38 The New York State College of Forestry 
dead stems, the compressed but not disintegrated sphagnum 
and the upper zone of peat. The environment thus created by 
the presence of sphagnum and its accumulated products is of 
a very specialized character. It is permanently wet and this 
fact increases the chance for seed germination and promotes 
constant vegetative multiplication. It is not well aerated and 
this fact entails a train of consequences of disadvantage to the 
associated vascular plants and affects the condition of the sub- 
stratum itself. It is deficient in the mineral constituents which 
one commonly associates with soil. While the nitrogen content 
is high, most of it is in forms not available for plant nutrition. 
It is peculiar in its chemical reaction. The peat soil of the 
Grasse River bog is strongly acid—a condition apparently 
always present in bogs. The temperature has been shown to 
run lower than in mineral soils. (6.) Finally, by reason of 
the peculiarities of sphagnum cells or of the conditions under 
which sphagnum peat is formed there appear always to be 
present chemical compounds or a condition of chemical ele- 
ments actively toxic to plants growing in this substratum. 
(15.)* The total result of these conditions is seen in the 
elimination of species from the habitat and in certain pecu- 
liarities of structure and growth of those tolerant of it. 
Xerophytism and dwarfing are well known phenomena in bog 
plants. It should be moeds however, that these conditions are 
not equally extreme in all phases 4 the sphagnum-peat sub- 
stratum. For example, in the older conifer forest association 
where the massive roots of trees, the fallen logs, stumps, 
uprooted trees and forest debris have elevated and loosened 
up the peat blanket and where there is consequently better 
drainage and aeration, the peat itself is blacker and more muck- 
like (decomposition has progressed farther) and many species, 
including balsam, appear. See list, p. 34. Even in wetter 
portions of the bog, if there is a fairly marked movement of 
the water one finds such marsh species as Calamagrostis cana- 
densis, Iris versicolor and Alnus imcana occupying the sphag- 
num-peat soils. 
* See also Rigg (13) Summary of Bog Theories. 
