Southeastern Washington and Adjacent Idaho. 87 



A. oregana is less abundant. As conditions become more meso- 

 phytic in the Larix- Abies community, Usnea dasypoga begins to 

 predominate, while in the climax cedar consociation the trees are 

 often beautifully draped with the long yellow strands of this 

 species. Under such conditions species of Alectoria are not fre- 

 quent. 



Other trees which are more or less important components of 

 these forests are the white pine, Pinus monticola, lodgepole pine, 

 Pinus murrayana, yew, Taxus brevifolia, and Engelmann spruce, 

 Picea engelmanni. 



The white pine, although more abundant and of greater value 

 on the bottom lands of streams in northern Idaho than anywhere 

 throughout its range, is not an important tree in the area under 

 consideration. It occurs only sparingly throughout and where it 

 is best developed on the moister slopes, seldom makes up more 

 than 5 per cent, of the forest and reaches this abundance in only 

 local areas. It appears to require a moister soil than white fir, but 

 its seedlings can stand considerable shading. Perhaps the dry- 

 ness of the climate combined with the ravages of forest fires 

 which may kill it and leave larch and red fir uninjured, combined 

 to make it an unsuccessful tree in this region. 



The lodgepole pine, Pinus murrayana, occurs very sparingly 

 throughout the western forest frontier of the region. Eastward 

 and northward, especially in cut-over and burned-over regions, it 

 assumes considerable importance, occurring in mixture through- 

 out all types of forest, and frequently forming dense even stands 

 over considerable areas. Unlike the yellow pine it seldom plays 

 the role of pioneering in grass land and since it is distinctly a " fire 

 tree " of a weedy nature, it had best be considered in another 

 place. 



Taxus brevifolia is very rare in this region, occurring only oc- 

 casionally along ravines and then taking on only a scrubby form. 

 Its role in the forests of the region is insignificant. 



Engelmann spruce, so characteristic of high mountain slopes 

 elsewhere, while never found in great abundance, is rather a fre- 

 quent forest tree at the highest altitudes, especially in wet ravines 

 and about the edges of alder swamps. It does best in soils where 



87 



