generally present with cover ranging from 1 to 20% include 

 Chrvsothamnus nauseosus , Tetradvroia canescens , Eriogonum 

 ovalifolium v. celsum , Linum perenne , Phacelia hastata , 

 Psoralea tenuifolia , Orvzopsis hymenoides , and Stipa comata . 



Physical Setting. — This type has only been observed in the 

 Centennial Valley. It occurs on sand dunes and blow outs at 

 elevations around 6700 feet. Bare soil (sand) cover ranges 

 from 60 to 90% and coarse fragments are absent. The soil 

 surface is usually unstable because of a lack of adequate 

 vegetation cover. 



Parent materials are eolian sand deposits. Soils are 

 very deep Ustic Torripsamments and lack coarse fragments and 

 are not calcareous. Textures are sands and available water 

 holding capacity is low due to the coarse texture. 



Adjacent Communities. — The Artemisia tripartita/Festuca 

 idahoensis and A^ tridentata/Festuca idahoensis types are 

 usually found on adjacent more stable soils and sites. 



Other Studies. — This type has not been previously described. 



15. Agropyron spicatum/Oryzopsis hymenoides Type 



(AGRSPI/ORYHYM; bluebunch wheatgrass/lndian ricegrass; G3? 

 S2?) 



Vegetation. — Total vegetation cover in this badlands type 

 seldom exceeds 15%. Characteristic species include Gutier- 

 rezia sarothrae , Agropyron spicatum . Aristida lonqiseta . and 

 Oryzopsis hymenoides . 



Physical Setting. --The type occurs on steep badland sites at 

 elevations around 5500 feet. Bare soil cover totals 20 to 70% 

 and most of the remaining ground cover is comprised of coarse 

 fragments. The soil surface is unstable because of a lack of 

 adequate vegetation cover and rill and sheet erosion is 

 common. 



Parent materials are sedimentary rocks and soils are 

 shallow and poorly developed. Soils range from not gravelly 

 to very gravelly and are strongly to violently effervescent. 

 Textures are sands to loams, and available water holding capa- 

 city is low. 



Adjacent Communities. --Vegetation on adjacent more stable 

 soils include the Artemisia tridentat a/ Agropyron spicatum and 

 Agropyron spica turn/ Bout eloua gracilis types. 



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