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The indicator measures the relative proportion of land covered by riparian hardwoods species which include alder, aspen, willow, cottonwood, and dogwood and are associated with moist soils adjacent to streams, springs, wetlands, and small lakes. The relative proportion of the riparian hardwoods is important as this vegetation type enhances vegetation richness in the Region, provides habitat for a relatively high diversity of wildlife species (including sensitive species) and is resilient to natural disturbances such as flooding and fire. TRPA has adopted several policies and ordinances designed to promote the conservation and protection of existing deciduous vegetation types and Environmental Improvement Program partners have implemented numerous deciduous riparian restoration and enhancement projects, restoring or enhancing aspen habitat.
Estimated percent of land area occupied by deciduous riparian vegetation in the Lake Tahoe Region relative to TRPA adopted numeric target (blue line). Changes in the percent cover are a result of different interpretations of the baseline amount of undisturbed vegetation and changing mapping techniques/resolution, not necessarily actual changes in vegetation type. Sources: ((TRPA, 2007, 2001; USDA, 2009)
- Status
- Considerably Worse Than Target
- Trend
- Little or No Change
- Confidence
- Low
- At 1.4 percent, deciduous riparian vegetation cover is far below the four percent target.
- Projects implemented through the Environmental Improvement Program have been effective at restoring riparian vegetation acreage (especially for aspen, where shade tolerant white fir were removed).
Vegetation Distribution in the Tahoe Region - 2010 Ecobject.
- This indicator measures the relative proportion of land covered by riparian hardwoods (known as deciduous riparian vegetation) in the Tahoe Region. This vegetation grouping is commonly associated with moist soils adjacent to streams, springs, wetlands and small lakes (Potter, 2005). Species considered to be riparian hardwood include alder, aspen, willow, cottonwood, and dogwood. The relative proportion of riparian hardwoods is important because this vegetation type enhances vegetation richness in the Region, provides habitat for a relatively high diversity of wildlife species (including sensitive species) and is rare in the Lake Tahoe Region (Manley and Schlesinger, 2001; Murphy and Knopp, 2010). Riparian hardwoods are also resilient to natural disturbance such as flooding and fire (Sheppard et al., 2006). This indicator does not measure the condition or vigor of riparian hardwoods.
- Moist soils, direct sunlight and natural disturbance influence the abundance and distribution of riparian hardwoods. Fire suppression has allowed encroachment of shade-tolerant white fir into areas previously dominated by riparian hardwood species.
EIP Indicators
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Acres of Habitat Restored or Enhanced
Since 2007, EIP partners have restored or enhanced over 1,000 acres of aspen habitat.
- Considerably worse than target. In the most recent data period available (2009), there was a total of 2,809 acres of deciduous riparian vegetation out of the total 193,979 undisturbed acres, for a total of 1.4 percent. This is 36 percent of the 7,759-acre target, and is therefore considerably worse than target.
- Little to no change. No major disturbance events (e.g. fires, disease, clearing) that would have significantly altered the extent of riparian vegetative communities in the Region has recently occurred.
- Low. Confidence in the status in 2011 was assessed as low, because no accuracy assessment was available for the map of riparian hardwood vegetation. In addition, a recently released map of the SEZ in the Region estimated that the forested SEZ class (which includes deciduous riparian) is the most widely distributed SEZ type in the Region (accounting for approximately 50 percent of the Region’s SEZ) and covering 14,578 acres (6.4 percent of the Region) (Roby et al., 2015).
- 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.
- Low. Overall confidence takes the lower of the two confidences determinations.
No photos available.
No documents available.
April 2017. EcObject Vegetation Map v2.1 Product Guide. USDA Forest Service, R5 Remote Sensing Lab.