The disturbed sites in the study area which 

 support C. lonaistvlum are vegetated primarily by 

 non-native, invasive species including: 



Carduus nutans 

 Phleum pratense 

 Poa pratensis 



TOPOGRAPHY: Cirsium lonaistvlum occurs primarily in 

 level to gently sloping meadows. Occasionally, 

 particularly in disturbed site populations, the 

 species will be on moderately steep, but vegetated 

 slopes. The species is known from an elevation 

 range of 4680-8000 feet. The Elkhorn Mountain 

 site is at 6920 feet on a very gentle, east-facing 

 slope. Cirsium lonaistvlum sites in the Big Belt 

 Mountains vary in elevation from 5220-7800 feet, 

 and grow on all aspects on level to moderately 

 steep sites in both ridgetop and valley bottom 

 settings, often in positions along run-off zones 

 or above palustrine / riparian habitat. 



SOIL RELATIONSHIPS: Cirsium lonaistvlum is usually 

 found on loamy or silty soils which are at least 

 seasonally moist. Often these soils are gravelly, 

 particularly in disturbed (i.e., roadside) 

 populations. It often occurs in settings with 

 extensive burrowing activity, providing a natural 

 disturbance habitat for establishment. 



REGIONAL CLIMATE: Central Montana has hot, dry 

 summers and cold, snowy winters. The 

 precipitation is greatest normally in May and 

 June, and comes in the form of wet snow and rain 

 (U.S. Department of Commerce 1982). Precipitation 

 is generally heavier in the mountains. The 

 average annual precipitation data from mountain 

 sites in the Elkhorns (Tizer Basin) and the Big 

 Belts (Boulder Baldy) are much higher (27.6 inches 

 and 43.2 inches, respectively) (U.S. Forest 

 Service 1992b and 1992c) than lower elevation 

 sites such as Townsend (3833 feet elevation, 11.11 

 inches), Helena (3784 feet, 11.37 inches), Boulder 

 State School (4904 feet, 11.12 inches), and Holter 

 Dam (3487 feet, 12.02 inches) (U.S. Department of 

 Commerce 1982) . Temperature varies from winter 

 and summer means of 18.1°F and 67.9°F in Helena, 

 24.8°F and 69.9°F at Holter Dam, 19.7°F and 66.8°F 

 in Townsend, and 19.6°F and 65.4°F at Boulder 

 State School (U.S. Department of Commerce 1982) . 

 Temperature is not measured at the mountain sites. 



