reasons. First, occurrences and population size fluctuate widely from year to year in response to climatic conditions, especially on the amount of rainfall. Desert cymopterus is dependent upon frequent spring rains. Furthermore, this species may remain dormant underground as a taproot and may not emerge when there isn’t enough rainfall, so the number of individuals underground could be greater than the number of individuals aboveground. Also, detectability many be low in years when plants only produce leaves and no inflorescence (NatureServe 2010). The largest and most robust populations of desert cymopterus occur on Edwards Air Force Base. Seventeen population surveys were performed during a study in 1995, a good year for the species, and population sizes at each location ranged from 1 to 1,929 individuals. In total, 14,093 individuals were counted over an area of 1,465 acres (Tetra Tech 1995, cited in NatureServe 2010). Threats and Environmental Stressors Desert cymopterus is potentially threatened by habitat alteration and destruction resulting from military activities on Edwards Air Force Base, the expansion of Fort Irwin, oil and gas development, utility construction, renewable energy development, off-road vehicle use, sheep grazing, Land Tenure Adjustment, and urban development (69 FR 64884–64889; CNPS 2011). However, according to the proposed rule (69 FR 64884–64889), the magnitude and relative importance of most of these potential threats were unknown. Grazing by native and non-native herbivores—presumably including mammals, insects, and desert tortoise (Gopherus agassizii)—is also a threat to this species. This may contribute to the low-density, dispersed nature of the majority of reported desert cymopterus populations by limiting the plants’ reproductive potential and reducing their vigor (Bagley 2006). Conservation and Management Activities The vast majority of plants and acreage of habitat for desert cymopterus are currently thought to occur on the Edwards Air Force Base. Therefore, this species is not covered by the West Mojave Habitat Conservation Plan (Edwards Air Force Base 2002).
reasons. First, occurrences and population size fluctuate widely from year to year in response to climatic conditions, especially on the amount of rainfall. Desert cymopterus is dependent upon frequent spring rains. Furthermore, this species may remain dormant underground as a taproot and may not emerge when there isn’t enough rainfall, so the number of individuals underground could be greater than the number of individuals aboveground. Also, detectability many be low in years when plants only produce leaves and no inflorescence (NatureServe 2010). The largest and most robust populations of desert cymopterus occur on Edwards Air Force Base. Seventeen population surveys were performed during a study in 1995, a good year for the species, and population sizes at each location ranged from 1 to 1,929 individuals. In total, 14,093 individuals were counted over an area of 1,465 acres (Tetra Tech 1995, cited in NatureServe 2010). Threats and Environmental Stressors Desert cymopterus is potentially threatened by habitat alteration and destruction resulting from military activities on Edwards Air Force Base, the expansion of Fort Irwin, oil and gas development, utility construction, renewable energy development, off-road vehicle use, sheep grazing, Land Tenure Adjustment, and urban development (69 FR 64884–64889; CNPS 2011). However, according to the proposed rule (69 FR 64884–64889), the magnitude and relative importance of most of these potential threats were unknown. Grazing by native and non-native herbivores—presumably including mammals, insects, and desert tortoise (Gopherus agassizii)—is also a threat to this species. This may contribute to the low-density, dispersed nature of the majority of reported desert cymopterus populations by limiting the plants’ reproductive potential and reducing their vigor (Bagley 2006). Conservation and Management Activities The vast majority of plants and acreage of habitat for desert cymopterus are currently thought to occur on the Edwards Air Force Base. Therefore, this species is not covered by the West Mojave Habitat Conservation Plan (Edwards Air Force Base 2002).
DesertCymopterus.docx