15 



5. Edaphic factors: All known sites of Tr i setum 

 or thochaetum are associated with poorly to 

 slightly drained loam soils. It is assumed 

 that these soils have been derived from the 

 parent materials comprising the granitic 

 Idaho Batholith. Only at the Granite Creek 

 North site is the soil slightly better 

 drained; all clusters at the other sites 

 occur in soils which are of a boggy muck 

 nature. The sites occur in an area of 

 Chryochrept-Ustochrep t-Cryor thent Incep t iso Is 

 (moderately sloping to very steep soils on 

 mountains), as mapped by Montagne et_ al . 



( 19S2) . 



6. Dependence of this taxon on natural 

 disturbance: Tr i setum or thochaetum does not 

 appear to depend on natural disturbance or 

 other dynamic aspects of its physical 

 habitat. The level meadow areas and adjacent 

 slopes are stable landforms. 



7. Other unusual physical features: At the 



Granite Creek South and Central sites, 

 Tr i setum or thochaetum is associated with 

 seepage areas at the bases of the adjacent 

 slopes. The extent to which the taxon 

 depends on this water flow, if at all, is 

 unknown . 



Biological characteristics. 



1. Vegetation physiognomy and community 

 structure: Associated with open graminoid 

 meadow communities, which contain a small 

 percentage of forb species. These meadows 

 are surrounded by temperate evergreen 

 conifer forests, dominated by trees with 

 more or less conical crowns. The known 

 sites are on the ecotonal margins of these 

 meadows, where some tree invasion is 

 occurr ing . 



2. Regional vegetation type: Mapped as Western 

 spruce-fir forest ( Picea-Ab ies ) by Kuchler 

 (196^). Occurs near the border between two 

 "Climax Forest Types" mapped by Ross and 

 Hunter (1976): a.) Subalpine 

 Fir/Douglas-f ir /Ponderosa Pine, and b.) 

 Subalpine Fir . 



3. Frequently associated species: 



Pinus contorta Dougl. ex Loud. 



