SILVICULTUBAL SYSTEMS. 27 



highest type of forest, full of tall straight trunks clear 

 of branches, and consequently yields a high grade of 

 timber and a large return in money. 



TWO-STORIED SEED FOREST. 



After a forest fire in Maine it frequently happens 

 that the first tree to cover the ground is the popple, or 

 quaking aspen. It is a slender, short-lived tree, intol- 

 erant of shade, with a light crown. After the popple 

 has grown for some years, spruce seedlings spring up 

 under the friendly cover, and rapidly follow the popple 

 in height. There grows up in this way a forest com- 

 posed of an upper and a lower story of growth, in 

 which, as so often happens, the lower story is of more 

 importance. 



The system of Two-Storied Seed Forest is useful 

 when a tolerant tree like the spruce is to be grown 

 under the shade of an intolerant tree like the aspen. 

 In countries where forestry is well developed it is 

 usual to plant young trees of tolerant species under 

 older intolerant trees, to make a cover for the soil and 

 to prevent the growth of grass and weeds. Forests 

 which closely resemble two-storied seed forests are 

 common in the United States, but usually as the result 

 of fire or careless cutting. Such are, for example, the 

 forests of pine over oak in the Southeastern United 

 States, and of birch, beech, and maple under white 

 pine in Michigan, Wisconsin, and Minnesota. It often 

 happens, as in the case of the spruce and aspen, that 

 both stories can not live on in good health together, 

 and that the upper one must die or be cut away if the 

 lower is to prosper. 



