24 



5. Evidence of reproduction: Flowering 

 and fruiting observed (1989) . 



6. Evidence of population expansion or 

 decline: Unknown. 



C. Phenology. 



1. Patterns: An early-blooming species, A. barrii 

 flowers from early May through mid-June, 

 depending on climatic conditions, latitude, and 

 aspect. At many sites, extensive vegetative 

 mats were observed without flowers. It is not 

 known if this condition is due to senescence of 

 the individuals through natural aging, advanced 

 succession within the habitat (i.e., increased 

 overstory cover) , an obscure life history 

 pattern, or other unknown factors. 



2. Relation to climate and microclimate: Many of 

 the known sites for A. barrii . especially the 

 populations where there is no overstory 

 present, occur on steep slopes with northeast 

 or northwest aspects. These sites are shaded 

 for at least some parts of the day. Drought 

 conditions existed throughout most of 

 southeastern Montana in 1987 and 1988. During 

 surveys in 1989, numerous plants were observed 

 to be partially or completely dead (See color 

 slide, p. 9) . Especially heavy losses were 

 incurred at sites located atop the highest, 

 most barren knolls and ridgelines. A long- 

 term climate change towards a warmer, drier 

 environment, would likely have a negative 

 effect on populations of A. barrii . 



/ 



Reproductive ecology. 



1. Types of reproduction: Little is known of the 

 reproductive biology of A. barrii except that 

 it reproduces by seed. However, A. barrii 

 produces few or no flowers in some years 

 (Locklear 1986) , and few seedling were observed 

 during survey work (Schassberger , pers. obs., 

 Shelly pers. comm.). 



Within the group Orophaca, a minimum age of 25 

 years was established for individual plants of 

 A. aretioides, and even small individuals of A. 

 tridactylicus averaged over 15 years of age 

 (Roberts 1977). Astragalus barrii also 

 produces large woody mats, and may be long 

 lived. If this is the case, observed low 



