INTRODUCTION 



In order to adequately protect populations of an organism, 

 it is necessary to understand its life history and population 

 dynamics (Massey and Whitson 1980, Sutter 1986, Palmer 1987). In 

 addition, many rare species are threatened by interactions with 

 non-native species that have been introduced into their habitat 

 (Drake 1988) . It is important to understand the nature of these 

 interactions in order to protect populations of rare species from 

 extinction. 



Sapphire rockcress ( 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 Range in Beaverhead and 

 Silver Bow counties, Montana (Lesica 1985, Schassberger 1988) . 

 Arabis fecunda generally occurs on steep, often eroding slopes 

 with low vascular plant density. In Ravalli County, populations 

 of A. fecunda are thought to be threatened by livestock grazing 

 and encroachment by an aggressive exotic weed, spotted knapweed 

 ( Centaurea maculosa ) (Lesica 1985, Schassberger 1988) . In Silver 

 Bow and Beaverhead counties, populations may be threatened by 

 mining activity and livestock grazing. 



This report documents the establishment of demographic 

 monitoring transects for Arabis fecunda at two sites in the 

 Pioneer Range, on Beaverhead National Forest lands. 



STUDY SITES 



, Lime Gulch 



Location: Five miles west of Interstate Highway 15, on the 

 north side of Birch Creek Road, approximately 1/4 

 mile up Lime Gulch from the road; T5S RlOW Sec 14; 

 ca. 6,200 ft elevation. 



a. South Transect 



Location: East-facing slope on the west side of the gulch, 

 ca. 20 m up from the bottom. 98 degrees from the 

 start pin to the summit of Limestone Mountain; 204 

 degrees to the summit of the grassy mountain south 

 of Birch Creek Road. The start pin is next to an 

 old juniper stump. 



Line bearing: 21 degrees 



Slope: 16 degrees 



1 



