This grassland associarion is found on soils ranging 

 from sandy loam to fine sand. It occurs on Big Island 

 across higher ground and warmer exposures. It is 

 dominated by needle-and-thread (Stipa comata), 

 usually having greater than 40% canopy cover. Blue 

 grama (Bouteloua gracilis) and threadleaved sedge 

 (Carex filifoUa) are consistently present, often as co- 

 dominants. Their cover can exceed that of Stipa comata 

 and varies greatly across the landscape with no obvious 

 correlation to site factors, whether due to disturbance 

 patterns, imperceptible environmental disturbances, or 

 chance. This type usually grades to grasslands 

 dominated by western wheatgrass (Pascopyrum smithii) 

 including PASSMI - CARFIL or PASSMI - 

 BOUGRA. While western wheatgrass is consistently 

 present in this prevailing association, it has low cover 

 values. Forbs are a minor component; only pricklypear 

 (Opuntia polyacantha) consistently occurrs in more than 

 trace amounts, favored by the sandy substrates or else 

 the land use history. Fringed sage (Artemisia frigida) is 

 consistently present, but seldom exceeds trace 

 amounts. This community type generally has only 

 minor populations of weedy or exotic species; for 

 example, crested wheatgrass (Agropyron cristatum) 

 occurs in scattered blocks. STICOM - BOUGRA - 

 CARFIL is a prevailing grassland association of the 

 Northern Glaciated Plains where medium- to coarse- 

 textured soils are found, as previously described for 

 Spring Creek RNA. [Plot MTNHECRA97SC0007] 



Hai\sen and Hofftnan (1988) recognize this type by the 

 dominance of Pascopyrum smithii over Stipa comata and 

 generally this occurs only on lower positions in this 

 landscape or those having planar surfaces and/or 

 having finer-textured soils. Where Pascopyrum smithii 

 and Stipa comata are co-dominant, or nearly so, we 

 have assigned these sites to PASSMI - BOUGRA - 

 CARFIL due to the appreciable cover of Pascopyrum 

 smithii indicating the higher moisture status of these 

 sites (technically, several examples of this community 

 with Carex spp. dominant do not "key out" to any 

 type). Note that Schneider et al. (1997) in the 

 provisional Great Plains vegetation classification of The 

 Nature Conservancy, recognize a Pascopyrum smithii - 

 Stipa comata community type but cite no parameters for 

 its recognition. The whole complex of community 

 types involving Pascopyrum smithii, Stipa comata, Carex 

 fiUfolia, Carex stenophylla, Bouteloua gracilis, andNasella 

 viridula needs extensive work to separate intrinsically 

 different environments from disturbance induced states 

 and a workable key for discriminating types one from 

 another. This, too, is a broadly distributed Northern 

 Great Plains plant association (CO, MT, ND, SD, SK, 

 WY). 



Pascopyrum smithii - Bouteloua gracilis - Carex fihfoUa 



Herbaceous Vegetation 



[PASSMI - BOUGRA - CARHL] 



western wheatgrass - blue grama - threadleaved sedge 



grassland 



This is an uncommon grassland asociation on the 

 island because fine-textured soils are limited. Western 

 wheatgrass (Pascopyrum smithii) is typically the 

 dominant graminoid in this grassland association, but 

 narrowleaved sedge (Carex sterwphyUa; synonym: C. 

 eleocharis) was the dominant graminoid (50% c.c.) in 

 the one island plot. Only two shrub-like plants, fringed 

 sage (Artemisia frigida) and broom snakeweed 

 (Gutierre^ia sarrothrae) , regularly occur but with low 

 cover values. Rush skeletonweed (Lygodesmia juncea) , 

 American vetch (Vicia americana), pricklypear (Opuntia 

 polyacantha) and scarlet globemallow (Sphaeralcea 

 coccinea) are the forbs with high coiistancy but seldom 

 do their coverages exceed 1 or 2% under natural 

 conditions. The occasional bunch of crested wheatgrass 

 (Agropyron cristatum) and patch of flixweed 

 tansymustard (Descurainia sophia) indicate past 

 disturbance. [Plot NHMTECRA97SC0008] 



42 



