48 



5. Edaphic factors: Silene spaldingii occurs on 

 loamy soils which are sparsely gravelly. These 

 soils are very productive, and much of the area 

 in Montana, Idaho, Oregon, and Washington where 

 they occur has been converted for agricultural 

 uses or grazing. 



6. Dependence of this taxon on natural 

 disturbance: None known. 



7. Other unusual physical features: None 

 observed. 



Biological characteristics. 



1. Vegetation physiognomy and community structure: 

 In Montana, S. spaldingii occurs mostly in 

 well-preserved grasslands, at the edges of the 

 lower treeline or near scattered trees. These 

 forested areas are composed principally of 

 Pinus ponderosa (ponderosa pine) and/or 

 Pseudotsuqa menziesii (Douglas fir) . The most 

 common shrub associate was Rosa woodsii (woods 

 rose) . Festuca idahoensis (Idaho fescue) , 

 Festuca scabrella (rough fescue) and Stipa 

 occidentalis (western needlegrass) are the 

 primary grass associates; however, in areas 

 that have been grazed Poa pratensis (Kentucky 

 bluegrass) has become dominant. 



2. Regional vegetation types: Ross and Hunter 

 (1976) place the Tobacco Valley sites in the 

 Foothills and Mountains Silty Range Site, 15-19 

 inch precipitation zone, and list as dominants 

 rough fescue, Idaho fescue, Columbia 

 needlegrass etc. They place the Niarada site 

 in the Foothills and Mountains Silty Range 

 Sites, 10-14 inch precipitation zone, and list 

 as dominants bluebunch wheatgrass, rough 

 fescue, needle-and-thread etc.. Kuchler (1964) 

 places both the Tobacco Valley sites and the 

 Niarada sites in the Western Ponderosa Forest, 

 described as medium to open forest of tall 

 needleleaf evergreen trees with a fairly open 

 ground cover of grasses and occasional shrubs. 

 The Mueggler and Stewart (1980) grassland 

 classification scheme places the S. spaldingii 

 sites in the Festuca scabrella / Festuca 

 idahoensis habitat type. 



3. Frequently associated species: In Montana, 

 associated species include: 



