Summary Sketch

Chapter 1: Ecological Integrity of Ecosystems

What are the resource conditions at the bio-regional level?

Aquatic Ecosystems

  • Rivers, streams, lakes, ponds, and springs make up diverse aquatic ecosystems across a wide variety of landscapes.
  • Conditions included here are water quality, biodiversity, and hydrology, and they vary widely by location and history.

Terrestrial Ecosystems

  • Forests, chaparral, grasslands, desert scrub, and alpine communities occur.
  • Geographical differences are related to differences in precipitation.
  • Conditions selected include: California habitat types; connectivity of forest carnivore habitat; vegetation heterogeneity; habitat elements; and fire restoration.
  • Vegetation is now more uniform and is younger.
  • High severity fires have created large patches of un-forested lands and fragmented landscapes.

Riparian Ecosystems

  • Vegetation, soils, and hydrology are important in every riparian ecosystem. These vary by location in landscape and types of aquatic and terrestrial ecosystems.
  • There are varying amounts of erosion and shifts in native plant communities.

Do these conditions across different areas of the bio-region? How?

  • The southern Sierra Nevada contains some of the least developed portions of the range, including national parks.
  • Important species limited to this area are the Giant Sequoia groves, Pacific fisher, and long-lived bristlecone pine and other subalpine conifers.
  • The lower elevation northern sub-region is more developed, with logging, ranching, and mining activities. Water quality is an issue in some of these areas.

What are the issues and problem areas at the bio-regional scale?

Aquatic Ecosystems

  • Fragmentation and climate change are the main issues at the bio-regional scale.
  • A high number of native fish species are of concern.
  • Unnaturally high severity fires cause fragmentation.
  • Water development is extensive in the bio-region.
  • Exotic, invasive species are degrading habitat in some areas.

Terrestrial Ecosystems

  • Fire suppression continues to influence landscapes.
  • Vegetation is more uniform than it was in the past, but overall it is denser with smaller trees or more decadent shrubs.
  • Important habitat elements of large trees and snags are at lower levels than in the past, and tend to be scattered or limited across the landscape.
  • Connectivity for mid and late-seral stage species is disrupted by large, more uniformly severe wildfires, particularly in montane pine and mixed conifer forests.
  • The Pacific fisher is limited to the southern Sierra Nevada, compared to historic records where it was throughout the range.
  • While the California spotted owl is well distributed, we have observed gradual but steady declines over the past 20 years.
  • Invasive species including barred owl, scotch broom, and cheat grass disrupt native communities.

Riparian Ecosystems

  • The issues experienced in riparian areas are a combination of aquatic and terrestrial ecosystems.
  • Fragmentation occurs from uncharacteristically severe wildfire, water development and flow, and fire suppression.
  • Denser conifer forests suppress riparian hardwoods.

Are there any specific issues and problem areas at each of the forest levels?

  1. The unique Sierran species, Giant Sequoia, Pacific fisher, and bristlecone pine, require specific management.
  2. Managed fire in upper elevations has restored fire to large landscapes. The challenge is to maintain and expand these areas.