198 INTERMEDIATE CUTTINGS 



Severance cuttings should be made early in the rotation 

 before natural pruning has progressed far, as the development 

 of windfirm individuals is a gradual process. 



Until a forest is organized for continuous production and 

 definitely divided into stands severance cuttings will find 

 slight application. Fire lines developed in the effort to pre- 

 vent and control forest fires will in many tracts serve as 

 severance cuttings, although not recognized as such at the 

 present time. 



Pruning. — This operation removes branches from stand- 

 ing trees for the purpose of increasing the quahty of the final 

 product. 



For the production of clear lumber the death and early 

 removal of all limbs from the main stems of trees are essential. 

 This may be accomplished in the forest naturally by means 

 of the crowding and shading of the individual trees. In fact 

 good natural pruning is the chief advantage of the dense 

 stands. Under certain conditions Nature's process is fully 

 satisfactory and produces a high percentage of clear lumber. 

 It requires great density of stand, with correspondingly slow 

 growth of the individuals and a comparatively long rotation 

 to accomplish nature's results. 



Nothing better can be expected where silvicultural prac- 

 tice must be of a crude and extensive nature. When inten- 

 sive methods are possible, applied silviculture aims to reduce 

 the density of the stand found in nature, with the purpose of 

 obtaining a reduction in the length of time necessary to 

 produce lumber of a given size. (See chapter on Thinnings.) 

 The long rotations, which, in the virgin forest, have accimiu- 

 lated stores of clear lumber developed under Nature's method 

 of pruning, cannot be tolerated in the managed forest due to 

 their poor financial showing. In order to produce a reason- 

 able percentage of clear lumber on a short rotation in stands 



