SHRUB- and DWARF SHRUB-DOMINATED VEGETATION TYPES 



Artemisia cana /Pascopyrum smithii Plant Association 



(ARTCAN / PASSMI; silver sagebrush / western wheatgrass) 

 MTNHP rank: G4/S4 



Environment: This habitat type occurs on level to gently sloping alluvial terraces receiving surface 

 runoff, and on sandy upland slopes in water collecting positions. It is usually restricted to overflow 

 range sites and is frequent on BLM land in the northwest and southwest comers of the county. It is a 

 relatively dry form of riparian habitat (Hanson et al. 1995). Two plots were sampled as 

 representative of native vegetation, and many more stands were observed with heavy invasion by 

 exotic species. The two plots were in close proximity in the vicinity of Newberry Knob at the north 

 end of the Chalk Buttes. 



Vegetation: The domxmni Artemisia cana is the only well represented shrub in the study area plots 

 with about 20% cover, a reduced value compared to the type as reported elsewhere (DeVelice et al. 

 1995, Hansen et al. 1984, Hansen and Hoffman 1988, Hansen et al. 1995). The herbaceous layer is 

 dominated by grasses with Pascopyrum smithii (syn. Agropyron smithii, Elymus smithii) having 

 about 20-30% cover, again low compared to other studies, and Stipa viridula having about 3-10% 

 cover. The sedge Carex filifolia is present in both plots and well represented in the plot on an upland 

 slope. The exotic grasses Poa pratensis and Bromus japonicus are present to varying amounts in the 

 plots. In contrast to other studies, our plots have relatively high diversity and cover by forbs. 

 Constant in both plots are Achillea millefolium, Artemisia ludoviciana, Echinacea angustifolia, 

 Orthocarpus luteus, Psoralea argophylla, P. esculenta, Ratibida columnifera, Tragopogon dubius 

 and Zigadenus venenosus. 



Vegetation types on adjacent dryer, upland slopes include Pinus ponderosa forests 

 (PINPON/JUNCOM) and grasslands (STICOM/CARFIL). Vegetation in adjacent wetter positions of 

 draws and shaded terrace bottom include woodlands of Fraxinus pennsylvanica and thickets of 

 Symphoricarpos occidentalis, Crataegus succulenta, and Shepherdia argentea. Hansen and 

 Hoffman (1988) sampled three stands of ARTCAN/PASSMI in Carter County in the Long Pines unit 

 of the Custer National Forest. 



Soils: Stands of ARTCAN/PASSMI are most extensive in Carter County on coarse textured alluvial 

 soils. Soil profiles are poorly developed. In areas lacking upland sandstone outcrops, similar lowland 

 positions are usually occupied by grasslands (ELYLAN), big sagebrush (ARTTSW/ELYLAN), or 

 greasewood (SARVER/ELYLAN) communities. In northeastern Montana (Branson et al. 1970) 

 found total moisture stress was less for coarse textured soils supporting ARTCAN/PASSMI than for 

 finer textured soils of nearby stands of ARTTRI/PASSMI. 



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