31 



(i.e., a higher percent cover of overstory vegetation and 

 ground litter is present) . Astragalus barrii plants at 

 these sites are generally large, vegetatively spreading 

 mats that do not appear to produce flowers on a yearly 

 basis. Almost all of the populations on the Custer 

 National Forest appear less affected by drought 

 conditions, probably due to shading by the overstory and 

 slightly higher amounts of precipitation. 



Drought conditions in 1987 and 1988 resulted in large 

 losses in A. barrii populations, especially at lower 

 elevations, in lower precipitation zones, and on more 

 exposed sites. This may be a common cyclical trend. It 

 does however indicate that A. barrii populations would 

 respond negatively to a long-term climate shift toward a 

 warmer, dryer environment. 



13. Recommendations for listing or status change. 



A. Recommendation to U.S. Fish and Wildlife Service: 

 On the basis of information obtained during recent 

 field surveys, and knowledge of the taxon, it is 

 recommended that Astragalus barrii be placed in 

 category 3C, as a species that has proven more 

 abundant than was previously thought. However, A. 

 barrii is a regional endemic; thus, should further 

 research or changes in land use indicate significant 

 decline in this taxon, it should be reevaluated for 

 possible inclusion in category 1 or 2 . 



B. Recommendations to other U.S. federal agencies: 



Astragalus barrii should remain on the U.S. Forest 

 Service Region 1 list of sensitive species. The 

 limited distribution of the species in Region 1, and 

 the potential loss of populations on private lands, 

 warrant this status. Also, populations in habitats 

 on the Custer National Forest appear to be buffered 

 more from seasonal changes in precipitation and 

 temperatures. 



C. other status recommendations. 



1. Counties and local areas: No recommendations. 



2. States: Astragalus barrii is currently listed 

 as "rare in Montana" (state rank = S3) by the 

 Montana Natural Heritage Program. 



3. Other nations: Not applicable. 



4. International: Not applicable. 



