Determining the population boundaries of a narrowly endemic perennial plant, Lane Mountain milk-vetch, in San Bernardino County, California

Abstract

The Lane Mountain milk-vetch (Astragalus jaegerianus) is a federally endangered species. It was first discovered in 1939 by Edmund Jaeger in the central Mojave Desert of California. This plant species was not collected again until the army became interested in expanding Fort Irwin’s western boundary in the 1980’s. Following its rediscovery, volunteers eventually found a few scattered plants in three populations within a 10-mile radius. Army-funded surveys since 1990 defined four generally distinct populations. The most extensive survey, in conjunction with a GIS analysis of potential habitat within 50 miles of the core populations, occurred in 2001. A total of 387 transects were surveyed within twelve 7.5 minute quadrangles and nearly 4,000 plants were found on 21,000 acres. The 2001 survey established that the milk-vetch is restricted to only 4 populations and that it has specific soil and elevation requirements. Ecological studies regarding moisture-holding capacity of the substrate, seed bank availability, seed germination, resprout frequency and pollination ecology have also been conducted. A population genetic study is underway.

Parent Publication

• Southwestern rare and endangered plants: Proceedings of the Fourth Conference

Citation

Charlton, David. 2007. Determining the population boundaries of a narrowly endemic perennial plant, Lane Mountain milk-vetch, in San Bernardino County, California. In: Barlow-Irick, P.; Anderson, J.; McDonald, C., tech eds. Southwestern rare and endangered plants: Proceedings of the Fourth Conference; March 22-26, 2004; Las Cruces, New Mexico. Proceedings. RMRS-P-48CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 24-31