types, the A^ tridentata type generally occurs on more mesic 

 sites. 



Other Studies. --This type has been described in Montana by 

 Mueggler and Stewart (1980). 



8. Artemisia tridentata/Agropyron spicatum Type 



(ARTTRI/AGRSPI; big sagebrush/bluebunch wheatgrass; G5 S5) 



Vegetation. — Artemisia tridentata and Agropyron spicatum are 

 abundant within this community type and dominate the shrub and 

 herb layers, respectively. Other species that are generally 

 present with cover exceeding 1% include Artemisia frigida . 

 Opuntia polyacantha . Bouteloua gracilis , Poa sandbergii . and 

 Stipa comata . 



Physical Setting. --The type occurs on flat to steep, rocky 

 plateaus, dip slopes, and residual mountain slopes at eleva- 

 tions between 5000 and 6000 feet. The total cover of soil, 

 gravel, and rock ranges from 20 to 70% and the soil surface is 

 stable with little or no evidence of accelerated erosion. 



Parent materials include igneous and metamorphic rocks. 

 Soils are generally Calciorthids or Argiborolls and are grav- 

 elly to very stony. The Calciorthid soils are violently 

 effervescent in portions of the profile. Soil depth ranges 

 from shallow to moderately deep. Textures are mostly loams to 

 clay loams. Available water holding capacity ranges from low 

 to high. 



Adjacent Communities. --The Artemisia tridentata/Agropyron 

 spicatum and A_^ arbuscul a/ Agropyron spicatum types are eco- 

 logically similar and often adjoin one another. Of the two 

 types, the A_^ arbuscula type generally occurs on more xeric 

 sites. The A_^ tridentata/Festuca idahoensis type occurs on 

 more mesic and cooler sites. The Agropyron spicatum/ Bouteloua 

 gracilis type is often found on adjacent less rocky and less 

 steep sites. 



Other Studies. — This type has been described in Montana by 

 Mueggler and Stewart (1980) , 



9. Artemisia tridentata/Festuca idahoensis Type 



(ARTTRI/FESIDA; big sagebrush/Idaho fescue; G5 S4) 



Vegetation .-- Artemisia tridentata and Festuca idahoensis are 

 abundant within this community type and dominate the shrub and 

 herb layers, respectively. Agropyron spicatum may also be 

 well represented to abundant. Other species that are gener- 



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