14. The New York State College of Forestry 
swamp type. White pine as a member of the swamp mixture is 
found occasionally due to slight variation in topography and 
soil site. | 
The soil may be deep or practically lacking, as on some 
boulder formations, but the permanent water table is generally 
so high as to make natural swamps a poor site for tree growth. 
The floor of the forest is spongy with common occurrence of 
sphagnum. | 
Effect of Drainage on Swamp Mixture: 
The typical tree of the undrained swamp is black spruce, and 
any appearance of balsam in the mixture is evidence of a flow 
of water in that area, either by seepage or direct stream drainage. 
The margins of bog swamp areas may have balsam in mixture 
and may be as wet to all appearances as the spruce section of 
the bog, yet there is doubtless movement of water from the 
higher land through the balsam section of the swamp which 
brings about the change of mixture commonly observed. 
The Stunted Spruce and Open Bog: 
Open heath covered bog with stunted growth of black spruce 
occurs over considerable areas of the undrained swamp type. 
A slight rise of the water table in such swamps is soon 
apparent in the loss of vigor and death of the spruce, while an 
equivalent lowering of the water table will result in a distinet 
recovery of the stunted trees and more rapid growth. This 
variation of the commercial swamp type offers possibilities of 
drainage in many places which will react favorably in introdue- 
tion of species from the higher ground. Young birch trees often 
invade this type where drainage permits, but these fail to 
mature or produce dwarfed specimens. ‘The swamp type has a 
normally high percentage of windfall due to the poor root sup- 
port, so that the existing forest is usually young as compared 
with the upland types. The outer margin of the swamp may 
be defined as the line at which a soil layer of depth sufficient 
to sustain mature hardwoods exist above the water table, and 
where the floor of the forest loses its spongy character. Yellow] 
birch appears in commercial size at about this line, and is 
surpassed by the red maple only in ability to take a wet site. 
