} 31905] LIVINGSTON—RELATION OF SOILS TO VEGETATION 39 
BS 2. Factors of distribution in the lowlands. 
y 
degree the conditions of soil moisture. In this case it seems better, 
however, to arrange the types in the reverse order and to present 
+ them as following conditions of drainage. As has been stated, all 
three types are composed of forms which can withstand a great deal 
of moisture. No positive evidence can be given as to whether or 
| ‘not there is any difference in water content between the soils of the 
open meadow and those of the tamarack-arborvitae forest. Noth- 
ing has been made out regarding the conditions which decide in 
favor of one or the other of these; but the mixed type is always found 
on the better drained portions, where there are hummocks raised out 
of the saturated soil, and where the general level is a few inches 
: higher. Often this better drainage seems to come about merely by 
accumulation of vegetable débris, a fact which suggests that perhaps 
in time the conifer swamp might give way to the mixed, and at last 
possibly to the hardwood upland type. 
Attention has already been called to the fact that this series of 
types have not been seriously altered by the hand of man. The 
large white pines have been taken from the mixed swamps, as have 
also many of the most valuable tamaracks and arbor vitae, but the 
forest conditions have not generally been destroyed. 
| The three types of lowland vegetation seem also to follow in some 
RELATION OF THE VEGETATION TO THAT OF KENT COUNTY. 
The predominance of the pines in the region under discussion is 
an expression of the fact that the flora here is a typical northern one. 
Only one pine (the white) is found in Kent county, and there it 
grows in poorer soil than it holds here. The presence of hickory 
_ and the better growth of the black, red, and white oaks in the more 
southern area is an indication of a more southern flora. The factor 
which keeps the jack pines out of the more southern county may 
be a climatic one; this species occurs with the white pine on the 
dunes at the extreme southern end of Lake Michigan. 
The hardwood forests of the two regions are very nearly the same 
in character. In the northern part of Kent county the hemlock 
begins to be an important tree in this group, as it is farther north. 
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