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 1985, 1992, Schassberger 1988). Arabis 

 fecunda generally occurs on steep, often eroding slopes with low 

 vascular plant density. Arabis fecunda is a candidate for 

 listing as a threatened or endangered species by the U.S. Fish 

 and Wildlife Service (USDI-FWS 1990) and is considered threatened 

 in Montana (Lesica and Shelly 1991) . 



Most sites at which Arabis fecunda occurs are grazed by 

 livestock, but little is actually know about the effects of 

 livestock grazing on this rare species. Recent 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, submitted) and may be 

 facilitated by disturbance associated with grazing. 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 



Locations of the study sites are shown in Figure 1. 



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 (TIS RlOW S8 NWl/4 of SEl/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. TIS RlOW S5 hfWl/4 of.NWl/4. 

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



Dewey Cemetery : From Dewey travel west on Hwy 43 ca. 0.3 miles 

 and then turn south on gravel road (Beaverhead Forest Road #187). 



