FOREST AND WOODLAND VEGETATION TYPES 



Juniperus scopulorum / Oryzopsis micrantha Plant Association 



(JUNSCO / ORYMIC; Rocky Mountain juniper / little seed ricegrass) 

 MTNHP rank G3/S3 



Environment: This is a localized woodland type that is found in breaklands and badlands 

 topography. It was sampled in one plot on highly dissected shale uplands above Keith Creek, a 

 Powder River tributary in west-central Carter County, where it is confined to moderate to steep 

 slopes with northerly aspects. It is considered a topographic climax type and has been found by 

 Hansen and Hoffman (1988) on similar exposures but with sandstone parent materials on the Custer 

 National Forest, as well as on porcellainite ("scoria"; Girard et al. 1988). It is susceptible to fire 

 under any bum regimes. We observed additional stands of JUNSCO/ORYMIC confined to north 

 aspects on BLM land in the badlands and breaklands of northeastern and southeastern Carter County. 

 Hansen and Hoffman (1988) also sampled plots of JUNSCO/ORYMIC in Carter County on the 

 Long Pines unit of the Custer National Forest. 



Vegetation: The sampled stand has 80% canopy cover by Juniperus scopulorum, forming dense 

 stand conditions with many low, stiff branches. Like virtually all other Rocky Mountain juniper 

 stands, it was logged in the past for fence posts. Moderately high cover (30%) by the palatable 

 bunchgrass Oryzopsis micrantha, the absence of the bunchgrass Agropyron spicatum, rich forb flora 

 and the nearly closed canopy distinguish this association from other Rocky Mountain juniper types. 

 It has a surprisingly mesic environment for a shale slope. Together with absence of livestock use, 

 there is a relatively high diversity of forbs, including species not found in other local habitats that are 

 indicative of mesic conditions (Campanula rotundifolia, Geum trijlorum, Maianthemum stellata and 

 Heuchera richardsonii) . These same species were also found in stands of JUNSCO/ORYMIC 

 nearby on the Custer National Forest (Hansen and Hoffman 1988). The plot has 20 % combined 

 ground cover of moss and lichen which is accord with Hanson and Hoffman (1988) findings for 

 southeastern Montana and Girard et al. for North Dakota (1988). Despite substrate differences, this 

 stand on shale closely resembles in overall physiognomy and floristics those on the Custer National 

 Forest which are on sandstone. It is also quite similar to stands sampled in northeastern and central 

 Montana (Culwell et al. 1986, DeVelice et al. 1995, Heidel 1996). 



The stand has a well-developed undergrowth (about 70% cover) by the low shrub Mahonia repens, 

 which Hansen and Hoffman (1988) consider a serai element in this habitat type of the Ashland 

 District where it is accidental or at the edge of the community rather than throughout the interior. 

 This shrub is not found in this plant association in adjoining states. In light of this component and 

 the exceptionally well developed Rocky Mountain flora, the JUNSCO/ORYMIC stands in this area 

 of the state are a priority for more sampling. 



Adjacent steeper, more eroded slopes have small patches of Artemisia longifolia communities, and 

 warmer aspects are nearly devoid of vegetation. Draw and gully bottoms are dominated by 

 rhizomatous wheatgrass {Elymus lanceolatus or Pascopyrum smithii). Nearby woodlands have 



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