Development of the Vegetation of New York State 115 
tree is blown over. ‘The size and durability of the woody 
structure introduce a factor of slow disintegration and decom- 
position not present in soft herbaceous vegetation. 
Thus, partly by the mechanical factors and effects just 
noted, partly by change of physical conditions as a result of 
forest crown — shading, intercepted air movements, moister, 
cooler air— and of aeration and drainage of the unequally 
built-up substratum, a radically different environment. re- 
sults. To put this significant matter in somewhat technical 
language, the development of a swamp forest results in or 
carries with it a rapid and marked differentiation of en- 
vironment which becomes in effect a stimulus calling forth a 
more diversified or differentiated condition of the plant com- 
munity. The tree trunks, the fallen logs, the elevated places 
about great trees, the depressions, differences of moisture 
and of illumination, of wind exposure, ete., are marks of 
the environment. The segregation into dominant and sub- 
dominant trees, shrubs, tussock forming ferns, swamp an- 
nuals, perennial herbs, vines, ete., including numerous fore- 
runners of climax forests; ground, log, and tree-base cover- 
ing of mosses, liverworts and lichens, and finally, a large ele- 
ment of forest fungi, particularly of wood inhabitating spe- 
cies, indicate fairly the diversity of growth forms and habi- 
tat relations of this diversified type of swamp forest society. 
Types of Swamp Forest. 
In general, the conifer versus hardwood dominance applies 
in swamp forest as under zonal relations we found it to apply 
to the State in general. In the coniferous forest region of 
the Adirondacks, mixed conifer (balsam, black spruce, white 
cedar and tamarack) or pure conifer (especially balsam) 
forests are the rule. In the lower Hudson region these 
species are largely or wholly wanting, the swamp forest 
