290 



George E. Niclwls, 



this time it is an old tree. For, while the hemlock at a hundred 

 years is still comparatively young, the balsam is already a veteran, 

 since (at least in northern Cape Breton) it seldom lives to be 

 more than 125 years old. 



To sum up, if it is assumed that the climatic conditions are 

 equally favorable to all the species concerned, the apparent 

 inability of the balsam fir to compete successfully with the 

 species which characterize the deciduous climax forest fomiation 



Figure 13. — Wind-felled balsam fir; Adirondack Mountains, Xew York. 

 The specimen in the background shows the manner in which the trunk 

 commonly splinters. 



can be attributed in large part to its shorter tenure of life, 

 coupled with which are its greater susceptibility to fungus 

 diseases and its less pronounced tolerance of shade. That the 

 climate in this region is favorable to the deciduous climax trees 

 is attested by their vigorous growth and the large size which 

 they commonly attain. That it is favorable to the balsam fir is 

 manifest from the manner in which this tree thrives wherever 

 there is freedom from competition. It should be added that, con- 

 sidering the transition region in its entirety, account must also 

 be taken of climate. Climatic factors without doubt have been 



