horizon ranged from 7.4 to 7.8, and conductivity varied from 210 

 to 270 uhmos/cm- (2 stands) . 



Other Studies- Knight et al. (1987) include this community type 

 in their description of big sagebrush steppe on Bighorn Canyon 

 NRA. This type appears to have northern Great Basin affinities. 

 Similar community types are described for Idaho, Oregon, Nevada, 

 Utah, Washington and Wyoming (Bourgeron and Engelking 1992). 



Natural Heritage Program Rank- G4/S4 



25. Atriplex nuttallii - Artemisia spinescens c.t. 



(ATRNUT-ARTSPI; Gardner saltbush-bud sagebrush) 



(4 stands) 



Environment- ATRNUT-ARTSPI occurs on broad alluvial plains in the 

 area around Gyp Springs near the Wyoming border. Elevations 

 range from 4,600 to 4,800 feet ARTTRI/STICOM or ARTTRI-ATRCON 

 occupy adjacent sites on better drained soils. ARTTRI/AGRSPI may 

 occur on adjacent slopes. 



Vegetation- Atriplex nuttallii and Artemisia spinescens occurred 

 in all stands with mean canopy covers of 38% and 20% 

 respectively. Ceratoides lanata is sometimes common. The herb 

 layer is very sparse. Poa sandbergii and Sitanion hystrix have 

 low cover in most stands. Opuntia polyacantha , Lappula echinata 

 and Ipomopsis pumila are present in most stands. Bryophytes and 

 lichens are absent or nearly so. 



Soils- ATRNUT-ARTSPI occurs only on fine-textured alluvial soil 

 derived from Chugwater sandstone. Soils are very deep, and 

 distinct horizons are undeveloped. Coarse fragments and gravel 

 are absent, and surface texture is silty clay. The soil subgroup 

 at our single soil characterization site was a Typic 

 Torriorthent . High concentrations of carbonates are present at 

 the surface and increase with depth. pH was 8.0 with 

 conductivity of 230 uhmos/cm". 



Other Studies- Kratz (1988) reports this type from the same area, 

 otherwise this community type is previously unreported for North 

 America. 



Natural Heritage Program Rank- Gl/Sl 



28 



