Soils- SARVER-ARTTRI is found on deep alluvial soils. Gravel and 

 coarse fragments are absent, and a carbonate layer occurs at 

 depths below 20 inches. The soil subgroup at our single soil 

 characterization site v;as a Ustic Torrif luvent . Surface texture 

 is silty. pH and conductivity of the one stand measured were 7.7 

 and 290 uhmos/cm- (1 stand) . 



Other Studies- Knight et al. (1987) report a greasewood desert 

 shrubland for the Bighorn Canyon NRA. Mueggler and Stewart 

 (1980) and Hansen et al. (1991) describe a Sarcobatus 

 vermiculatus - Artemisia tridentata habitat type for western 

 Montana; however, they do not include Artemisia tridentata as a 

 common species. Although greasewood communities are reported 

 throughout the Intermountain West, this type is reported only for 

 Montana (Bourgeron and Engelking 1992) , but is certainly also 

 present in Wyoming. 



Natural Heritage Program Rank- G4/S4 



24. Artemisia tridentata / Stipa comata c.t. 



(ARTTRI/STICOM; big sagebrush/needle-and-thread) 



(18 stands) 



Environment- Wide alluvial valleys, fans, toeslopes and terraces 

 are most often occupied by ARTTRI/STICOM. This type is very 

 common between 4,000 and 5,000 feet in the outwash plains and 

 foothills on the south side of the Pryor Mountains. Adjacent 

 community types include ARTTRI/AGRSPI and Utah juniper woodlands 

 on steeper slopes and stonier soils and ARTTRI-ATRCON or 

 ARTTRI/AGRSMI on heavier or more saline soils. 



Vegetation- Artemisia tridentata was present in nearly all of the 

 stands with a mean cover of 23%. Ceratoides lanata and 

 Gutierrezia sarothrae have low cover in many stands. Atriplex 

 conf ertif olia and Grayia spinosa are common in some stands. 

 Stipa comata and Bouteloua gracilis were present in most stands 

 with mean canopy covers of 11% and 25% respectively. Oryzopsis 

 hymenoides and Poa sandbergii were present in approximately half 

 of the stands, but their cover was generally low. Aristida 

 purpurea , Sitanion hystrix and Sporobolus cryptandrus are common 

 in some stands. Forb cover is low, but Opuntia polyacantha and 

 Sphaeralcea coccinea are common, and Ipomopsis pumila is present 

 in many stands. Bryophytes and lichens are present in many 

 stands but are usually not common. 



Soils- ARTTRI/STICOM occurs on deep soils derived from sandstone 

 or limestone. Coarse fragments or gravel are absent in most but 

 not all stands, and texture is silty or sandy loam. The soil 

 subgroups at our two soil characterization sites included a 

 Ustollic Calciorthid and a Ustollic Haplargid. pH of the surface 



27 



