Distribution of Clokey's Eggvetch

Abstract

The Environment, Safety and Health Division of the U.S. Department of Energy, Nevada Operations Office implements the Ecological Monitoring and Compliance Program on the Nevada Test Site (NTS). This program ensures compliance with applicable environmental laws and regulations, delineates and describes NTS ecosystems, and provides ecological information for predicting and evaluating potential impacts of proposed projects on those ecosystems. Over the last several decades, has taken an active role in providing information on the tatus of plant species proposed for protection under the Endangered Species Act(ESA). One such species is Clokey's eggvetch (Astragalus oophorus var. clokeyanus), which is a candidate species under the listing guidelines of the ESA. Surveys for this species were conducted on the NTS in 1996, 1997, and 1998. Field surveys focused on potential habitat for this species in the southern Belted range and expanded to other areas with similar habitat. Over 30 survey day s were completed; five survey days in 1996, 25 survey days in 1997, and three survey days in 1998. Clokey's eggvetch was located at several sites in the southern Belted Range. It was found through much of the northern section of Kawich Canyon, one site at the head of Gritty Gulch, and a rather extensive location in Lambs Canyon. It was also located further south at Captain Jack Springs in the Eleana Range, in much of Falcon Canyon and around Echo Peak on Pahute Mesa, and was also found in the Timber and Shoshone Mountains. Overall, the locations of Clokey's eggvetch on the NTS appears to form a distinct bridge between populations of the species located further north in the Belted and Kawich Ranges and the population located in the Spring Mountains. Clokey's eggvetch was commonly found along washes and small draws, and typically in sandy loam soils with a covering of light tuffaceous rock. It occurs primarily above 1830 meters (6000 feet) in association with single-leaf pinyon (Pinus monophylla), Utah juniper (Juniperus osteosperma), and big sagebrush (Artemisia tridentata ssp. tridentata). Overall, the populations of Clokey's eggvetch on the NTS appear to be vigorous and do not appear threatened. It is estimated that there are approximately 2300 plants on the NTS. It should be considered as a species of concern because of its localized distribution, but it does not appear to warrant protection under the ESA.