THE CARE OF TOUKG PLANXATIONS. 113 



(3) The subdued, which are overgrown by both the 

 preceding cLisses. 



'' There is no doubt that the latter class should be taken 

 out entirely, while the first should remain intact, except- 

 ing those trees which are infested with dangerous insects, 

 or have incurable defects in the bark and trunk. In 

 such cases, even dominant but faulty trees should be 

 removed in time, to avoid spreading of evil, and to give 

 the confined trees in their neighborhood the possibility 

 of extending laterally and attaining a larger growth. 



As to class 3, it makes a difference as to what kind of 

 trees are growing in the forest. The lighi-neeiling 

 species require a more open position, and, therefore, a 

 stronger thinning; while the shade-enduring thrive even 

 when they are so closely grown that sunlight cannot fall 

 upon the lower brunches of the trunk, and, therefore, 

 require but a moderate thinning. 



The iQcatiaii has great influence upon the extent to 

 which the thinning out is to be carried. Upon good, 

 fertile soil the gaps and openings made by a more ex- 

 tensive thinning will fill up soon, even if there be a 

 northern or northwestern exposure. But on poor soil, 

 even a small interruption of the density of tlie tree- 

 growth is apt to cause drying up of the soil, spring- 

 ing up of weeds, blowing away of the leaves on the 

 ground — all these being conditions detrimental to tree- 

 growth, and which should be strictly avoided. For this 

 reason the wood-material obtained by thinning out 

 forests upon poor soil, and, which usually is removed 

 at once, is often not taken away, but is left on the spot 

 to fall a prey to the destroying effect of the elements, 

 ythus enriching the soil by the decay of twigs and leaves. 



As to what age the trees should attain before the^ 

 forest is thinned out, we must remember that , the 

 younger trees have a tendency to grow upward rather 

 than to extend laterally. They, therefore, can stand a 



