3. REPRODUCTIVE BIOLOGY: The rounded, inflated seed pods can 

 disperse by rolling downhill on slopes as found at the 

 Garfield County site. 



POPULATION ECOLOGY 



1. BIOLOGICAL INTERACTIONS 



a. COMPETITION: A major segment of the Garfield County 

 population is subject to noxious v/eed invasion and 

 encroachment by other exotics, including Melilotus 

 officinalis and Salsola kali . In the Pryor Mountains, it 

 may be threatened by encroachment of exotic annuals such as 

 Haloqeton glomeratus and Salsola kali . 



b. HERBIVORY: None observed. 



LAND OWNERSHIP: All of the Pryor Mountain populations of this 

 species are documented from BLM lands. The Garfield County 

 collection is from U.S. Fish and Wildlife Service lands on Hell 

 Creek Recreation Area v/ithin CM. Russell Wildlife Refuge. Land 

 ownership at the other two eastern Montana sites is unknown. 



ASSESSMENT AND MANAGEMENT RECOMMENDATIONS 



1. . THREATS TO CURRENTLY KNOWN POPULATIONS: Weed encroachment 

 and management factors affecting weed invasion are 

 identified as potential threats. 



2. MANAGEMENT PRACTICES AND RESPONSE: Factors affecting weed 

 invasion are to be addressed in review of proposed projects 

 or plans in potential habitat for Astragalus geyeri , i.e., 

 on sandy range sites located closest to Fort Peck Reservior. 

 The only knov/n population in the study area is on secondary 

 range, although it is on primary range in the Pryor 

 Mountains . 



SUMMARY: Geyer's milkvetch ( Astragalus geyeri ) is a watch 

 species in the Big Dry Resource Area and a sensitive species in 

 the Billings Resource Area. It has little potential habitat on 

 BL14 lands in the Big Dry study area. It is an annual species at 

 the northern limits of its range here, and appears to be very 

 susceptible to v/eed encroachment. 



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