In the Ruby Range, the population of Loniadum attenuatum is on south to southwest facing 

 canyon slopes at 6,240 to 6,400 feet elevation across a range of slope positions from ridgetop to 

 lower slope. The site is within the Wliitecow-rock outcrop complex. 25-90% slope soil mapping 

 unit (USDA Soil Conservation Service 1989). The unstable, well drained, gravelly soil has 

 limestone parent material and supports a Pseudotsuga menziesii/scree habitat type (Cooper et al. 

 1995) with Cercocarpus ledifolins assuming dominance around the eastern subpopulation. The 

 tree canopy, made up of Pseudotsuga menziesii, Pinusflexilis, and Juniperus scopulorum is 

 sparse, and the slopes were logged in the past. Ground cover by grasses and forbs is low and 80- 

 90% of the ground is bare gravel and soil. The vegetation was sampled by a plot and is described 

 under Pseudotsuga/scrce in the Ecological Results section of this report. A photographic of the 

 habitat is provided in Appendix E. This habitat, as represented by the soil series and vegetation is 

 common in canyons in the northeastern Ruby Range. 



POPULATION INFORMATION: Reported population estimates of the nine known Montana 

 occurrences range from a few to over 10,000 plants extending over areas of 5 to 160 acres, and 

 many occurrence records cite additional unsurveyed suitable habitat. In the Ruby Range about 50 

 plants were counted widely scattered across about 10 acres of apparently suitable habitat, but a 

 complete survey was not conducted. 



Lomatium attenuatum is a geophyte which completes its phase of active growth and reproduction 

 early in the season, corresponding with months of cool temperatures and peak rainfall. Most 

 plants had immature fruits at survey dates in late May and early June and mature fruits in July. At 

 the Ruby Range site plants were observed in fruit on July 3, but by August 22 only a couple of 

 dead stalks with aborted fruits were found. Populations are likely to go undetected by late 

 summer surveys. 



Poor seed production was observed in the study area and may be a cause of rarity. Evert (1983) 

 mentions low fecundity in the description of the species from Wyoming, and Montana plants 

 follow this pattern. 



MANAGEMENT CONSIDERATIONS: Current Montana Natural Heritage Program G2/S2, 

 and BLM Sensitive status remain appropriate. Lomatium attenuatum is a globally rare regional 

 endemic with two separate population centers in Wyoming and Montana. The species was 

 recently given higher conservation priority in Wyoming because surveys showed it had a more 

 limited geographic range than previously assumed (W. Fertig, pers. commun.). Populations in 

 Montana may represent the largest numbers and broadest distribution of the species, although it 

 was not known in the state prior to 1993. All Montana occurrences but one are on BLM lands in 

 the Dillon Resource Area. This species warrants special attention as a rare regional endemic and 

 it is recommended that it be made the focus of a species status survey in Montana. 



The 1996 discovery in the Ruby Range is an eastern extension of the known Montana range of 

 the species, but it is unknown whether the occurrence is a small, disjunct population or represents 

 a broader distribution in Madison County. June fieldwork in the Ruby Range only covered the 

 southernmost canyons on the east flank, as far north as Hinch Creek, with negative results. June 

 field survey of the following canyons with potential habitat for Lomatium attenuatum is needed to 

 assess its status in the Ruby Range: Taylor Canyon, Spring Canyon, Porier Canyon, Laurin 

 Canyon, Robinson Canyon, Bouge Canyon. 



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