Indicator
Vegetation Community Richness
2023 Evaluation
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Vegetation community richness measures the number and persistence of major native vegetation communities (associations) throughout the Tahoe Region. It is not a measure of plant species richness but it can be used to indicate whether a major vegetation community has been lost in the Region. Climate, elevation, soils, aspect, geomorphology, interspecies competition, and wildlife are natural influences on pattern and expression of vegetation communities in the Tahoe Region. Wildfires, fire suppression activities, and unmanaged recreation also influence the distribution and structure of vegetation communities. Policies and ordinances for the conservation of Tahoe’s native vegetation communities have been adopted in the TRPA Regional Plan and are implemented through the permitting process. In addition, the Environmental Improvement Program has a forest restoration program.

 

Angora Resized.jpg
Status

Estimated proportion of land covered by different TRPA vegetation communities (associations) in the Lake Tahoe Region (USDA, 2010).

Data provided by the USDA Forest Service, R5 Remote Sensing Lab. Access detailed datasets on Tahoe Open Data, including, vegetation type summary, vegetation spatial data, and detailed vegetation attributes.

2023 Evaluation
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Status
At or Somewhat Better Than Target
Trend
Little or No Change
Confidence
Moderate
Applicable Standard
VP3: Maintain the existing species richness of the Region by providing for the perpetuation of the following plant associations: • Yellow pine forest: Jeffrey pine, white fir, incense cedar, sugar pine • Red fir forest: red fir, Jeffrey pine, lodgepole pine, western white pine, mountain hemlock, western juniper • Subalpine forest: whitebark pine, mountain hemlock, mountain mahogany • Shrub association: greenleaf and pinemat manzanita, tobacco brush, Sierra chinquapin, huckleberry oak, mountain whitethorn • Sagebrush scrub vegetation: Region sagebrush, bitterbrush, Douglas chaenactis • Deciduous riparian: quaking aspen, mountain alder, black cottonwood, willow • Meadow associations (wet and dry meadow): mountain squirrel tail, alpine gentian, whorled penstemon, asters, fescues, mountain brome, corn lilies, mountain bentgrass, hairgrass, marsh marigold, elephant heads, tinker's penney, mountain timothy, sedges, rushes, buttercups • Wetland associations (marsh vegetation): pond lilies, buckbean, mare's tail, pondweed, common bladderwort, bottle sedge, common spikerush • Cushion plant association (alpine scrub): alpine phlox, dwarf ragwort, draba
Key Points
  • 52 species and species families are listed in the threshold standard under nine major native vegetation communities. Using more than 30,000 observations reported on the https://www.inaturalist.org/ platform all were identified as still present in the Tahoe Region.
  • The most significant disturbance to vegetation communities in the Tahoe Basin during the reporting period (2020 to 2023) was the Caldor Fire, which burned 10,000 acres within the Tahoe Basin, with 5,900 acres experiencing moderate to high severity.
  • Additionally, there was unprecedented tree mortality in the Region, particularly affecting yellow pine forest types and specifically impacting white fir trees along the west shore.
Evaluation Map
Description

Distribuiton of dominant vegetation types in the Tahoe Region.

About the Threshold
This indicator measures the number and persistence of major native vegetation communities (associations) throughout the Lake Tahoe Region. It is not a measure of plant species richness. This measure can be used to indicate whether a major vegetation community has been lost in the Region.
Climate, elevation, soils, aspect, geomorphology, interspecies competition, and wildlife are natural influences on pattern and expression of vegetation communities in the Lake Tahoe Region. Wildfires and fire suppression also influence the distribution and structure of vegetation communities. For example, the montane chaparral vegetation type has been decreasing in areal extent by about 10 percent per decade due to fire suppression (Nagel and Taylor, A.H., 2005). However, the Gondola (2002) and Angora fires (2007) created hundreds of acres of early successional vegetation. More recently the Caldor Fire (2021) burned 10,000 acres on the south side of the Region. Forest treatments designed to remove biomass and reduce the risk of high-severity fires can also influence vegetation communities. Treated areas in the yellow pine forest have been shown to support higher plant species richness than in neighboring untreated forest (Safford et al., 2012b); although this indicator category is not a direct measure of plant species richness, fostering intra-community species richness can potentially lead to future vegetation community richness. Trampling associated with unmanaged recreation can degrade rare high elevation plant communities, such as the cushion plant community.
Delivering and Measuring Success

EIP Action Priorities

Example EIP Projects

Monitoring Programs

  • iNaturalist

    iNaturalist is global biodiversity citizen science platform with more than 3 million reporters and 200 million observations.

Rationale Details
At or Somewhat Better Than Target. Each iNaturalist record, referred to as an ‘observation’, is typically identified and verified through a combination of user input, including from both amateur naturalists and experts, and suggestions offered by iNaturalist’s Computer Vision, a machine learning/AI tool.
Little or No Change. The threshold standard has been found to be in attainment in each of the prior threshold evaluations in which is was evaluated. There is no reason to believe that any of the communities listed is no longer present in the Region.
Confidence Details
Moderate. The threshold standard contains references to both species and species families. For family level, any observation of the family was considered a positive indicator that the family was present in the region.
Moderate.
Moderate.
Additional Figures and Resources

No photos available.

No documents available.

References

April 2017. EcObject Vegetation Map v2.1 Product Guide. USDA Forest Service, R5 Remote Sensing Lab.