Page:Popular Science Monthly Volume 85.djvu/346

342 phenomenon, which has almost no counterpart in the coniferous forests farther south, where fires are nearly always ground-fires, and do not kill the trees outright.

The economic aspects of these northern forests are numerous and varied. The soil and climate are not very favorable for agriculture, so that the farmer, the greatest enemy of forests in this country, has done little damage, and the timber is in no immediate danger of exhaustion. The trees are used to a considerable extent for lumber, and almost as much for pulp-wood; nearly all the large paper mills in North America being located not far from such forests. Logging is nearly all carried on in winter, when the snow facilitates hauling the logs to the nearest river or railroad. The Christmas trees used in northern cities are nearly all brought from the same region. The same forests furnish our spruce gum and Canada balsam, and among them are found the most important peat deposits in North America.

The boreal conifer region is a favorite resort for hunters, trappers, fishermen, berry-pickers, campers, canoeists, hay-fever sufferers, etc., most of whom migrate northward in summer from the densely populated regions a little farther south. At certain times and places mosquitoes and black-flies make life in the north woods somewhat burdensome, but the mosquitoes are at least not of the malarial variety, and poisonous snakes and some other pests are conspicuous by their absence.

The White Pine (Pinus Strobus) ranges from Newfoundland and Manitoba to the mountains of Georgia, and associates with many other trees, mostly hardwoods, in various parts of its range; pure stands of it being the exception rather than the rule. It grows in almost any kind of soil except the richest and poorest, wettest and driest, but seems to prefer that containing a moderate amount of humus. From its distribution we may infer that it is confined to climates where the average temperature is less than 55° F., and the growing season not more than half the length of the year: climates pretty well suited for apples but not for cotton.

This species is rather sensitive to fire, at least when young, and perhaps up to middle age. In northern lower Michigan and doubtless elsewhere there are large areas said to have been covered with white pine forests up to about thirty years ago, when the lumberman came along and felled them. Since then fires, mainly of human origin, have been too frequent to allow the pine to reproduce itself except in protected places like islands and shores of lakes and streams, and the uplands are