PREVIOUS RESEARCH 



Grasslands and shrublands cover about 65 percent of the 

 Montana landscape yet are the most poorly described vegetation 

 types of the state. In contrast, the classification of the forest 

 types of Montana is largely complete. Filling the gap in grass- 

 land/shrubland community type characterization constitutes a 

 primary goal of the Montana Natural Heritage Program's grasslands/ 

 shrublands ecological classification project of which this study is 

 a component. This study constitutes a major and necessary step 

 towards developing a comprehensive classification of all Montana 

 plant communities. 



To date, studies characterizing grassland and shrubland 

 communities of Montana have been of limited geographical and 

 ecological scc.e. The most extensive existing studies include 

 Mueggler and Stewart's (1980) in western Montana, Jorgensen's 

 (1979) and Harvey's (1982) studies in central Montana, the DeVelice 

 et al. (1991) study in northeastern Montana, and Hansen (1985) and 

 Hansen and Hoffman's (1985) work in southeastern Montana. 



The classification of Montana's upland forest plant associa- 

 tions provided by Pfister et al. (1977) has been refined and 

 extended by the work of Cooper and Pfister (1981; 1985), Hansen and 

 Hoffman (1985), Hoffman and Hansen (1981), and Roberts (1980). A 

 comprehensive classifications of Montana riparian sites (including 

 forested, shrub dominated, and herb dominated communities) is 

 nearing completion (Hansen et al. 1991). 



Prior to initiating field sampling, literature review and data 

 from previous research were used to develop a preliminary classifi- 

 cation of southwestern Montana's plant communities. Forested 

 communities in the study area have been largely described by 

 Pfister et al. (1977) and riparian community types have been 

 defined by Hansen et al. (1989). Mueggler and Stewart (1980) 

 provide a relevant classification for the area but emphasized more 

 common communities and predominantly sampled USDA Forest Service 

 lands in their study. The present study is largely an expansion of 

 Mueggler and Stewart's work to include descriptions of rare 

 communities and also extends sampling onto selected BLM lands. 



STUDY AREA 



The study area basically includes the southern portion of 

 Silver Bow County, the western portion of Madison County, and the 

 eastern portion of Beaverhead County. 



Physiography 



The study area encompasses approximately 2.5 million acres and 

 ranges in elevation from about 4,500 feet on the Beaverhead River 



