52 



A PRIMER OF FORESTRY. 



more or less exx^osed to the sun and wind, and so 

 has become dryer and less fertile than if it had been 

 under cover, and consequently the growth has been 

 slow. But now that the crowns are meeting, the situa- 

 tion becomes wonderfully changed. The soil begins 

 to improve rapidly, because it is protected by the 

 cover of the meeting crowns and enriched by the 



leaves and twigs which 

 fall from them. (See figs. 

 48, 49.) 



THE BEGINNING OF THE 

 STRUGGLE. 



In SO far the condi- 

 tions of life are better, 

 and in consequence the 

 growth, and more espe- 

 cially the height growth, 

 begins to show a marked 

 increase. (See fig. 50.) 

 On the other hand, all the 

 new strength is in im- 

 mediate demand. With 

 the added vigor which the trees are now helping each 

 other to attain comes the most urgent need for rapid 

 development, for the decisive struggle is at hand. 

 The roots of the young trees contend with each other 

 in the soil for moisture and the plant food which it 

 contains, while in the air the crowns struggle for 

 space and light. The latter is by far the more im- 

 portant battle. The victors in it overcome by greater 

 rapidity of growth at the ends of the branches, for it 

 is bj^ growth there, and there only, that trees increase 



Fig. 49.— Group of White Pines (small 

 saplings) in an opening among older 

 trees. Milford, Pa. The lower 

 branches are crowding each other 

 vigorously, and will soon begin to die. 



