Vegetation Map of Rare Plant Community Types 



in the Pryor Mountains and Pryor Mountain Desert, 



Carbon County, Montana 



Introduction 



The Pryor Mountains and adjacent desert lowlands of Carbon 

 county, Montana support a diverse array of plant communities 

 rLesic4 et al. 1992). Many of these are rare in Montana, and 

 io^e a?e conildered^lobaliy rare (DeVelice and Vesica 1993) 

 Plant communities are a good surrogate for overall ^^^^^H^j}:.^ 

 diversity (Lesica 1993, Noss 1987, Ryti 1992 . Thus protecting 

 high-guaiity examples of rare plant communities should protect 

 populations of less conspicuous organisms such as invertebrates 

 and fungi. The ability to locate critical plant communities on 

 ?he landscape is essential to managing for biological diversity. 



DeVelice and Lesica (1993) sampled vegetation on lands 

 administered by the Bureau of Land Management (BLM) ^^^.^he Pryor 

 fountains and the desert areas south of the mountains in Montana. 

 They used data from their survey to develop a classification 

 system, and they provided descriptions of the plant communities 

 in addition, they assigned global and state conservation ranks to 

 these communities following Natural Heritage P^°g^^\"^^^^°^^ . ^^ 



(DeVelice and Lesica 1993). Fourteen of the 33 plant community 

 types described were ranked as globally threatened or endangered 



(G1-G3) . 



The purpose of this study was to use the classification 

 system developed by DeVelice and Lesica (1993) to map occurrences 

 of rare plant communities on BLM lands in the Pryor Mountain 

 study area. A secondary goal was to refine the classification 

 system based on observations made in areas that were not sampled 

 during the original study. 



The Study Area 



The Pryor Mountains and Pryor Mountain Desert are described 

 in DeVelice and Lesica (1993), Lesica and Achuff (1992) and 

 Knight et al. (1987). I mapped vegetation north of the Wyoming 

 border and south of the Crow Indian Reservation. My study area 

 was bounded on the east by the Big Horn River and on the west by 

 the Clarks Fork of the Yellowstone River. Within this area, I 

 confined my mapping to public lands administered by BLM. I did 

 nSt attempt to map isolated parcels or areas with large private 

 inholdings. 



Methods 



on June 11-17, 1993 I drove and hiked though the study area 

 and mapped plant community types onto aerial photographs 

 (1:29000) provided by BLM. I mapped ca. 35% the area east of Hwy 



