THE BASIS FOR FOREST MANAGEMENT 37 
duction of the Spruce be simplified, but on lands where 
the hardwoods have possession the cuttings can be so 
directed that the inferior species will greatly decrease 
in the new crop. 
THE EFFECT OF THINNING 
The advantage of conservative lumbering is, how- 
ever, not confined to the protection of young trees and 
the encouragement of new growth. The trees which 
remain after lumbering may be made to grow more 
rapidly than before. 
When a piece of ground is fully covered with forest 
trees, the latter stand so close together that they 
crowd each other, and a struggle follows in whichsome 
trees are suppressed and checked in their development 
and others are so shaded that they die, and the rate of 
growth in diameter of every individual in the forest 
falls behind that of trees in like situations in the open. 
But while the rapidity of growth of the individual 
tree is less, the total product is greater than it would 
be if the ground were covered with scattered trees 
only, and it is far better in quality, for in the deep 
shade of crowded woods the lower branches of the 
trees die and fall off, and long trunks clear of knots are 
produced. 
It has been found that when a crowded stand is 
thinned the trees which remain grow more rapidly 
than before. This accelerated growth is caused : First, 
by the more rapid disintegration of the humus and the 
consequent liberation of an increased amount of availa- 
