River, and in several smaller drainages on 

 the north and east flanks of the Pioneer 

 Mountains, including: Jerry Creek, Quartz 

 Hill Gulch, Canyon Creek and Birch Creek. 

 These sites fall within Beaverhead and Silver 

 Bow counties, Montana. The new sites along 

 the flanks of the Pioneer Mountains extend 

 the range of this species ca. 75 miles to the 

 southeast. The global distribution for this 

 species is shown on Map 1, p. 4. 



I.5.B.I. Populations currently known extant: 



e. Montana: Populations are listed in 



Table 1, pp. 5-6; exact locations are 

 provided on Maps 2-8, pp. 7-13. All 

 twelve extant populations are included 

 in these tables and maps, as additional 

 subpopulation were discovered for the 

 three sites described in the original 

 report. 



I. 6. A. Concise statement of general environment and 



habitat: Populations are now known to occur 

 up to 8,000 ft. in elevation. 



I.e.B.l.b. Regional macroclimate: The long-term weather 

 station nearest to the newly discovered 

 populations in the Pioneer Mountains is at 

 Divide, approximately 11 miles east of the 

 sites, at 5,395 ft. in elevation. For the 

 period from 1951-1980, the July mean 

 temperature was 63.3 F, the January mean was 

 19.1 °F, and the average annual precipitation 

 was 12.39 in. (Department of Commerce, 1982). 



I.6.B.4. Physiographic and topographic 



characteristics: The new sites along the 

 flanks of the Pioneer Mountains occur on the 

 Madison Limestone Formation, comprised of 

 metamorphosed limestone and sandstones, and 

 on the Threeforks Formation, comprised of 

 grayish-brown argillaceous limestone 

 (Richards and Pardee, 1925) . These sites 

 appear to be on substrates similar to those 

 occupied by the Sapphire Range populations. 



I.6.B.5. Edaphic factors: Arabis f ecunda may be 



associated with cryptogamic soil crusts. The 

 initial results of ongoing monitoring and 

 ecological studies in Ravalli County are 

 included in Appendix B, p. 36 (Lesica and 



