INTRODUCTION 



Arabis fecunda Rollins is a rosette-forming perennial in the Mustard Family 

 (Brassicaceae). This recently described species (Rollins 1984) is endemic to highly calcareous, 

 azonal soils in the foothills of the Sapphire Range in Ravalli County and in the Pioneer and 

 Highland ranges of Beaverhead and Silver Bow counties, Montana (Lesica 1993). Arabis 

 fecunda generally occurs on steep, often eroding slopes with low vascular plant density. Arabis 

 fecunda is considered threatened in Montana (Lesica and Shelly 1991) and is listed as a sensitive 

 species by the U.S. Forest Service and the Bureau of Land Management. 



Most sites at which Arabis fecunda occurs are grazed by livestock, but little is actually 

 known about the effects of livestock grazing on this rare species. Studies have shown that A. 

 fecunda is more common on soil occupied by cryptogamic soil crust (Lesica and Shelly 1992). 

 These crusts are easily disturbed by livestock grazing; consequently, grazing may reduce A. 

 fecunda populations at these sites (Lesica and Shelly 1992). Furthermore, A. fecunda often 

 occurs on steep slopes with unstable soil. Trampling by livestock could reduce the number of A. 

 fecunda plants on these slopes. On the other hand, A. fecunda seems to require open soil for 

 seedling establishment (Lesica and Shelly 1996) and may be facilitated by disturbance associated 

 with grazing at some sites. The purpose of this study is to determine the effects of livestock 

 grazing on populations of Arabis fecunda. on the north side of the Pioneer Range. 



STUDY SITES 

 Quartz Hill : From Dewey travel west on Hwy 43 ca. 0.3 miles and then turn south on gravel 

 road (Beaverhead Forest Road #187). Proceed ca. 1 mile up the road. Exclosure is on a steep 

 hillside west of the road (T1S R10W S8 NW1/4 of SE1/4). Aspect: 95°, Slope: 40° Elevation: 

 5,900 ft. 



Thompson's Corner : From Dewey, travel west on Hwy 43 ca. 3.2 miles and then turn north on 

 gravel road (Beaverhead National Forest Road #83). Continue ca. 0.2 miles and turn east on a 

 small dirt road along the north side of the Big Hole River. Continue ca. 2 miles. Site is on the 

 north side of the road on the west side of a small draw. T1S R10W S5 NW1/4 of NW1/4. 

 Aspect: 100°, Slope: 20°, Elevation: 5,600 ft. 



Dewev Cemetery : From Dewey travel west on Hwy 43 ca. 0.3 miles and then turn south on 

 gravel road (Beaverhead Forest Road #187). Proceed ca. 0.5 mile up the road to just past the 



