FOREST PLANTING IN" THE LAKE STATES 3 
For example, the annual snowfall at Marquette, Mich., is 117 inches, 
as compared with 44 inches at Saginaw. The irregular occurrence 
most commonly in spring and fall, of drought periods of 10 to 20 or 
30 clays, with little or no rain, is characteristic. This is apparently 
a more important factor in forest planting than the quantity or dis- 
tribution of annual or seasonal precipitation in the region. 
Temperatures tend to be lower in the northwestern part than in the 
southeastern part of the region. The annual average at Interna- 
tional Falls, Minn., is 35° F., as compared with 46° at Saginaw, 
Mich. Maxima of 90° to 100° are recorded throughout the region 
almost every summer. The effects of different temperatures, how- 
ever on the length of the growing season, on the amount of frost 
damage, or on the damage from excessive heating of the seedlings 
do not appear to be noticeably different in any part of the region. 
MICHIGAN 
Figure 1. — The northern Lake States region 
Three zones of natural forest growth may be distinguished: (1) 
The spruce-fir forests of the north, (2) the maple-basswood-hem- 
lock and Norway pine- jack pine forests of the central zone, and (3) 
the white pine-oak-maple forests of the southern zone. The tree 
species which have been planted most extensively and which are 
best suited for planting in the region as a whole, succeed in all three 
of these zones. 
The topography of the region varies locally, but does not serve 
to distinguish any one large portion from another, with the possible 
exception of the triangular area in northeastern Minnesota where 
in many places the bedrock is exposed or is covered with only a thin 
layer of soil. The rest of the region is overlaid by comparatively 
thick glacial deposits, which form the confusing array of hills and 
valleys, plains, ridges, swamps, and lakes characteristic of the region, 
and which have much to do with the character of the soil. 
Differences in the soil underlie the differences in the natural forest 
growth and are equally important in forest planting. The soils vary 
widely, from the droughty dune, beach, and outwash sands to the 
clays of the old lake beds and the mucks and peats of the swamps. 
