834 JdrUNAL OF FORESTRY 



pine gives way to spruce. Red maple is also a common tree, aspen is 

 not infrequent, and cherry (chiefly Prunus pennsylvanica, with some 

 P. serotina) is abundant, but seldom reaches tree size. 



Portions of the white-pine association are composed of white pine 

 and red pine, the latter having possibly come in after ancient fires. 

 Here white-pine reproduction, mixed with young spruce and cedar, is 

 abundant, and red-pine reproduction is scarce. There are patches in 

 which spruce predominates, with cedar next in abundance and an occa- 

 sional hemlock; near by are odd mixtures of white pine, red pine, hem- 

 lock, spruce, and cedar all growing together in the main canopy, with 

 dense spruce and cedar reproduction underneath. 



Evidence favors the hypothesis that this white pine-red pine stand 

 with reproduction of white pine, spruce, and cedar is a temporary asso- 

 ciation or stage in a fire-started succession leading to the spruce asso- 

 ciation. But the abundance of white-pine reproduction shows that the 

 final result, though it may be spruce, will yet contain a large propor- 

 tion of white pine. This in itself is an indication of the encroachment 

 of white pine on spruce, and perhaps throws light on how the encroach- 

 ment takes place. 



On some of the rock ledges there occurs a mixture of stunted white 

 and red pine which appears to owe its origin to the poverty of the site 

 rather than to fire. In this kind of forest red oak and gray birch are 

 common associates. 



The understory is far richer in number of species and variety than 

 that of the spruce association. The more conspicuous shrubs are blue- 

 berry (Vaccinium pennsylvanicitm and V. canadcnse L.), huckleberry 

 (Gaylussacia baccata), and sheep laurel (Kalmia an gtisti folia). There 

 is also some wild rose, some blackberry, and a little high-bush blue- 

 berry. 



Occurrence. — The white-pine association grows on warmer, and also 

 perhaps drier, sites than the spruce. The character of the soil seems 

 to be a matter of indifference, and white pine sometimes, though less 

 often than spruce, grows on nearly bare rock. The bare rock of the 

 moister sites is occupied by spruce, and that of the drier sites is too 

 dry for white pine and is left to the pitch pine (Pinus rigida). 



Distribution of Age Classes.— The. association is, in general, approxi- 

 mately even-aged. In mixtures with spruce the pine far overtops all 

 other trees. This does not mean that it is older. Its demand for light 

 compels the pine to dominate or at least to occupy an important place 

 in the upper canopy, its rapid growth enabling it to fulfill this require- 

 inent. The cedar, though shade-enduring and often of the understory, 

 establishes itself in the open with the pine and spruce. 



