IMPROVEMENT CUTTINGS. 71 
consideration. Tt 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: 
(1) 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 on 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 trees, 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 
