262 THE STUDY OF PLANT COMMUNITIES • Chapter X 



cover is sparse and made up largely of dwarf Vacciniums, while 

 the moister west slope has an abundance of bryophytes and herbs. 

 Northward, the bryophytes increase until they practically cover 

 the ground, and the vascular plants, both herbs and shrubs, also 



increase. 



The most conspicuous succession in the subalpine zone follows 

 fire and may result in subclimax stands of lodgepole pine (Finns 



FIG. 132. Dense aspen stand (Populus tremidoides) that came in after fire 

 in the subalpine zone in New Mexico. Spruce reproduction underneath.— 

 U. S. Forest Service. 



contorta var. murrayana), aspen (Populus tremidoides), or Doug- 

 las fir (Pseudotsuga taxifolia). Progression to climax is extremely 

 slow. Lodgepole pine is absent in the southern Rockies, but else- 

 where aspen is favored over the pine on moist sites, and after light 

 fires it has an advantage, probably because of its ability to regen- 

 erate from sprouts. Near timber line, burned areas are revegetated 

 directly by climax. 



