INTRODUCTION 



Passage of the Federal Endangered Species Act of 1973 and 

 subsequent recognition of the value of conserving biotic 

 diversity (Wilson 1988) have resulted in many government agencies 

 becoming active in species conservation. Surveys to determine 

 the location and size of populations of rare species are being 

 conducted on public lands throughout the west. These surveys are 

 necessary in any species conservation program; however, knowing 

 the location and size of populations at any one point in time is 

 only the first step in a long-term protection strategy. (Sutter 

 1986) . Extinction is a process requiring an understanding of 

 population dynamics (Menges 1985) . Periodic inventories can 

 detect trends but will do little to determine causality or help 

 generate predictive hypotheses (Palmer 1987) . Long-term 

 conservation requires a knowledge of many life history parameters 

 including fecundity, recruitment, survivorship, age structure, 

 and population flux. Demographic monitoring techniques can 

 provide information on factors regulating population density and 

 persistence (Palmer 1987). This information, in turn, provides 

 an essential basis for management decisions. 



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, Lesica 

 1992) . 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. 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) . 



Little is known about the life history and demography of 

 Arabis fecunda populations. The purpose of this study is to 

 determine demographic patterns and variability for this rare 

 species and to use this knowledge to recommend appropriate 

 management strategies for conservation. 



METHODS 

 Study Sites 



We conducted our study at Birch Creek and Charleys Gulch in 

 Ravalli County and Lime Gulch and Vipond Park in Beaverhead 

 County, Montana. Both Ravalli County sites are on moderate 



