832 JOURNAL OF FORESTRY 



spruce would fall under this classification. The chief coniferous asso- 

 ciates of the spruce are balsam fir (Abies halsamea), white pine (Pinus 

 strobus), white cedar {Thuja occidentalis), hemlock (Tsuga canaden- 

 sis), and sometimes a little red pine (Pinus resinosa). All of these 

 trees do not occur together with the spruce; all may be present, but 

 sometimes one or more is lacking. Fir, white pine, and white cedar 

 are seldom absent, and hemlock is not uncommon, but is not often 

 found with all the others. The broadleaf associates are red maple 

 (Acer rubrmn), paper birch (Betula papyrifera), yellow birch (Betula 

 lutea), occasional aspen (Populus tremuloides and grandideiitata) , and 

 sometimes, but not often in this locality, a beech (Fagus americana), 

 and still more rarely a sugar maple (Acer saccharum). The propor- 

 tion of broadleaf trees, except beech and maple, appears to bear a more 

 or less distinct relation to the age of the stand, the younger stands hav- 

 ing more broadleaf trees than the older ones. This is but natural in 

 that after a fire the broadleaf trees, especially the light seeded and in- 

 tolerant aspen and birch, have an opportunity to establish themselves ; 

 later the spruce comes up, crowds out the broadleaf trees, and by its 

 dense shade prevents their establishment. The beech and maple are 

 sufficiently shade enduring to be able to compete with the spruce and 

 to maintain themselves in the older stands. On this island beech is 

 fairly common in the older forests ; maple is rare except in the cool and 

 moist ravines. 



The understory, aside from reproduction, varies with the density of 

 the overhead canopy. The commonest shrubs are moosewood maple 

 (Acer pennsylvanicum), hobble bush (Viburnum alnifolium), and 

 mountain maple (Acer spicatum). There are also numerous herbs 

 which alone would give ample material for an extended study in the 

 relation of plants to habitat. 



Occurrence. — The spruce association grows on the poorer rockier 

 sites, often covering areas devoid of soil except for the layer of moss 

 and "duff" derived from plant remains. This layer can often be lifted 

 like a blanket, exposing the bare rock beneath. But though the soil 

 may be extremely poor or even lacking, there must not be strong inso- 

 lation. The association never occupies the warm south aspects, seem- 

 ing to prefer the vicinity of the sea where it gets the fogs, apparently 

 not suffering much from the strong winds. The association, though 

 abundant, does not cover extensive stretches of land, but is constantly 

 interrupted by the white pine or the cedar associations or by burns 

 filled with gray birch and aspen. 



Distribution of Age Classes. — One of the most important features 



