9. Pseudotsuga menziesii/Cercocarpus ledifolius c.t. G3/S3. 



110 acres 



12. Juniperus osteosperma/ Artemisia tridentata c.t. G5/S2 



670 acres 



13. Juniperus osteosperma /Cercocarpus ledifolius c.t. G3/S3. 



1990 acres 



14. Juniperus scopulorum/ Artemisia nova c.t. G2/S2 



250 acres 



15. Pinus flexilis /Juniperus osteosperma c.t. G2?/S2 



2510 acres 



18. Artemisia pedatifida/Agropyron spicatum c.t. G4/S1. 



240 acres 



25. Atriplex nuttallii/ Artemisia spinescens c.t. Gl/Sl 



310 acres 



26. Artemisia tridentata/ Atriplex nuttallii c.t. G37/S3? 



3080 acres 



27. Atriplex nuttallii /Monolepis nuttalliana c.t. G37/S2. 



720 acres 



30. Agropyron spicatum/ cushion plant c.t. G3/S3 



3970 acres 



31. Chrysothamnus nauseosus/Eriogonum brevicaule c.t. G2/S2 



1540 acres 



BL. Badlands (mosaic of 19, 22, 26, 27) 



2020 acres 



Discussion 



The presence of 11 rare community types makes the Pryor 

 Mountains-Big Horn Basin area one of the most biologically unique 

 areas in Montana. Many of these plant communities are currently 

 known from nowhere else in the world (DeVelice and Lesica 1993). 

 Threats to these communities have been discussed by DeVelice and 

 Lesica (1993). The two high ranking (Gl or G2) plant communities 

 that are currently most threatened are Atriplex nuttallii/ 

 Artemisia spinescens and Chrysothamnus nauseosus/Eriogonum 

 brevicaule. Both occupy very arid and edaphically harsh 

 environments. Vegetation is sparse and not resistant to 

 livestock grazing or invasion by exotics such as Halogeton 

 glomeratus . Management options that minimize the impacts of 

 livestock grazing in these areas should be considered. 



