Sequoia National Forest
Chapter 1: Assessing Terrestrial Ecosystems, Aquatic Ecosystems, and Watersheds

Landscape Setting


Overview

The Sequoia National Forest encompasses a broad range of habitats and elevations, ranging from blue oak woodland at 1,000 feet to alpine fell fields at over 12,000 feet. Five major biotic provinces converge on the Sequoia National Forest. Floristically, the High Sierra Nevada, Central Valley, Southern California Mountains, Great Basin Desert, and Mojave Desert all overlap here. The 1.2 million acres of the Sequoia National Forest provides a diverse range of habitats that support viable populations of a diversity of plants, wildlife and fish and wildlife, including those found only in the southern Sierra or on the Forest. The Sequoia National Forest contains the Giant Sequoia National Monument, home to the majestic Giant Sequoias. Wilderness Areas constitute approximately 28 percent (314,000 acres) of the Sequoia National Forest (Figure 1.1). The multitude of landscapes across the Forest is a result of the differences in elevation, topography, temperature, and precipitation.

The Forest can be roughly divided into three distinct ecological environments: the Greenhorn Mountains; The Kern Plateau; and the Breckenridge, Piute, and Scodie Mountains. The Greenhorn Mountains are the wettest and all of the Giant Sequoia groves are present here. To the east of the Greenhorn Mountains the Kern Plateau rises to over 9,000 feet. The Breckenridge, Piute, Scodie Mountains are islands in the midst of lowlands and are influenced by the nearby Mohave Desert (see CH1 Ecosystems - Sequoia - Brekenridge.pnginset photo). These southern mountains are drier than the Kern Plateau or the Greenhorns. In the Greenhorns, precipitation falls mainly from October through April as rain in the lower elevations and snow at the higher elevations. Winter temperatures below freezing and summer temperatures above 100 degrees indicate the normal seasonal spread.

Breckenridge, Piute, and Scodie mountains in the southern part of the Forest.




An uplifted, westward-titled Sierra Nevada block that has been deeply incised by large rivers (Wakabayashi and. Sawyer 2001), such as the Kings, Kaweah, Tule and Kern Rivers, provides a geomorphic foundation for the Forest. Volcanism also shaped the landscape; volcanic fields in the Kern and Kings Rivers were present in the Little Kern River, Domelands, and Hume Lake (Farmer et al. 2002). Great variability in aspect and slope were created by these rivers and their tributaries over millennia. Bedrock is primarily granite, along with metamorphic and volcanic presence. Terrain is dominated by steep slopes and rocky canyons intermixed with meadows, fens and riparian areas. Some areas of the Forest contain unusual rock types like limestone/marble and gabbro that create unique soil chemistry that support unique plant communities and often harbor rare plant species.

Influences of Past Management

Historic logging, livestock grazing and residential development influenced current ecological conditions and management across the landscape (McKelvey and Johnston 1992). The timber industry officially started in the southern Sierra in the mid 1800’s with sawmills located in the foothills at lower elevations near the mines they were supplying (see review in McKelvey and Johnston 1992). By the late 1800’s and early 1900’s, owners moved their sawmills to places like Hume Lake, where large diameter trees including large diameter sugar pine and giant sequoias were cut to make shakes and grape stakes (McKelvey and Johnston 1992). Flumes, roads, and other features changed the landscape. The ecology of terrestrial and aquatic systems began an additional enormous change as thousands of sheep were pastured in meadows changing soil to dust; which either blew away or washed into streams. This soil was noted as covering up swamps and meadows in 1894 (see review in McKelvey and Johnston 1992). Travelers could find no food for their horses due to the lack of herbaceous vegetation.

The Sequoia National Forest has been largely affected by fire suppression for almost a century. As a result, live and dead fuels have increased in some forest types (e.g. Westerling et al. 2006). These conditions, along with predicted warming or increased lightening during the dry season may create forests highly susceptible to an increase in frequency of large-scale, high severity fire (Long et al. 2012). CH1 Ecosystems - Sequoia - Greenhorn.pngThese past activities, combined with fire suppression since the 1920s, reduced landscape-level ecosystem heterogeneity
(see review in Collins and Skinner 2013).
This is particularly evident in current conditions with extensive areas dominated by shade-tolerant conifers, especially white fir and incense cedar. Tree encroachment has altered meadows, riparian areas, aspen clones, and other sensitive areas (see review in Long et al. 2013). Overall, this loss of heterogeneity unless remedied may detrimentally affected wildlife and plant habitat diversity, as well as reducing ecosystem resilience in the face of climate change (Thompson et al. 2009).

However, six empirical studies have been conducted in California’s forests to assess the longstanding forest management assumption that the most fire-suppressed forests (i.e., the forests that have missed the largest number of fire return intervals) burn “almost exclusively high-severity”, as the 2004 Sierra Nevada Forest Plan Amendment Final EIS (Vol. 1, p. 124) presumed. These studies found that the most long-unburned (most fire-suppressed) forests burned mostly at low/moderate-severity, and did not have higher proportions of high-severity fire than less fire-suppressed forests. Forests that were not fire suppressed (those that had not missed fire cycles, i.e., Condition Class 1, or “Fire Return Interval Departure” class 1) generally had levels of high-severity fire similar to, or higher than, those in the most fire-suppressed forests.
1)

fig 5.jpg
Figure 5 from Odion and Hanson (2006) (Ecosystems), based upon the three largest fires 1999-2005, which comprised most of the total acres of wildland fire in the Sierra Nevada during that time period (using fire severity data from Burned Area Emergency Rehabilitation (BAER) aerial overflight mapping), showing that the most long-unburned, fire-suppressed forests (Condition “Class 3+”, corresponding to areas that had missed more than 5 fire return intervals, and generally had not previously burned for about a century or more) experienced predominantly low/moderate-severity fire.
2)
fig 2.jpg

Figure 1 from Odion and Hanson (2008) (Ecosystems) (using fire severity data from satellite imagery for the same three fires analyzed in Odion and Hanson 2006), showing that the most long-unburned, fire-suppressed forests (no fire for a century or more) burned mostly at low/moderate-severity, and had levels of high-severity fire similar to less fire-suppressed forests (in one case, even less than Condition Class 1).

3) Van Wagtendonk et al. (2012) (Fire Ecology), analyzing 28 fires from 1973-2011 in Yosemite National Park, found the following:
“The propor­tion burned in each fire severity class was not significantly associated with fire return interval departure class…[L]ow severity made up the greatest proportion within all three de­parture classes, while high severity was the least in each departure class (Figure 4).”
The most long-unburned, fire-suppressed forests—those that had missed 4 or more fire return intervals (in most cases, areas that had not burned since at least 1930)—had only about 10% high-severity fire (Fig. 4 of van Wagtendonk e al. 2012).

4) Odion et al. (2004) (Conservation Biology), conducted in a 98,814-hectare area burned in 1987 in the California Klamath region, found that the most fire-suppressed forests in this area (areas that had not burned since at least 1920) burned at significantly lower severity levels, likely due to a reduction in combustible native shrubs as forests mature and canopy cover increases: “The hypothesis that fire severity is greater where previous fire has been long absent was refuted by our study…The amount of high-severity fire in long-unburned closed forests was the lowest of any proportion of the landscape and differed from that in the landscape as a whole (Z = -2.62, n = 66, p = 0.004).”

5) Odion et al. (2010) (Journal of Ecology), empirically tested the hypothesis articulated in Odion et al. (2004)—i.e., that the reduction in fire severity with increasing time-since-fire was due to a reduction in combustible native shrubs as forests mature and canopy cover increases—and found the data to be consistent with this hypothesis.

6) Miller et al. (2012a) (Ecological Applications), analyzing all fires over 400 hectares 1987-2008 in the California Klamath region, found low proportions of high-severity fire (generally 5-13%) in long-unburned forests, and the proportion of high-severity fire effects in long-unburned forests was either the same as, or lower than, the high-severity fire proportion in more recently burned forests (see Table 3 of Miller et al. 2012a).

These studies demonstrate that it cannot be assumed that the most fire suppressed forests will burn primarily at high-severity.

Greenhorn Mountains contain the Giant Sequoia Groves, and a diverse array of habitats for plants and wildlife.

In addition to the diverse environmental conditions present in the Forest, past management has helped cumulatively create the conditions of wildlife habitats that are currently present. For many habitat types within the Forest, fire or the exclusion of fire has had a significant effect on distribution, species composition, and stand structure. As a result, live and dead fuels have increased, along with the development of denser conifer forests and chaparral ecosystems to abnormally high levels of abundance, greater than the natural range of variability. However, it is important to understand that dense forest habitat, especially dense mature forest habitat, was historically abundant (see, e.g., Lydersen et al. 2013, Table 1), and is critical habitat (i.e, what the literature shows they preferentially select) for rare species like the California spotted owl, Pacific fisher, and black-backed woodpecker. The fire return interval is an indicator of how close the Forest is to the historic fire regime. The fire return interval for a given vegetation type can be used in conjunction with fire history maps to determine which areas in the Forest have missed natural fires. This information, known as the fire return interval departure (FRID) is presented in Figure 1.2. Numerous recent smaller fires and the McNally Fire are indicated by the blue areas around the Kern River Canyon indicating that the fire return interval is within normal range. Similarly in parts of the Breckenridge, Piute and Scodie Mountains the fire return interval is within normal range (Figure 1.2). Sections along the Greenhorn Mountain around 5-7,000 feet have not burned as frequently as expected under a natural fire regime.

During the last decade, Sequoia National Forest has made progress in improving and sustaining ecological heterogeneity within the natural range of variability. Some major actions include integrating more wildfire back into fire adapted ecosystems, retaining and developing large live and dead tree structures, and conducting tree thinning to develop and maintain forest heterogeneity, including opening forest canopy gaps to promote oaks, and shade intolerant pines (North et al. 2009, North 2012). Mechanical thinning, however, does not mimic natural wildfire and can eliminate or reduce the value of mature forest habitat by eliminating or reducing structural complexity (which many rare wildlife species preferentially select for). Structural complexity is key for species like the California spotted owl, Pacific fisher, and black-backed woodpecker (see, e.g., Zielinski et al. 2006, Purcell et al. 2009, Verner 1992, Bond et al. 2009). Although current management in the Sequoia National Forest is making important strides toward integrating and sustaining ecological restoration of mixed conifers, oaks and meadows, additional restoration actions, adaptive management and public involvement are needed to fully meet these ecosystem restoration goals.CH1 Ecosystems - Sequoia - Kern.png





Kern River Plateau has lush meadows, and currently plenty of water from snow-melt in its streams and meadows.





CH1 Ecosystems - Sequoia - Wilderness.png
Figure 1.1. Wilderness areas (names in legend) depicted within the Sequoia National Forest Administrative boundary (indicated by thick black line). The light purple (magenta) line depicts the boundaries of the Sequoia National Monument. The inset shows the location of the Forest in California.




















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Figure 1.2 Departure of the average Fire Return Interval Departure (FRID) as compared with an average historical condition for the Sequoia National Forest. The higher percentages represent the greater divergence from average reference conditions.



Terrestrial Ecosystems

Vegetation


The Sequoia National Forest encompasses a broad range of habitats and elevations, ranging from blue oak woodland at 1,000 feet to alpine fell fields at over 12,000 feet. Six major biotic provinces converge on the Sequoia National Forest and Monument. Floristically, the High Sierra Nevada, Central Valley, Sierra Nevada Foothill, Southern California Mountains, Great Basin Desert, and Mojave Desert all overlap here (Miles and Goudey 1997). The southern Sierra Nevada is a giant floristic melting pot between the Central Valley and the Mojave Desert and also between the High Sierra and the southern California Mountains (Figure 1.3). This confluence of diverse floras creates a high density of rare endemic plants and many unique plant communities.

The Sequoia National Forest can be roughly divided into three distinct environments: the Greenhorn Mountains (the southern extension of the Great Western Divide); The Kern Plateau; and the Breckenridge, Piute, and Scodie Mountains. The Greenhorn Mountains are the wettest and most productive area of the Forest. These mountains found in the Western portions of the Sequoia National Forest. Here we find all of the Giant Sequoia groves along with mixed coniferous forest (the “great green wall”) and deciduous Black Oak woodland. Because the greenhorns drop back down to 3,000 feet into the Kern River Gorge, the plant communities of the eastern slope mirror that of the western slope, including the easternmost (and most unique) Giant Sequoia groves. To the east of the Greenhorn Mountains and the Kern River Gorge, the Kern Plateau rises to over 9,000 feet. The Kern Plateau is drier and colder, because of its proximity to the Mojave and Great Basin deserts of eastern California. The Kern Plateau supports extensive stands of white and red fir forest along with the endemic southern Foxtail pine, a close relative of Bristlecone pine. The Breckenridge, Piute and Scodie Mountains are areas of dis-continuous conifer habitat totally surrounded by lowland annual grass and shrub habitat. This biologic isolation is has created unique plant communities and habitat such as Piute Cypress woodlands (see photo inset), a local endemic tree.


piute.jpg

Piute Cypress requires fire for reproduction. This is illustrated in this photograph from the Piute Mountains of an even age stand resulting from fire 80 years ago.









Foothill Zone

The foothill ecological zone occurs at the lowest elevations and is comprised of chaparral, blue oak savannahs, live oak woodlands and forests, narrow riparian stringers along rivers and streams, seeps, and scattered pine (Barbour et al. 2007). Overall, the vegetation and fire patterns in this zone are outside of the range of variability (Estes 2013, Merriam 2013, and Sawyer 2013). The foothill zone of the Forest captures a small proportion of the western foothill belt which is mostly in private ownership throughout the Sierra Nevada (Britting et al. 2012). Nineteenth century livestock g razing is considered to be the primary factor in changes in the blue oak foothill woodlands (Vankat and Major 1978). Vegetation is mostly out of the natural range of variability as a result of persistent non-native species, urbanization, water development, changed fire regime, and agricultural uses. Because of these factors, the small amount of this biologically diverse vegetation type that is in public ownership is disproportionately important for long-term conservation. This vegetation zone falls within Sierra Nevada Ecological Section Sierra Nevada Foothills in the USDA Forest Service National Hierarchical Framework of Ecological Units (Figure 1.3, Miles and Goudey 1997).

Tree-dominated plant communities are blue oak (Quercus douglasii) woodland or savannah, with foothill pine (Pinus sabiniana), California buckeye (Aesculus californicus), and interior live oak (Quercus wislizenii) present to varying degrees. Other tree-dominated types in the foothills are foothill pine and valley oak forests. Within the Sequoia National Forest, as is typical for the Southern Sierra Nevada, the understory biomass is dominated by non-native grasses while paradoxically native herbaceous and shrub species diversity is high. Non-native annual grasses include brome (Bromus spp.), wild barley (Hordeum sp.), wild oats (Arena spp.), and annual fescues (Festuca myuros) (Parsons and Stohlgren 1989).

Trends
Although a valued system, oak woodlands are located in areas highly valued for other uses, resulting in conflicts. Blue oak woodlands in the western Sierra Nevada display considerable fragmentation. Oak woodlands largely exist on private lands (>90%), where conflicts with agriculture (Jimerson and Carothers 2002), grazing, water use and development exist. Increased urbanization in the Southern Sierra will lead to increased pressures on oak woodlands unless ecological land use complementation is employed (Colding 2007). Overall exposure of blue oak to climate change is expected moderate to high by late century (Kueppers et al. 2005). Warmer temperatures, decreased precipitation and wildfire would all be important in a northward range shift (Kueppers et al. 2005). The effects of climate change projected to 2070 forecast increases of blue oak (Quercus douglasii)/foothill pine (Pinus sabiniana) in the Sierra Nevada ecoregion (23 to 97%) (Gardali et al. 2011). Some oaks may benefit from climate change in the short term, given that mature trees are generally drought and fire resistant. Although not currently exposed, oaks are sensitive to both insects and disease (Jimerson and Carothers 2002, Rizzo and Garbeletto 2003), which may become significant in the future. Seedlings and saplings, however, are sensitive to soil moisture and precipitation, affecting the long-term vulnerability of the oak woodland system. Predation of saplings by cattle and deer (Adams and McDougald 1995,Hall et al. 1992) reduced oak recruitment and increases vulnerability in the long-term. Modern oak understories are dominated by nonnative European annuals (Roche et al. 2012). Due to the rapid onset of climate change, plants and animals associated with oak woodlands must move to higher elevations or northward or be extirpated (Loarie et al. 2009). Stressors include fire, grazing, pollution, and climate change. These stressors could potentially alter these communities (NPS 2013). While disturbances like fire are natural, frequency and intensity of fires outside their historic range of variation may cause a change in vegetation type (NPS 2013).


Figure 1.3. Ecological Sections within California ; the Forest is influenced by High Sierra Nevada (beige), Sierra Nevada Foothill (brown), Central Valley (cream), Southern California Mountains (Orange), and the Mohave desert (pink).
CH1 Ecosystems - Sequoia - EcoSections.png

Montane Zone

Ponderosa pine, black oak, mixed conifer, riparian forests, chaparral and meadows comprise the vegetation mosaic in the west-side montane zone (Fites-Kaufman et al. 2007). The lower and mid-elevation mixed conifer forest on the western slopes of the Sierra occurs from 1000 to 1,500 m at its lower margin to 3,000 to 3,500 m at its upper limit. Black oak is important throughout the lower elevations of the lower montane forests (Fites Kaufman et al. 2007). In the Greenhorns and Kern Plateau, Jeffrey pine (Pinus jeffreyi), incense cedar (Calocedrus decurrens), and white fir (Abies concolor) are common. Sugar pine (P. lambertiana) used to be a dominant conifer but is rare or absent (Fites Kaufman et al. 2007). The upper montane zone comprised of a mosaic of conifer forest, meadows, and montane chaparral. On the western slopes red fir (Abies magnifica), Jeffrey pine (Pinus jeffreyi), and lodgepole pine (Pinus contorta subspecies murrayana) are the dominant forest species (Fites – Kaufman et al. 2007).


Special Habitats


There are some habitats that are less common, yet support a high level or specialized type of biodiversity. Information is often limited on these habitats but they are important to include. While not an exhaustive list, some of the special habitats noted on the forest include: old forest, complex early seral forest, rock outcrops, and Giant Sequoia groves. There are other riparian or wetland associated habitats, including fens and aspen, which are discussed later. The Giant Sequoia groves occur throughout the Greenhorn Mountains and across the Sequoia National Park to the Hume Lake District and into the Sierra National Forest. The Sequoia National Monument contains the giant sequoias and their watersheds on the forest. Further discussion is not included here because they were addressed in the recent Giant Sequoia National Monument Plan.

Rock outcrops support a variety of uncommon and often rare plants. These include limestone, metamorphic, gabbro, and granite rock outcrops. Plants associated with these habitats are described in Chapter 5. These areas are impacted by invasive plant species, habitat fragmentation, uncharacteristically frequent fire, surface mining, post-fire disturbance (e.g., intensive grazing), illegal marijuana cultivation, and climate change.


Aspen is a broad-leaved tree that occurs in diverse habitats on the Sequoia National Forest, from wet areas to subalpine rock talus. It occurs most commonly around meadows and streams in the upper montane red fir and lodgepole pine forests. Although it currently encompasses less than 1% of the assessment area, it supports very diverse understory plant and bird communities. Several bird species of management interest are associated with aspen including Northern Goshawk, Red-breasted Sapsucker, Warbling Vireo, and Mountain Bluebird. Aspen distribution is greatly reduced compared to pre-European settlement, and many stands are in poor condition due to conifer encroachment and poor regeneration. Estimates suggest its extent in western North America has been reduced by as much as 96%, primarily because of fire suppression and historic overgrazing. Fire is also important in aspen stands because it kills young conifers that shade out light-loving aspen. Mule deer uses aspen stands to feed and cover for fawning. Grazing by domestic livestock, sheep and cattle, increased dramatically in the mid-1800’s and had a dramatic effect on aspen and meadows in general. Aspen sprouts, or regeneration, are favored browse. Reduction in aspen regeneration was noted in the early 1900’s (Sampson 1919). Fencing can result in higher aspen sprouts. In the intermountain west, decreased aspen growth has already been attributed to higher temperatures and extended drought. Annual fluctuations in available soil moisture resulting from El Niño influences on snow pack depth may have a significant influence on establishment of plants.


After moderate to intense fire early seral habitat is formed. If, across the landscape patchiness of habitat were maintained all species dependent on old growth and early seral habitat could be maintained across the landscape. However, fire suppression has suppressed these landscape level processes of habitat creation and succession. If in the past fire, drought, and wind combined to create openings in the canopy, patches of early seral habitat would have been created across the landscape. Without fuels management and a return of controlled fire to the landscape the patchy nature




Trends:
Composition, structure, and fire regimes have changed considerably since pre-settlement times (Van de Water and Safford 2011), and are largely outside the natural range of variability in the Greenhorn Mountains. Pines and oaks have decreased substantially and shade tolerant species, such as cedar and fir, have increased. White pines across the Sierra Nevada are currently threatened by a combination of factors including outbreaks of native and exotic insects and diseases, altered fire regimes, air pollution, and climate change (NPS 2013). Forest density is higher, canopy cover of trees more uniformly higher, small and medium tree density is higher and large tree density is lower. Within stand variation in tree size and density has decreased. Drought has triggered tree mortality in mixed conifers (Guarin and Taylor 2005); and large tree mortality has doubled in the last 2-3 decades across the West (van Mantegem et al. 2009). This pattern is associated with increases in temperature and droughts, rather than fire history, stand density or insects (Briting et al. 2012). Also, the raw data in van Mantgem et al. (2009) (obtained directly from the authors) do not indicate a reduction in large trees (e.g., those 60-90, or >90 cm dbh) in Yellow Pine/Mixed Conifer over time in Sierra Nevada forests, and the largest size class category presented in van Mantgem et al. (2009) was >40 cm dbh (i.e., over 16 inches dbh). The van Mantgem et al. (2009) data are consistent with old stands self-thinning their understories in the long absence of significant fire. Based on growth rates of Giant Sequoias over a 2089 year record, the last one hundred years has had below average frequency of drought (Hughes and Brown 1991).The Giant Sequoias are particularly vulnerable to climate change, because wetter areas they depend on are expected to shrink.

Subalpine and Alpine Zones

Coniferous forest types within this zone are upper coniferous forest dominated by red fir and lodge pole pine, with an increasing component of western white pine (Pinus monticola) and some stands of mountain hemlock (Tsuga mertensiana). Whitebark pine is found in harsh, windswept areas of the alpine zone, and singleleaf pinyon (Pinus monophylla) is present in sparse amounts in the high elevations of the Forest, though it is primarily an east slope of the Sierra Nevada species. Montane chaparral may cover extensive acreage in this zone, sometimes naturally on thin, rocky soils or in response to natural disturbances such as fire or avalanches; or in many cases shrub-dominated areas prevail in areas that have been logged or otherwise disturbed by Forest management activities.

The subalpine meadows of the Forest are also rich in peatlands (fens) and many are inhabited by Sphagnum moss, which was formerly thought to be rare in the High Sierra. Meadows of the subalpine zone in areas with non-granitic geology are prime habitat for rare moonworts, Botrychium spp., and more of these unusual ferns are being found in the central Sierra each year. The alpine zone is generally referred to as “above timberline” but may have stunted or krummholz trees, especially of lodgepole pine. Granitic outcrops are abundant in this zone as well, with many Forest endemics and other rare plants such as the Kaweah fawn lily (Erythronium pusaterii), Pierpoint Springs Liveforever (Dudleya cymosa ssp. costafolia) and the Piute Buckwheat (Eriogonum breedlovei var. breedlovei) growing exclusively on rock outcrops.

Trend
Since alpine environments are found at the extreme end of the temperature gradient in the Sierra NEvada, the life forms that are narrowly adapted to those conditions essentially have “nowhere to go”, making them among the most vulnerable to climate change (Loarie etal. 2009, NPS 2013). Due to the high elevation on the Sequoia National Forest, the last cold refugia may be in the mountains surrounding the Kern Plateau. These alpine ecosystems are one the more threatened due to rapid climate change (Loarie et al. 2009).

Riparian ecosystems


Riparian areas in the drier southern Sierra Nevada Mountains provide vital habitat diversity and habitat for plants and animals (Loheide et al. 2009). Riparian areas and their habitats encompass everything from rivers and creeks, to meadows and springs. These areas represent an interface between terrestrial and aquatic parts of the ecosystem (Gregory et al. 1991). The microhabitats of the riparian and aquatic environments influence the distributions of many amphibian, reptiles and fish species (Welsh et al. 2005).The Sequoia National Forest and Monument has large rivers (such as the Tule, Kings and Kern) and numerous small and mid-size creeks which provide moist areas for vegetation and wildlife. Riparian areas serve as important corridors for species dispersal; as well as for production of nutritional resources for aquatic species (Gregory et al. 1991). The water, relative humidity; cooler temperatures and complex cover provided result in high in biodiversity (Naiman et al. 1993).Two distinct riparian ecosystems can be differentiated; 1) riparian meadow systems; and 2) riparian non- meadow systems (Fites-Kaufmann et al. 2007).

The riparian non- meadow systems of the Forest can be divided into two broad categories: forest/woodland or scrub-shrub vegetation. Scrub-shrub habitats are characterized by low, multi- stemmed woody vegetation in young or stunted stages of growth. These habitats support a diversity of shrubs. Riparian forest woodlands can be dominated by a variety of coniferous trees, such as pines, firs and incense cedar), and to a less extent deciduous trees, such as black oaks, white alder, Oregon ash, and cottonwood. Having tall shading cover and a large source of organic matter dead-fall (leaves/needles) provides excellent habitat for a diversity of plants and animals. These types of riparian areas provide a rich dense humid habitat for plants, amphibians, and small birds.

Historically, riparian ecosystems were valued for their economic uses: transportation corridors, water supply and electricity, construction materials and waste disposal, agriculture and livestock, and settlement. (Hunsaker et al. 2013a). Biologically riparian areas provide special habitat for some endangered or threatened species, refugia and water for upland species, corridors for species movements, and thermal refugia for aquatic species (Hunsaker et al 2013a).

Montane meadows of the Sierra Nevada are largely defined by their hydrology and the dominance of herbaceous vegetation (Weixelman et al. 2011). Four water sources dominate montane meadows: snowmelt, overland flow, surface flow from streams and/or spring networks, and direct precipitation (Germanoski, et al. 2011, Lord et al. 2011, Viers et al 2013). Gradual melting of snow allows for periods of saturation and infiltration, maintaining the groundwater table (Loheide & Gorelick 2007). Meadows in the southern Sierra Nevada, from the San Joaquin River to the Kern River, have the highest overall elevation, and retain snowfall for a greater proportion of the watershed than northern or lower-elevation watersheds (Viers et al. 2013). These meadows have the lowest absolute water yield in the Sierra (Viers et al.2013). A high groundwater table is essential for hydrophilic meadow plants, (Viers et al. 2013). The fibrous root systems in meadow vegetation provide bank stability and reduce bed sheer stress, limit channel incision (Viers 2013). This stability amplifies overbank flooding events (Loheide & Gorelick 2005), promoting groundwater recharge, the extension of baseflow, and the persistence of meadow vegetation (Viers 2013). Meadows on the Sequoia National Forest range from extremely large (Big Meadow on the Hume District and Big Meadow on the Kern River District) to tiny meadows around springs.

Springs, seeps, and fens often have specialized plants associated with them. The spatial variation of water-table depth exerts strong control on vegetation composition and spatial patterning. A high of inflow from lateral area encourage the persistence of a high water table and wet-meadow vegetation, particularly at the margin of the meadow, even in cases with moderate stream incision (Loheide et al. 2009). Large diverse meadow complexes are found in the wetter areas throughout the Forest from the Paiutes to the most northern areas of the Greenhorns, because of persistent snow pack and extensive shallow groundwater systems. Aspen are associated with moister areas and are valuable habitat and resource for wildlife (Shepperd et al. 2006).

Herbaceous perennial vegetation and forbs dominated riparian areas can be found along small creeks and within dry or wet meadows. These areas are usually dominated with wild onion, lupine, bistort, senecio, or corn lilies. Grasses dominated riparian areas can also be found along small creeks and within wet meadows. These habitats usually have close to 100 percent cover of sedges, grasses, and rushes (Loheide et al. 2009). Drier meadows tend to have vegetation communities dominated by grasses (Poaceae) and support a much higher proportion of annual and perennial forbs and shrubs characteristic of the upland vegetation community (Viers et al. 2013).

Fens and Meadows
Some meadows contain areas of peat soils called fens. Fens are areas of perennial saturation where peat soils form because accumulation of organic matter exceeds decomposition (Cooper and Wolf, 2006). Fens are of significance because of their contribution to hydrologic function in meadows and because they provide habitat for several rare plant species. Riparian areas are extremely important sources of shade, food, and refuge during high flow events for aquatic organisms. These habitats are influenced by similar factor, dams, density of roads near streams, alterations of hydrology through dewatering or grazing (Kondolf et al. 1996). While the field base may not be available across the Sierra Nevada, the Sequoia National Forest in the past inventoried many meadows and other important ecological areas including those that have not retained ecological functions expected of a healthy watershed or reference condition (cf. Stoddard et al, 2006).

Fens, also called peatlands, are perennially saturated areas, usually within meadows, dominated by mosses and herbaceous wetland vegetation. Fens are important because of their function in meadow water storage, and their role in maintaining water quality and hydrologic integrity in meadows. In addition, several sensitive plant species are found primarily in fen habitats. Fens are defined by having at least 40 cm of organic soil within the top 80 cm that has formed in place and where peat-forming vegetation (generally certain species of sedges and mosses) occurs and is entirely rooted within the peat body (Cooper and Wolf, 2006). In the Sierra Nevada, the type of peatland is termed a fen rather than a bog, because the primary source of water is groundwater, although precipitation contributes water as well (Cooper and Wolf, 2006). Inventories of Sierra Nevada fens began in 2003, and are ongoing. The extent to which livestock grazing and trampling affect fens was investigated in a preliminary study (Cooper and Wolf 2006), and will continue to be studied in an attempt to determine the amount of use fen ecosystems can sustain.

Trend

Meadows in the Sierra Nevada were identified as one of the most altered, impacted and at-risk landscapes in the range (Loheide et al. 2009, Viers et al. 2013). Meadows are vulnerable to climate change (Hopkinson et al. 2013). Water regulation,, in which meadows serve to attenuate flood flows, sustain base flows, and filter out undesirable constituents are important services (Viers et al. 2013). Storage of carbon and nitrogen is high in functioning wetlands (Norton et al. 2011). Because much soil carbon and nitrogen is stored under low oxygen (anaerobic) conditions, changes in the meadow ecosystem that lead to drying cause loss of carbon and nitrogen to the atmosphere (Norton et al. 2011). Historic alterations to Sierran meadows included livestock grazing, railroad grades, diversions and ditching, and culverts from roads (Viers et al. 2013). Currently, most impaired Sierran meadows are, or have become, highly eroded due to anthropogenic factors such as grazing, hydrologic regulation or construction of roads (Viers et al. 2013). Critical functions provided by montane meadows including water filtration, flood attenuation, support of biodiversity, and critically, water storage have been lost or impaired (Kattleman and Embury 1996). However, hydroclimatic changes have the potential to further degrade currently impaired meadows as well as alter conditions for unimpaired meadows. Many meadow systems on the Sequoia National Forest are continuing to erode due to past and present land uses and this trend will continue under current conditions.

The potential for channel incision to pierce low-permeability layers and alter stream hydrology is a particular concern (Long et al. 2013) on the Sequoia National Forest. Where channels have active headcuts such as is found in meadows around the forest, herbaceous vegetation may not be effective in preventing bank erosion (Long et al.2013). Because of the profound losses in ecosystem functions that can occur as a result of incision, management strategies would benefit from focusing on this process (see review in Long et al. 2013). Restoration of these systems holds great potential to provide multiple ecological and social benefits, despite their small share of the landscape (Long et al. 2013). Evaluating the role of natural processes such as wildfire and management practices (e.g., prescribed grazing practices) on a larger, watershed scale, could aid the design of more effective strategies to promote long-term resilience of these valuable systems (Long et al. 2013).

Over the next century, climate change will alter hydrologic regime, precipitation patterns and the role of fire in riparian areas. Fire history in riparian areas appeared similar to that of the surrounding areas (Hunsaker et al. 2013b). However, post fire seedling recruitment and sprouting allowed riparian vegetation to be resilient (Hunsaker et al 2013b). Riparian ecosystems are naturally resilient, provide connectivity among habitats, and create thermal refugia for fish and wildlife (Seavy et al.2009). Whether these valuable ecosystem services can adapt to changing conditions will be dependent on location (Seavy et al. 2009). Common riparian species such as alder or willow can be sensitive to temperature. As these species migrate to higher elevations; more productive species from warmer areas could be planted to maintain these important wildlife habitats (Grady et al. 2011). Since these riparian plant species support a diverse community that includes endangered and sensitive species replacement of plants would be a viable option for increasing resilience (Grady et al. 2011).



Terrestrial Wildlife Species


The Sequoia National Forest is inhabited by hundreds of species of terrestrial wildlife, including birds, mammals, reptiles, and invertebrates. Nine of those species are classified as federally threatened or endangered, with two additional species listed as candidates for listing under the Endangered Species Act (ESA). Two federally endangered birds, the California condor and the southwest willow flycatcher also have federally designated critical habitat present on Sequoia National Forest. An additional 16 species are classified as Forest Service sensitive species known to occur, or have the potential to occur, within Sequoia National Forest.

Habitat

Environment and past management

The 1.2 million acres of the Sequoia National Forest provides a diverse range of habitats that support viable populations of terrestrial wildlife species. The multitude of landscapes across the Sequoia National Forest is a result of the differences in elevation, topography, temperature, and precipitation. Elevations range from 1,000 feet in the lower canyons to peaks over 12,000 feet on the crest of the Sierra. Precipitation falls mainly from October through April as rain in the lower elevations and snow at the higher elevations. Winter temperatures below freezing and summer temperatures above 100 degrees indicate the normal seasonal spread.

In addition to the diverse environmental conditions present in the Forest, past management has helped cumulatively create the conditions of wildlife habitats that are currently present. For many habitat types within the Forest, fire or the exclusion of fire has had a significant effect on distribution, species composition, and stand structure. As a result, live and dead fuels have increased, along with the development of denser conifer forests and chaparral ecosystems to abnormally high levels of abundance, greater than the natural range of variability. However, it is important to understand that dense forest habitat, especially dense mature forest habitat, was historically abundant (see, e.g., Lydersen et al. 2013, Table 1), and is critical habitat for rare species like the California spotted owl, Pacific fisher, and black-backed woodpecker. What is no longer available like it once was is the post-fire (ealry seral) habitat condition (and its associated heterogeneity) that hasbeen reduced via fire suppression and logging. In other words, what is needed on the landscape is more fire created habitat (that does not get salvaged logged) to accompany dense mature forest habitat. Both are similar in that they are structurally complex (see, e.g., Donato et al. 2012), but offer different attributes (e.g., shrub habitat, snag forest habitat, resting habitat, denning habitat, nesting habitat, foraging habitat). The fire return interval is an indicator of how close the Forest is to the historic fire regime. The fire return interval for a given vegetation type can be used in conjunction with fire history maps to determine which areas in the Forest have missed natural fires. This information, known as the fire return interval departure (FRID) is presented in Figure 1.1. These uncharacteristically severe fires can have substantially negative consequences to the long-term sustainability of forests, particularly older-age forests that provide habitat for the California spotted owl and Pacific fisher. The available science, however, shows that the mixed-severity fires that are occurring, such as the McNally Fire, which have a mosaic of low, moderate, and high severity areas, are critical habitat for many rare species, and are within the natural range of variability. In regard to the McNally Fire, for example, 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). And emerging research is indicating that Pacific fishers may benefit from mixed-severity fire (e.g., Hanson, C.T. (in preparation 2013—this is the only study to date that examines fisher response to an actual wildfire event, here, the McNally Fire).

The timber industry officially started in the southern Sierra in the mid 1800’s with sawmills located in the foothills at lower elevations. By the late 1800’s and early 1900’s, owners moved their sawmills to the mountains of Sequoia National Forest, where large diameter trees including giant sequoias were cut and removed. Forested habitats were altered not only from the logging operations, but from the construction of roads, buildings, and flumes to transport the cut material. After the depression era, the style of logging changed. New technology and equipment made timber operations much more efficient. By 1948, the timber harvest had reached 25 million board feet, increasing to 69 million board feet in the 1960’s, peaking in the late 1970’s with over 100 million board feet removed, then decreasing in the 1980’s and 1990’s to 75 million board feet. Since 2000, the current estimate for timber harvest average 8 million board feet per year for the Sequoia National Forest.

Other types of management, in addition to fire suppression and timber harvest, have affected the current conditions of wildlife habitats, including large areas designated by Congress as Wilderness. Wilderness Areas constitute approximately 28 percent (314,000 acres) of the Sequoia National Forest (Figure 1.2). These areas have typically been excluded from development or other types of management other than for recreation, grazing, and various degrees of fire suppression.

These cumulative factors, combined with nearly a century of fire suppression, have contributed to reducing overall landscape-level ecosystem heterogeneity and to some extent wildlife habitat diversity. This is particularly evident with abnormally high levels of fuels accumulation in the form of coarse woody debris and ladder fuels. These areas are often dominated by shade-tolerant conifers, particularly white fir and incense cedar. Past fire suppression as well as limitations for mechanical forest restoration work during recent decades, has also contributed to the reduction of meadow and black oak habitat, due to high tree density and encroachment. Overall, this loss of vegetation heterogeneity can detrimentally affect wildlife habitat diversity, as well as reducing ecosystem resilience to environmental stressors, such as climate change, severe wildfires, drought, disease and pest infestations.

Terrestrial ecosystems of the Sequoia National Forest are expected to experience dramatic changes in climate in the coming decades (Meyer and Safford 2013, Safford et al. 2012). Consequently, the future range of variation in climate exposure for these ecosystems will almost certainly exceed the NRV. Schwartz et al. (2013) evaluated future climate exposure to vegetation using downscaled climate projections for the southern Sierra Nevada, including the Sierra and Sequoia national forests. Their results indicate a high proportion (typically ≥70%) of all terrestrial ecosystems will be moderately, highly, or extremely vulnerable to future climate by the end of the century .


As forest restoration and fuel reduction treatments were applied extensively to dry coniferous forests of western North America, increases in herbaceous species richness and community heterogeneity can occur (Dodson and Peterson 2010). These understory plants are important as a source of temporary cover for smaller wildlife.


Classification and Inventory

Wildlife habitats are identified and categorized using a variety of methods. The primary classification system used in California is the California Wildlife Habitat Relationships (CWHR) system - Ver. 8.2 (CDFG 2008). CWHR is a tool used in wildlife habitat management to classify vegetation types and structural classes using canopy closure density and tree size. Therefore, land managers can use CWHR to evaluate change in vegetation type and structure under various resource management scenarios and natural events, such as wildfire. This comprehensive system is used throughout California’s National Forests, and it is the system we use here to provide an overview of habitats within the Sequoia National Forest.

The Sequoia National Forest contains a total of 37 habitat types, including 19 tree dominated habitats, six shrub dominated habitats, three herbaceous dominated habitats, three desert habitats, two aquatic habitats, two agricultural habitats, one barren/rocky outcrop, and one urban habitat, as defined by CWHR (Table 1). Some of these habitat types may also be combined to form an ecosystem type, as displayed in Figure 1.4. A large percentage of the habitats on the west side of the Sequoia are dominated by hardwood and mixed conifer ecosystem types (Figure 1.4). The central portion of the Forest primarily consists of chaparral, mixed conifer, yellow pine, and red fir ecosystem types, while the eastern side is comprised of pinyon-juniper, riparian, yellow pine, and chaparral types (Figure 1.4). Although, meadow and riparian habitats include only a small percentage of the ecosystem types across the Forest, they also tend to have greater species diversity per unit area than most other types of habitats.

Composition of habitat types including density of canopy closure and size of trees play an important role in providing suitable habitat for several sensitive species. Old forest habitat types in particular, support populations of the Pacific fisher and California spotted owl, which use large, decadent trees and snags in stands with moderate to dense canopy closure for roosting, resting, nesting, and denning. More information on terrestrial habitat use by Pacific fishers and California spotted owls can be found in the next section. Land managers can use CWHR to evaluate change in structural complexity of an area by examining differences in density and size class. Current conditions of canopy closure density and tree size classes for Sequoia National Forest habitats are shown in Figures 1.5 and 1.6, respectively, and criteria and acreages for those density and size classes are provided in Tables 1.2 and 1.3.

Table 1.1 Sequoia National Forest wildlife habitats (excluding private land) as defined by the California Wildlife Habitat Relationships (CWHR). Vegetation types and acres of each found on the Forest are listed.
CWHR Habitat Type
Acres
CWHR Habitat Type
Acres
Alpine Dwarf Shrub
1025
Mixed Chaparral
138690
Annual Grassland
54941
Montane Chaparral
120375
Alkali Desert Scrub
43
Montane Hardwood-Conifer
39211
Aspen
22
Montane Hardwood
129175
Barren
34981
Montane Riparian
5976
Blue Oak-Foothill Pine
7430
Perennial Grassland
829
Blue Oak Woodland
14314
Pinyon-Juniper
58089
Closed-Cone Pine-Cypress
257
Ponderosa Pine
27556
Chamise-Redshank Chaparral
6479
Red Fir
105801
Cropland
12
Riverine
1140
Deciduous Orchard
7
Subalpine Conifer
3331
Desert Scrub
2582
Sagebrush
24921
Eastside Pine
8276
Sierran Mixed Conifer
229423
Jeffrey Pine
50112
Urban
251
Joshua Tree
24
Valley Oak Woodland
12918
Juniper
107
Valley Foothill Riparian
457
Lacustrine
12838
White Fir
2853
Lodgepole Pine
15471
Wet Meadow
4424
Low Sagebrush
236



Table 1.2. Canopy closure class definitions and associated acres per the California Wildlife Habitat Relationship (CWHR) classification system for the Sequoia National Forest, excluding private land. The “X” class refers to those habitats without measured canopy closure such as grasslands, urban, barren, etc.
CWHR
CWHR Closure Class
% Canopy Closure
Acres
X
None Reported
---
409,526
S
Sparse Cover
10-24%
34,714
P
Open Cover
25-39%
122,031
M
Moderate Cover
40-59%
269,532
D
Dense Cover
60-100%
278,775

CH1 Ecosystems - Sequoia - CWHR.png
Figure 1.4 California Wildlife Habitat Relationship (CWHR) habitat types for Sequoia National Forest grouped to form ecosystem habitat types.
CH1 Ecosystems - Sequoia - CWHRDen.png
Figure 1.5 Canopy closure density on the Sequoia National Forest based on the California Wildlife Habitat Relationship (CWHR) system.

CH1 Ecosystems - Sequoia - CWHRSize.png

Figure 1.6. Tree size class distribution on the Sequoia National Forest based on the California Wildlife Habitat Relationship (CWHR) system.

Table 1.3. Tree size class definitions and associated acres per the California Wildlife Habitat Relationship (CWHR) classification system for the Sequoia National Forest, excluding private land. The “0” class refers to those habitats without measured size class such as grasslands, urban, or barren.
CWHR
CWHR Size Class
dbh
Acres
0
None Reported
---
408,577
1
Seedling Tree
< 1"
2,093
2
Sapling Tree
1-6"
17,136
3
Pole Tree
6-11"
134,579
4
Small Tree
11-24"
427,450
5
Medium/Large Tree
  • 24"
124,744


Figures 1.7 Within Stand Variability Coefficient of Variation of Basal Area for Selected Tree Species which indicates the oversimplified stand structure for blue oak and eastside pine. Other species or communities show a range of sizes indicating some reproduction has occurred.
Chap1_WSV_SequoiaNF_BOW_01.png
Chap1_WSV_SequoiaNF_EP_02.png
Chap1_WSV_SequoiaNF_JP_03.pngChap1_WSV_SequoiaNF_LP_04.png
Chap1_WSV_SequoiaNF_MH_05.png
Chap1_WSV_SequoiaNF_MHC_06.png
Chap1_WSV_SequoiaNF_PJ_07.png
Chap1_WSV_SequoiaNF_PP_08.png
Chap1_WSV_SequoiaNF_RF_09.png
Chap1_WSV_SequoiaNF_SMC_10.png

Large Trees for the Sequoia National Forest

 

Blue Oak Woodland: Number of Plots 10

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

1.7

0.3

0.1

0.0

0.0

Median

0.5

0.0

0.0

0.0

0.0

CV

169%

161%

316%

0%

0%

Blue Oak-Foothill Pine: Number of Plots 3

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

1.0

1.0

0.0

0.0

0.0

Median

0.0

0.0

0.0

0.0

0.0

CV

173%

173%

0%

0%

0%

Eastside Pine: Number of Plots 5

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

13.0

8.0

4.1

0.7

0.0

Median

14.3

9.3

3.8

0.7

0.0

CV

20%

31%

37%

0%

0%

Jeffrey Pine: Number of Plots 23

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

14.6

9.3

5.1

1.4

0.2

Median

11.8

8.5

3.8

1.0

0.0

CV

60%

56%

90%

163%

87%

Lodgepole Pine: Number of Plots 6

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

21.9

14.7

4.2

0.7

0.1

Median

22.5

15.0

4.5

0.5

0.0

CV

28%

24%

44%

68%

112%

Montane Hardwood: Number of Plots 43

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

3.9

1.9

0.4

0.1

0.0

Median

1.8

0.8

0.0

0.0

0.0

CV7

6%

58%

103%

176%

0%

Montane Hardwood-Conifer: Number of Plots 25

DBH Classes

≥ 21"

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

18.0

9.5

4.1

1.0

0.0

Median

16.0

6.0

1.0

0.0

0.0

CV

90%

102%

129%

203%

500%

Pinyon-Juniper: Number of Plots 8

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

6.0

3.0

1.1

0.1

0.0

Median

1.5

1.5

0.5

0.0

0.0

CV

188%

122%

138%

283%

0%

Ponderosa Pine: Number of Plots 25

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

12.8

6.2

2.8

0.4

0.0

Median

13.0

6.0

2.0

0.0

0.0

CV

95%

85%

123%

255%

0%

Red Fir: Number of Plots 36

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

33.2

28.1

17.0

4.0

0.8

Median

32.0

26.0

17.0

3.5

0.5

CV

52%

56%

55%

53%

80%

Sierran Mixed Conifer: Number of Plots 143

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

15.1

12.1

6.3

1.6

0.5

Median

12.0

10.3

4.5

0.8

0.0

CV

84%

94%

95%

137%

102%

Valley Oak Woodland: Number of Plots 3

DBH Classes

 

≥ 21"

≥ 24"

≥ 30"

≥ 40"

≥ 50"

Mean

0.0

0.0

0.0

0.0

0.0

Median

0.0

0.0

0.0

0.0

0.0

CV

0%

0%

0%

0%

0%


Shade Tolerance by Species

 

Blue Oak Woodland: Number of Plots 10

DBH Classes

 

< 12"

≥ 12"

Mean

30%

5%

CV

161%

316%

Blue Oak-Foothill Pine: Number of Plots 3

DBH Classes

 

< 12"

≥ 12"

Mean

40%

0%

CV

131%

0%

Eastside Pine: Number of Plots 5

DBH Classes

 

< 12"

≥ 12"

Mean

6%

6%

CV

81%

72%

Jeffrey Pine: Number of Plots 23

DBH Classes

 

< 12"

≥ 12"

Mean

42%

18%

CV

90%

161%

Lodgepole Pine: Number of Plots 6

DBH Classes

 

< 12"

≥ 12"

Mean

10%

16%

CV

110%

99%

Montane Hardwood: Number of Plots 43

DBH Classes

 

< 12"

≥ 12"

Mean

29%

18%

CV

36%

57%

Montane Hardwood-Conifer: Number of Plots 25

DBH Classes

 

< 12"

≥ 12"

Mean

56%

35%

CV

75%

100%

Pinyon-Juniper: Number of Plots 8

DBH Classes

 

< 12"

≥ 12"

Mean

13%

3%

CV

223%

283%

Ponderosa Pine: Number of Plots 25

DBH Classes

 

< 12"

≥ 12"

Mean

70%

50%

CV

50%

77%

Red Fir: Number of Plots 36

DBH Classes

 

< 12"

≥ 12"

Mean

14%

9%

CV

71%

86%

Sierran Mixed Conifer: Number of Plots 143

DBH Classes

 

< 12"

≥ 12"

Mean

59%

33%

CV

66%

98%

Valley Oak Woodland: Number of Plots 3

DBH Classes

 

< 12"

≥ 12"

Mean

92%

0%

CV

13%

0%


Snags Sierra NF

 

Blue Oak Woodland: Number of Plots 10

DBH Class

 

≥ 15"

Mean

0.0

Median

0.0

St Deviation

0.0

CV

0%

Blue Oak-Foothill Pine: Number of Plots 3

DBH Class

 

≥ 15"

Mean

0.0

Median

0.0

St Deviation

0.0

CV

0%

Eastside Pine: Number of Plots 5

DBH Class

 

≥ 15"

Mean

0.3

Median

0.3

St Deviation

0.7

CV

59%

Jeffrey Pine: Number of Plots 23

DBH Class

 

≥ 15"

Mean

3.4

Median

0.5

St Deviation

6.3

CV

187%

Lodgepole Pine: Number of Plots 6

DBH Class

 

≥ 15"

Mean

6.0

Median

3.7

St Deviation

11.7

CV

58%

Montane Hardwood: Number of Plots 43

DBH Class

 

≥ 15"

Mean

2.5

Median

0.0

St Deviation

12.9

CV

128%

Montane Hardwood-Conifer: Number of Plots 25

DBH Class

 

≥ 15"

Mean

2.7

Median

0.0

St Deviation

5.2

CV

191%

Pinyon-Juniper: Number of Plots 8

DBH Class

 

≥ 15"

Mean

2.6

Median

1.0

St Deviation

3.2

CV

120%

Ponderosa Pine: Number of Plots 25

DBH Class

 

≥ 15"

Mean

2.4

Median

0.0

St Deviation

3.3

CV

140%

Red Fir: Number of Plots 36

DBH Class

 

≥ 15"

Mean

3.7

Median

2.0

St Deviation

6.7

CV

61%

Sierran Mixed Conifer: Number of Plots 143

DBH Class

 

≥ 15"

Mean

3.7

Median

1.5

St Deviation

5.9

CV

160%

Valley Oak Woodland: Number of Plots 3

DBH Class

 

≥ 15"

Mean

0.0

Median

0.0

St Deviation

0.0

CV

0%

 

 




California Spotted Owl Habitat

California spotted owl habitat on the northern two districts of Sequoia National Forest is quite varied. The majority of nest and roost sites occur in mid slope regions between 4,000 and 7,500 feet in Sierran mixed conifer, montane hardwood conifer and giant sequoia vegetation types, with flying squirrels as the main prey source. At the lowest elevations in the oak woodland belt, owls can be found along canyon ravines within stringers of canyon live oak and most commonly consume woodrats. Common elements noted within most occupied stands regardless of vegetation type include: adequate flight space from the near the ground region to mid canopy, dense canopy (at least 50%) either in pockets or more uniform in nature, large woody debris, and large snags. Owls using the upper elevation band tend to consume more flying squirrels, whereas the diet of lower elevation birds is primarily composed of woodrats. Bond et al. 2013 assessed the diets of seven Spotted Owls occupying burned forests in the southern Sierra Nevada 4 years after a fire and compared the results with data from previous studies in unburned forests within the range of the subspecies. Prey captured by owls in the burned area comprised 40.3% (by biomass) pocket gophers and 25.9% northern flying squirrels. In contrast, in unburned areas of the Sierra Nevada, Spotted Owls fed primarily on flying squirrels, or on both flying squirrels and woodrats; in unburned southern California forests they fed overwhelmingly on woodrats. Also, the owls’ mean home range in the burned forest covered 402 ha, an area similar to that recorded in unburned forests of the Sierra Nevada.

The southernmost district on the Sequoia National Forest is a transition zone between the southern Sierra Nevada, desert environments to the east that do not support spotted owls and spotted owl populations that occupy small pockets of suitable habitat on isolated mountains in southern California and the coast range. Spotted owls in this transition zone nest from low elevation pockets of live oak at 1,000 feet up to successful nests at over 9,000 feet in elevation. However the majority of known owl territories are in the black oak-conifer transition at 4,500 feet up to the mixed conifer- red fir transition near 8,500 feet. This district is comprised of a number of mountain ranges with unique characteristics, such as the Greenhorns, Breckenridge, and Piute Mountains, and the Kern Plateau.

The Greenhorn Mountains are an extension of the west side Sierra Nevada mixed conifer habitats. The Greenhorns are primarily dense, second-growth fir and cedar that resulted from pre-1900 timber harvest and fire exclusion. These habitats appear to support a full spotted owl population that is connected to the rest of the Sierra Nevada spotted owl population. Breckenridge Mountain and the Piute Mountains are isolated from the Greenhorn populations by gaps of several miles of unsuitable habitat. Both Breckenridge and the Piutes are further isolated by loss of habitat to large, stand replacing fires. These areas also have lower quality habitat that is closer to east-side Sierran pine due to poor site quality and lower mean annual precipitation. The owl territories on these mountains are few and widely separated due to habitat limitations.

The southern Kern Plateau is also an isolated and low density population. There are no spotted owl populations to the north, east or south of the Kern Plateau. Linkage to the north and west is limited by a major river canyon and past large, stand-replacing fire effects. The majority of spotted owl territories are located in pockets of deeper soils on north facing slopes and drainage bottoms.

Trend:
Ongoing research of recent population trends indicates there may be evidence for slight population declines on the three studies on National Forest Service lands (Lassen, Eldorado, and Sierra) and a stable/increasing population on the National Park Service study area (SEKI), and it is providing new approaches for evaluating spotted owl population trends and interpreting the probability of population declines (Conner et al., in review; Tempel and Gutiérrez, in review). The factors driving these population trends are not known and further meta-analysis of ongoing research is expected in 2014 (Keane 2013).

Although the distribution of the spotted owl is still intact, there have been concerns raised since 1992 about areas where there are low numbers of owls, high fragmentation from past, large, high intensity fires, or mixed ownership with less certainty of owl habitat management. These were called “areas of concern” in a comprehensive scientific report in 1992 (Verner et al. 1992). Although some low to moderate severity fire has little to no effect or is beneficial, fires that are high severity across much of the nest stands can impede breeding and survival (WIKI Bioregional assessment). However, Bond et al. 2009 found that California spotted owls preferentially forage in areas that have burned at high-severity, and Bond et al. 2013 found that home range size of spotted owls in the McNally fire was similar to, or smaller than, home ranges in unburned forests in the Sierra Nevada. Moreover, Lee et al. 2012 found that mixed-severity wildland fire, averaging 32% high-severity fire effects, did not decrease California spotted owl territory occupancy, but post-fire salvage logging doe appear to adversely affect occupancy. Thus, it is important to recognize that the impact of fire to California spotted owls is not a one-size fits all analysis and is instead a nuanced situation in which mixed-severity fire can be highly beneficial to owls (e.g., for foraging habitat). On the Sequoia National Forest, large high intensity fires and historical logging practices created areas of concern in the tens of thousands of acres. In unburned forests, large snags tend to be of low density, and smaller snags can be of higher density. In burned forests, there may be extensive areas of snags of all sizes. The latter pattern is most prevalent in montane hardwood and mixed conifer forests, but more uncommon and uncertain relative to the natural range of variability in upper montane forests (WIKI). High snag density is a key habitat attribute of numerous species including rare species like the California spotted owl and Pacific fisher (see, e.g., Gutierrez et al. 1992 re California spotted owl, Nesting: Snag basal area = 30-55 ft2/acre Large snag basal area = 20-30 ft2/acre; Foraging: Snag basal area = 15-30 ft2/acre Large snag basal area = 7-17 ft2/acre). It is also one of the most important habitat attributes of the black-backed woodpecker which can require about 133 snags per acre (e.g., Seavy, et al. 2012.)

Fisher Habitat

The Sierra Nevada status and trend monitoring project (USDA-FS, 2006, 2009) has detected fishers as low as 3,110 feet and as high as 9,000 feet in the southern Sierra Nevada, which are considered to be extremes of the elevation range. On the Sequoia National Forest, Western Divide District, mapped female home ranges from the Tule River area were between 3,600 and 7,500 feet in elevation. Males appear to have a much wider range in elevation, 4,000 to 9,300 feet, but also appear to be much less selective in use of habitat in general (Zielinski et al. 2004a). The following California Wildlife Habitat Relationships (CWHR) types are thought to be important to fishers: generally structure classes 4M, 4D, 5M, 5D and 6 (stands with trees 11” diameter at breast height or greater and greater than 40% cover) in ponderosa pine, montane hardwood-conifer, white fir, Sierran-mixed conifer, montane riparian, Jeffrey pine (Macfarlane, 2010) and differ slightly between males and females (Zielinsky et al. 2004a).

Fishers use large areas of primarily coniferous forests with fairly dense canopies and large trees, snags, and down logs. A vegetated understory and large woody debris appear important for their prey species. It is assumed that fishers will use patches of quality habitat that are interconnected by other forest types, whereas they will not likely use patches of habitat that are separated by large open areas lacking canopy cover (Buskirk, et al., 1994). Riparian corridors (Heinemeyer, et al., 1994) and forested saddles between major watersheds (Buck, 1983) may provide important dispersal habitat or landscape linkages for the species. Riparian areas are important to fishers because they provide concentrations of large rest site elements, such as broken top trees, snags, and coarse woody debris (Seglund, 1995), perhaps because they persisted in the mesic riparian microtopography through historic fires.

Habitat suitable for resting and denning sites is thought to be most limiting to the population; therefore, these habitats should be given more weight than foraging habitats when planning or assessing habitat management (Powell and Zielinski 1994). Zielinski et al. (2004b) argue that retaining and recruiting trees, snags and logs of at least 39 inch diameter basal height (dbh), encouraging dense canopies and structural diversity, and retaining and recruiting large hardwoods are important for producing high quality fisher habitat; and resting and denning sites. Zielinski et al. (2004c) speculated that the relatively small home range sizes of fisher in the southern Sierra Study Site located on Sequoia National Forest reflect higher habitat quality due to greater abundance of black oak that provides cavities and prey food resources.

Most models for fisher indicate that the Kern Plateau is low quality habitat for fisher due to the lower density and more open canopy of the forest in the area. However, there have been consistent detections of fisher on the Kern Plateau (Grinnell 1937, Schempf and White, 1977, Zielinski et al. 1995) despite the generally more open habitats. It is presumed that fisher use the more open habitats for foraging and denser steep, north facing slopes and pockets of deeper soils with higher tree density for den sites.

Trend:
The estimates of fisher population numbers in California are fewer than 500 animals in the southern Sierra Nevada (CDFG 2010). The fisher population in the Sierra Nevada is assumed to be at risk due to its small size, geographic and genetic isolation, and the fact that much of its historical range is unoccupied (Grinnell et al. 1937; Zielinski et al. 2005). Zielinski et al. (2013) analyzed 8 years (2002-2009) of detection data from the USFS long-term monitoring program across the southern Sierra and found that the fisher population is stable. It is encouraging that the small population in the southern Sierra does not appear to be decreasing. However, given the habitat degradation that has occurred on private and public lands in the southern Sierra, continued monitoring should be conducted to determine whether fisher occupancy increases as land managers implement measures to restore conditions favorable to fishers.
In Naney et al. (2012), habitat loss to uncharacteristically severe wildfire was evaluated to be the single most important threat for the southern Sierra Nevada population. It is important to keep in mind, however, that no published studies yet exist that examine how fisher respond to actual fires. The studies that do exist are modeling studies that examine the relative risks to Pacific fishers of mechanical thinning versus wildland fire and base their assessments on the assumption of 90% to 100% tree mortality from fire, while actual mortality rates are far lower. (Odion and Hanson 2006, Odion and Hanson 2008, Collins et al. 2009, Collins and Stephens 2010.) Severe wildfire can affect large areas, and potentially remove or modify forest structure, including large trees, snags, canopy cover, and understory vegetation (Kennedy and Fontaine 2009). On the other hand, mixed-severity fire (and its associated high severity fire) can be beneficial to Pacific fisher by creating large snags, heterogeneity, shrub habitat, and overall structural complexity (e.g., Donato et al 2012). These habitat changes may also increase predation risk through reduced cover and decrease prey abundance. On the other hand, they can, via the structural complexity that results, provide cover for fisher and can increase prey abundance. Further studies are necessary to evaluate the changes in habitat use by a fisher population post-fire.

Aquatic Ecosystems

Species

Fish

The Sequoia National Forest is at the southern end of the Sacramento-San Joaquin zoogeographic province as described by Moyle (2002). The Kern, Tule, Kaweah and Kings River connected to the Sacramento - San Joaquin estuary only when Tulare and Buena Vista Lakes flooded and flowed into the San Joaquin River (Moyle 2002). Fish communities historically found on the forest include “Rainbow Trout”, “ Pikeminnow-hardhead minnow- Sacramento sucker”, and “California Roach” (Moyle 2002). Moyle (1996, 2002) identifies much of the west slope of the Sierra Nevada range above 5,000 feet as being historically fishless due to glaciation during the Pleistocene and steep topography. However, glaciation did not extend down below 8,000 feet in elevation in the Middle Fork Kings River, upper Kern River or Little Kern River in the Southern Sierra Nevada during the Pleistocene (Moore and Mack 2008). Trout may have occurred in the Middle Fork of the Kings River (Moyle et al 1996a,b) and occurred in the Kern River above the current Lake Isabella to high elevations, in all of the Little Kern River and South Fork Kern River. The Upper Kern River sub-province is treated separately because it is the only major river system in the Sierra Nevada that was not glaciated (Moyle 2002) in the past 60,000 years (Moore and Mack 2008), and thousands of years ago was connected to the ocean. Historic distributions of native fishes found on the Sequoia National Forest are shown in Figure 1.8.

The Sequoia National Forest was occupied by at least nine known native fish species prior to 1850: Kern brook lamprey (Lamptera hubbsi); Kern rainbow trout (Oncorhynchus mykiss gilberti); Little Kern golden trout (O. mykiss whitei), California golden trout (O mykiss aguabonita), Hardhead minnow (Mylopharodon conocephalus); Sacramento pikeminnow (Ptychocheilus grandis); Sacramento hitch (Lavinia exilicauda exilicauda), California roach (Lavinia symmetricus); and Sacramento sucker (Catostomus occidentalis occidentalis). Threespine stickleback (Gasterosteus aculeatus microcephalus) and Sacramento Perch (Archoplites interruptus) were introduced onto the Forest in years past. Stocked or self-sustaining populations of rainbows (Oncorhynchus mykiss), nonnative brown (Salmo trutta) and brook trout (Salvelinus fontinalis): smallmouth and largemouth bass: and green sunfish occur in the Forest rivers and streams, White catfish, bluegill, kokanee salmon, carp, bullheads, and crappie and a number of other non-native fish occur in the Kern River below Lake Isabella; but whether these are self-sustaining populations or just swept out of the lake is unknown (USDA 1988). 24 species of fish were listed for the Forest in the past (USDA 1988), how many of these fish had self- sustaining populations was not been evaluated.

One of the nine native fish species, Little Kern Golden Trout, is classified as federally threatened (USFWS 1978), an additional 4 species are classified as Forest Service sensitive species known to occur, or have the potential to occur, within Sequoia National Forest. These are: Kern Brook Lamprey, Kern River Rainbow, California Golden Trout and Hardhead minnow. Golden Trout are found in the Golden Trout Wilderness, primarily on the Inyo National Forest. Little Kern golden trout critical habitat and Critical Aquatic Refuge (CAR) is in the Golden Trout Wilderness on the Sequoia National Forest. Little Kern Golden Trout are listed as threatened under the Endangered Species Act and covered under a Recovery Plan (Christianson 1984). CARs are sub-watersheds with known locations of threatened, endangered, or sensitive species; highly vulnerable populations of native plant or animal species; or localized populations of rare native aquatic- or riparian-dependent plant or animal species. The primary role of CARs is to preserve, enhance, restore or connect habitats for these species at the local level and to ensure the viability of aquatic or riparian dependent species.

ArriskfishSQF.jpg

Figure 1.8. Historic Fish distribution native fishes of the Sequoia National Forest. The data on historic range came from University of California (UC) Davis PISCES website; and sub-watersheds are the divisions indicated within each species range. The indicators for historic range are as follows: Kern rainbow trout -light blue, Little Kern golden trout - gold, golden trout - gold stripes, hardhead minnow - dark blue outline, Sacramento hitch - brown pattern and outline, and Kern Brook Lamprey – orange stripes.

Higher elevation streams, lakes, fens, and meadows in most of the Greenhorn Mountains and Breckenridge, Scodie and Piute Mountains were barren of fish prior to man's transplanting activities starting in the late 19th Century (Moyle 2002). Steep topography and natural barriers to fish passage would have prevented native fish from entering these areas. However, if streams above approximately 2,500 feet had no natural barriers and were a tributary of the lower Kern River they might have supported the native rainbow trout (Oncorhynchus mykiss gilberti) assemblage. Water temperatures seldom exceed 70 degrees Fahrenheit (21° Celsius). Currently, rivers and stream above 2,500 feet throughout the Greenhorn Mountains have stocked rainbow trout and non-native brown and brook trout present (USDA 1988).

At lower elevations, the” pikeminnow- hardhead minnow-sucker assemblage” and “California Roach assemblage” (Moyle 2002) are a natural part of permanent streams occurring within Greenhorn Mountain foothills (Moyle 2002), the area surrounding Lake Isabella, the lower Kern River, Breckenridge and parts of the Scodie Mountains. Water temperatures within this transitional zone from the valley floor to the mountains may exceed 70° Fahrenheit (21° Celsius) during the summer, especially during “dry and critically dry” water years. Warm water fisheries in these transition zones in the North Fork Kern and at Lake Isabella flood control reservoir are more likely to be occupied by introduced non-native bass and other species from the bass/sunfish families. Angler experience and success may be affected by the time of year since stream and lake levels may be influenced by spring runoff of snow-melt low summer or fall flows; drought; or draw down of Lake Isabella reservoir in the fall. Most of the hydroelectric projects on the Forest are run of the river and do not store much water; they do divert water through penstocks to lower elevation areas.

Of the approximate 1,280 miles of perennial streams on the Forest, 732 miles are estimated to contain fish, with rainbow trout the dominant harvest species (USDA 1988). In streams and lakes above approximately 2500 feet elevation anglers may catch rainbow (Oncorhynchus mykiss), Little Kern Golden (O.m.whitei), Golden (O. m. aquabonita), brown (Salmo trutta), or eastern brook trout (Salvelinus fontinalis). The distribution of fish across the Forest has been greatly expanded, and most of the waters on the Forest are currently occupied by non-native fish, hatchery trout, or introgressed native trout (Sprowles et al. 2006, Stephens et al. 2009, Stephens 2007). At lower elevation in the reservoirs warm water species such as bass are valued by fishermen and women.

Trend
Past distribution of native trout on the Kern River Plateau (Figure 1.6), included Golden Trout throughout most of the South Fork, Kern River rainbows throughout most of the main stem, and Little Kern Golden Trout throughout the Little Kern (http://pisces.ucdavis.edu). However transplanting activities introduced other trout species and hatchery rainbows. On the Tule River over the last five years nonnative brown trout numbers have increased while rainbow trout numbers have declined (AECOM 2012). Introgression with hatchery fish and rainbow trout introduced into the Kern River threaten the genetic integrity of native trout (Stephens 2007). During the mid-20th century, barriers to passage of non-native brown trout and hatchery rainbow trout were constructed to prevent these fish from reaching the pure lineages of Little Kern Golden and Golden trout (Pister 2008).

The projected impacts of warming temperatures on trout and salmon species are a concern because of their vulnerability to increased stream temperatures and changes in flows (Wenger et al. 2011, Moyle et al. 2011). Climate modeling predicts a loss of snowpack for the Sierra Nevada as air temperatures rise (Hunsaker et al. 2012b ); while on the Kern Plateau snow melt appears to be occurring earlier (Peterson et al. 2008). Warming temperatures can drive cold water fishes into higher elevations where they are not impeded; fish already at the higher elevations may be affected by these fish as well as by climatic changes (Wenger 2011). Not only does temperature have a direct effect on the habitat quality for native cold water trout but also indirectly through increased risk of wildfire (Isaak et al. 2010).The Kern River Valley already burns in several places every year. When fires are followed with intense rainfall as happened in Erskine Creek after the Piute Fire; swift and destructive post-fire debris flows can occur in streams (DeGraff et al. 2011).

Native fish species are increasingly threatened by habitat changes in California (Moyle et al. 2011). On the Sequoia National Forest, native trout currently are restricted to a few small tributaries in upper elevations areas (Stephens 2007). The widespread concern for native fishes in California (Moyle et al. 2011) is reflected by the limited distribution and abundance of native fish on the Forest. Native trout populations are vulnerable due to their small and isolated populations. This trend is predicted to continue under current conditions.

Amphibians


The Breckenridge Mountains, the Greenhorn Mountains and the Kern Plateau provide an array of habitats for amphibians. Plentiful springs, seeps, fens and meadows make the Greenhorn Mountains and the Kern Plateau appear as a haven for amphibians. In the Greenhorn Mountains and Kern Plateau, aquatic systems are driven by snow; many amphibians are not active until conditions begin to warm in the spring. The low and intermediate elevations have long, hot, dry summers restricting summer activity to perennial aquatic areas. Proceeding east from the Breckenridge Mountains and Scodie, the climate is drier and less hospitable for amphibians. However, throughout the Sierra Nevada, amphibians have been in decline (Lannoo 2005) due to disease (Bradford et al. 2011), human disturbance (Jennings 1996), and pesticides (see review in Bradford et al. 2011).

By the mid-1990s, both frogs and salamanders native to the Sierra Nevada were in need of some type of protection (Jennings 1996). The northern distinct population unit (DPS) for Rana muscosa is listed as a Candidate for federal listing; while the southern DPS is listed as endangered (also see trends in next paragraph). Native amphibians with habitat within or adjacent to the Forest were identified as Sensitive Species by the Forest Service: foothill yellow-legged frog (Rana boylii), mountain yellow-legged frog (R. muscosa), yellow-blotched salamander (Ensatina eschscholtzii croceater), the Relictual Slender Salamander (Batrachoceps relictus), Fairview Slender Salamander (Batrachoceps bramei), and Kern Canyon Slender Salamander (B. simatus). Vredenburg et al. (2007) examined the distribution and genetics of Rana muscosa and determined that R. muscosa occurs in the southern Sierra Nevada north to the Kings River. Recent genetics work has shown the restricted range of many slender salamanders in the Greenhorns (Jockusch et al. 1998, Jokusch et al. 2012). The degree of genetic variation suggests most of these species of salamander have been isolated from one another for a long time (Jockusch and Wake, 2002). Recently, the Breckenridge Mountain populations were found to be the same as the lower elevation Kern Canyon population (Jockusch et al. 2012), and were assigned to B. relictus. On the western margin of the Kern Plateau (www.amphibiaweb.org), and in the Greenhorn Mountains, salamanders previously considered to be B. relictus were placed into the Greenhorn Mountain Slender Salamander (B. altasierrae) (Jockusch et al. 2012) and the Fairview Slender Salamander (B.bramae). The Kern Canyon Slender Salamander (B. simatus) is found in the lower Kern Canyon and Paiute Mountains (Hansen and Wake 2005b). The southern- most salamanders in the Greenhorn Mountains remained as the Relictual Slender Salamander (B. relictus) (Jockusch et al.1998).

Trend
A precipitous decline in frogs appears to have occurred over the past 3-4 decades (Bradford 1991; Lannoo 2005, Vredenburg et al. 2010). Across the Sierra Nevada, the declines of some amphibian species resulted from increased distribution of fish (Jennings 1996, Matthews et al.2001). Local extirpation of southern mountain yellow-legged frog populations (Rana Muscosa/Rana sierrae) were thought to be due to introductions of trout (Bradford et al. 1993); frogs may move into an area once fish are removed (Knapp et al. 2007, Vredenburg 2004). In Sierran lakes introduced trout were better competitors for large aquatic insects which adult frogs rely on for food (Finlay and Vredenburg 2007). Trout removal by the California Department of Fish and Wildlife in the Little Rock Creek in the Angeles National Forest, resulting in increased numbers of the mountain yellow legged frog (Salzberg 2009; Lewis 2009, see updates at Amphibiaweb). Historically, mountain yellow legged frogs were documented in approximately 166 localities in creeks and watersheds in the mountains of southern California (Jennings and Hayes 1994). Currently the species is known from only seven or eight widely scattered locations, most with very small populations of fewer than 20 adults (Backlin et al. 2004, Knapp and Matthews 2000. Schoville 2011; Vredenburg et al. 2007). The southern mountain yellow legged frog used to occur on Breckenridge Mountain, in the Greenhorn Mountains and on the Kern Plateau, extending north to Mather Pass (Vredenburg et al. 2007). These frogs are now extirpated in the Breckenridge Mountains and in much of the former range elsewhere in southern California and the southern Sierra Nevada (Vredenburg et al. 2007). Disease, airborne pesticides from agriculture, and recreation may also be influential in declines (Vredenburg et al. 2007, www.Natureserve.org). Pesticides have been found to be prevalent in Sierra frogs even though they are many miles from where the pesticides are used (Smalling et al. 2013). Adult population size on the Forest is unknown; available information does not indicate how many viable populations remain within the range of the species (www.natureserve.org). Mountain yellow legged frog’s populations are only found in higher elevations and far from the Central Valley, where the initial spread of the amphibian disease chytridiomycosis started moving eastward (see review in Bradford et al. 2011). Heavily infected wild mountain yellow-legged frogs suffer from severe dehydration despite the aquatic environment (Voyles et al. 2012). For rescue efforts (e.g. Lubick 2010) see latest updates at Amphibiaweb. This downward trend is expected to continue under current conditions.

For amphibians lower in elevation in the Greenhorn Mountains, such as the foothill yellow legged frog (Rana boylii), pesticides from the San Joaquin Valley may be responsible for population declines (see review in Bradford et al. 2011). While this frog has a wide distribution in California and western Oregon; it is undergoing a substantial decline, apparently due to habitat alteration, impacts of airborne agrochemicals, and/or effects of exotic species (www.natureserve.org). Recolonization abilities may be greatly restricted by local extirpation patterns. The species apparently has disappeared from portions of its historical range, especially in southern California (see Hayes and Jennings 1988); only 12 percent of the streams supported populations in the Sierra Nevada foothills (Fellers 2005). The Upper Kern and the South Fork Kern watersheds on the Kern Plateau had records of foothill yellow legged frog; while in the Greenhorn Mountains records show Upper Deer-Upper White, Upper Tule, Upper Kaweah, and Upper King watersheds (www.natureserve.org). While the steep topography of the mountainous terrain throughout the Forest provided many natural barriers to fish passage, transplantations above these barriers introduced fish into previously fishless areas, impacting native amphibians (Knapp 1996). Under current conditions frogs in general are declining and are expected to continue declining.

Trend: Historically, the slender salamanders were found in the Piute, Scodie and Breckenridge Mountains, the Greenhorn Mountains, and up on the Kern Plateau (Hansen and Wake 2005 a, b). Each species range within the Sierra Nevada is restricted; within these ranges the salamanders occur in isolated colonies (Jockusch et al. 2012). We do not have data on the number of occurrences of these species or how many populations are on the Forest, or how many have stability and have good viability (www.natureserve.org). These salamanders are secretive, and have no aquatic larval stage; and depend on moist microhabitats including springs or seeps in upland areas (Hansen and Wake 2005 a, b). Timing of reproductive activities is likely to vary with elevation and seasonal precipitation (Hansen and Wake 2005 a, b). For this species multiple year droughts and later heavy rains may restrict activity to February to March (Hansen and Wake 2005b). The yellow-blotched salamander occupies similar habitat to the slender salamanders: coniferous forest, deciduous forest, oak woodland, coastal sage scrub, and chaparral. Individuals are found in thermally buffered, mesic microclimates, such as under logs, bark, and moss, under leaf litter, in talus, and in animal burrows (see review in Kuchta and Shawn 2005). The slender salamanders were found recently in the Piute and Breckenridge Mountains, the Greenhorn Mountains, and up on the Kern Plateau (Jockusch et al. 2012, Hansen and Wake 2005 a, b). The small range for these salamanders makes them vulnerable to roads, land clearing, high intensity fire and other human or natural disturbances. Based on habitat considerations and recent monitoring of extent of occurrence, salamanders appear relatively stable and are predicted to decline at a rate of less than 10% over the next 10 years (www.natureserve.org). Small isolated populations makes salamanders vulnerable under current conditions.

Reptiles
Western Pond turtles were found throughout the lower elevations of the Southern Sierra (see maps in Bury et al. 2012a). However, recent surveys indicate lower numbers (Bury et al. 2012b). Western pond turtles are present in lower elevation rivers and stream on the Sequoia National Forest. No known trend data are available specific to forest. Even less data are available on snakes and lizards.

Aquatic invertebrates

Two hundred years ago Sierra Nevada streams were continuous running-water systems: there were no dams, reservoirs, water diversions, or inter-basin transfers of water (Erwin 1996). Due to the steep mountains and isolated seeps and meadows, many aquatic invertebrates are endemic to the Sierra Nevada (Erwin 1996). Aquatic invertebrates are affected by excess sediment, changes in hydrology and other changes in the watershed due to altered land use patterns (see review in Erman 1996). Non-native fish or fish introduced above natural barriers affected both zooplankton and aquatic invertebrate communities in the Sierra Nevada (Knapp 1996, 2005). A similar pattern exists for aquatic invertebrates in lakes, with many species with free-swimming larvae being absent or reduced in lakes occupied with introduced fish (Bradford 1989). While aquatic invertebrates were sampled throughout the Forest in the last 10 years as a part of stream inventories; a comprehensive assessment is still underway and a Forest specific draft report is not available yet.

Habitat

Four major rivers drain parts of the Sequoia National Forest. The Kings, Kaweah, and Tule Rivers flow almost due west through deep canyons in the northwestern portion of the Greenhorn Mountains. Several smaller watersheds such as Deer Creek or White Creek flank the western side of the Greenhorn Mountains. On the southern portion of the forest, below Lake Isabella reservoir, the Kern River separates the Breckenridge Mountains from the Greenhorn Mountains. The Kern River drains the southern and eastern portions of the Greenhorns and is impounded at Lake Isabella. Upstream from the reservoir, the South Fork of the Kern River divides the Piute Mountains and Scodie Mountains from the Kern Plateau. The North Fork of the Kern River divides the Greenhorn Mountains from the Kern Plateau.

The low and intermediate elevations on the western half of the Forest, like most of southern California, has a Mediterranean-type climate comprised of relatively mild winters, limited precipitation, and long, hot, dry summers. Mean annual precipitation ranges from 10 to 50 inches with 79-90 percent of it falling between November and April. In the montane and subalpine elevations of the Greenhorn Mountains and Kern Plateau, most of the precipitation during this period is in the form of snow. On the eastern half of the Forest, precipitation ranges from a high of 35 inches on the Kern Plateau to less than eight inches on the eastern slopes of the Scodie Mountains (USDA Sequoia Forest Plan, 1988).

The mainstem of the Kern River above the Johnsondale Bridge and the South Fork of the Kern River are classified as Wild and Scenic Rivers. The Kern Rainbow trout used to occur on the Kern Plateau in the mainstem Kern River. However despite past occurrenc in tributaries in roadless areas, introgression with introduced rainbows has degraded the genetic integrity of rainbows in this area. The Golden Trout Wilderness, located on the Little Kern River, contains the Critical Habitat for Little Kern Golden Trout and habitat for Golden Trout. This wilderness includes montane, subalpine, and alpine ecosystems; and is administered by both the Sequoia National Forest and the Inyo National Forest. At lower elevations, hardhead minnows, and a few warmer water native fish still occur in the Tule and Kern Rivers.

For aquatic species such as the endemic mountain yellow legged frog, the elevation range on the Kern Plateau is 1,220-7,560 feet (370-2,300 meters) (Vredenburg et al. 2005). This species’ tadpole stage can last from two to four years at higher elevation, so unaltered perennial streams, rivers, permanent pools within intermittent streams, ponds, or lakes are required (www.natureserve.org). This frog seldom is found away from water, but it can cross upland areas to move between summer and winter habitats (Matthews and Pope 1999). Most mountain yellow legged frog wintered in the same lake in consecutive years (Pope and Matthews 2001). Basins with a variety of fishless deep lakes and shallow ponds may contain the best habitat for this declining species (Pope and Matthews 2001).
These frogs used to occur in streams in the southern Sierra Mountains where few ponds or lakes occurred naturally (Vredenburg et al. 2005).

The foothill yellow legged frogs in southern California were typically found in steep gradient streams in the chaparral belt such as in the foothills of the Greenhorn Mountains. These populations may not remain viable for much longer (Fellers 2005). At higher elevations in the mixed conifers in the Greenhorns or on the Kern Plateau these frogs may range into small meadows and other small to medium streams. Foothill yellow-legged frogs prefer to lay eggs in riffles containing cobbles (7.5 cm diameter) or larger rocks as substrate (Fellers 2005).

The slender salamanders occur in mixed oak conifer woodlands, and mixed conifers throughout the Greenhorn Mountains and the Kern Plateau. In the Breckenridge Piute, and Scodie Mountains, slender salamanders are found in talus slopes, grasslands, shrub lands, and pinyon pine forests (Hansen and Wake 2005 a,b). Jockusch et al. (2012) typically found relictual slender salamanders directly associated with a small seep or surface water in the Breckenridge Mountains (1665–1700 m elevation). Their ranges are small as roads and rivers are barriers to their movements. In the Greenhorns, slender salamanders occur from 330 to 3,000 meters in elevation (Hansen and Wake 2005 a,b). These salamanders have been found in riparian and terrestrial habitat, on north-facing slopes and small wooded tributary canyons. They live under rocks, fallen logs and debris; or in crevices in bare rock or talus; most often at the edges of springs and seeps (Hansen and Wake 2005 a,b). They burrow into soil in any moist upland or riparian habitats to overwinter or to stay cool in the hot dry summers. Information gaps for this group of species include delineation of the distribution of the species, habitat associations, understanding threats to the species, and distribution of risk factors throughout the species range. The Kern River serves as a biogeographic break with the Kern Canyon slender salamander known only from the south side of the river (Jockusch et al.2012). Some researchers had thought that populations from Fairview, on the Kern Plateau might be Kern Canyon slender salamanders but Jockusch et al. (2012) assigned those salamanders to a new species, the Fairview slender salamander (B. bramei).

During the period 1992 to 2009 biological assessments indicated that over half the streams were in good to very good condition, while a quarter were fair or poor (Table 1.4). Additional assessments using aquatic invertebrates will be assessed in the near future using several invertebrate indices.

Table 1.4. Summary of the condition class of streams in the southern Sierra Nevada based on aquatic invertebrate indices, developed for Giant Sequoia National Monument Plan.
Site Condition Summary
Condition
Number
Percent
Very Good
13
24
Good
26
47
Fair
13
24
Poor
3
5
Total
55
100

Impaired aquatic systems


Major watersheds within the Sequoia National Forest including those in the Greenhorn Mountains, The Kern Plateau, and the Breckenridge and Scodie Mountains were assessed for biological health as part of a Sierra Nevada wide assessment (Moyle and Randall, 1996). Native ranid frogs such as the foothill yellow-legged frog, or mountain yellow-legged frog, native fishes, and native fish assemblages were used to evaluate major watersheds on the Forest (Moyle and Randall, 1996). Of the approximately 11 major watersheds evaluated, the aquatic communities in seven were listed as in good condition. The remainder of the watersheds, the lower Kings River, North Fork Tule River, Poso Creek, and the Kern River below Lake Isabella reservoir were ranked in fair condition. Drivers for lower scores included dams, reservoir capacity, the percentage of hectares containing roads with streams, and historically fishless areas (Moyle and Randall 1996). The scarcity or absence of native frogs, once an important part of aquatic ecosystems in the Sierra Nevada lowered many scores (Moyle and Randall 1996). A similar study in the Lower Colorado River Basin found similar effects (Paukert et al.2011).

The greatest impacts on fish habitat have historically come from livestock grazing and water diversion for domestic use and energy production (USDA 1988). Present conditions can, in most cases, be traced to events of those types that occurred 50 or more years ago. Livestock grazing began in the area about 130 years ago, and the number of animals (over 100,000 sheep and cattle) remained high until the 1930's. The heavy grazing denuded meadows and stream banks; caused sedimentation of streams and corresponding damage to fish habitat quality (USDA 1988). Eliminating grazing from the Golden Trout wilderness area is still a conservation concern (www.natureserve.org,). Other management activities, such as road construction, timber harvest, and recreational developments can adversely impact fish habitat. In many cases, the direct impacts can be and are mitigated. However, as access for fishing improved, resident fish populations dropped and most were then stocked and habitat quality declined with increasing use (USDA 1988).

Introductions of non-native species such as predatory bass or brown trout cause degradation of habitat for native fishes and amphibians (see review in Moyle and Randall 1996). Introduced trout and warm water fishes such as the green sunfish eat both the eggs and tadpoles of foothill yellow legged frogs (Fellers 2005). However, amphibians respond to removal of introduced fish at higher elevation (Vredenburg 2004). Livestock grazing in the arid west was found to negatively affect water quality and seasonal quantity, stream channel morphology, hydrology, riparian zone soils, vegetation, and aquatic and riparian wildlife (see review in Belsky et al. 1999). High levels of stream sediment (Ashton et al. 1997, Jennings and Hayes 1994); and loss of riparian areas are threats to the foothill yellow legged frog (www.natureserve.org). In the Sierra Nevada foothills, air-borne pesticides (that move east on the prevailing winds blowing across the highly agricultural Central Valley) are a primary threat to amphibians (Fellers 2005, Sparling and Fellers 2007). Chytrid fungus (Bradford et al. 2011, Davidson et al. 2007) is the primary threat to amphibians in the Sierra Nevada.

The Breckenridge Mountain population of the relictual salamander (or Greenhorn Mountain Salamander) has suffered from habitat loss and degradation. The population east of Squirrel Meadow was severely degraded by the construction of a logging road through the seepage area subsequent to its discovery in 1979 (Jockusch et al. 2012). A subsequent fire and timber harvest further compromised this site, and salamanders were not found here despite multiple searches over the next 22 years (Jockusch et al. 2012). Recent visits suggest that the population has rebounded somewhat, but prime seep habitat is quite small (Jockusch et al. 2012). The Kern Plateau salamander is vulnerable to habitat degradation through capping of springs by humans and other alterations of spring water or habitat (NatureServe 2013).

Dams/Diversions and Habitat Connectivity


Connectivity among habitats is interrupted by diversions and impoundments. At lower elevations on streams and rivers in the Greenhorns, water withdrawals, diversions for hydropower and impoundments alter habitat for native warm water species that would historically be distributed from the lower elevations of the Forest down to the valley floor and the Tulare and Buena Vista Lakes (Moyle 2002, PISCES). Localized geomorphic/fluvial, macro-habitat influences such as increased sediment or decreased summer flows in these lower elevation rivers are very basic to native fish abundance and distribution (Rinne and Miller 2006). Introduced predatory fish such as bass and non-native trout could further influence hardhead minnows and other native warm water fishes. An integrated aquatic invertebrate and biotic integrity index was assessed below hydroelectric dams on the Western Slope of the Sierra Nevada (Rehn 2009). This study indicated that aquatic invertebrates were most affected by altered hydrologic regime and loss of fine sediments in a system (Rehn 2009). Due to their importance in the food web, alterations to aquatic invertebrates can have cascading effects on amphibians, birds, and fish (see review in Erman 1996).

As described under the Sierra Nevada Ecosystem Project (SNEP 1996), connectivity of aquatic habitat on the Sequoia National Forest has been altered by dams, diversions, and road crossings.. In a twist on the concept of connectivity, introduction of non-native fish above natural barriers has expanded the distribution of fish across the Forest. Distribution of native frogs has declined where fish were introduced (e.g. Bradford et al. 1993). Amphibians have highly permeable skin and egg membranes and complex life cycles with aquatic and terrestrial life history stages that make them sensitive to environmental change (Hansen and Wake 2005 a,b,c). As a result of their isolated and small populations these slender salamanders are further fragmented by roads and destruction of habitat and could become vulnerable to extirpation or extinction.

There are several dams and diversions on the Forest or just off the Forest, which have been built for flood control, generation of hydroelectric power, and water rights. Dam and diversions may contribute to aquatic habitat alteration through removal of water, alteration of flow regime, blocking fish movement or migration, and can contribute to species isolation (Moyle et. al 1996). Water temperatures downstream of dams are affected by volume of flow and temperature of the upstream reservoir. The Kings River, Tule River and Kern River are subject to flow regulation under licenses from the Federal Energy Regulatory Commission (FERC). Rivers under FERC licenses have conditions for providing minimum instream flows (MIF).

Additionally, Federal Energy Regulatory Commission (FERC) relicensing results in a review of the ecosystem conditions and watershed function and in operational changes that benefit watershed function, such as more ecosystem-friendly flow patterns or more cold water being released. The hydropower licensing process provides an important opportunity to restore wetlands, rivers, and watersheds through intensive and long-term collaboration with project licensees, federal and state agencies and non-government organizations. Some opportunities for watershed restoration include restoring essential river flows where projects have diverted water for generations; protecting fish.

Approximately 23 percent of the Sequoia National Forest is in Wilderness (Chapter 15 WIKI). Remaining roadless area encompass about 29 percent of the forest (Chapter 15). On the remaining lands, culverts on road crossings can disrupt habitat connectivity by restricting upstream movement by species. Culverts may represent a total barrier to fish upstream movements, or force amphibians and reptiles to attempt road crossings that may subject them to mortality. Fish passage success is dependent on the swimming capability of the fish, life-stage of concern, stream discharge, and the relationship of fish movement with stream discharge. While surveys of culverts on Forest Service roads were done in conjunction with a preliminary assessment of passage problems; the percentage of the culverts that do not provide for upstream passage is in the process of being assessed.

Sediment/Water Quality


The Sierra Nevada Ecosystem Project (SNEP) identified both excessive sediment yield and water quality impacts as stressors of aquatic systems (Kattlemann 1996). 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 National Forest lands in the Sierra Nevada. Roads are a documented source of disturbance in managed watersheds (Trombulak and Frissell 2000; Switalski et. al 2004). Roads and cattle grazing represent sediment sources mentioned in SNEP (1996). In addition to sediment temperature, pH, dissolved oxygen are also considered factors that can degrade water quality in the State of California.

Sediment

Sediment studies have identified roads producing more sediment than other forest management practices (Kattelmann 1996, Robichaud et al 2010). Failure of inadequately designed and constructed culverts adds large amounts of sediment to streams. The most serious impacts of roads occur where roads are close to streams or wetlands. Stream crossings by ford, culvert, or bridge have direct effects on the channel and local sediment regime (Kattelmann 1996). Roads can also affect meadows and wetlands directly by encroachment and indirectly by altering surface and subsurface flow paths. Alteration of the hydrologic flow can indirectly affect meadow and wetland function, with the effects extending far beyond the area road itself. The effects can include erosion and/or lowering of the water table.

The potential for water to run down roads or trails is termed ‘diversion potential’. When this occurs, stream flow diversions can be a major cause of road-related erosion (Furniss et al 1997). When roads concentrate surface flow and deliver it to streams via surface flow paths, they are termed ‘hydrologically connected’ and they functionally increase the drainage density (Wemple et al. 1996). In a study of forest road segments on the Eldorado NF, found that 75 percent of the road segments surveyed lacked hydrologic connectivity (Coe 2006). A local study in the Kings River Experimental Watershed (KREW) area found that 13 percent of the road length in the study area had hydrologic connectivity (Korte 2010). Robichaud and others (2010) note that studies in the western U.S. have found between 23 and 75 percent hydrologic connectivity of roads. The Forest has surveyed at the landscape scale to identify sources of sediment from roads, and to identify hydrologic connectivity and potential barriers to aquatic organisms. The percent of roads with hydrologic connectivity and ample aquatic organism passage has not been estimated yet, and a report of the assessment has not been drafted yet. However, road inventories alone may not accurately predict the processes that affect road sediment production; road runoff may be the more important variable to measure (Surfleet et al. 2011).

The majority of the Forest includes cattle grazing under permits. Numerous effects on aquatic habitat and species have been attributed to prolonged use of riparian areas by cattle. Literature suggests potential effects from cattle grazing such as altering channel function, which reduces natural processes, habitat diversity and habitat complexity for aquatic or riparian animals (Clary and Webster 1989, EPA 1991,Meehan 1991, Belsky et. al. 1999). Many of the effects described in literature are noted as resulting from “heavy” or “overgrazing”. A comparative study of the effects of cattle grazing indicated that between 1990 and 1996 that stream conditions improved under all grazing pressures (Clary 1999). However, narrowing and deepening of the streams was inversely associated with grazing intensity (Clary 1999). Simulated grazing treatments showed a reduction in bank stability as the surface structure became progressively more deformed and broken with grazing (Clary and Kinney 2002)). Stream bank stability improved the most in ungrazed treatments, and embeddedness was higher in medium grazing pressure than light or no pressure. While willow cover improved with all treatments, the greatest increase occurred in the absence of grazing (Clary 1999). In a recent study of cattle exclusions, significant differences existed in the stream conditions between the exclusion area and grazed areas due to trampling of the banks(Herbst et al. 2012). Trampling alongside streams eroded and flattened banks; and increased stream temperatures (Herbst et al 2012).

Water quality

Stream flow in the Sierra Nevada is generated by seasonal rainfall and snow-melt About 50% of annual precipitation falls as snow at 1,700 m (5,600 ft.); below 1,500 m (4,900 ft.) stream flow is mostly associated with storms; while stream flow above 2,500 m (8,200 ft.) is primarily a product of spring snow-melt (Kattelmann 1996). Snow plays a dominant role in the overall hydrology of the Forest. Storage of frozen precipitation in winter as snow cover in higher elevations and its subsequent release during the spring snow-melt controls the seasonal distribution of flow (Kattelmann 1996) in the Kern River and to a lesser extent the other rivers draining the Greenhorns. Peak discharge occurred about 60 days later than peak snow accumulation; and snow-melt dominated the daily stream flow for about 30 days at the higher elevations (Hunsaker et al 2013a). Due to the El Nino Southern Oscillation and other decadal long oscillations in rainfall patterns in California, flow in Sierra Nevada rivers is highly variable in time. Annual volumes can be twenty times greater in very wet years than in very dry years (Kattelmann 1996).

The Forest manages its watersheds and water supply in cooperation with the Central Valley Regional Water Quality Control Board and Tulare Lake Basin Water Quality Control Plan (CVRWQCB 2004). These plans designate the beneficial uses to be protected, water quality objectives, and an implementation program for achieving objectives. Beneficial uses identified in the plans include: Municipal and Domestic Supply; Hydropower Generation; Water Contact Recreation; Non-contact Water Recreation; Rare, Threatened, or Endangered Species; Warm Freshwater Habitat; Cold Freshwater Habitat; Spawning, Reproduction, and/or Early Development; Freshwater Replenishment; and Wildlife.

Summer water temperature monitoring has been implemented as part of the re-licensing for hydroelectric projects. However, no baseline data from a range of elevations and streams exist for the Sequoia National Forest. At this time we cannot document the change in transitional zone between cold and warm-water fish habitat on major watersheds. In the Tule River rainbow trout are found at late August an elevation of 2900 ft. where water temperatures of 20.2 degrees centigrade (C) (AECOM 2012). Water temperature even at higher elevations can be impaired by changes in stream morphology. In the Golden Trout Wilderness temperature was higher in grazed streams when compared to non grazed streams (Herbst et al. 2012).

Several major sources of impairment face the Sierra Nevada stream and lakes. Lake Isabella, Hume Lake and Lake Success are all impaired water bodies (The 303(d) List of Impaired Water Bodies). Animal wastes from livestock directly impaired water quality through bacterial contamination and increasing nutrient levels (EPA 1991; Derlet et al. 2006; 2008; 2010). No significant differences in nutrients were observed when evaluating grazing effects on water quality in oak woodlands (Campbell and Allen-Diaz 1997). In a recent study algae considered to be indicators of high nutrient conditions were found in grazed areas, while in wild sites, algae indicated low nutrient conditions (Derlet et al. 2012). Where algae was thick (grazed sites) bacteria (E. coli) were present in high levels (Derlet et al. 2012). Eastern Sierra water standards for fecal coliform call for less than 20 Colony Forming Units (CFU) per 100 milliliters (ml) of stream water. Western Sierra standard is 200 CFU/100 ml. The levels seen in the recent study on grazing violated both these standards (Derlet et al. 2012).

Other pollutants that affect aquatic ecosystems were discussed in Pope and Long (2013). Pesticide residues from Central Valley agricultural areas have been found in samples of air, snow, surface water, lake sediments, amphibians, and fish across the Sierra Nevada (Cory et al. 1970, McConnell et al. 1998, Fellers et al. 2004, Hageman et al. 2006, Pope and Long 2013

‍Drivers and Stressors

(NOTE - This belongs in Chapter 3 under Drivers and Stressors)

Perturbations, changes in climate, and disturbances have occurred for millennia, and plant species and communities have evolved and adapted to them over time. Fire was used by native Americans to manage oaks in the lower elevations and in the mixed oak conifer woodlands Fire is a “keystone” ecosystem process in the bioregion and Sierra National Forest (McKelvey et al. 1996, van Wagtendonk and Fites-Kaufman 2006). Keystone means that it is of key importance to ecosystem composition, structure, and function. Fire shaped the ecosystems. Here, a brief discussion of fire as an ecological process and the implications of fire suppression are described. The patterns and history of fire on the Sequoia National Forest and bioregion are discussed in Chapter 3 of this assessment. A normal or reintroduced fire regime (Allen et al. 2002, Miller et al. 2009), topographic variability, and other natural processes perform important functions within the Sierra Nevada ecosystem. However, many of the normal ecosystem processes were interrupted by plantations, clear cuts, suppression of fire, and other past management actions. In addition, past logging of the large trees and recent introduced diseases meant the disappearance of important wildlife trees such as sugar pines. Increased frequency of fires, increased intensity and extended fire seasons are predicted to occur with climate change ( Westerling et al. 2006). Predicted warmer temperature and earlier snow melt, have implications for aquatic species as well as terrestrial plants and animals.

Fire

Fires may have become larger and more frequent in the Sierra Nevada in recent years (Miller et al, 2009). Large fires like the McNally Fire on the Forest have occurred in recent years throughout the Sierra Nevada (Miller et al. 2009). Hanson and Odion (in press, 2013), however, assessed those findings when it conducted the first comprehensive assessment of fire intensity since 1984 in the Sierra Nevada using 100% of available fire intensity data, and, using Mann-Kendall trend tests (a common approach for environmental time series data—one which has similar or greater statistical power than parametric analyses when using non-parametric data sets, such as fire data). Hanson and Odion found no increasing trend in terms of high-intensity fire proportion, area, mean patch size, or maximum patch size. Hanson and Odion checked for serial autocorrelation in the data, and found none, and used pre-1984 vegetation data (1977 Cal Veg) in order to include any conifer forest experiencing high-intensity fire in all time periods since 1984 (the accuracy of this data at the forest strata scale used in the analysis was 85-88%). Hanson and Odion also checked the results of Miller et al. (2009) and Miller and Safford (2012) for bias, due to the use of vegetation layers that post-date the fires being analyzed in those studies. Hanson and Odion found that there is a statistically significant bias in both studies (p = 0.025 and p = 0.021, respectively), the effect of which was to exclude relatively more conifer forest which could have experienced high-intensity fire in the earlier years of the time series, thus creating the false appearance of an increasing trend in fire severity. Miller et al. (2012) acknowledged the potential bias that can result from using a vegetation classification data set that post-dates the time series. In that study, conducted in the Klamath region of California, Miller et al. used a vegetation layer that preceded the time series, and found no trend of increasing fire severity. Miller et al. (2009) and Miller and Safford (2012) did not, however, follow this same approach. Hanson and Odion (in press, 2013) also found that the regional fire severity data set used by Miller et al. (2009) and Miller and Safford (2012) disproportionately excluded fires in the earlier years of the time series, relative to the standard national fire severity data set (www.mtbs.gov) used in other fire severity trend studies, resulting in an additional bias which created the inaccurate appearance of relatively less high-severity fire in the earlier years, and relatively more in more recent years. The results of Hanson and Odion are consistent with the other recent studies of fire severity trends in California’s forests that have used all available fire intensity data, including Collins et al. (2009) in a portion of Yosemite National Park, Schwind (2008) regarding all vegetation in California, Hanson et al. (2009) and Miller et al. (2012) regarding conifer forests in the Klamath and southern Cascades regions of California, and Dillon et al. (2011) regarding forests of the Pacific (south to the northernmost portion of California) and Northwest.

Fire, precipitation, and elevation are major influences on type, composition and juxtaposition of ecosystems across the Sequoia National Forest. Within the Southern Sierra Province, fire occurred frequently within the mixed-conifer forests. Since fire is a natural part of the Southern Sierra ecosystem, one of the most significant changes during the past century has been fire suppression management (Miller et al. 2009). The accumulation of live and dead fuels has increased to high levels in parts of the Forest, possibly greater than the historic range of variability .

One of the ways to limit scale disease outbreaks and fire is to restore the ecological integrity of the forests. Indications from historic photographs or written descriptions were that fewer larger trees were present prior to 1940. As temperatures warm and the hydrology changes, trees may need to be further apart so as to reduce competition for water and reduce the spread of diseases.

Giant sequoia (Sequoiadendron giganteum [Lindl) groves are part of the Sequoia National Monument. Giant sequoia regeneration can occur following prescribed fire and wildfire, both with and without harvest, if intensity is sufficient for creating openings in the canopy to increase sunlight and remove litter (Meyer and Safford 2011). As the length of fire season may extend due to the changing climate; reducing tree densities and clearing built up fuels could restore a fire resilient landscape. Reducing fire intensity through management actions will enable human communities and help restore ecological processes to the ecosystem. However, restoration to a more resilient condition may require repeated treatments over time. Resilience, however, requires reestablishing the ecological disturbances that forests and wildlife have evolved with. Wildlife evolved with fire, not with mechanical treatments, and therefore resilience is achieved through management that puts fire back on the landscape such as via prescribed fire and managed wildland fire. (see, e.g., Thompson et al. 2009. [The authors contrast ecological resilience, which pertains to the maintenance of the full complement of native biodiversity by maintaining active natural disturbance regimes, with engineering resilience, which pertains to the suppression of natural disturbance and the habitat structures and complex early-successional habitat created by such disturbance.]

Fire can be a key landscape driver contributing to ecological integrity and landscape sustainability, as well as the amount, juxtaposition and quality of wildlife habitats. However, the use of managed fire, fire suppression and exclusion, and post-fire management can all be stresses on wildlife and aquatic species. Possible effects or issues surrounding fire for these species are as follows:
  • Land managers are faced with balancing the challenges of maintaining fisher habitat and reducing the threat of uncharacteristic fire can and can take relatively simple steps to mitigate the effects of vegetation management projects on fisher habitat (Truex and Zielinski 2013). Fuels treatments, if not managed appropriately, can eliminate the structural complexity important to fisher and owls (Purcell et al. 2009).
  • Species such as fisher that depend on large trees for resting and forage, as well as high basal area of small trees (i.e., less than 20 inches dbh, Zielinski et al. 2006) can be influenced by mechanical thinning and prescribed fire (Truex and Zielinski 2013). Careful timing of fuel treatments and maintenance of habitat elements important to fisher can mitigate the negative effects of treatments (Truex and Zielinski 2013). Evaluating the effects of fuels management at the resting site, home range and landscape scales will be necessary to administer a treatment program that can restore resilience while also restoring and maintaining fisher habitat (Truex and Zielinski 2013).
  • Low to moderate severity fires, historically common within montane forests of the Sierra Nevada, California, maintain habitat characteristics essential for spotted owl site occupancy (Roberts et al. 2011).
  • Spotted owls occupied, both nested and foraged in high and mixed -severity burned areas (Bond et al. 2009, Lee et al. 2012). However post fire salvage logging may have an negative effect on owls (Lee et al. 2012).
  • Riparian plant species possess adaptations to fluvial disturbances that facilitate survival and reestablishment following fires, thus contributing to the rapid recovery of many streamside habitats (Dwire et al. ???). While riparian areas appear to burn as frequently as the upslope areas patchiness of fire effects occurs (Olson and Agee 2005).
  • With an active fire regime, conifers are excluded from meadows and soils too saturated for their survival. As conifers begin to encroach on a meadow, if they are not occasionally set back by fire, they transpire water out of the meadow, reducing the saturation of the soils, and facilitating further conifer encroachment (Meyer 2013, Natural Range of Variation paper for Meadow is a good reference for additional citation on encroachment in meadows (see pages 20-21 on structure and conifer abundance).
  • A large, high severity fire in a watershed could disrupt the flow regime and alter stream channel dynamics. Soil carbon and water storage; base flow; streamflow regime; peak flow; water quality (sediment, temperature, pH, ash slurry); and chemical characteristics can be affected by wildfire (Neary et al. 2005).
  • Removal of course woody material during fuels reduction activities reduces cover for amphibians and alters nutrient cycling in nearby streams (Bury 2004). Even low intensity prescribed fires can create or destroy snags and influence amphibians for several years (Bagne and Purcell 2009a); although suitable habitat can be maintained by patchy burning characteristic of prescribed fire.
  • Nesting birds may benefit long term by development of essential habitat components, such as oaks and large ponderosa pines which may depend on reintroducing fire; negative impacts of fire can be reduced by protecting preferred nesting snags and adjusting timing in response to breeding activities (Bagne and Purcell 2009b).
  • On the forest the distribution of Golden Trout and Kern River Rainbow Trout are two examples of isolated remnants of populations. Significant questions regarding the influence of fire on aquatic ecosystems, changing fire regimes, and the effects of fire-related management remain unresolved and contribute to the uncertainty (Rieman et al 2003).
  • The McNally Fire is a good example of detrimental effects of stand replacing fires on sediment production, stream sedimentation and loss of riparian vegetation. Frog eggs do not survive sedimentation, and many aquatic invertebrates do not tolerate increased runoff and sediment. Salamanders in the soil due to the hot dry summer are vulnerable to hot fire sweeping through their habitats.
  • However, 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).
  • The McNally Fire is a good example of the ecological benefits of the mosaics created by mixed-severity fire. For example, a study (Buchalski et al. 2013) of bats in the McNally Fire found that bat activity in burned areas was either equivalent or higher than in unburned stands of mixed-conifer forest for all six phonic groups studied. Of the six phonic groups, two groups showed differing response to fire severity with positive response to high-severity fire and neutral response to moderate-severity. The study noted that "the effects of mixed-severity burns appear to be particularly important for highly mobile wildlife, including bats, which are well suited to exploit a mosaic of forest patches at differing stages of succession." Another study in the McNally Fire, regarding spotted owls, found that for 5 of 7 owls, strongest selection for foraging areas was in high-severity burned forest (Bond et al. 2009).
  • Moreover, 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).
  • The Lion Fire burned into the Golden Trout Wilderness through the watersheds (see photo inset) of several of the pure strains of Little Kern Golden Trout. However, preliminary monitoring the year after the fire indicated that young of the year Little Kern Golden trout were present.
  • Restoring a lost process to the Forest ecosystems is important, managing wildfires and prescribed fires so the effects are patchy within a watershed and across the landscape is also important.
  • In the drier areas of the Breckenridge Piute and Scodie Mountains salamanders and fish are present in aquatic habitats. Protecting seeps from retardant in these dry area is important.
  • Amphibians like the slender salamanders were most susceptible to wildfire; and effects were greatest in forests where fire had been suppressed and in areas that burned with high severity (Hossack and Pilliod 2011). Species, like foothill yellow legged frogs, that breed in streams are also vulnerable to post-wildfire changes in habitat (Hossack and Pilliod 2011). Wildfire may also increase the risk of decline or extirpation for small, isolated, or stressed (e.g., from drought or disease) populations (Hossack and Pilliod 2011). Improved understanding of how these effects vary according to changes in fire frequency and severity are critical to form more effective conservation strategies for amphibians in the Sierra Nevada.
  • Fire is a major agent of spatial pattern formation in forests, as it creates a mosaic of burned and unburned patches. However, interaction between surface fires and forest pattern may be quite different from forest patterns observed after crown fires (Miller and Urban 1999).
  • Fuels treatments in California yellow pine and mixed conifer forests that include removal of surface and ladder fuels are highly effective management tools for reducing fire severity and canopy tree mortality (Safford et al. 2012). However, there is currently a severe deficit of mixed-severity fire, and its associated high-severity fire, on the landscape (see, e.g., Stephens et al 2007, Miller et al 2012, Odion and Hanson 2013). Consequently, there is a need for more, not less, such fire, in order to maintain ecosystem integrity
  • However removal of surface and ladder fuels are highly effective management tools for reducing fire severity and retention of canopy trees (Safford et al. 2012). However, there is currently a severe deficit of mixed-severity fire, and its associated high-severity fire, on the landscape and post-fire landscapes create high bio-diversity (when not salvage logged) and are essential habitat for species like the black-backed woodpecker (e.g., Burnett et al. 2012, Hanson and North 2008, Hutto 2008, Saab et al. 2009, Seavy et al. 2012, Siegel et al. 2010, 2011, 2012, 2013).
willow creek.jpg

Willow Creek was burned in the 2011 Lions Fire. This photograph illustrates that in 2012, willows sprouted in patches along the stream (above).

Climate Change
Climate change is a key landscape stressor affecting long-term ecological conditions. It is expected that air temperatures and precipitation patterns may change across the Forest over time. Most precipitation above 5500 feet falls in the form of snow from fall through spring. Change is expected to be reflected through an increase in daily maximum, minimums, and mean air temperatures, along with altered precipitation patterns. Modeling specific to California predicted that the recent increased fire activity would persist and intensify due to increased growth of fuels under higher CO2 combined with low fuel moistures from longer and warmer summer temperatures, and possibly increased thundercell activity (Meyer and Safford 2010).

The following are some key points pertaining to climate change ecosystem stressors:
  • Climate change can have several possible effects on aquatic habitats. Warmer temperatures will make frogs more vulnerable to disease. The slender salamanders as a whole rely on moist habitats which could dry and become unsuitable with warming. Warmer summer temperatures may lead to other changes in the fire regime which in turn will have effects on aquatic species if uncontrolled. Changes in management of higher elevation refugia may be needed to sustain threatened or endangered species.
  • As temperatures rise and wildfires become more common, conditions for cold water salmon will alter (Isaak et al. 2010). The Sequoia National Forest supports several endemic strains of native trout (Figure 1.7). The Kern River Valley already burns in several places every year. When fires are followed with intense rainfall as happened in Erskine Creek after the Piute Fire; swift and destructive post-fire debris flows can occur, a significant concern in the southern Sierra Nevada, which experience high-intensity rain storms (DeGraff et al. 2011).
  • Snowpack currently provides 20 percent of California’s total runoff and 35 percent of its usable surface water. Climate modeling predicts a loss of snowpack for the Sierra Nevada as air temperatures rise (Hunsaker et al. 2012b). On the Kern Plateau snow melt appears to be occurring earlier (Peterson et al. 2008). The projected impacts of warming temperatures on trout and salmon species are concern because of their vulnerability to increased stream temperatures (Moyle et al. 2011). Hydrologic changes are expected with a quicker snow melt (Null et al. 2010). Warming temperatures can drive cold water fishes into higher elevations.
  • The small population of fishers in the southern Sierra does not appear to be decreasing. However, given the habitat degradation that has occurred in forests of the region,continued monitoring is necessary to determine whether fisher occupancy increases as land managers implement measures to restore conditions favorable to fishers (Zielinski et al. 2013)
  • Climate change may facilitate expansion of non-native invasive species. Invasive species such as brown or hatchery rainbow trout have altered aquatic systems and biodiversity of natives across the Forest.
  • Climate change has been suggested as a contributing agent in the decline of amphibians. Reaser and Blaustein (in Lannoo 2005) summarize that site specific review of amphibian declines indicate possible global changes, and that regional warming, increasing ultraviolet radiation, and diseases are a potential result of global change. California anticipates warmer temperatures, accompanied by altered patterns of precipitation and runoff related to climate change (DWR 2007). Annual runoff in the San Joaquin River basin has declined by 19% over the past 100 years, and projected precipitation alterations could reduce the snow pack by 25% by the year 2050. Spring runoff is appearing to occur earlier than 10 years ago on the Kern River (Hunsaker et al. 2013)
  • Thompson (2005) suggests that direct solar radiation has a strong effect on water temperature, thus managing to maintain or improve shade is important to reduce heat flux. The projections at Grant Grove in Kings Canyon National Park project no change in annual precipitation (Meyer and Safford 2010). Spring runoff is occurring earlier in the year (Hunsaker et al. 2013) and fraction of runoff occurring in the spring is decreasing. With less snowfall expected to result from elevated air temperatures associated with climate change, it is likely that less water would be available during the late summer and that the water would be warmer than current conditions. A similar effect to shallow lakes would reduce the suitability of habitat for mountain yellow-legged frog, which could result in localized extirpations in a species with a high degree of site fidelity.
  • Lind (2008) notes that amphibian and reptile populations respond to changes and variability in air or water temperature, precipitation, and the hydro-period of their environments. Over the short-term (annually), these factors can influence reproductive success rates and survival to metamorphosis. Over the long term, the frequency and duration of extreme temperature and precipitation events can influence the persistence of populations and structure of meta-populations on the landscape. The net effect of less water and higher temperatures would be a reduction in the quantity and quality of aquatic/riparian habitat. Reptiles and amphibians would likely be concentrated at sites where water is available, increasing their susceptibility to predators at these sites. The changing conditions of habitat would provide conditions more favorable for invasion by species currently occurring at lower elevation sites, and possibly an increase in non-native species. It is probable that the range of bullfrog would continue to expand across the Forest without active management to extirpate.

‍Invasive Species

The influx of non-native species of animals and plants since the first Europeans arrived in California has changed the ecosystems of the Sierra Nevada and this continues to be a major and increasingly important stressor on the Sequoia NF. Non - native grasses, hatchery or nonnative fish, bullfrogs or other introduced frogs or toads can all influence native species.

‍Management and Land Use

The following are some key points pertaining to current management and land use:
  • Vegetation and ecosystem management actions can affect the quality and juxtaposition of habitats used by hunted and non-hunted wildlife populations, particularly in how conditions diverge from the natural range of variability.
  • Illegal marijuana growing operations and the poisons they use can have detrimental impacts on species such as mice, rats and squirrels, which in-turn can also detrimentally influence the well being of hunted and non-hunted wildlife populations, as well as potentially negative affects to humans which consume those species (Gabriel et al. 2012). In addition these poisons can get into the water supply and affect aquatic species. Thompson et al 2013 recently found that in regard to fishers, likelihood of exposure was related to the presence of marijuana cultivation sites, and female fisher survival was influenced by the number of cultivation sites within its home range.
  • Hunting regulations and hunter harvests affect wildlife populations, as well as prey species used by some of those populations.
  • Existing conditions of aquatic/riparian habitat have been influenced by a variety of drivers and stressors, most relating to human disturbance since 1850. Among the findings within the Sierra Nevada Ecosystem Project (SNEP 1996) was that the aquatic/riparian systems were the most altered and impaired habitats of the Sierra Nevada. This finding was based on effects to stream flow (through dams and diversions altering stream-flow patterns and water temperatures); effects to riparian areas damaged by placer mining and grazing; excessive sediment yield into streams; water-quality impacts; introduced aquatic species; amphibian species declines; decline in or loss of native salmonids; aquatic invertebrates local degradation of habitat; and due to food chain relationships, impacts to invertebrates have significant cascading effects on other animals.
  • One class of small but important habitats for many native flora and fauna are the fens. Many peat forming fens, especially in the Sierra and Sequoia National Forests showed evidence of major impacts from grazing. Removal of biomass for peat, and intensive use, with repeated hoof punching can lead to floristic changes. In particular, the loss of clonal rhizomatous sedges and other peat forming species changes the fens. These species are then replaced by non-peat forming, short lived species (with tap roots) such as Phalacroseris bolanderi, Mimulus primuloides, Hypericum annagalloides and others, which are tolerant of trampling. Unfortunately it is likely that even relatively light grazing will maintain degraded sites in a degraded condition for many decades and are in need of restoration (Cooper and Wolf 2006).
  • Lowered water quality from pollutants from the air or due to animals in the water can influence amphibians and fish. Changes in water quality and algae (a food source for tadpoles) were seen with grazing (Derlet et al. 2012).
  • Grazing can influence food-web dynamics in streams. Benthic invertebrate richness metrics were significantly higher in the un-grazed reaches when compared to grazed reaches where the percentage of tolerant taxa increased (Herbst et al. 2012). Golden trout density and biomass were significantly higher in the un-grazed than the grazed streams areas (Knapp and Matthews 1996).
  • Cattle grazing permits are administered under U.S. Forest Service, which include compliance with standards and guidelines from the Sequoia National Forest Land and Resources Management Plan (USDA 1988). However, a recent study indicated that few records were kept for the number of units of cattle in an allotment and monitoring reports of condition after cattle were taken to lower elevations (Herbst et al. 2012). While grazing permits are subject to project level analysis where identified negative effects can be identified, mitigation is difficult in the Wilderness areas. If the monitoring of the effects on recreation and streams is not compiled annually across the landscape of the Forest, the need for mitigation may not be evident to decision makers.
  • Thistles and other invasive weeds are dispersed in cattle or livestock feed
  • Domestic animals can spread diseases to native species.
  • Snowmobiles – which are permitted to travel off designated routes -- put increased stress on wildlife, including ungulates and subnivean species. Snowmobile emissions also contribute to acid pulse during spring runoff which impacts aquatic species. [See, e.g. Ingersoll, G.P., 1998. Effects of Snowmobile Use on Snowpack Chemistry in Yellowstone National Park. J. Ruzycki and J. Lutch, “Impacts of Two-Stroke Engines on Aquatic Resources” 1999 (available at http://beringiasouth.org/impacts-of-two-stroke-engines-on-aquatic-resources.) Jarvinen, J.A., and W. D. Schmid. Snowmobile Use and Winter Mortality of Small Mammals. Pp. 131-141 in M. Chubb (ed.), Proc. of the Snowmobile and Off-Road Vehicle Research Symposium. Michigan State Univ. Tech. Rep. 8, 1971. Severinghaus, C.W. and Tullar, B.F. 1978. Wintering Deer versus OSVs. New York State Department of Environmental Conservation]
  • Snowmobiles may be significant contributors to aquatic and terrestrial pollution in off-road areas. High-speed snowmobile free-play can damage high alpine slopes and meadows. Acid pulse during spring runoff, created by motorized use such as snowmobiles, can harm aquatic species. [Ingersoll, G.P., 1998. Effects of Snowmobile Use on Snowpack Chemistry in Yellowstone National Park. J. Ruzycki and J. Lutch, “Impacts of Two-Stroke Engines on Aquatic Resources” 1999 (available at http://beringiasouth.org/impacts-of-two-stroke-engines-on-aquatic-resources) E. Gage and D.J. Cooper, “Winter Recreation Impacts to Wetlands: A Technical Review”, Mar 2009 (Submitted to Arapaho-Roosevelt National Forests). Shaver, C., Morse, D., and O’Leary, D., 1998. Air Quality In the National Parks. U.S. Department of the Interior, National Park Service, Air Quality Division. Report prepared by Energy and Resource Consultants, Inc., NPS Contract No. CX-0001-4-0054]

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Also, the raw data in van Mantgem et al. (2009) (obtained directly from the authors) do not indicate a reduction in large trees (e.g., those 60-90, or >90 cm dbh) in YPMC over time in Sierra Nevada forests, and the largest size class category presented in van Mantgem et al. (2009) was >40 cm dbh (i.e., over 16 inches dbh). The van Mantgem et al. (2009) data are consistent with old stands self-thinning their understories in the long absence of significant fire.
[snapshot taken 8/2/2013 @0600]