The California Botanic Garden made a conservation seed collection from a population of Astragalus albens (Cushenbury milkvetch) located near Baldwin Lake in the San Bernardino Mountains of San Bernardino County, California on June 3, 2021. This is a recollection of the 1995 seed collection made by Michael Gonnela (CalBG Accession #20919), and a seed sample was sent to the National Laboratory for Genetic Resources Preservation for use in the CPC/IMLS RNA Integrity Study.
In 2021, CPC contracted the California Botanic Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.
Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 5 accessions of Astragalus albens in orthodox seed collection. There are as many as 5253 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.
Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 2 seed accessions of Astragalus albens from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 25 maternal plants
Restricted to a carbonate belt in the northeastern San Bernardino Mountains, San Bernardino County, California. Approximately 16 occurrences are believed extant (with another 2 historical and 1 of unknown status) within an area of approximately 80 square kilometers. Population size was estimated to be 7000-7500 plants, but is likely less in drought years. Habitat destruction and degradation associated with limestone mining is the major threat to this species. Other threats include off-highway vehicle use, target shooting, road building and maintenance, trash dumping, and potential development. The U.S. Fish and Wildlife Service (2002) has designated Critical Habitat and the U.S. Forest Service has developed the Carbonate Habitat Management Strategy (2003) with the aim of mitigating these threats.
Threats and disturbances to the natural habitat of carbonate endemic plants within this region are primarily associated with limestone mining and include destruction of habitat by open or terraced mining techniques and quarries and associated overburden d
Cushenbury milkvetch is known from 30-50 small occurrences with a total estimate of 2,000-7,000 individuals. Sizes of populations fluctuate with rainfall patterns, with larger-sized populations in years of substantial rain (USFWS 1997; Soza pers. comm.).
Research has been conducted on habitat characteristics of this particular species in the San Bernardino Mountains with respect to restoration potential (Gonella and Neel 1993).
The majority of carbonate deposits within the San Bernardino Mountains are owned by the USDA Forest Service, San Bernardino National Forest (SBNF), which has developed a forest management plan that aims to conserve some of the existing populations of the carbonate endemics by setting aside refugia. As part of this plan, the SBNF has supported ongoing surveys of carbonate habitat within the SBNF to expand knowledge of species distribution patterns and assist in identification of refugia potential (USFWS 1997).
Management needs that have been identified by the USFWS include protection of significant extant populations by developing a reserve system on federally owned land of occupied areas, buffer zones, and habitat connections; restoring habitat, reintroduction efforts and enhancing populations; monitoring populations; and conducting surveys and taxonomic assessments to locate new populations and resolve questions about the identity of several existing populations (USFWS 1997).
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