^taphvlos uva-ursi , Hanlopappus acaulis, Agropyron spicatum , 

 Carex rossii, and Orvzopsis hyroenoides. 



Physical setting.— The type occurs on steep dip slopes and 

 residual mountain slopes at elevations between 6000 and 6800 

 feet. The total cover of soil, gravel, and rock exceeds 90^ 

 on some sites and is always higher than 30% The^°il surface 

 is usually unstable because of the general lack of adequate 

 vegetation cover. 



Soils are derived from limestone parent materials and are 

 Lithic Ustorthents and are often very gravelly. Textures vary 

 from sands to loams. Strong effervescence characterizes the 

 surface of most of the soils and violent effervescence is 

 usually present within the profile. Available water holding 

 capacity varies from low to high. 



Adiacent Communities.— Adjacent communities on deeper, less 

 rocky, and more stable soils include Pinus f lexilis / Festuca 

 idahoensis, Pseudotsuga menziesii/Agro pyron spicatum , and 

 Pseudotsuga menziesii/Festuca idahoensis. 



Other Studies.— This type has not previously been reported in 

 Montana but has been reported in Idaho, Utah, and Wyoming 

 (Bourgeron and Engelking 1991) . 



4. Pseudotsuga menziesii/cercocarpus ledifolius Type 



(PSEMEN/CERLED; Douglas-fir/mountain mahogany; G3? S3?) 



vegetation.— Pseudotsma menziesii characterizes the open tree 

 layer, sometimes in association with Juniperus scopulorum . 

 Abundant Cercocarpus ledifolius characterizes the undergrowth. 

 Other species that are generally present with cover exceeding 

 1% include Artemisia frigida . A^ tridentata, and Agropyron 

 spicatum . 



Physical setting.— The type occurs on generally steep residual 

 mountain slopes and ridges at elevations between 5900 and 6600 

 feet. The total cover of soil, gravel, and rock ranges from 

 40 to 90%. The soil surface is usually unstable because of a 

 general lack of adequate vegetation cover. 



Soils are generally derived from igneous or metamorphic 

 parent materials and are non-effervescent (not calcareous). 

 Textures vary from sands to clay loams and are gravelly to 

 very cobbly. Soil depth varies from shallow to moderately 

 deep. Available water holding capacity varies from low to 

 medium. 



Adjacent Communities. —Forested communities on adjacent more 

 mesic and less rocky sites include Pseudotsuga menziesii / 



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