weeds may obscure the native species, 

 than 25% - about 60%. 



is characterized as open woodland with oak over from less 



This community type is geographically restricted, barely entering Montana. It has not been 

 previously described in the state, but it has been characterized for adjoining Wyoming (Jones 1992). 

 A similar type with Pinus ponderosa codominant with Quercus macrocarpa and Juniperus 

 scopulorum in about equal proportions was sampled by three plots nearby in Montana on the same 

 ridge system (Ecological Consulting Service 1975). That study identified the wetland sedge, Carex 

 viridula, as an important understory element in the plots, but this is a likely misidentification of 

 Carex imps. There is a need for further sampling to sort whether there are one or two plant 

 associations of oak on the Alzada shale ridges. 



Note: Bur oak forest and woodland plant associations are found in the Black Hills (Hoffman and 

 Alexander 1987), and this study area represent the northern extremity of the Black Hills ecoregion. 

 However, the QUEMAC/CARINO plant association is compositionally different from Black Hills 

 oak commimities and the environment is edaphically distinct. 



Soils: The relatively high proportion of the sand fraction (38%) indicates that soils have not been 

 derived from shale alone but are probably influenced by lenses of sandstone. Soil reaction is 

 distinctly acidic as is knovm for some marine shales. 



Comments: This area of shale ridges has been extensively altered by bentonite mining, associated 

 haul roads, and grazing by sheep and cattle. Nevertheless, it is part of the westernmost stand in the 

 continent. Tree genetics research shows that bur oak in the Black Hills shows some attributes of 

 Quercus Gary, a southwestern oak species. 



BLM tracts represent the only portion of the Montana stands on public lands administered by 

 agencies with sensitive species or natural areas programs. The BLM-administered tracts within the 

 Alzada Oaks are said to have been withdrawn from ACEC consideration (Vosen pers. commun.), 

 and land exchanges for high quality oak stands have not been considered to date. We recommend 

 exchanging information with Wyoming to determine if there are any stands documented without 

 exotic annual species, and if there is a mitigation need to conserve this threatened plant association. 



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