288 George E. NicJwls, 



age, the fir reproduction is nearly all composed of large seedlings 

 approximately 1-3 feet in height; young seedlings are scarce," 

 is of interest. As indicated above, parallel conditions have 

 frequently been observed in the lowland climax forests of north- 

 ern Cape Breton. Moore suggests that, "In these cases it 

 appears that the fir came in profusely under a set of environmen- 

 tal conditions different from the present ones .... One of 

 them may have been stronger light than at present. Indications 

 of this were found in the fact that some of these cases of fir 

 reproduction occur in stands which were formerly more open 

 than they are now." In one striking case of this sort, observed 

 by the writer, the abundance of young balsam in a primeval 

 hardwood forest is certainly correlated with the occurrence, 

 about fifteen years ago, of a fire which, while it was not suffi- 

 ciently severe to seriously injure the larger trees, must have 

 resulted temporarily in a considerably increased illumination 

 of the forest floor. Certain it is that the balsam reproduces 

 best and grows most vigorously in well-lighted situations, and 

 there seems to be little question that it is less tolerant of shade 

 than sugar maple, beech, and hemlock. Nevertheless, repeated 

 observations have led to the conclusion that at any rate tolerance 

 alone, even in the broadest interpretation of the term (see 

 Burns '16, pp. 3. 4, 22), cannot be regarded as the cause for 

 the elimination of the balsam. 



(2) It has been suggested by Murphy ('17) that the burial 

 of the seeds of the spruce by a mulch of hardwood leaves may 

 be a very important factor in the suppression of this tree in 

 competition with deciduous trees. That the yearly accumulation 

 of leaf litter on the floor of a deciduous forest is, in a some- 

 what similar manner, responsible for the poor development of 

 the bryophytic ground cover, was a conclusion already arrived 

 at by the writer (see page 284) ; and it seems not impossible 

 that this may also be a factor of some significance as afifecting 

 the reproduction of the balsam fir. 



(3) In the opinion of the writer, however, longevity, in the 

 last analysis, is the critical factor which enables the maple, beech, 

 hemlock and the associated climax trees of the deciduous forest 

 climatic formation of eastern North America to win out in 

 competition with the balsam fir. In this connection, the behavior 

 of the hemlock, as studied in the primeval forests of north- 



