30 FORESTRY 



A very tolerant tree like the beech, hard maple, or 

 spruce, will start as a seedling tinder heavy shade and 

 grow slowly, in a state of suppression for many years 

 under the old trees. Finally, the old timber falls or dies 

 and the small tree takes on new vigor and grows as rap- 

 idly as if it had never been held back in early youth. This 

 capacity for survival and complete recovery from long pe- 

 riods of shading and suppression give the tolerant trees 

 their chief weapon of attack in the struggle for moist 

 sites. 



Indications of Tolerance in the Form of Trees. The 

 demands of a tree for light are indicated by its form and 

 crown. The best place to study tolerance is in crowded 

 stands, where the struggle for light is most severe. Tol- 

 erant trees may be recognized first, by their dense crowns, 

 with many successive layers of leaves, most of which are 

 partially shaded; secondly, by their presence under the 

 shade of other trees and their survival in such situations. 

 Intolerant trees will have leaves only on the outer por- 

 tions of the crown, arranged so that each leaf gets plenty 

 of light, and small trees will be entirely absent from shad- 

 ed places. It follows, too, that the more intolerant a tree 

 is, the shorter will be its length of crown compared with 

 a more tolerant tree. 



The Formation of Forests of Tolerant Versus Intoler- 

 ant Trees. If a tree is not only tolerant but capable of 

 living to a great age and attaining large sizes, it is well 

 equipped to survive. In some sections, forests are almost 

 never destroyed over large areas at once, either by fire 

 or wind. Such a region is seen in portions of the Adiron- 

 dacks. It is here that extremely tolerant trees like the 

 hard maple, beech and spruce have taken absolute pos- 

 session of the forest, forming a dense stand composed of 

 trees of all ages and sizes. This is the final result of such 

 a struggle when not interfered with by the elements of 

 destruction. But to a much greater degree and over much 



