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The indicator measures the proportion of land cover dominated by shrub vegetation in the Tahoe Region. Shrub vegetation represents an early successional stage of forest vegetation. The relative proportion of shrub type is important as it provides habitat for a wide diversity of wildlife species and complements vegetation diversity in the Region. The primary factors responsible for shrub vegetation are light exposure, soil type and moisture content, and extent and frequency of wildfire and other natural disturbances. TRPA has adopted policies and ordinances designed to promote a diversity of native vegetation communities in the Region. Forest fuels reduction projects affiliated with the Environmental Improvement Program tend to target the removal of understory shrubs to meet fuels reduction objectives and to prevent an overabundance of shrub-dominated vegetation type.
Estimated percent of land area dominated by “shrub” vegetation in the Lake Tahoe Region relative to the TRPA-adopted target of 25 percent. The effects of the 2021 Caldor Fire and the recent mortality event in the yellow pine and red fir communities along the west shore, are anticipated to significantly impact future abundance distributions. These disturbances are likely to reshape the landscape and may facilitate a transition to shrub vegetation types in those areas, necessitating a reevaluation of baseline data in future assessments. Sources: (USDA 2017)
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.
- Status
- Considerably Better Than Target
- Trend
- Little or No Change
- Confidence
- Moderate
- Keeping shrub vegetation to a maximum of 25 percent is beneficial for wildlife when mixed with other vegetation types like forests and meadows.
- During the 2021 Caldor Fire, 156 acres of shrub vegetation experienced moderate to high severity burns.
- Shrub plant communities make up 4.4 percent of the total undisturbed acreage in the Region.
Vegetation Distribution in the Tahoe Region - 2010 Ecobject.
- This indicator measures the proportion of land cover dominated by shrub vegetation in the Tahoe Region. Shrub vegetation represents an early successional stage of forest vegetation. The relative proportion of shrub type is important because it provides habitat for a wide diversity of wildlife species (Airola and Barrett, 1985; Coppeto et al., 2006; USDA, 2011) and complements vegetation diversity in the Region (Murphy and Knopp, 2010). The relative abundance of shrub vegetation type in the Tahoe Region is intended not to exceed 25 percent since it is valued as habitat by an array of wildlife species when interspersed between other vegetation types, such as forests and meadows. Shrub vegetation is comprised of sagebrush, whitethorn, manzanita, bitterbrush, huckleberry oak, and chinquapin.
- Several factors can influence the extent of shrub vegetation in the Tahoe Region. The primary factors responsible for shrub vegetation are light exposure, soil type and moisture content, and extent and frequency of wildfire and other natural disturbances. Canopy-replacing wildfire create openings conducive to the establishment of shrub vegetation. Shrub vegetation is also known to occupy the understory of most mixed conifer forest landscapes in the Region.
EIP Action Priorities
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Reduce Hazardous Fuels
The Tahoe Fire and Fuels Team is working to thin overstocked forests to reduce hazardous fuels and improve ecosystem resilience. As of 2023, partners have completed 90,000 acres of forest treatments.
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- Considerably better than target. Shrub communities cover 7,538 acres, approximately 4 percent of the total undisturbed vegetation in the Region. This is approximately 18 percent of the maximum allowable shrub coverage (42,859 acres), and is therefore considerably better than target. The management target for this threshold standard sets an objective to achieve and maintain less than 42,859 acres (or less than 25 percent of the land area) of this vegetation type.
- Little or no change. Minimal change has been observed during this evaluation period. However, two significant disturbance events are anticipated to affect the relative abundance of shrub vegetation types in future assessments. In 2021, the Caldor Fire impacted 5,901 acres of vegetation communities, including 156 acres of existing shrub types, at moderate to high severity. This area is likely to transition to shrub-type vegetation. Additionally, the west shore of the Lake Tahoe Basin experienced substantial mortality in the yellow pine and red fir communities, potentially creating more openings and opportunities for shrub types to thrive.
- High. Forest managers employ the best available technology and field reconnaissance to map and classify vegetation types across the Lake Tahoe Region approximately every five years. The U.S. Forest Service’s vegetation mapping procedures adhere to regional and national standards (FGDC, 1997; Warbington et al., 2011). Since vegetation communities are broadly defined and cover larger spatial areas than individual habitat types, changes in the status and trends of the vegetation community richness indicator may not be readily apparent over the relatively short timeframes for which the indicator is remapped and reassessed.
- Moderate. There is moderate to high confidence that, in the absence of disturbance events (e.g., fires, disease, clearing), the spatial extent of vegetation communities at the regional scale would not change significantly over a four-year period. However, given the recent disturbance events, we anticipate that the future spatial dynamics of these communities may be affected, potentially leading to more notable changes in their distribution.
- Moderate. If one confidence rating is high and the other is moderate, the overall confidence rating is the lower confidence rating.
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April 2017. EcObject Vegetation Map v2.1 Product Guide. USDA Forest Service, R5 Remote Sensing Lab.