METHODS 



Ecological Methods 



Preparation for plant ecology studies in Carter County began with compilation of existing 

 information on the vegetation of Carter County, and southeastern counties in general. There is no 

 published literature from BLM lands in the county, and few unpublished reports. We drew from a 

 running compilation of Montana vegetation references started in the work of Bourgeron et al. (1988), 

 with major additions for southeastern Montana represented in vegetation classification studies 

 through the U.S. Forest Service (Hansen and Hoffman 1988) that include information from Carter 

 County. This has been used to produce working drafts of a list of state plant associations 

 (represented in Bourgeron and Engelking 1995) and the start of regional vegetation classifications 

 (e.g., Cooper et al. 1995). 



Systematic survey was planned to include each large area of BLM-administered land, the range of 

 substrates as represented by bedrock geology (Ross et al. 1955), and the observed array of habitat 

 types. Landforms and surface water features depicted on BLM surface management maps 

 (1 : 100.000) and observed in the field were also considered in order to traverse the hydrological and 

 topographic gradients. Finally, U.S.G.S. topographic maps (7.5') and BLM aerial photographs (black 

 and white or color at 1 : 1 5,840) were carried into the field as an aid in determining routes and 

 selecting sites. Bureau of Land Management surface management maps (1:100,000) were used to 

 delimit BLM-administered lands. 



Besides the aerial photographs and other references, we drew heavily upon the road log notes kept by 

 Keith Dueholm of vegetation types encountered in the 1996 field season during sensitive species 

 survey. In addition, we had use of a land-cover map produced by the EROS Data Center (Brookings, 

 SD) from Landsat Thematic Mapper imagery (30 m pixel resolution) that included all of Carter 

 County. It showed the distribution of land cover types, e.g. cropland, forest, grassland; in order to 

 focus sampling in settings of extensive rangeland. 



Vegetation and site characteristics were documented for 52 circular I/IO acre plots according to 

 methodology described in Cooper et al. (1995); see Figure 4 for sampling locations. The criteria for 

 selecting sampling sites included uniformity in the vegetation and setting, relative absence of exotic 

 species, and high condition. Standard MTNHP community survey forms were used to record plot 

 data including location, environmental features (e.g. elevation, slope, landscape position, substrate, 

 and ground cover) and ocular canopy cover estimates (Daubenmire 1 959) for all vascular plant 

 species and common mosses and lichens. We sought to sample high quality condition examples of 

 extensive and rare plant community types. This meant that some uncommon community types were 

 not sampled at all (e.g. Frcainus pemylvanicus woodlands), while other widespread types were 

 undersampled (e.g. Artemisia cana/Pascopyrum smithii). 



We also considered any established study areas that might be appropriate vegetation benchmarks. 

 The two sites in Carter County that were studied as part of the statewide inventory of soils and 

 vegetation at near-pristine sites (Ross et al. 1973) were in the Chalk Buttes. There are also two ^ 



existing exclosures on BLM lands and they were visited in the course of the study, though they were 



% 



