Carex oblusata is abundant and the grass Poa cusickii is well represented in the southern, lower 

 elevation plot but are absent from the northern, higher elevation plot. Low growing mats of 

 Calamgrostis pnrpurescens are dominant in some nearby areas outside and is present within the 

 high elevation plot. The grass Koeleria macrantha (syn. Koeleria cristata) is present in trace 

 amounts in both plots. Selaginella densa, a ground hugging fern ally, is well represented to 

 abundant in both plots. Cymopteris bipinnatus is the only forb present (in trace amounts) in both 

 plots. The forbs Antennaria microphylla and Gewn triflorum are well represented in the low 

 elevation plot and Oxytropis sericeus is well represented within and is dominant in some nearby 

 areas outside the high elevation plot. The southern plot has a higher diversity of forbs and 

 grasses. The indicator species for which the type is named, Potentilla diversifolia, was not found 

 in either plot and is not common in the study area (see Cominents Section for further 

 elaboration). 



Comments: These high-elevation grasslands are only lightly impacted by cattle grazing and are 

 probably in the best condition of any grasslands in the study area. They constitute an important 

 part of elk summer range. The absence or replacement of dominant and diagnostic species, and 

 high variability between plots in the study area indicate a need for further refinement of the 

 southwestern Montana high elevation grassslands classification; perhaps new indicator species 

 will need to be identified. The two plots were placed in the FESIDA/POTDIV c.t. (Cooper and 

 Lesica 1992), a type generally associated with upper subalpine and alpine environments, because 

 of the considerable contribution of Carex obtusata and no contribution by Agropyron caninum, a 

 highly constant species, often having high cover values, in the next most ecologically similar 

 type, ¥ESlDA-Agropyron caninum (Mueggler and Stewart 1980). FESIDAVPOTDIV also bears a 

 strong degree of resemblance in terms of sites occupied (higher elevations, generally >8,000 ft.) 

 to both the Festuca idahoensis-Carex scirpoidea c.t. (speculated to occur in the Pryor Mountains 

 vicinity by Mueggler and Stewart [1980]) and the FESIDA-Carex obtusata c.t. listed for 

 Wyoming's Big Horn Mountains (Bourgeron and Engelking 1994, originally cited as Festuca 

 idahoensis/Lupinus sericeus plant association). The forb compositions of both FESIDA- 

 AGRCAN and FESIDA-CARSCI bear a strong resemblance to that of FESIDA/POTDIV. 



Festuca idahoensis-Agropyron spicatum plant association 



(FESIDA/AGRSPI; Idaho fescue/bluebunch wheatgrass; MTNHP G5/S5; 

 WHTF designation Festuca idahoensis-Pseudoroegneria spicata; one plot) 



Environment: FESIDA/AGRSPI was sampled by one plot along the Left Fork of Stone Creek in 

 an area which burned five or more years ago. It is in a midslope position on a dissected moderate 

 slope with easterly aspect at 7,420 feet elevation. Unbumed slopes in the area support extensive 

 Artemisia tridentata ssp. vasyana/Festuca idahoensis communities. 



Soils: The plot is within the Sebud-Hapgood rock outcrop complex, the dominant soil mapping 

 unit of the southern part of the study area (USDA Soil Conservation Service 1989). These are 

 deep, well drained CryoboroUs of colluvium parent material derived from metamorphic basement 

 rocks, mostly gneiss and schists. 



Vegetation: The potential climax vegetation of the site is clearly Artemisia ti-identata ssp. 

 vasyana/Festuca idahoensis (see description in this report for ARTTSV/FESIDA), but the slirub 

 component has not yet reestablished after a fire five or more years ago. There is currently a trace 



25 



