216 



WOOD AND FOREST. 



In general, cold affects the foiest just as poor soil and drought do, 

 simplifying its composition and stunting its growth. In Canada there 

 are only a few kinds of trees, of which the hardwoods are stunted ; 

 south of the Great Lakes, there is a great variety of large trees; 

 farther south in the southern Appalachian region, there is a still 

 greater variety, and the trees are just as large; and still farther south 



in tropical Florida, there is 

 the greatest variety of all. 

 Tlie slopes of a high mottn- 

 taiu furnish -an illustration 

 of the effect of temperature. 

 In ascending it, one may 

 pass from a tropical forest 

 at the base, thru a belt 

 of evergreen, broad-leaved 

 trees, then thru a belt of de- 

 ciduous brnad-leaved trees, 

 then thru a belt of conifers 

 and up to the timber line 

 wlioie tree life ceases. Figs, 

 til, and G'3. 



LIGHT. 



^lorc than liy any other 

 factor, the growth of trees 

 in a forest is determined by 

 the effect of light. All 

 trees need light sooner or 

 later, but some trees have 

 much more ability than 

 others to grow in the shade when young. Such trees, of which nutple 

 and spritce are cxamjiles, are called tolcraul, v.hile others, for in- 

 stance, larch, which will endure only a comparatively thin cover or 

 none at all, are called intolerant. The leaves of to'erant trees endure 

 shade well, so that their inner and lower leaves flourish under the 

 shadow of their upper and outer leaves, with the result that the whoh-" 

 tree, as beech and maple, makes a dense shadow; whereas the leaves 

 of intolerant trees are either sparse, as in the larch, or are so hung 

 that the light sifts thru them, as in pojilar and oak. The spruces and 



Fi;^. III). N(}rthei"ii Forest,— You njj Spruce 



G rowing" Under Yellow Birch. Sauta Clara, 



New York. f. S. Forrst Sitrvir,:. 



