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and light. 
The answer to the second question involves 
the consideration of the relative physiological response 
of other species, especially maple and yellow birch, to the 
conditions imposed by the dominant hemlock. Hemlock and 
sugar maple, are the most conspicuous examples in the lake 
Region of what Fro thing ham calls intensive reproducers, 
i.e., species which are more aggressive inside than outside 
the forest. The effective aggressiveness of each species 
i3 due to a oonbination of factors. Both species, when 
growing under forest conditions, are likely to have a 
suppressed period of growth for at least the first 50 years. 
Quadrat studies show a great variation in age of individ¬ 
uals, even among the adult trees forming the forest crown, 
mature trees varying from 100 to 300 years or more. One 
hemlock, measuring about 1 m. in diameter, was estimated 
at over 400 years. The greatest tolerance of maple, how¬ 
ever, seems to be in the seedling stage, quadrat studies 
often showing hundreds of seedlings in the dense shade of 
the hemlocks. On the other hand, the seedlings of hemlock 
are rather critical in their light requirements, being 
killed by too much or too little shade. In general, they 
grow more abundantly in the more open part of the forest, 
but not necessarily in a windfall. 
