200 A MANUAL OF FORESTRY. 



Most of these find suitable conditions for multiplying in 

 the presence of dead and dying trees, refuse wood, 

 stumps, &c. Hence it is advisable that all such material 

 should be removed as speedily as possible. 



Where regular thinnings, presently to be prescribed, 

 are carried out, all dead and dying trees are removed at 

 the same time. Such thinnings occur only at certain 

 intervals, and as it would be detrimental in many cases 

 to leave the dead material in the forest until the next 

 thinning comes round, it is frequently necessary to make 

 special cuttings for the purpose of removing it; these 

 are called " dry ivood cuttings" or "cleaning cuttings" 

 In carrying these out, all valuable material should be 

 used or sold, and the refuse, if possible, burned under 

 supervision. If danger from insects be imminent, it may 

 be necessary to remove the stumps of trees as well, or at 

 any rate to cover them with earth. 



B. Pruning. 

 1. Objects of Pruning. 



Where the object of management centres in the pro- 

 duction of valuable timber, in other words of trees with 

 long clean boles, it is necessary for them to lose their 

 side branches up to a certain height from the ground. 

 Trees which grow up in crowded woods lose their lower 

 branches naturally, owing to the insufficiency of light, and 

 this process proceeds up the stem with the elevation of the 

 leaf canopy from the ground. A great difference exists, 

 however, in this respect between the various species 

 of forest trees. Broadly speaking it may be said 

 that, the rapidity with which trees lose their lower 

 branches, in crowded woods, is inversely proportional to 



