a longer fire interval and absence of a single hay-cutting that the Pascopyrum smithii dominated 

 butte top had received. 



We did not identify Pascopyrum smithii in our plots, but its absence is not certain. Elymus 

 lanceolatus and Pascopyrum smithii have similar ecological adaptations and may grow intermixed 

 (Coupland 1960, Ecological Consulting Service 1975, Jorgensen 1979, Quinnild and Cosby 1958). 

 DeVelice et al. (1995) treat the two wheatgrasses as ecological equivalents in their discussion of a 

 Pascopyrum smithii / Stipa viridula plant association in northeastern Montana. 



Abundance of Stipa viridula is thought to be indicative of fine- to medium-textured soils, mesic soil 

 moisture regimes, and low levels of grazing (Branson et al. 1970, Jorgenson 1979, Coupland 1960, 

 DeVelice et al. 1995). However, in southern Carter County, Stipa viridula was less abundant in 

 drainage bottom grasslands dominated by nearly pure stands of Elymus lanceolatus (see discussion 

 of ELYLAN) than it was in uplands. Our plots of EL YL AN / STIVIR probably represent outliers of 

 the type, appearing to differ fi-om like-named communities described in the literature in the 

 following respects: 1) relatively low cover by grasses despite low levels of grazing 2) absence of the 

 graminoids Koeleria macrantha, Bouteloua gracilis, and Carex filifolia , 3) presence of Eriogonum 

 paucijlorum (perhaps indicative of some admixture of acid shale circumstantially suggested by the 

 low pH values relative to PASSMI [ELYLAN] and 4) distinct composition and high diversity of 

 forbs, including obligate selenophytes. The best modal description of this association is found in 

 Jensen etal. (1992). 



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