Vegetation of Northern Cape Breton. 287 



is abundantly represented in the younger generation, but is 

 virtually absent from among the mature trees. The absence of 

 mature balsam, however, is far from being the rule. In the 

 majority of cases it grows along with the more southern climax 

 trees, forming an important constituent of the stand, and con- 

 tributing to the formation of the mixed deciduous-evergreen 

 forest which is the prevailing climax type throughout the low- 

 lands. In competition with the deciduous climax trees, however, 

 the balsam seldom retains a position of dominance, and occasional 

 tracts of primeval forest are encountered in which not only all 

 the mature trees, but practically all the younger ones as well, 

 are hardwoods or hemlock. Forests of this sort are essentially 

 similar to the type which formerly prevailed in many parts of 

 southern New England (see Nichols '13). 



In view of the facts set forth above, the query naturally 

 arises : Assuming the climatic conditions to be equally favorable 

 to all the species concerned, why is it that, in competition with 

 maple, beech, hemlock, and the other species which characterize 

 the deciduous climax forest, the balsam fir is unable to hold its 

 own? For obvious reasons this is an important question, and 

 one to which various answers may be suggested. 



(i) The relative tolerance of shade exhibited by the various 

 species concerned, at first thought, seems to afford the most 

 likely explanation. Beech, sugar maple, and hemlock are 

 notably tolerant species: they are capable of successful repro- 

 duction in their own shade. Regarding the tolerance of the 

 balsam fir there seems to be a discrepancy of opinion. According 

 to Cooper ('13, pp. 17-22, 42, 43), the balsam demands abundant 

 light for successful reproduction : "Later in life the young trees 

 can endure severe shading, but for a successful start abundant 

 light seems to be a necessity." Zon ('14, p. 39), on the other 

 hand, states that, "For the first five or six years of its life, 

 balsam will grow in dense shade, but as it develops it demands 

 more and more light." In northern Cape Breton, the sparsity 

 of balsam seedlings • and young trees in many hardwood tracts 

 might well harmonize with Cooper's conclusions, were it not for 

 the fact that in other equally shady forests the young balsam 

 growth is quite abundant. In this connection the observation 

 of Moore ('17, p. 157), made on Mount Desert Island, that, 

 "Under many spruce stands which have reached about middle 



