84 NORTH AMERICA 



Like the tundra, this forest appears to play an impor- 

 tant part in the economy of the animal world, being the 

 summer resort of many migrant species from the south, 

 and the winter refuge of many others from the far north. 

 Its destruction might therefore mean serious trouble for 

 vast numbers of useful birds and mammals, and involve 

 the disappearance of many helpful animal workers. 

 Man is only beginning to realize the cost of recklessly 

 interfering with the established economy of nature. He 

 has often acted in ignorance, or disregard, of the inter- 

 relations between the various sections of the plant and 

 animal world, with serious losses in life, time, and energy 

 for himself. 



Great Lake Region, or South Canadian Forest. 

 In the eastern half of North America, the climates 

 change much more rapidly from north to south than in 

 the west. The belts of vegetation are narrower and 

 follow one another in more rapid succession ; thus the 

 forests which extend east of Winnipeg across the Great 

 Lakes and New England are of a richer type than those 

 of the Hudsonian region. Although more extreme than 

 that of western Europe, and resembling that of Amuria, 

 the climate allows a variety of species of plants to take 

 advantage of all the modifications of soil and other 

 conditions ; hence, while this region is primarily one of 

 conifers, it is distinguished by a large proportion of 

 summer- green, broad-leaf forests. On sand, pine-forests 

 predominate with the Weymouth pine, the pitch pine, 

 and others ; hemlock-spruce forms dark and damp 

 clumps, and on marshy grounds tamarack and cedar 

 swamps are developed. Broad-leaf, summer-green forests 

 prefer richer and deeper soils, and either combine in pure 

 growths or are found interspersed among the conifers. 

 Eight species of oak, one of chestnut, six of birch, two 



