FOREST REGENERATION" AND TREATMENT. 77 



careful consideration. It is seldom desirable, as it lets 

 in much sunlight and may encourage a growth of grass. 

 Where natural regeneration is practised, only such open- 

 ings should be made as will be shortly covered with valu- 

 able 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 valuable 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 branchv/ood 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 overcrowding 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 consider- 

 ing 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 dian> 



