tahoemonitoring.org

  • Increase font size
  • Default font size
  • Decrease font size
Home Land Upland Habitat and Vegetation

Relative Abundance of Meadows and Wetland Vegetation Types

Status and Trend

Interpretation and Commentary

Relative Abundance of Meadows and
Wetland Vegetation Types


Click to interpret this icon

Status: Somewhat Worse Than Target
Trend: Unknown
Confidence: Moderate

  • Relevance - This indicator measures the proportion of land cover dominated by meadow (wet and dry variants) and wetland vegetation in the Tahoe Basin. The relative proportion of meadows and wetlands is important because the areas provide for a number of ecosystem services including flood attenuation, wildlife habitat diversity, ground water recharge, water filtration, and aesthetic and recreation values. According to USDA (2000), about 75% of the freshwater marshes and 50% of the meadows have been disturbed or developed since 1860. This indicator does not measure the relative condition of meadows and wetlands or their ability to support various ecosystem services or attributes.
  • Adopted Standards  - (Relative Abundance) Of the total amount of undisturbed vegetation in the Tahoe Basin - Maintain at least 4% meadow and wetland vegetation.
  • Indicator - Percent (%) of the landscape dominated by meadow and wetland vegetation.
  • Status – The most recent data (USDA 2009c)indicates that there is about 7,385 acres of the meadow and wetland vegetation types in the Region. The management target set an objective to achieve and maintain at least 7,956 acres (or 4% of the land area) of these vegetation types. Based on this target, the region is at about 93% of the management target or about 7% below the management target. Consequently, a determination of “somewhat worse than target” was assigned to this indicator.
  • Trend – The trend determination was “unknown” due to differences in mapping approach and resolution across years.

Click here for more information...

  • Confidence 
    • Status - According to an accuracy assessment conducted by the U.S. Forest Service Remote Sensing Lab (2009) on the most recent vegetation type map, there is 100% confidence that the mapped data accurately represents the distribution and extent of these vegetation types (herbaceous) on the landscape. Therefore a confidence of “high” was assigned to status.
    • Trends - Due to differences in mapping resolution and evaluation approach over time, there was “low” confidence assigned to trend.
    • Overall Confidence - Confidence assigned to status was ‘high,” and to trend “low,” therefore, according to rules established for this report, overall confidence was assigned a “moderate” determination.
  • Human and Environmental Drivers - Several factors can influence the extent of meadow vegetation in the Tahoe Basin. The primary factors responsible for meadow and wetland vegetation are the geomorphic setting and the seasonal or permanent presence of surface groundwater, subsurface groundwater, and/or saturated soil(Potter 2005; Mitsch et al. 2009). A regular fire-return frequency in the Region historically contributed to the maintenance of meadow vegetation by eliminating encroaching conifer trees (USDA 2000). Historical grazing and Comstock era land uses changed how water moves through meadows and wetlands, resulting in dryer soils not capable of supporting meadow and wetland vegetation (USDA 2000). Urbanization has similarly altered the movement of water through meadow and wetland systems through impoundments, water rerouting, and the creation of impervious surface such as paved roads and building footprints (USDA 2000). Groundwater extraction for consumptive use may also influence the vigor of meadow and wetland vegetation in localized areas.
  • Monitoring Approach – Every five years, the Tahoe vegetation map is updated with new satellite data (if available) and/or modeled and calibrated using field-based Forest Inventory and Analysis (FIA) data to assess the extent of different vegetation types and associated forest structure characteristics for the Basin (USDA 2009c; Warbington et al. [no date]). For this evaluation, vegetation types associated with meadows and wetlands (CWHR type “WTM” [wet meadow] and “PGS” [Perennial Grassland]) were queried and enumerated from the most recently available vegetation map (U.S. Forest Service - Remote Sensing Lab Pacific Southwest Region: TMU_Strata_07 [published 2009]).
  • Monitoring Partners – U.S. Forest Service, US Geological Survey and Tahoe Regional Planning Agency

Links

 
click map for larger image

Map

Distribution and extent of the meadow and wetland vegetation types (red areas in figure) in the Lake Tahoe Basin (USDA 2009c).

 

Trend Charts

Chart data not available at this time.
Estimated percent of land area occupied by meadow and wetland vegetation in the Lake Tahoe Basin relative to TRPA adopted numeric target (red line). Sources: TRPA 2001; TRPA 2007c; USDA 2009c.

Additional Info

References

  1.  
  2.  
  3.  

Additional Information

  1.  
  2.  
  3. Conceptual Model:
  4. Monitoring Plan:
Last Updated on Tuesday, 13 November 2012 11:33