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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 TRPA adopted numeric target (25%). Recent changes in the percent cover of Shrub can be attributed to the 2007 Angora fire, as well as different interpretations of the baseline amount of “undisturbed” vegetation and changing mapping techniques/resolution, not necessarily actual changes in vegetation type. Sources: (USDA 2009)
- Status
- Considerably Better Than Target
- Trend
- Little or No Change
- Confidence
- Low
- Maintaining no more than 25 percent shrub vegetation type is valued as wildlife species habitat when interspersed with other vegetation types, such as forests and meadows.
- Shrub plant community acreage is 14 percent of total undisturbed acreage in the Region, considerably better than target.
- Changes in the percent cover of shrub vegetation type from 2007 to 2011 are a result of the 2007 Angora fire as well as different interpretations of the baseline amount of “undisturbed” vegetation and changing mapping techniques/resolution, not necessarily actual changes in vegetation type.
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
-
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 2020 partners have completed 87,000 acres of forest treatments.
- Considerably better than target. Shrub communities cover 26,945 acres, approximately 14 percent of the total undisturbed vegetation in the Region. This is approximately 54 percent of the maximum allowable shrub coverage (48,495 acres), and is therefore considerably better than target. The management target for this threshold standard sets an objective to achieve and maintain less than 48,495 acres (or less than 25 percent of the land area) of this vegetation type.
- Little to no change. One major disturbance events (e.g. fires, disease, clearing) that would have altered the extent of vegetative communities in the Region occurred in 2016 with the 176 acre Emerald Fire. New LIDAR has not been acquired and analyzed to take this into account.
- Moderate. The USDA Forest Service Remote Sensing Lab (2009) with regard to the most recent vegetation type map, there is 88 percent confidence that the mapped data accurately represents the distribution and extent of this vegetation types (shrub) on the landscape. Therefore, a confidence of moderate was assigned to status.
- Moderate. There is moderate to high confidence that in the absence of disturbance events (e.g. fires, disease, clearing) the spatial extent of the vegetation communities at the regional scale does not change considerably over a four-year period.
- Moderate.
No photos available.
No documents available.
April 2017. EcObject Vegetation Map v2.1 Product Guide. USDA Forest Service, R5 Remote Sensing Lab.