[Chap. LIU THE VEGETATION OF NORTH AMERICA 785 



of Douglas fir and Englemann spruce. This spruce forms the highest 

 belt of widespread forests in the Cordillera. The lodgepole pine grows 

 best in cool moist regions where the Douglas fir belt and Englemann 

 spruce overlap. 



Englemann spruce dominates on cool, moist slopes where there is 

 abundant snow and a long dormant period. In British Columbia these 



Fig. 413. A mature stand of western larch (Larix occidentalis) in the Lolo National 

 Forest, Montana. Photo from U. S. Forest Service. 



slopes are only a few thousand feet above sea level while in Arizona 

 they lie between ten and twelve thousand feet. Associated with the 

 Englemann spruce in various parts of its range are several species of 

 fir, the alpine larch, mountain hemlock, white-bark and bristle-cone 

 pines. Above this belt lie the Alpine meadows, or high mountain tundra, 

 dominated by sedges, grasses, heaths, and low-growing willows, birches, 

 and alders. 



