tahoemonitoring.org

  • Increase font size
  • Default font size
  • Decrease font size
Home Land Upland Species and Communities

Cup Lake Draba (Draba asterophora var. macrocarpa)

Status and Trend

Interpretation and Commentary

CUP LAKE DRABA


Click to interpret this icon

Status: Considerably Better Than Target
Trend: Little or No Change
Confidence: Moderate

 

  • Relevance - Cup Lake draba (Draba asterophora var. macrocarpa) is a small alpine perennial plant in the Brassicaceae (Mustard) family. The species has small yellow flowers and is characterized by a cushion growth form where all the foliage grows close to the ground in a short mound or mat (Baad 1979). Cup Lake draba is only known to occur at Cup Lake, which is outside of the Basin, and within the Basin on a ridge between Saucer Lake and Ralston Peak (Figure 1).More than half of the known plants occur in the Basin population; thus this population is critical to the viability of the entire species.Cup Lake draba has special designations by TRPA and the U.S. Forest Service who provide the plant with increased levels of protection.
  • Adopted Standards  - Maintain two Cup Lake draba population sites.
  • Indicator - The total number of population sites that are maintained as suitable habitat as determined by a qualified expert.
  • Status – Cup Lake draba currently exists in a total of six population sites in the Basin, which is three times the target of two population sites. Therefore, the Threshold Standard was determined to be “considerably better than target.”
  • Trend – Quantitative monitoring of Cup Lake draba began in 2004 when plants were located and counted at six population sites (Engelhardt and Gross 2011b). All sites were re-surveyed in 2009. Between 2004 and 2009, plant counts at three of the population sites were stable (50%), two increased (33%), and no plants were found at one site (17%) (see above figure). The site where no plants were found (Site 1a) in 2009 occurred in marginal habitat with large amounts of litter. With only one data set it is not possible to know if the site has become unsuitable habitat over the last five years, or if there was just insufficient rainfall/snowpack in 2009 to support plants. With only two years of survey data it is not statistically possible to assess a trend for Cup Lake draba. However, plant counts at 83% of the population sites were stable or increased over the last five years, and the high elevation cushion plant community where Cup Lake draba occurs is known to be naturally stable. This leads to the conclusion that there was “little or no change” in the trend.

Click here for more information...

  • Confidence  - There is a high degree of confidence in the status based on the quality of the data collected and the robust nature of the monitoring program. However, there is low confidence in the trend determination because the trend analysis is based on data from only two sampling periods in 2004 and 2009.Therefore, there is a “moderate” level of confidence in the status and trend.
  • Human and Environmental Drivers - Human activities that pose direct threats include recreational activities that might trample or uproot plants (e.g., camping, hiking, equestrian use, trail construction, snowmobiles) (Englehardt and Gross 2011b).However, the known populations in the Basin are located in remote, off-trail areas, and the greater concern is the potential threat of climate change. Climate change may adversely affect Cup Lake draba populations through its influence on precipitation type, timing, and quantity. Decreased snowpack or a change in snowmelt timing could alter plant community composition and species interactions, and/or decouple plant flowering periods and insect pollinator visitation.
  • Monitoring Approach – A long-term monitoring program for Cup Lake draba was initiated in 2010 (Engelhardt and Gross 2011b).Plant populations are visited every five years, or more frequently when data suggests the population is decreasing. The monitoring objective is to provide a quantitative and consistent method for evaluating status and trend, especially at sites comprised of large numbers of plants where it is difficult to accurately count individuals. Monitoring at permanent plots allows for more repeatable and efficient surveys.
  • Monitoring Partners – Ecology and botany staff from theU.S. Forest Service – LTBMU, and Eldorado National Foresthas developed, and currently implement, a long-term monitoring plan for the species. 

Links

 

Map

 

 

 

click map for larger image

Trend Charts

Chart data not available at this time.
Census results for six Cup Lake draba population sites in 2004 and 2009. The number of plants found in the various plant categories are: 1 = 1-14, 2 = 15-99, 3 = 100-249, 4 = 250-499, 5 = 500-1000, 6 = >1000. Source: U.S. Forest Service-LTBMU

Additional Info

References

  1.  
  2.  
  3.  

Additional Information

  1.  
  2.  
  3. Conceptual Model:
  4. Monitoring Plan:
Last Updated on Tuesday, 13 November 2012 11:57