all aspects as well as ridgetops, terraces and alluvial fans. 

 Juniperus osteosperma woodland is common on adjacent sites with 

 more exposed bedrock, and black sagebrush steppe is frequently 

 found on sites with shallower soils. Adjacent sites with deep 

 but less well-drained soils are often dominated by big sagebrush 

 but with Aqropvron smithii or Atriplex conf ertif olia as 

 codominants. Birdfoot sagebrush is often dominant on adjacent 

 communities in the southwest portion of the study area. 



Vegetation- Typically this type has a rather sparse shrub layer, 

 1 to 3 feet tall, and a moderate cover of grasses. Artemisia 

 tridentata was present in all stands with a mean cover of 23%. 

 Gutierrezia sarothrae was present in most stands, but had a mean 

 cover of only 1%. Artemisia nova , Chrysothamnus nauseosus , C. 

 viscidif lorus and Ceratoides lanata are present in some stands. 

 Aqropvron spicatum was present in all stands with a mean canopy 

 cover of 23%. Poa sandberqii and Stipa comata were frequent in 

 ca . half the stands. Aqropyron dasystachyum , Carex f ilif olia and 

 Koeleria pyramidata are common in some stands. Arenaria hookeri , 

 Phlox hoodii , Opuntia polyacantha and Vicia americana are common 

 f orbs . Allium textile is abundant in some stands, and Penstemon 

 eriantherus , Platyschkurhria inteqrif olia and Sphaeralcea 

 coccinea are frequent but never common. Soil lichens are present 

 in most stands, and bryophytes are common in some stands. 



Soils- ARTTRI/AGRSPI is found on moderately deep to deep soils 

 derived from limestone, shale, sandstone or alluvium. Surface 

 gravel is common in some stands and common textural classes are 

 silt, silt-loam and clay-loam. The soil subgroups at our five 

 soil characterization sites included a Ustollic Calciorthid, a 

 Ustollic Haplargid, Ustic Torriorthents, and a Argic Cryoboroll. 

 pH varied from 6.5 to 7.8, and conductivity ranged from 175 to 

 230 uhmos/cm^ (5 stands). 



Other Studies- Knight et al.(1987) describe this type for the 

 adjacent Bighorn Canyon NRA. Jorgensen (1979) , Mueggler and 

 Stewart (1980) , and Hansen and Hoffman (1988) describe an 

 Artemisia tridentata / Aqropyron spicatum for Montana. Similar 

 communities are described for British Columbia, Washinqton, 

 Oreqon, Idaho, Nevada, Utah, Wyominq and Colorado (references in 

 Mueggler and Stewart 1980 and Bourgeron and Engelking 1992). 



Natural Heritage Program Rank- G5/S5 



22. Artemisia tridentata - Atriplex conf ertif olia c.t. 



(ARTTRI-ATRCON, big sagebrush-shadscale) 



(4 stands) 



Environment- ARTTRI-ATRCON occurs on terraces and alluvial fans 

 at 4,200 to 4,700 feet in the outwash plains scuth of the Pryor 



25 



