood products industry adds further uncertainty to projections of the size of the carbon pool in harvested wood products, and the use of woody biomass to displace fossil fuels.

Potential Mitigation Options
Prompt Regeneration of Disturbed Areas
Rapid tree planting in areas severely disturbed by wildfire can accelerate carbon accumulation, and thus increase stand- and landscape-level carbon density over time. An evaluation of management options to modify the net carbon balance of Canadian forests found that the potential for increasing the forest carbon sink strength was largest with reducing regeneration delays after natural disturbances (Chen et al. 2000). In a recent study in Sierra Nevada mixed-conifer forests, however, the highest total aboveground carbon storage was found to occur in mature/old forest that experienced 100% tree mortality from wildland fire (and was not salvage logged or artificially replanted) relative to lightly burned old forest and salvage logged areas (Powers et al. 2013 [Fig. 1b]).

Within the assessment area, Forests have historically regenerated approximately 10% of severely burned areas. In the unplanted areas, rates of natural regeneration of disturbed areas vary depending primarily upon size of severely burned areas and proximity to natural seed sources. The interior of very large high severity burn patches are most prone to long-delayed tree regeneration. In these areas, rapid post-fire tree planting may accelerate forest development and carbon accumulation. However, such treatments are costly and may be financially infeasible (Chen et al. 2000), and can have significant detrimental effects on wildlife that relies on post-fire habitat.

Extended Rotations
Several commentators have suggested that increasing timber harvest rotation length can produce global carbon benefits by increasing forest carbon storage (Birdsey et al. 2007a; Nabuurs et al. 2007; Ingerson 2007; Leighty et al. 2006; Birdsey et al. 2000). In concept, increasing rotation ages can result in increased stand- and landscape-scale carbon storage by holding more carbon in forests and avoiding emissions from harvesting. However, there are several factors which suggest that achieving carbon benefits from extended rotations may be problematic.

Extended harvest rotations focused on specific ownerships, forests, and regions that will reduce annual timber harvest levels and wood products production in the affected area. It is likely that such local and regional reductions will be offset by market-driven harvest increases by other timberland owners and in other regions. For example, more than 85 percent of the reductions in timber harvest levels on western federal forests in the late 1980s and 1990s were replaced by increased harvest by other timberland owners and regions, including international imports (Wear and Murray 2004; Murray et al. 2004). As a result of this "leakage," it is likely there would be little or no net effect on national or global terrestrial carbon balance, and no net effect on atmospheric concentrations of CO2, as a result of increasing rotation lengths. In addition, increased lumber prices resulting from timber sale reductions (Wear and Murray 2004) could lead to increased utilization of more energy-intensive materials (e.g., steel and cement), and net increases in greenhouse gas emissions from fossil fuel combustion.

Extending rotation ages also increases exposure of landscape-scale carbon stocks to high severity disturbances such as wildfires and may even increase the probability of bark beetle outbreaks . In fire-prone areas, this increases the probability that the theoretical carbon storage benefits of extended rotations will be substantially reduced. Thus, the carbon storage benefits may not persist or be sustainable for extended periods. Recent analysis indicates that the risk of carbon loss due to wildfire is higher in the assessment area than many other forested areas of the U.S. (Hurteau et al. 2009).

Fire Suppression
Several authors have suggested that continued or increased fire suppression effort can help maintain or increase landscape-level carbon density and storage in the forest of the US (Birdsey et al. 2007a; Nabuurs et al. 2007; Birdsey et al. 2000). However, fire management strategies to increase forest carbon storage must consider both the amount of carbon stored and the stability of that storage as climate and fire regimes change (Schimel 2004; Schimel and Braswell 2005).Within the assessment area, the number of large forest fires in the assessment area have increased in both size and severity (Westerling et al. 2008).

Aggressive fire suppression can limit the number and size of large fires, and therefore may increase forest carbon storage and sink strength, at least for the short-term. However aggressive fire suppression efforts fail to address fundamental susceptibility of forest stands to inevitable igntions and potential extreme weather and fuel condition events that will consume these forest carbon stocks. Numerous simulations of the effects of projected climate change on wildfire in western North America all indicate an increasing probability of increased annual area burned and increased frequency of high severity fires (Westerling and Bryant 2008; Nitschke and Innes 2008; Bachelet et al. 2007; McKenzie et al. 2004; Brown et al. 2004). If observed trends continue or if the projected changes in fire regimes are even partially realized, aggressive fire suppression is likely to lead in the long run to most acres burning in fewer, more extreme and unmanageable events with greater losses of forest carbon stocks (Hurteau et al. 2008). Thus, it is likely that, at best, the carbon benefits of aggressive fire suppression are temporary, not permanent, and may even result in greater greenhouse gas emissions from fires and loss of forest carbon stocks than would occur with less aggressive fire suppression (Kirschbaum 2006; Breshears and Allen 2002).

Carbon Management in Fire Prone Forests
In the past, some groups have suggested that converting old forests to young, fast-growing plantations, whose harvested wood products could store carbon for several decades, would create a net increase in long-term carbon stocks. This approach was based on the idea that old forests are slow growing and carbon neutral because respiration costs nearly balance carbon uptake (Odum 1969). More recent research generally does not support this idea, as a global survey of old forests found that many continue to sequester carbon and have stocks that far exceed young, managed forests (Luyssaert et al. 2008). In addition, there is some evidence (Sillett et al. 2010) that large trees may contain even more carbon than our current estimates predict. This is because a tree’s carbon storage is estimated from its diameter and, unlike younger trees upon which most carbon allometric equations are based, old trees may be allocating most of their growth to the upper bole (Sillett et al. 2010). If young forest stocks could be efficiently harvested and their carbon sequestered in wood products for centuries, after several rotations they might match carbon stores in old forests dominated by large trees. However, this would be difficult with current wood use practices. The problem is not with the immediate carbon expense from machinery, because generally the amount of carbon loss from fossil fuel used in the forest operations (i.e., diesel and gasoline) is quite small (often <5 percent) compared with the carbon captured in the harvested forest biomass (Finkrel and Evans 2008, North et al. 2009a). The problem is that the carbon is not stored for long and often ends up, through decomposition, back in the atmosphere. A recent global analysis of the longevity of harvested forest carbon found that after 30 years, in most countries (90 of 169), less than 5 percent of the carbon still remained in longer storage, such as wood products and landfills (Earles et al. 2012). Most temperate forest countries with longer-lived products, such as wood panels and lumber, had higher carbon storage rates, with Europe, Canada, and the U.S. averaging 36 percent of the forest carbon still stored after 30 years (Earles et al. 2012). This higher rate, however, is still far short of what large long-lived trees would continue to accumulate and store over several decades to centuries.

In fire-prone forests, there has been substantial debate about whether carbon loss through fuels treatment (mechanical thinning and/or prescribed fire) is offset by lower carbon emissions if the treated stand is later burned by wildfire (Hurteau et al. 2008, Hurteau and North 2009, Mitchell et al. 2009, North and Hurteau 2011, Campbell et al. 2012). Different results from these studies and others are in part due to the spatial and temporal scale over which the carbon accounting is assessed, the ‘fate’ of the carbon removed in the fuels treatment, and whether long-term carbon emissions from dead trees are included (Hurteau and Brooks 2011). In general, treating forests often results in a net carbon loss due to the low probability of wildfire actually burning the treated area, the modest reduction in wildfire combustion and carbon emissions, and the need to maintain fuels reduction through periodic additional carbon removal (Campbell et al. 2012, Campbell and Ager 2013). Over the long term (i.e., centuries), Campbell et al. (2012) suggest that carbon stores in unthinned forests and those that experience infrequent high-severity fire will exceed those exposed to frequent low-severity fire. Forest location, however, is an important consideration, as some areas have much higher risk of ignition (e.g., road corridors, ridge tops) and carbon loss from wildfire than other areas. For most policy and economic analysis, Campbell et al.’s (2012) temporal scale is not as relevant as carbon dynamics over the next few decades (Hurteau et al. 2013).

Recent research has proposed the idea of carbon carrying capacity (Keith et al. 2009). This concept may be particularly relevant to forest managers because it emphasizes carbon stability and the level of storage that forests can maintain. In the absence of disturbance, a forest may ‘pack’ on more carbon as the density and size of trees increase. This additional biomass, however, makes the forest prone to disturbances, such as drought stress, pests, pathogens, and higher-severity wildfire, which increase tree mortality. This mortality reduces carbons stocks as dead trees decompose and through efflux, much of the carbon returns to the atmosphere. Carbon carrying capacity, therefore, is lower than the maximum storage potential of a forest, but represents the biomass that can be maintained given disturbance and mortality agents endogenous to the ecosystem. In frequent-fire forests such as Sierra Nevada mixed conifer, the carbon carrying capacity is the amount that a forest can store and still be resilient (i.e., have low levels of mortality) to fire, drought, and bark beetle disturbances.

One factor that would change this long-term balance is if management led to increased carbon storage by altering the amount and longevity of sequestered carbon. In Sierra Nevada mixed-conifer forests, two studies that examined historical forest conditions have suggested that this might be possible. Although historical forests were less dense due to frequent fire, they may have stored more carbon because the number and size of large trees was greater (Fellows and Golden 2008, North et al. 2009a) than in current forests that have fewer large trees, possibly due to increased mortality rates from increased stand density (Smith et al. 2005). Carbon stores are calculated from total tree biomass (a three dimensional measure) and will be much higher in a stand with a few large trees compared with a stand with many small trees, even if both stands have similar basal area (a two dimensional measure). Other studies (Hurteau et al. 2010, Scholl and Taylor 2010), however, have found higher carbon storage in modern fire-suppressed than in historical active-fire forests, suggesting that there may be considerable variability between different locations and levels of productivity. In general, forests managed so that growth and carbon accumulation are concentrated in large trees will also have longer, more secure carbon storage than in stands where growth is concentrated in a high density of small trees prone to pest, pathogen, and fire mortality.

Harvested Wood Products
Carbon stored in wood products in use and in landfills, during the 2005-2007 time period was estimated at 2.3-2.4 billion tonnes. During this same period, the annual rate of carbon accumulation in these same pools was estimated to be 28-29 million tonnes. This rate provides for 14.8% of that accumulated in forests (Malmsheimer, R.W. et al, 2011).

Lippke and Edmonds (2009) provide life cycle data related to alternative flooring and wall construction components and assemblies. Figure 4, below, reveals, for example, that Engineered Wood I-Joists, with wood covering, store less carbon than dimension joists because they use less fiber but all combinations of wood joist and wood covering store substantial amounts of carbon compared to nonwood joists and floor covering which result in significant emissions. While influenced by regional differences in energy sources, production processes, and species availability, the results of this analysis illustrate the potential benefits of approaches that utilize wood products.

Figure 4. Process Emissions less Carbon Stored in Floor Structure Components and Assemblies
Ch4_Fig1.png

Utilization of harvested forest biomass will continue to store carbon in wood products and landfills (US EPA 2008; Skog 2008; Skog and Nicholson 2000; Skog and Nicholson 1998) and produce further carbon benefits by reducing the demand for more fossil-fuel intensive products such as steel and cement (Malmsheimer et al. 2008; Perez-Garcia et al. 2005). In addition, both existing and emerging markets in forest biomass for use in energy production could offset fossil fuel emissions (Nichols et al. 2009; Malmsheimer et al. 2008).

Utilization of Forest Biomass for Energy Production-Bruce
According to the IPCC, “When used to displace fossil fuels, woodfuels can provide sustained carbon benefits, and constitute a large mitigation option” (Nabuurs et al. 2007 pg. 551). A recent study estimates that U.S. forests are capable of sustainably producing 368 million dry tons of wood per year, with 41 million dry tons from currently unused logging residues and 60 million dry tons from hazardous fuel treatments (Perlack et al. 2005). If applied to bioenergy production, this wood residue could offset a substantial percentage of U.S. CO2 emissions from fossil fuels (Richter et al. 2009).

In addition to ongoing energy production from milling byproducts at area wood processing facilities, several opportunities exist to utilize wood residues from timber harvest, hazardous fuel reduction projects, and other silvicultural treatments in the assessment area. These opportunities include an extensive network of bioenergy facilities, potential to develop a network of small bioenergy systems under California Senate Bill 1122, as well as a strong interest in biomass interests in developing strategically located wood heating systems to offset propane, diesel and electric systems. There is potential for a substantial increase in wood energy production in the assessment area that could replace CO2 emissions from fossil fuels while also reducing CO2 emissions from pile burning and other forest residue treatments.

Land Exchange
National Forests have the opportunity to exchange lands with willing landowners. Where land exchanges result in a net increase in forest productivity or net forested acres within the National Forest System, they may maintain or increase the area of productive forests.

Summary of Mitigation Options
The primary forest management action to mitigate increasing atmospheric CO2 concentrations is the sustainable use of woody biomass to generate energy and biofuels, and displace more fossil-fuel intensive construction materials (Nabuurs et al. 2007). As the IPCC concluded; “In the long term, a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, fibre or energy from the forest, will generate the largest sustained mitigation benefit” (Nabuurs et al. 2007, page 543).

Knowledge Gaps/Uncertainty
Long-term projections of regional net carbon balances depend upon assumptions about the future vegetation composition of currently forested areas (Canadell et al. 2008; Kashian et al. 2006). In coming decades, climatically suitable habitat for many tree species may shift from their current locations (Rehfeldt et al. 2006). Some models suggest that changes in climatically suitable habitat combined with amplified disturbance regimes may result in some forests of the Assessment area converting to non-forest vegetation (Westerling et al. 2012). However, there is considerable uncertainty regarding the effects of climate change on the composition of forest vegetation. These uncertainties in future forest composition and structure contribute to the uncertainty in long-term projections of forest carbon stocks and flux, and regional net carbon balances (Smithwick et al. 2008; Rhemtulla et al. 2009).

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  • Intergovernmental Panel on Climate Change [IPCC]. 2007. Climate Change 2007: Synthesis report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. R. Pachauri and A. Reisinger. Geneva, Switzerland.
  • Janzen, H. 2004. Agriculture, Carbon cycling in earth systems—a soil science perspective 2004. Ecosystems and Environment 104 () 399-417.
  • Kashian, D.M., W. H. Romme, D.B. Tinker, M.G. Turner, and M.G. Ryan. 2006. Carbon storage on landscapes with stand-replacing fires. BioScience 56: 598-606.
  • Kurz, W.A., G. Stinson, and G. Rampley. 2008. Could increased boreal forest ecosystem productivity offset carbon losses from increased disturbances? Philosophical Transactions of the Royal Society B 363: 2259-2268.
  • Kurz, W.A., G. Stinson, G.J. Rampley, C.C. Dymond, and E.T. Neilson. 2008a. Risk of natural disturbances makes future contribution of Canada’s forests to the global carbon cycle highly uncertain. Proceedings of the National Academy of Sciences 105: 1551-1555.
  • Kurz, W.A., C.C. Dymond, G. Stinson, G.J. Rampley, E.T. Neilson, A.L. Carrroll, T. Ebata, and L. Safranyik. 2008b. Mountain pine beetle and forest carbon feedback to climate change. Nature: 452: 987-990.
  • Law, B. E., M. E. Harmon. 2011. Forest sector carbon management, measurement, and verification, and discussion of policy related to mitigation and adaptation of forests to climate change. Carbon Management (2)1:73-84.
  • Le Quéré, M.R. Raupach, J.G. Canadell, G. Marland and others. 2009. Trends in the sources and sinks of carbon dioxide. Nature Geoscience 2:831-836.
  • Lehmann, J., Gaunt, J., Rondon, M. 2006. Bio-char Sequestration in Terrestrial Ecosystems--A Review. Mitigation and Adaptation Strategies for Global Change: 11: 2: 395-419.
  • Lenihan, J.M., D. Bachelet, R.P. Neilson, R. Drapek. 2008a. Simulated response of conterminous United States ecosystems to climate change at different levels of fire suppression, CO2 emission rate, and growth response to CO2. Global and Planetary Change 64: 16-25.
  • Lenihan, J.M., D. Bachelet, R.P. Neilson, and R. Drapek. 2008b. Response of vegetation distribution, ecosystem productivity, and fire to climate change scenarios for California. Climatic Change 87(Suppl 1): S215-S230.
  • Linares, J. C. and J. J. Camarero. 2012. From pattern to process: linking intrinsic water-use efficiency to drought-induced forest decline. Global Change Biology 18(3):1000-1013.
  • Luo, Y., B. Su, W. Currie. [and others] 2004. Progressive nitrogen limitation of ecosystem responses to rising atmospheric carbon dioxide. Bioscience 54(8):731-739.
  • Malmsheimer, R.W., P. Heffernan, S. Brink, D. Crandall, F. Deneke, C. Galik, E. Gee, J.A. Helms, N. McClure, M. Mortimer, S. Ruddell, M. Smith, and J. Stewart. 2008. Forest management solutions for mitigating climate change in the United States. Journal of Forestry 106: 115-171. [Used?]
  • Malmsheimer, R.W., J.L. Bowyer, J.S. Fried, E. Gee, R.L. Izlar, R.A. Miner, I.A. Munn, E. Oneil, and W.C. Stewart. 2011. Managing Forests because Carbon Matters: Integrating Energy, Products, and Land Management Policy. Journal of Forestry 109(7S):S7–S50.
  • McCarl, B.A., and Sands, R. D. (2007). Competitiveness of terrestrial greenhouse gas offsets: are they a bridge to the future? Climate Change (2007) 80:109-126 doi: 10.1007/s10584-006-9168-5.
  • McElligott, K. et al. 2011. Bioenergy Production System and Biochar Application in Forests: Potential for Renewable Energy, Soil Enhancement, and Carbon Sequestration. Res. Note RMRS-RN-46. Fort Collins, CO; U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.
  • McKinley, D. C., M. G. Ryan, R. A. Birdsey, C. P. Giardina, M. E. Harmon, L. S. Heath, R. A. Houghton, R. B. Jackson, J. F. Morrison, B. C. Murray, D. E. Pataki, and K. E. Skog. 2011. A synthesis of current knowledge on forests and carbon storage in the United States. Ecological Applications 21(6):1902-1924.
  • McKnechie, J., S. Colombo, J. Chen, W. Mabee and H. l. Maclean. 2012. Forest Bioenergy or Forest Carbon? Assessing Trade-Offs in Greenhouse Gas Mitigation with Wood-Based Fuels. Environ. Sci. Technol. 45:789-795.
  • Meyer, S.E. 2012. Restoring and managing cold desert shrublands for climate change mitigation. In: Finch, Deborah M., ed. Climate change in grasslands, shrublands, and deserts of the interior American West: a review and needs assessment. Gen. Tech. Rep RMRS-GTR-285. Fort Collins, CO: US Department of Agriculture, Forest Service, Rocky Mountain Research Station. P. 21-34
  • Murray, B. C., B. A. McCarl and H. C. Lee. 2004. Estimating Leadage from Forest Carbon Sequestration Programs. Land Economics 80(1):109-124.
  • Nabuurs, G.J., O. Masera, K. Andrasko, P. Benitez-Ponce, R. Boer, M. Dutschke, E. Elsiddig, J. Ford-Robertson, P. Frumhoff, T. Karjalainen, O. Krankina, W.A. Kurz, M. Matsumoto, W. Oyhantcabal, N.H. Ravindranath, M.J. Sanz Sanchez, X. Zhang. 2007. Forestry. Pages 541-584 In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on ClimatChange [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
  • Nicholls, D., R.A. Monserud, and D.P. Dykstra. 2009. International bioenergy synthesis – lessons learned and opportunities for the western United States. Forest Ecology and Management 257: 1647-1655.
  • Norby, R., E. DeLucia, B. Gielen. [and others] 2005. Forest response to elevated CO2 is conserved across a broad range of productivity. Proceedings of the National Academy of Sciences 102(50):18052-18056.
  • Norby, R. J. and D. R. Zak. 2011. Ecological Lessons from Free-Air CO2 Enrichment (FACE) Experiments. Annu. Rev. Ecol. Evol. Syst. 42:181-203.
  • North, M., Hurteau, M. and Innes, J. 2009. Fire Suppression and Fuels Treatment Effects on Mixed-Conifer Carbon Stocks and Emissions. Ecological Applications, 19(6): 1385-1396, 2009.
  • Norton, B., Horwath, W., Tate, K. 2006 Soil Carbon and Land Use in Upper Montane and Subalpine Sierra Nevada Meadows
  • Ogle, S. M., D. Dojima and W. A. Reiners. 2004. Modeling the impact of exotic annual brome grasses on soil organic carbon storage in a northern mixed-grass prairie. Biological Invasions 6: 365-377.
  • Pan, Y., R.A. Birdsey, J. Fang, R. Houghton, P.E. Kauppi, W.A. Kurz, and others. 2001. A Large and Persistent Carbon Sink in the World’s Forests. Science 333: 988-993.
  • Pearson, TRH, K. Goslee, and S. Brown. 2010. Emissions and potential emission reductions from hazardous fuel treatments in the WESTCARB region. California Energy Commission, PIER. CEC-500-XXXX-XXX. Available at: http://www.winrock.org/ecosystems/files/WestcarbRPT/WCHazardousFuelsReport.pdf.
  • Perez-Garcia, J., B. Lippke, J. Comnick, and C. Manriquez. 2005. An assessment of carbon pools, storage, and wood products market substitution using life-cycle analysis results. Wood and Fiber Science 37: 140-148.
  • Pfeifer, E. M., J. A. Hicke, and A. J. H. Meddens. 2011. Observations and modeling of aboveground tree carbon stocks and fluxes following a bark beetle outbreak in the western United States. Global Change Biology 17:339-350.
  • Potter, 1994 Estimating potential reduction flood benefits of restored wetlands. Water Resource Update, 97: 34􀂱38
  • Povirk et al, 2001 Carbon sequestration in Arctic and Alpine Tundra and Mountain Meadow Ecosystems. In: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect. Follett, R.F., Kimble, J.M., and R. Lal, Eds. CRC Press. 442pp.
  • Powers, E.M., J.D. Marshall, J. Zhang, and L. Wei. 2013. Post-fire management regimes affect carbon sequestration and storage in a Sierra Nevada mixed conifer forest. Forest Ecology and Management 291: 268-277.
  • Reinhardt, E. D., R. E. Keane, D. E. Calkin, J. D. Cohen. 2008. Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States. Forest Ecology and Management 256:1997-2006.
  • Robards, T. A., 2010. Current Forest and Woodland Carbon Storage and Flux in California: An estimate for the 2010 Statewide Assessment. 11pp
  • Ryan, M.G., B.E. Law. 2005. Interpreting, measuring, and modeling soil respiration. Biogeochemistry 73: 3-27.
  • Ryan, M. G., M. E. Harmon, R. A. Birdsey, C. P. Giardina, L. S. Heath, R. A. Houghton, R. B. Jackson, D. C. McKinley, J. F. Morrison, B. C. Murray, D. E. Pataki, and K. E. Skog. 2010. A Synthesis of the Science on Forests and Carbon for U. S. Forests. Issues in Ecology Report 13. Available online: http://www.fs.fed.us/rm/pubs_other/rmrs_2010_ryan_m002.pdf.
  • Sabine, C.L., M. Heinmann, P. Artaxo, D.C.E. Baker, C.A. Chen, C.B. Field, N. Gruber, C. Le Quéré, R. G. Prinn, F.E. Richey, P. Romero Lanko, J.A. Sathaye, and R. Valentini. 2004. Current Status and Past Trends of the Global Carbon Cycle. Pages 17-44 In: The Global Carbon Cycle: Integrating Humans, Climate, and the Natural World [C.B. Fields and M.R. Raupach (eds.)] Island Press, Washington, DC.
  • Safford, H. D., and D. A. Schmidt. 2007. Historic reference condition mapping: Lake Tahoe Basin Management Unit. USDA Forest Service Pacific Southwest Region, Regional Ecology Program, and The Nature Conservancy, California. Vallejo, CA. 20 pp.
  • Safford, H. D., D. A. Schmidt, and C.H. Carlson. 2009. Effects of fuel treatments on fire severity in an area of wildland–urban interface, Angora Fire, Lake Tahoe Basin, California. Forest Ecology and Management. 258(5):773-787
  • Schultz, E.D., C. Korner, B. E. Law, H. Haberl and S. Luyssaert. 2012. Large-scale bioenergy from additional harvest of forest biomass is neighter sustainable nor greenhouse gas neutral. Bioenergy doi: 10.1111/j.1757-1707.2012.01169.x
  • Skog, K.E. 2008. Sequestration of carbon in harvested wood products for the United States. Forest Products Journal 58: 56-72.
  • Skog, K.E. and G.A. Nicholson. 1998. Carbon cycling through wood products: the role of wood and paper products in carbon sequestration. Forest Products Journal 48: 75-83.
  • Skog, K.E. and G.A. Nicholson. 2000. Carbon Sequestration in Wood and Paper Products. Pages 79-88 In: The Impact of Climate Change on America’s Forests: A Technical Document Supporting the 2000 USDA Forest Service RPA Assessment (Joyce, L., and R. Birdsey eds.). General Technical Report RMRS-GTR-59. Fort Collins, CO, USA.
  • Shaw, M., Harte , J., 2001.Control Litter Decomposition in a Subalapine Meadow-Sagebrush Steppe Ecotone under Climate Change. Ecological Applications, Vol 11, No 4.pp.1206-1223
  • Smith, J. E., L. S. Heath, K. E. Skog, R. A. Birdsey. 2005. Method for Calculating Forest Ecosystem and Harvested Carbon with Standard Estimates for Forest Types of the United States. Gen. Tech. Rep. NE-GTR-343. Newton Square, PA. U.S. Department of Agriculture, Forest Service, Northern Research Station. 218 p.
  • Smithwick, E.A.H., M.E. Harmon, and J. B. Domingo. 2007. Changing temporal pattern of forest carbon stores and net ecosystem carbon balance: the stand to landscape transformation. Landscape Ecology 22: 77-94.
  • Smithwick, E.A.H., M.G. Ryan, D.M. Kashian, W.H. Romme, D.B. Tinker, and M.G. Turner. 2008. Modeling the effects of fire and climate change on carbon and nitrogen storage in lodgepole pine (Pinus contorta) stands. Global Change Biology 14: 1-14.
  • Stephens, S. L., R. E. J. Boerner, J. J. Moghaddas, E. E. Y. Moghaddas, B. M. Collins, C. B. Dow, C. Edminster, C. E. Fiedler, D. L. Fry, B. R. Hartsough, J. E. Keeley, E. E. Knapp, J. D. McIver, C. N. Skinner, and A. Youngblood. 2012. Fuel treatment impacts on estimated wildfire carbon loss from forests in Montana, Oregon, California, and Arizona. Ecosphere 3(5):38. http://dx.doi.org/10.1890/ES11-00289.1.
  • Sun et.al., 2011. Grazing depresses soil carbon storage through changing plant biomass and composition in a Tibetan alpine meadow.
  • Svejcar, T., R. Angell, J. A. Bradford, W. Dugas and others. 2008. Carbon fluxes on North American rangelands. Rangeland Ecology and Management 61: 465-474
  • Syphard, A. D., V. C. Radeloff, J. E. Keeley, T. J. Jawbaker, M. K. Clayton, S. I. Stewart, and R. B. Hammer. 2007.
  • Human Influence on California Fire Regimes. Ecological Applications 17(5):1388-1402.
  • USDA Forest Service. 2002 - 2011. Cut and Sold Report FY2011. http://www.fs.fed.us/forestmanagement/products/sold-harvest/cut-sold.shtml.
  • Westerling, A. L., H. G. Hidalgo, D. R. Cayan, and T. W. Swetnam . 2006. Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity. Science 313 (5789), 940.

Additional climate change/carbon references to consider (reviewed in TACCIMO: http://goo.gl/Lg3Bn):

  • Lenihan, J. M., Bachelet, D., Drapek, R., & Neilson, R. P. (2006). The response of vegetation distribution, ecosystem productivity, and fire in California to future climate scenarios simulated by the MC1 dynamic vegetation model. California Energy Commission, PIER Energy-Related Environmental Research Program, CEC-500-2005-191-SF, 25pp.
  • Liu, J., Vogelmann, J. E., Zhu, Z., Key, C. H., Sleetere,B. M., Price, D.T., Cheng, J. M., Cochrane, M. A., Eidenshink, J. C., Howard, S. M., Bliss, N. B., & Jiang,H. (2011). Estimating California ecosystem carbon change using process model and land cover disturbance data: 1951–2000. Ecological Modelling, 222, 2333-2341.
  • Potter, C. (2010). The carbon budget of California. Environmental Science and Policy, 13, 373-383.
  • Shaw, M. R., Pendleton, L., Cameron, D., Morris, B., Bratman, G., Bachelet, D., Klausmeyer, K., MacKenzie, J., Conklin,D., Lenihan, J., Haunreiter, E., & Daly, C. (2009). The impact of climate change on California's ecosystem services. California Energy Commission Public Interest Energy Research (PIER) Program, CEC-500-2009-025-F.
  • Winford, E. M. & Gaither, J. C. (2012). Carbon outcomes from fuels treatment and bioenergy production in a Sierra Nevada forest. Forest Ecology and Management, 282, 1 – 9.


[snapshot: 4/9/2013 @1016]
[snapshot 7/3/2013 @1030 for SNF Assessment]



Chapter 5

Bio-Region NF Composite Links
Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 - Water | Chapter 8 - Fish, Plants and Wildlife | Chapter 8 - Range | Chapter 8 - Timber | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Chapter 14 | Chapter 15
Sierra Nevada Bio-region
Chapter 5: At Risk Species and Species for Special Concern

At Risk Species


At risk species focus is on current species status and the ecological conditions needed to support the species. In Chapter 1, many influences of ecological conditions were documented. Here in Chapter 5, the species identified should show influences on the ecological condition both on and off the plan area. Specifically, the process should identify key risk factors that later may be used to inform the development of plan components.

Determining the At Risk Species included the following:
  • List of all the Threatened, Endangered, Proposed and Candidate Species
  • Development of Species of Conservation Concern
These species need to be known to occur on National Forest System Lands.

Threatened, Endangered, Proposed and Candidate Species


Appendix A is the entire bio-regional list of threatened, endangered, proposed and candidate species. Listed below are the species or their listed critical habitat which are known to occur within the Southern Sierra Forest Planning Area on National Forest System Lands. All other species will not be addressed here.

In general, information on these species can be found in a variety of Biological Assessments and NEPA documents. Click the species name in the table below for draft versions of accounts for each Federally threatened, endangered, proposed, or candidate species known within the National Forest System Area of the Southern Sierras.

Scientific Name
Common Name
FederalStatus*
Inyo
Sequoia
Sierra
Desmocerus californicus dimorphus

Valley elderberry longhorn beetle

T

X
X
Gila bicolor snyderi

Owen’s Tui Chub

E
X


Oncoryhynchus aguabonita whitei

Little Kern golden trout

T

X

Oncorhynchus aguabonita whitei

Little Kern golden trout

critical habitat

CH

X

Oncorhynchus clarki seleniris

Paiute cutthroat trout

T
X

X
Oncorhynchus clarki henshawi

Lahontan cutthroat trout

T
X

X
Rana aurora draytonii

California red-legged frog

T

X
X
Empidonax traillii extimus

Southwestern willow flycatcher

E

X

Empidonax traillii extimus

Southwestern willow flycatcher

critical habitat

CH

X

Gymnogyps californianus

California condor

E

X
X
Gymnogyps californianus

California condor critical habitat

CH

X

Vireo bellii pusillus

Least Bell’s vireo

E

X

Ovis canadensis sierrae

Sierra Nevada bighorn sheep

E
X
X
X
Ovis canadensis sierrae

Sierra Nevada bighorn sheep

critical habitat

CH
X


Vulpes macrotis mutica

San Joaquin Kit Fox

E

X

Calyptridium pulchellum

Mariposa pussy paws

T


X
Caulanthus californicus

California jewelflower

E

X

Clarkia springvillensis

Springville clarkia

T

X

Opuntia basilaris var. trelease

Bakersfield cactus

E

X

Pseudobahia peirsonii
San Joaquin Adobe Sunburst
T

X

Sidalcea keckii

Keck’s checker-mallow

E

X
X
Anaxyrus canorus

Yosemite toad

C
X

X
Rana muscosa

Mountain yellow-legged frog

C
X
X
X
Coccyzus americanus occidentalis

Western yellow-billed cuckoo

C

X

Centrocercus urophasianus

Greater sage grouse, bi-state population

C
X


Martes pennant

Fisher

C

X
X
Abronia alpina

Ramshaw Meadows sand-verbena

C
X


Pinus albicaulis

Whitebark pine

C
X
X
X
* E = Endangered; T = Threatened; CH = Critical Habitat; C = Candidate

Development of Species of Conservation Concern


Final list of the Species of Conservation Concern will be developed by the Regional Forester which is based upon the best available scientific information indicating substantial concern about the species’ capability to persist over the long-term in the plan area (36 CFR 219.9).

At this point, we pulled the list for the greater Sierra Nevada area, but focused in on the species that were within the Southern Sierra planning area. Appendix xx-xx show the species and the known information for each of the species.

The process that was followed is shown below:

Development of Species of Conservation Concern include:
  • Species with status rankings of G/T 1-2 on the NatureServe Ranking System.
  • Species petitioned for Federal Listing with a positive “90-day finding”. (Sierra Nevada Red Fox, C species)
  • Species that are Federally delisted in the last 5 years or other delisted species for which regulatory agency monitoring is still considered necessary. (only Bald Eagle to add)
  • Secondary criteria consideration granted to:
    • Species with status ranks of G/T 3 or S 1-2 on the NatureServe ranking system
    • Species listed as threatened or endangered by California or federally recognized tribes. Note: No specific species have been highlighted by a tribe on their individual websites.
    • Species identified on other relevant Federal, State, federally recognized tribes as being a high priority for conservation. Note: (some addressed; California Fully protected Species, California State Species of Special Concern, Potentially FWS Birds of Conservation Concern )
    • Species where valid existing information indicates the species are of local conservation concern due to: (will have to check this after the other list is created to the Regional Forester's Sensitive Species list for comparisons and additional concerns/threats/declining trends)
      • Significant threats to populations or habitat from stressors on and off the plan area.
      • Declining trends in populations or habitat.
      • Restricted ranges (for example, narrow endemics, disjunct populations, or species at the edge of their range).
      • Low population numbers or restricted habitat within the plan area.
      • Note: this is where the Regional Foresters Sensitive Species list will be considered.
  • Species must be native and have a record of occurrence in the last 15 years. Do not include species that are thought to be accidental or well outside their current range. Note: for plants this may be extended.
  • The best available scientific information indicates substantial concern about the species capability to persist over the long-term in the plan area. (scientific literature, species studies, habitat studies, analysis of information obtained from a local area, result of expert opinion, or panel consensus)
    • Do not include species where the species is secure and its continued long-term persistence in the plan area is not at risk based on knowledge of its abundance, distribution, lack of threats to persistence, trends in habitat, and responses to management.
    • Do not include species where there is insufficient scientific information available to conclude that there is a substantial concern about the species capability to persist in the plan area over the long term.

Information about a Species of Special Concern that may be consider include: (if it was considered as part of Regional Forester's Sensitive Species list, then it has a write-up)
  • Current taxonomy
  • Distribution (including historical and current trends), especially species known from only a relatively few, discrete locations, and the status of those locations).
  • Abundance (including historical and current trends).
  • Demographic and populations trends, including population effects resulting from hunting, fishing, trapping, and natural population fluctuations if available.
  • Diversity (phenotypic, genetic, and ecological)
  • Habitat amount, quality, distribution, connectivity, and trends
  • Ecological function
  • Important biological interactions and ecological processes, such as periodic fire, flooding, groundwater discharge, and so on.
  • Limiting factors
  • Uncharacteristic natural events like severe wildfire or insect epidemics.
  • Effects of changing climate and susceptibility to stressors caused by human disturbances or activities like air and water pollution, invasive species, trails, roads, and dams.

Lists of Species


Statewide



Sierra Nevada wide

Southern Sierra



Additional references to consider for climate change/at risk species (reviewed in TACCIMO:http://goo.gl/Lg3Bn)):


Amphibians:

Davidson, C., Shaffer, H. B. & Jennings, M. R. (2001). Declines of the California red-legged frog: Climate, UV-B, habitat, and pesticides hypotheses. Ecological Applications, 11(2), 464 – 479.

Lacan, I., Matthews, K. & Feldman, K. (2008) Interaction of an introduced predator with future effects of climate change in the recruitment dynamics of the imperiled Sierra Nevada yellow-legged frog (Rana sierra). Herpetological Conservation and Biology, 3 (2), 211 – 223.



Birds:

Gardali, T., Seavy, N. E., DiGaudio, R. T. & Comrack, L. A. (2012) A climate change vulnerability assessment of California’s at-risk birds. PLoS ONE, 7(3), e29507. doi:10.1371/journal.pone.0029507

Bond, M. L., Gutierrez, R. J., Franklin, A. B., LaHaye, W. S., May, C. A. & Seamans, M. E. (2002). Short-term effects of wildfires on spotted owl survival, site fidelity, mate fidelity, and reproductive success. Wildlife Society Bulletin, 30 (4), 1022 – 1028.

LaHaye, W. S., Zimmerman, G. S. & Gutierrez, R. J. (2004). Temporal variation in the vital rates of an insular population of spotted owl (Strix occidentalis occidentalis): contrasting effects of weather. The Auk, 121(4), 1056 – 1069.

North, M., Steger, G., Denton, R., Eberlein, G., Munton, T., & Johnson, K. (2000). Association of weather and nest-site structure with reproductive success in California Spotted Owls. Journal of Wildlife Management, 64(3), 797-807.

Peery, M. Z., Gutierrez, R. J., Kirby, R., Ledee, O. E. & Lahaye, W. (2012). Climate change and spotted owls: potentially contrasting responses in the Southwestern United States. Global Change Biology, 18, 865 – 880. doi: 10.1111/j.1365-2486.2011.02564.x

Weathers, W. W., Hodum, P. J. & Blakesley, J. A. (2001). Thermal ecology and ecological energetics of California spotted owls. The Condor, 103 (4), 678 – 690.

Bond, M. L., R. B. Siegel &, D. L. Craig, editors. (2012). A Conservation Strategy for the Black-backed Woodpecker (Picoides arcticus) in California. Version 1.0. The Institute for Bird Populations and California Partners in Flight. Point Reyes Station, California.

Green, G. A., Bombay, H. L. & Morrison, M. L. (2003). Conservation assessment of the willow flycatcher in the Sierra Nevada. Sacramento, CA: US Forest Service Region 5.

Siegel, R. B., Wilkerson, R. L. & DeSante, D. F. (2008). Extirpation of the willow flycatcher from Yosemite National Park. Western Birds, 39, 8 – 21

Keane, J. J., Morrison, M. L. & Fry, D. M. (1999). Prey and weather factors associated with temporal variation in northern goshawk reproduction in the Sierra Nevada, California. Studies in Avian Biology, 31, 85 – 99.



Mammals

Epps, C. W., McCullough, D. R., Wehausen, J. D., Bleich, V. C. & Rechel, J. L. (2004) Effects of climate change on population persistence of desert-dwelling mountain sheep in California. Conservation Biology, 18 (1), 102 – 113.

Davis, F. W., Seo, C. & Zielinski, W. J. (2007). Regional variation in home-range-scale habitat models for fisher (Martes pennanti) in California. Ecological Applications, 17 (8), 2195 – 2213.

Krohn, W.B., Zielinski, W. J. & Boone, R. B. (1997). Relations among fishers, snow, and martens in California: Results from small-scale spatial comparisons. In, G. Proulx, H. N. Bryant, & P. M. Woodard (Eds.), Martes: Taxonomy, ecology, techniques, and management (pp. 211 – 232). Edmonton, Alberta, Canada: Provincial Museum of

Scheller, R. M., Spencer, W. D., Rustigian-Romsos, H., Syphard, A. D., Ward, B. C., & Strittholt, J. R. (2011). Using stochastic simulation to evaluate competing risks of wildfires and fuels management on an isolated forest carnivore. Landscape Ecology,

[snapshot: 4/9/2013 @1022]



Chapter 6

Bio-Region NF Composite Links
Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 - Water | Chapter 8 - Fish, Plants and Wildlife | Chapter 8 - Range | Chapter 8 - Timber | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Chapter 14 | Chapter 15
Sierra Nevada Bio-region
Chapter 6: Assessing Social, Cultural, and Economic Conditions


Introduction


Purpose of Assessing Social, Cultural, and Economic Conditions

Sustainability is the capability to meet the needs of the present generation, without compromising the ability of future generations to meet their needs. According to the “National Report on Sustainable Forests” (USDA Forest Service 2011), through sustainable management, forests can contribute to the resilience of ecosystems, societies, and economies, while safeguarding biological diversity and providing a broad range of goods and services for present and future generations. Land management decisions need to account for influences and interactions among the three arenas of environment, society, and economy in order to achieve sustainability. Figure I-1 from the report, presented below, shows the current model. This new model reflects the understanding that the environmental realm is the foundation of strong sustainability. The benefits of nature are irreplaceable and the entire economy is reliant on society, which in turn is entirely dependent on the environment, emphasizing the interdependence and interconnectedness between our society, our economy, and the natural environment.

Figure I-1 from the National Report on Sustainable Forests.png
Figure I-1 taken from the National Report on Sustainable Forests – 2010 (USDA Forest Service 2011).




















Strong Sustainability represents an evolution in the thinking within resource management agencies. Sustainability has often been conceived as a "three-legged stool" suggesting that social and economic issues exist outside of an ecological foundation (Dawe and Ryan 2003). Weak sustainability envisioned the environmental, social and economic realms as intersecting, yet separate parts of a system. This updated model of strong sustainability, adopted by the Forest Service (USDA Forest Service 2011), reflects a more holistic and scientifically rigorous understanding of the role and need for a healthy environment to sustain human society and economies, in sink with intact ecosystems.

Nearly twenty years ago the Forest Service wrote in the RMRS-GTR-246 --An Ecological Basis for Ecosystem Management (Kaufmann et al. 1994), "ecosystem management involves a shift in focus from sustaining production of goods and services to sustaining the viability of ecological, social and economic systems now and into the future…by bringing ecosystem capabilities and social and economic needs into closer alignment."

Callicot and Mumford (1998) further refined the connection between human use of resources and the ecosystem by defining ecological sustainability "as meeting human needs without compromising the health of the ecosystem."

The need for a clear commitment to strong sustainability in forest planning for the next planning cycle has never been more urgent as we face a changing and uncertain future. In the Convention on Biodiversity (Thompson et al. 2009) found that, "the best available scientific evidence strongly supports the conclusion that the capacity of forests to resist change, or to recover from disturbance, is dependent on biodiversity at multiple scales." The protection and enhancement of biodiversity coupled with robust monitoring plans to ensure we can learn and adapt is the underpinning of a commitment to strong sustainability (USFS 2012e).

The 2012 Planning Rule for National Forest System (NFS) land management planning recognizes that social, economic, and ecological systems are interdependent, without one being a priority over the other. As such, the planning rule requires the consideration of social, economic, and ecological factors in all phases of the planning process. National forest management can influence social and economic conditions relevant to a planning area, but cannot ensure social and economic sustainability, because many factors are outside the control and authority of the responsible official. For that reason, the Planning Rule requires that plan components contribute to social and economic sustainability within Forest Service authority, and the inherent capability of the plan area. We used Forest Service proposed directives to provide some guidance for assessing social, cultural, and economic conditions in the bio-region, specifically, Forest Service Handbook 1909.12, Chapter 10, section 13.1.

The first part of this chapter describes the social, cultural, and economic context of the Sierra Nevada bio-region and how that influences National Forest System lands. The second part identifies key social, cultural, and economic conditions that national forests in the bio-region influence, as well as trends affecting these conditions. At the end of this chapter, we describe potential areas of opportunity for forest management to contribute to social, economic, and ecological sustainability.

‍‍Assessment Area‍‍

Ecological and social systems are not confined within forest boundaries. The 2012 Planning Rule requires that assessments identify and evaluate existing and potential future conditions on National Forest System lands in the context of the broader landscape. We plan to use multiple scales for each forest plan revision effort in California to capture important influences on forests, as well as effects of forest management on key social, cultural, and economic conditions. Assessing and comparing social, cultural, and economic conditions at a variety of scales is important because it allows decision making to incorporate the fact that socioeconomic conditions in one area can differ from another, and therefore the implications of management actions may differ as well. A bio-regional assessment can also identify those areas where we need consistent management strategies across forest boundaries.

This chapter primarily focuses on assessing social, cultural, and economic conditions at the scale of the Sierra Nevada bio-region.The boundary of the Sierra Nevada bio-region is the full study area boundary used in the 1996 Sierra Nevada Ecosystem Project (SNEP) final report to Congress. This is different than the boundary used by the Sierra Nevada Conservancy, a California state agency that recently developed a report on socioeconomic indicators in the Sierra Nevada. Differences between the report and this chapter are further discussed at the end of this section.

Influences beyond the bio-region will also be considered and incorporated. The social, cultural, and economic conditions of the Sierra Nevada bio-region are heavily influenced by factors outside their boundaries. Management decisions can also have impacts far beyond the boundary of the bio-region. For example, a large number of visitors to the national forests come from urban areas outside the bio-region, such as Sacramento, San Francisco, Los Angeles, Reno, and Las Vegas. In fact, people come from around the world to visit these national forests. "The Sierra Nevada contains features, species, and areas with heightened social value; these present management concerns that extend well beyond local communities" (Winter et al. 2013b, p.6).The 1996 Sierra Nevada Ecosystem Project (SNEP) found that most recreation in the Sierra Nevada was not by local residents, but instead by those from other areas of California. Out-of-state and foreign visitors also made up significant proportions with 15% and 10% of summer visits respectively. These non-Californian visitors tended to be primarily drawn to the unique, “world class” recreational resources in the Sierra Nevada and tied their recreation into activities in other areas of the region. Recreation numbers in more isolated areas of the Sierra Nevada were highly dependent on access to urban centers in California (Duane 1996). A layering of scales provides a more complete picture of the socioeconomic conditions in the bio-region and how they interact with individual forests. Separate chapters are available for assessing social, cultural, and economic conditions at the forest scale.

Resources in the Sierra Nevada provide significant value to geographically disparate populations, even to those not directly engaging with the region, through passive-use values including existence, option, and bequest values. These values are often found to represent the majority of economic values for a region (Richardson 2002). For example, Loomis (1989) found that the passive-use value of Mono Lake represented 94% of the total economic value of the resource. Richardson (2002) estimates that the passive-use value for the Eastern Sierra Nevada at $321 million per year for just local residents, suggesting that out-of-state and international values could be even higher.

In the first part of this chapter, we present aggregated socioeconomic data for the set of census county divisions (CCDs) that intersects the bio-region (also see table below). CCDs are county subdivisions delineated by the United States Census Bureau in cooperation with state, tribal, and local officials for statistical purposes. Many counties that intersect the bio-region have large areas that lie outside the bio-region. Using CCDs, rather than entire counties, provides a closer fit to the geographical footprint of the bio-region. However, we also present data for the set of counties that intersects the bio-region (also see table below) to compare how these two footprints may differ. In some cases, such as with the economic portions of this chapter, CCD-level information is not available and county-level data are used. Counties represent a good economic study area for examination since much of the economic activity associated with the forests occurs near the forest and in the larger cities along the Central Valley, such as Sacramento, Merced, Fresno and Bakersfield.

We also present socioeconomic data at state and national levels, and provide comparisons across different sub-regions within the Sierra Nevada. We identified eight sub-regions (also see table below) within the bio-region, adapted from the state's Sierra Nevada Conservancy sub-regions. We use the aggregate of CCDs that intersect each sub-region to describe demographic data for sub-regions. Again, due to the nature of the data, economic information will be described for the aggregate of counties that intersects each sub-region. The table below lists the 108 CCDs, 32 counties, and 8 sub-regions in California and Nevada that make up the bio-region.

List of sub-regions, counties, and CCDs.png
List of sub-regions, counties, and census county divisions in the Sierra Nevada bio-region.

In 2011, the Sierra Nevada Conservancy (SNC) published a Demographic and Economic System Indicators report for the Sierra Nevada. ‍‍While examining similar types of socioeconomic data, the data in this chapter differ from the report due to difference in geographic scope between the two analyses‍‍. The SNC’s boundary for the Sierra Nevada was established by statute, and the report either uses census block data that closely aligns with the boundary or county-level data. The SNC boundary is similar to the SNEP boundary of the Sierra Nevada used in Forest Service’s bio-regional assessment, but excludes the Tahoe Basin, a portion of Nevada, and a portion in the northwest along the boundary with Oregon. Using census block data allows for a precise definition of the Sierra Nevada as defined by the SNC boundary, with the toe of the Sierra foothills forming the western boundary. Alternatively, using CCDs that intersect the SNEP boundary, as we do in this chapter, results in the inclusion of certain Central Valley cities, such as Fresno and Bakersfield. The SNC report is more descriptive of local socioeconomic conditions in the Sierra Nevada and brings a valuable perspective to the information presented in this chapter.The SNC population base is much smaller than what is used in this chapter, and portrays a substantially different picture of the region in terms population growth, diversity, employment, and other socioeconomic measures. Please visit the report using the link above. Providing a broadened definition of the Sierra Nevada is also vital to understanding the region and potential future changes. Many of the changes occurring in the communities immediately outside the Sierra Nevada will influence national forest system management, and these communities are also areas the Forest Service is trying to better understand, outreach to, and engage with. Again, a layering of scales will help develop the fullest picture possible of Sierra Nevada forests. Forest-level assessment chapters dive more deeply into local conditions.

Governance and Information in a Multilevel World


In addition to the transition in thinking from weak sustainability to strong sustainability, there is a lower profile but also important transition towards thinking at multiple scales and multiple levels with regards to environmental management. Cash et al. (2010) provide a good overview of this trend and a conceptual framework that provides good food for thought regarding the forest assessment and plan revision process.

Sources of Information

A primary source of socioeconomic data for the bio-region, including population, age, gender, race, ethnicity, language, education, housing, poverty levels, household earnings, and employment were taken from the Economic Profile System – Human Dimension Toolkit (EPS-HDT) developed by Headwaters Economics (2012a) in partnership with the Bureau of Land Management and the U.S. Forest Service (http://headwaterseconomics.org/tools/eps-hdt). EPS-HDT is a free software application that runs in Microsoft Excel and produces detailed socioeconomic reports of communities, counties, states, and regions, including custom aggregations and comparisons. EPS-HDT uses published statistics from federal data sources, including the Bureau of Economic Analysis and Bureau of the Census, U.S. Department of Commerce; Bureau of Labor Statistics, U.S. Department of Labor; and others.

EPS-HDT develops CCD-level reports using data from the Census Bureau's American Community Survey (ACS). The ACS is a nation-wide survey conducted every year by the Census Bureau that provides current demographic, social, economic, and housing information about communities—information that until recently was only available once a decade. The ACS is not the same as the decennial census, which is conducted every ten years (the ACS has replaced the detailed, Census 2000 long-form questionnaire). One disadvantage of using this data is that smaller scale geographies are presented as multiyear estimates, and cannot be used to describe any particular year in the period, only what the average value is over the full period. Thus, 2010 ACS data presented here represent an average during the period from 2006 to 2010. In addition, because the ACS collects data from a sample of the population, it is subject to error. For details on the accuracy of the data see the document “American Community Survey Multiyear Accuracy of the Data.”

The "Science Synthesis to Support Land and Resource Management Plan Revision in the Sierra Nevada and Southern Cascades", developed by the USDA Forest Service Pacific Southwest Research Station, provided most of the scientific, peer reviewed information that we included here. This synthesis focused on peer-reviewed science that has become available since the development of existing land management plans in the Sierra Nevada. Other major sources of information that we used to describe conditions in the Sierra Nevada bio-region include: the 1996 Sierra Nevada Ecosystem Project (SNEP) final report to Congress, the California Department of Forestry and Fire Protection’s 2010 assessment of California’s forests and rangelands, the Sierra Nevada Conservancy 2011 Strategic Plan and 2011 System Indicators Report for Demographics and the Economy, and Sierra Business Council documents. The boundary for the “Sierra Nevada” varies somewhat across these different sources.


Social, Cultural, and Economic Context of the Sierra Nevada Bio-region


The focus here is to provide the social, cultural, and economic context of the Sierra Nevada bio-region. It includes information on history and culture, population, demographics, settlement patterns and housing, human well-being, the political environment, economic health, and economic diversity. This context is important because it influences national forests and forest management in the bio-region. Thus, while national forest management can, to an extent, influence social, cultural, and economic conditions, larger socioeconomic forces may be at play that influence the agency’s management decisions and outcomes and, thereby, its ability to influence some of these conditions.

History and Culture


Historical context

The Sierra Nevada bio-region has a rich history and culture that has always been deeply connected to the land and its natural resources. Native Americans first settled the region over 10,000 years ago, sustaining themselves through hunting, fishing, gathering, quarrying, and trade (Sierra Nevada Ecosystem Project Science Team 1996). They moved with the seasons to harvest Sierra oaks and wildlife, practiced agriculture, and managed the landscape through fire to promote desirable conditions for flora and fauna (Duane 1999). Settlers to the area mainly saw the massive mountain range as a barrier to migration with too harsh of a climate for settlement (Duane 1999). It was not until 1848, when John Marshall discovered gold at Sutter’s Mill that the region captured the attention of the world, starting the migration of tens of thousands of people into and throughout the Sierra Nevada, beginning a series of boom-and-bust cycles of resources use (Sierra Nevada Ecosystem Project Science Team 1996).

Early mining activity led to significant timber harvesting, ranching, farming, and water diversions that laid the foundation for today’s hydrologic system (Sierra Nevada Ecosystem Project Science Team 1996). Between 1848 and 1860, 150,000-175,000 people moved into the Sierra Nevada. At the same time, the Native American population sharply declined because of disease, starvation, warfare, resettlement and extermination (Sierra Nevada Ecosystem Project Science Team 1996, Mittelbach and Wambem 2003). The ideologies of the Gold Rush era had long-lasting cultural effects on the Sierra Nevada as a place valued for resource production (Walker and Fortmann 2003).

The population exodus following the end of the Gold Rush was reversed in the 1920s as a result of tourism-oriented innovations (Loeffler and Steinicke 2006). By the 1950s, commercial mining had practically stopped and was followed by a growing number of exurban migrants who wanted a refuge from city life and were attracted to the natural beauty and cultural history of the Sierra Nevada (Walker and Fortmann 2003). According to the Sierra Business Council (2007), “People no longer come to the Sierra with ambitions of finding gold or hauling away large trees. In the new and changing Sierra Nevada, housing prices are rising, the economy is shifting, jobs that depend on natural resources are diminishing, new populations are arriving, air quality is declining, new investment is flooding in, and communities are in transition.”

As shown in the timeline below, various large-scale studies and management frameworks have occurred over the past couple decades in the Sierra Nevada. This history highlights the long involvement and concern stakeholders have had regarding Sierra Nevada resources and management of national forest system land. These events also speak to the complexity of management in the region and challenge of balancing across the triple bottom line.
Jun 1990
Northern spotted owl is listed as a Threatened species under the Endangered Species Act, prompting concern about the status of the California spotted owl in the Sierra Nevada range and in southern California.
Jul 1992
California Spotted Owl: A Technical Assessment of its Current Status (PSW-GTR-133; CASPO Technical Report) is released by an interagency scientific committee. The report raises concern over the effects of intensive timber harvest practices allowed in the forest plans along with the threat of loss from wildfires to the large and old trees that provide habitat for the California spotted owl. They recommend an Interim Approach that focuses on treating understory fuels while protecting large and old trees.
Jan 1993
California Spotted Owl Sierran Province Interim Guidelines (CASPO Interim Guidelines): This regional environmental assessment amended the forest plans for the 10 Sierra Nevada national forests in Region 5 to adopt interim direction similar to the CASPO Technical Report’s recommended Interim Approach. Intended to be in place for 2 years.
1993-2012
Herger-Feinstein Quincy Library Group (HFQLG):
  • 1993 Grassroots organization “Quincy Library Group” organizes to develop the “Community Stability Proposal”
  • 1998 Congress passes the Forest Recovery Act, with a pilot project for Northern California which i