Vegetation is predominantly sagebrush steppe, with limestone ridges of sparse grass cover or mountain 

 maliogany scrub, and occasional limber pine and Douglas fir woodland (on sheltered slopes and at upper 

 elevations). Well-developed riparian vegetation is found along the Grasshopper Creek, Beaverhead 



River, and its major tributaries. 



Upper Madison Valley Study Area 



The Upper N4adison Valley Study Area consists of scattered tracts, excluding foothills, along a valley 

 segment of the Madison River in Madison County (Figure 3). This study area is made up of 

 discontinuous BLM tracts, forming an interrupted pattern in comparison to the other study areas. These 

 scattered BLM tracts represent the largest areas of public lands at low elevations in the vicinity. 



Madison River valley bottom and stream terraces are mainly made up of Tertiary sediments and of more 

 recent alluvium, of which the coarse sand, gravel, and cobble is interbedded with imper\'ious layers. 

 Coarse sediments have developed into extremely dry soils, and the impervious layers are associated with 

 springs, seeps, and other wetland features. Elevation ranges from ca. 5000 ft. at the north end to ca. 

 6000 ft. at the north end. 



Vegetation is an arid grassland, interrupted by the above-mentioned wetlands and riparian thickets. 

 Dominant grasses are Agropyron spicatum, and to a lesser extent Stipa comata. These grasses represent 

 an admixture of the Agropyron spicatum/Bouteloua gracilis h.t. and Stipa comata/Bontelona gracilis h.t. 

 (Mueggler and Stewart 1980), with little of the short grass component on the coarse cobble substrate. 

 The ground cover of Selaginella densa is extensive in some areas of the valley, depending on soil texture 

 and land use history. 



