Comments: Due to high productivity of palatable grass and central position in the landscape, stands 

 of ELYLAN (PASSMI) usually receive heavy use by livestock. Some remote BLM lands (e.g. 

 Cottonwood Creek Drainage), however, have stands that have been lightly grazed or ungrazed for up 

 to twelve years (C. Fruit, pers. commun.). Four good to excellent condition stands of ELYLAN 

 (PASSMI) were sampled on BLM lands, all in southern Carter County, two are in floodplains and 

 two are on lower slopes, one of the latter is within an exclosure. 



The dominant species have broad ecological amplitudes and discrete modalities that sort by multiple 

 environmental and disturbance factors, so it is particularly challenging to differentiate this type from 

 other types and circumscribe the variation within it. As here described, PASSMI (ELYLAN) most 

 closely resembles descriptions in the literature of grassland types dominated by Pascopyrum smithii. 

 Although landscape position is similar, our plots lack the indicated codominants oi Pascopyrum 

 smithii / Bouteloua gracilis communities in northeastern Montana (DeVelice et al. 1995) and 

 Pascopyrum smithii / Carex filifolia communities cited for North and South Dakota (Hansen et al. 

 1984, Hansen and Hoffman 1988). In muUi-state classifications (Schneider et al. 1997) the two 

 previously mentioned plant associations were combined into the Pascopyrum smithii - Bouteloua 

 gracilis - Carex filifolia plant association when analyses showed no difference in site descriptors 

 between the two community types, they differed only in relative proportions of the sub-dominant 

 graminoids. A community dominated by Pascopyrum smithii and Bouteloua gracilis (also with 

 abundant Bromus japonicus) was described from the Thompson Creek drainage in southern Carter 

 County (Ecological Consulting Service 1975) and this community type was observed in northern 

 Carter County on reconnaissance surveys. Bouteloua gracilis is favored by overgrazing (Hansen and 

 Hoffman 1988) and it is difficuU to attribute its dominance in some Carter County grasslands 

 (usually with Bromus japonicus also abundant) to either edaphic factors (more coarse textured soil) 

 or grazing pressure. 



Hansen et al. (1995) describe late serai to climax wetland communities in Montana dominated by 

 nearly pure stands of Pascopyrum smithii; Bouteloua gracilis was found only in disturbed, and/or 

 early to mid serai stands of this sample set. In contrast, one northeastern Montana study (Branson et 

 al. 1970) illustrates the influence of soil type on distribution of Bouteloua gracilis; the species was 

 absent from floodplains dominated by Pascopyrum smithii but the two grasses were codominant 

 nearby on dryer, warmer soils. An abundance of Nasella (Stipa) viridula is documented for some 

 wetland and drainage bottom Pascopyrum smithii types (Culwell and Scow 1982, Hansen et al. 

 1995), but it is interesting to note that N. viridula is more abundant in upland grasslands in southern 

 Carter County (see discussion of ELYLAN (PASSMI) / STIVIR). This may reflect their occupying 

 collecting positions in the landscape and having medium to coarse-textured soils (which may have 

 greater amounts of water above the wilting point available to N. viridula). 



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