at Silver Star to 11,150 feet at the summit of Torrey Mountain in 

 the Pioneer Mountains. The diverse topography of the area is 

 matched by a diversity of soil parent materials including hard 

 coarse-grained metamorphic rocks, limestone, shale, sandstone, 

 intrusive and extrusive igneous rocks, and valley fill sediments 

 (Veseth and Montagne 1980) . The Pioneer Mountains and the Beaver- 

 head, Gravelly, Snowcrest, and Centennial ranges all featured 

 alpine glaciation during the Pleistocene (Montagne 1972) . 



Climate 



Most of the study area experiences a continental climate. 

 Average annual precipitation varies from over 50 inches at the 

 crest of the Pioneer Mountains to between 8 and 16 inches through- 

 out the bulk of the study area (see sheets 3 and 4 in Ross and 

 Hunter 1976) . The average length of the freeze-free season varies 

 from less than 30 days to more than 70 days at high and low eleva- 

 tions, respectively (see Figure 13 in Montagne et al . 1982). 



METHODS 



Data Collection 



Most field sampling was restricted to ten areas specifically 

 selected by the USDI Bureau of Land Management. The ten areas 

 examined and the survey acreages specified in the assistance agree- 

 ment were as follows: 



1. Centennial Sandhills (2400 acres) 



2. Lime Gulch - Moose Creek (1000 acres) 



3. Sheep Creek - Cabin Creek Slide (1000 acres) 



4. Block Mountain - Hogback (500 acres) 



5. Hahnkamp Island (50 acres) 



6. Nemesis Mountain (100 acres) 



7. Big Hole - Charcoal Gulch (350 acres) 



8. Scudder Creek Exclosure (200 acres) 



9. Johnson Creek Exclosure (200 acres) 

 10. Maiden Rock Exclosure (200 acres) 



General descriptions of each of these sites, including assess- 

 ments of their biodiversity significance, current and past landuse, 

 and suggested conservation management needs, appear in Volume II, 

 Appendix A. In addition to the 10 sites listed above, the site 

 basic records provided in Volume II, Appendix A include eight 

 additional sites not specified in the assistance agreement. 



Within each of these areas, sampling focused on rare or 

 previously undescribed communities and on common communities in 

 particularly good condition. To minimize the confounding nature of 

 heavy disturbance on vegetation occurrence, areas severely over- 

 grazed, herbicide treated, mechanically disturbed, artificially 



