DISCUSSION 



Recommendations concerning U.S. Forest Service sensitive species 

 designation are based on the following Region 1 criteria: rangewide 

 abundance, distribution within the Region, degree of threat or 

 habitat loss, ecological amplitude, and downward trend (USDA Forest 

 Service Region 1 ranking guidelines, no date) . We considered only 

 those species whose presence on the district has prospective 

 conservation significance, ruling out those rare Montana species 

 which are present in the South Dakota units of the District, and 

 those rare South Dakota species which are present in the Montana 

 units. 



Based on the above critera, we are recommending four Sioux District 

 species for sensitive status, in addition to Eriogonum visheri 

 which is already designated sensitive as known from other Custer 

 National Forest districts. The four species include: 



Asclepias ovalifolia 



Gentiana af finis 



Mertensia ciliata 



Sphenopholis obtusata var. major 



Five Sioux District species are recommended for watch status: 



Aster paucif lorus 

 Carex torreyi 

 Chenopodium subqlabrum 

 Phlox andicola 

 Physaria brassicoides 



Watch status species represent taxa for which there is preliminary 

 but incomplete information available to make a recommendation for 

 designation as sensitive; recognition of watch species is at the 

 discretion of Custer National Forest. The remaining nine species 

 of state concern on the District do not warrant special U.S. Forest 

 Service consideration. 



The majority of the species targets in this study are peripheral. 

 Eight of the original target species are regional endemics or 

 otherwise restricted and possibly vulnerable rangewide; two of 

 these are now documented on the District (asterisked in the 

 following list) : Astragalus barrii , Astragalus paucif lorus , 

 Ceanothus herbaceus , Chenopodium subglabrum , Eriogonum 

 visheri * , Lomatium nuttallii , Physaria brassicoides * , Psoralea 

 hypogaea . Conservation of rare Great Plains species warrants the 

 special attention of land-managing agencies on the Great Plains. 



The isolated escarpments making up the Sioux District units 

 represent significant habitat features on the high plains, with 

 woodland and riparian habitats which are elsewhere rare or absent. 

 This corresponds with a relatively diverse flora of typical Great 



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