IMPROVEMENT CUTTINGS. 71 



consideration. It is seldom desirable, as it lets in too much sun- 

 light and may encourage a growth of grass. Where natural 

 regeneration is practiced, only such openings should be made 

 as will be shortly covered with valuable species. 



Important Principles that Should be Remembered: 



(i) That increase of wood is proportional to leaf surface and 

 therefore the lands should be kept as nearly as possible covered 

 with a canopy of leaves, which should be on trees that are valua- 

 ble for their timber. (2) That leaves need light; therefore 

 partly shaded branches form but little and imperfect wood, and 

 those that are very heavily shaded die out; crowding prevents 

 the formation of branches on trees and is important in securing 

 the best timber. The amount of waste in branchwood varies 

 greatly, it being very much in trees that are entirely open grown, 

 and very little in trees that have been severely crowded. But 

 as over-crowding causes decay it is important to do the thinning 

 as soon as the tree has taken on a proper form. Crowding on 

 one side causes crooks, and these can be prevented by cutting 

 off the crowding tree or branch. 



Waste in Forests occurs, as has been partially stated, in 

 branchwood, crooks, rot, and in growing of the kinds of trees 

 that are not marketable. The kinds that are marketable depend 

 largely oh the demand. In considering this subject it is best 

 to be conservative and to select kinds that are of stable value, 

 and not likely to go out of fashion. Since crowding is best done 

 by small trees among the large timber trees, they should be of 

 a kind that are marketable when small. 



Much waste in timber is caused by cutting trees when small. 

 The amount of waste in the shafts of straight treej, excluding 

 trunks, branches and bark, may vary from eighty-one per cent 

 in a tree eight inches in diameter and ninety feet high, to six 

 per cent in a tree forty inches in diameter on the stump and 

 one hundred feet high. It will thus be seen that there is great 

 loss from cutting trees when small, especially if they are growing 

 rapidly. 



Improvement Cuttings is a term used to signify an 

 improvement of forests by cutting out inferior and crowding 

 trees. This is a very important matter in getting almost any 

 forest tract into a condition where it can be managed to best 



