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 occurs on eroding slopes with low vascular plant 

 density. Often these sites have a relatively high cover of 

 cryptogamic soil crust. In Ravalli County, populations of Arabis 

 fecunda are thought to be threatened by livestock grazing and 

 encroachment by an aggressive exotic weed, spotted knapweed 

 ( Centaurea maculosa) (Lesica 1985) . 



This paper is a progress report on two studies being 

 conducted on populations of Arabis fecunda in Ravalli County. 

 The studies and their purposes are: 



Study 1. Long-term monitoring of Arabis fecunda 



populations. Purpose: Determine important life 



history attributes, and determine trends in 



overall recruitment and mortality. 



Study 2. Spotted knapweed removal study. Purpose: 

 Determine the effects of spotted knapweed 

 competition on the reproductive performance and 

 survivorship of Arabis fecunda . 



METHODS 



Study Areas 



We conducted our studies at two sites in Ravalli County, 

 Montana: Charleys Gulch and Birch Creek. The Charleys Gulch 

 site is on a steep, eroding, southwest-facing slope along the 

 gulch at an elevation of ca. 5,000 ft. (T6N R19W S29, NWl/4). 

 The Birch Creek site is on a steep, eroding, southeast-facing 

 slope above the creek at an elevation of ca. 4,700 ft. (T7N R19W 

 S16, NWl/4) . More complete descriptions of the study sites can 

 be found in Lesica (1985) and Schassberger (1988) . 



