Lane Mountain Milk-vetch

Astragalus jaegerianus

Description

The Lane Mountain milk-vetch (Astragalus jaegerianus ) is a wispy perennial that is somewhat woody at the base, with stems 12-20 in (30.5-50.8 cm) long that often grow in a zigzag pattern, usually up through low bushes. Leaves have seven to 15 silvery pubescent linear leaflets 0.2-1 in (5.1-25.4 mm) long. The flowers, five to 15 per stalk, are cream to purple or lighter with veins of a deeper color. The keel petals are less than 0.4 in (1 cm) in length. Fruits are pencil shaped, linear, smooth, pendant, and 0.6-1.0 in (1.5-2.5 cm) long.

Habitat

Lane Mountain milk-vetch occurs in granitic soils in San Bernardino County. At the northern sites, it has been found most often in shrub associations where Mormon tea or Cooper goldenbush are the dominant or subdominant shrub species within the larger creosote bush/white bursage community. At all sites Lane Mountain milk-vetch plants are almost exclusively found growing up through shrubs or, occasionally, through clumps of dead bunchgrass.

Distribution

After the early collections in 1939 and 1941, the plant was not collected again until it was rediscovered in 1985, when 87 plants were counted about 5 mi (8 km) north of the first collection. Intensive surveys over the next seven years led to the discovery of a few additional small populations. The most recently discovered population, located a few miles west of Lane Mountain, closely approximates the type locality.

In the mid-1990s Lane Mountain milk-vetch was known from four general sites. Three of the sites occur within an area of about 14 sq mi (36.3 sq km), and the plants within each site are widely scattered. Fewer than 130 plants were located at these three sites in the 1990s, although repeated searches of suitable habitat have been made. The fourth site, near Lane Mountain, is located about 9 mi (14.5 km) to the south. No more than 30 plants have been found at the Lane Mountain site since its discovery in 1992. At the northern sites, Lane Mountain milk-vetch occurs on lands managed by the U.S. Department of Defense at the National Training Center of Fort Irwin and on adjacent lands managed by the Bureau of Land Management (BLM). At the southernmost site, near Lane Mountain, plants are known to occur on BLM lands, although Lane Mountain Mesa is a patchwork of public and private lands.

Threats

Threats to Lane Mountain milk-vetch include habitat destruction from dry wash gold mining, other mining activities (materials lease mining), rock and mineral collecting, off-highway vehicle activity, and potentially from increasing fire frequency and any associated fire suppression activities. Military vehicles remain a potential threat. In addition, an expansion of the National Training Center at Fort Irwin onto surrounding BLM lands has been proposed.

Lane Mountain milk-vetch is also vulnerable to unplanned, potentially destructive, human activities. The majority of Lane Mountain Mesa, where Lane Mountain milk-vetch occurs, and all of the adjacent Coolgardie Mesa, are covered by mining claims. Dry wash gold mining operations result in removal of vegetation as surface soils are mined. Mining that falls under the definition of casual use also can destroy the habitat of Lane Mountain milk-vetch in the Lane Mountain area. Casual use mining is small-scale recreational mining that can be carried out by a claim holder without submission of any plan or notice to the BLM. In 1993 Coolgardie Mesa experienced a sharp increase in recreational gold mining. Within a few miles of the Lane Mountain population of Lane Mountain milk-vetch, the BLM recorded 300-400 people mining within a 1-sq mi (2.6-sq km) area during a single weekend. Joshua trees and other vegetation were uprooted and destroyed in this process. The BLM has since developed guidelines to limit activities that fall under the definition of casual use mining. Under the new definition, casual use mining is limited to the use of nonmechanized tools and cannot result in the destruction of perennial vegetation. This still permits the digging of mining pits and soil surface disturbance that degrade habitat and could impact Lane Mountain milk-vetch. Past disturbance has also resulted in an increase in non-native annual grasses in the area, and this ongoing small-scale disturbance provides new opportunities for further invasions of these highly competitive specie. The sites where Lane Mountain milk-vetch occurs on BLM land to the north, while not currently under claim, are available for claim, should mining interest renew in that area.

Conservation and Recovery

Lane Mountain milk-vetch is included within the planning area of the West Mojave Coordinated Management Plan, a multiagency effort to coordinate resource information and provide general resource management direction in the western Mojave Desert. Unresolved issues stalled the planning team's progress in 1996. The planning effort has since been reinitiated, with a modified objective and fewer species to be addressed.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 6 October 1998. "Determination of Endangered or Threatened Status for Five Desert Milk-vetch Taxa from California." Federal Register 63 (193): 53596-53615.