20. Artemisia tridentata / Agropyron smithii c.t. 

 (ARTTRI/AGRSMI, big sagebrush/western wheatgrass) 



(6 stands) 



Environment- Alluvial fans, toeslopes and terraces in the 

 southwest portion of the study area are often dominated by 

 ARTTRI/AGRSMI. Elevations range from 4,100 to 4,800 feet 

 Adjacent communities include Artemisia tridentata / Agropyron 

 spicatum on better drained soils, v/hile Sarcobatus vermiculatus 

 or Artemisia pedatif ida may dominate on more saline soils. 



Vegetation- This community has a moderately dense shrub layer 1 

 to 3 feet tall and a fairly continuous cover of rhizomatous 

 grasses. Artemisia tridentata was present in but one all stand 

 with a mean cover of 48%. Other shrub species are not common, 

 but Chrysothamnus nauseosus and Sarcobatus vermiculatus were 

 present in some stands. Agropyron smithii / dasystachyum was 

 present in all stands v;ith an mean canopy cover of 27%. Poa 

 sandbergii and Koeleria pyranidata are common in most stands. 

 Forbs diversity is low, but Phlox hoodii and Vicia americana are 

 common in most stands, and Lomatium f oeniculaceum is common in 

 some plots. 



Soils- ARTTRI/AGRSMI occurs on deep soils developed from 

 alluvium. Gravels and coarse fragments are absent, and 

 carbonates are leached well below the surface. The soil subgroup 

 at our single soil characterization site was a Ustollic 

 Haplargid. Surface texture is silt to clay loam. The single pH 

 measurement was 7.4, and conductivity was 210 uhmos/cm" (1 

 stand) . 



Other Studies- Communities dominated by Artemisia tridentata and 

 Agropyron smithii / A. dasystachyum are described for central and 

 eastern Montana by Jorgensen (1979) and Hansen and Hoffman 

 (1988) . The type also occurs in North and South Dakota (Hansen 

 and Hoffman 1988) , Wyoming and Colorado (Bourgeron and Engelking 

 1992) . Throughout all of eastern Montana this community type has 

 low species richness. 



Natural Heritage Program Rank- G5/S5 



21. Artemisia tridentata / Agropyron spicatum c.t. 

 (ARTTRI/AGRSPI, big sagebrush/bluebunch wheatgrass) 



(24 Stands) 



Environment- ARTTRI/AGRSPI is common on gentle to moderately 

 steep (and occasionally very steep) slopes in the outwash plains 

 and foothills of the Pryor Mountains. Occasional examples may 

 also be found v;ell up into the mountains, and elevations range 

 from 4,200 feet to over 6,700 feet This type occurs on slopes of 



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