18 



forB5t5» or on exposed ridges surrounded by them. Other commonly 

 lecies include limber pine ( Pinus flexilis ) 



__, _ t-me-i 



(Carex rupestris) , 



TOrBSv5» or on e«^»u3«rvi i lutji^a swiiuuhuew w^ ...w.... _ — , 



associated species include limber pine (Pinus flexilis ), Howard's 

 alpine forget-me-not ( Eritrichium howardii) , and curly sedge 



B. Physical characteristics. 



1. Climate. 



a. Koppen climate classification: Type BSw, a steppe 

 climate with a winter dry season east of the Rocky 

 Mountains, where winter cold prevents appreciable 

 precipitation; and type Dfb, the Canadian climate, with 

 snowy winters and moderately warm summers (Visher, 

 195^). 



b. Regional macroclimate: Red Lodge, at an elevation of 

 5,250 feet, is approximately 5 miles northwest of the 

 Beartooth Mountain site and ^0 miles west of the Pryor 

 Mountain sites. For the thirty year period ending in 

 19B0, mean July maximum and mean January minimum were 

 79.3*F and 11.7«F, respectively. Mean annual 

 precipitation was S5.0 inches (U.S. Department of 

 Commerce 1988). 



c. Local microclimate: Shoshonea pulvinata generally 

 occurs in areas which are exposed to full solar 

 insolation, and in very windswept situations. 

 Evapotranspiration and diurnal fluctuation in 

 temperature is expected to be high. Snow accumulation 

 in these areas is minimal, and sites are probably free 

 of snow early in the spring. Although these areas 

 appear dry, the soils beneath the stoney surface may 

 hold moisture well into the summer. 



2. Air and water quality requirements: Unknown. 



3. Physiographic province: Fenneman (1931) places the range of 

 Shoshonea pulvinata in the Middle Rocky Mountain Province, 

 Hunt (197^) also classifies this area as part of the Middle 

 Rocky Mountain Province, within the Rocky Mountain System. 



^. Physiographic and topographic characteristics: In Montana, 

 Shoshonea pulvinata occurs on soils derived from limestones 

 and dolomites of the Madison group of formations (Perry 

 1962, Richards 1955). The Madison limestones lie on top of 

 limestones of the Jefferson Formation. Although it is 

 possible that Shoshonea occurs on soils derived from this 

 latter formation also, it is believed to be mainly 

 associated with the Madison formations. Perry (1962) 

 indicates that both the Beartooth and Big Horn Mountains 

 have been glaciated, while the Pryor Mountains have not. 



In Montana, known sites occur at elevations of 6, 800-7, '♦00 



