THE MONTANE ZONE 137 



spicuous in the mesophytic pine forest, where openings of the 

 forest permit, are Popuhts trichocarpa and Betula papyrifera, 

 often well shaped trees of unusual size. 



The mesophytic forest as disieussed above is essentially the 

 same as the Pacific Coast Humid Transition. It merges by 

 degrees into the Montane or Canadian forest in northern 

 Montana at an altitude of near 4,000 feet. The white pine shows 

 a tendency to ascend the slopes ahead of its usual companions 

 on the lower levels and so in places becomes identified with the 

 mountain forests. 



The Montane Zone. 



The forests of the Montane or Canadian zone are not 

 clearly differentiated from those of the sub-alpine or Hud- 

 sonian. By reason of the occurrence of some trees more 

 abundantly at higher altitudes and the restriction of a few 

 species of herbs and shrubs to the same elevations the areas im- 

 mediately below the highest peaks and ridges have a physiognomy 

 more or less their own, but the trees that constitute the bulk 

 of this so called sub-alpine zone also enter largely into the com- 

 position of the lower belt, if indeed they do not in some places 

 constitute it fully. The same species ^vhich on high and exposed 

 sites are depressed and misshapen may form the main stand of 

 good form and quality a thousand or two thousand feet lower 

 on the mountain side. The species which form the bulk of the 

 Canadian forest zone are Pinus contorta, P albicaulis, Picea 

 EngelmaiUiii and Abies lasiocarpa. An examination of Table 

 20 will show the wide range of vertical distribution of these 

 species and reference to the tables presented under the discus- 

 sion of the sections will show that this feature is not confined 

 to one locality. On the eastern slope of the main Rockies the 

 limber pine (P. flexilis) has also a large part in the forests of 

 this zone. 



At about 4,000 feet one begins to meet occasional representa- 

 tives of the higher mountain flora and with mounting altitude 

 their numbers increase until the level of maximum development 

 is reached. This level is not the same on different ranges nor 

 on different peals of the same range, since the conditions vary. 



