54 THE PRINCIPLES OF HANDLING WOODLANDS 



ber of sound trees of different diameters. It is then 

 assumed that all trees above a fixed diameter will be cut, 

 and those below it left standing. In practice, the limit 

 is somewhat elastic, but usually the trees left standing 

 above a limit about equal in volume those cut below it. 

 An inspection of the forest shows that the limit will 

 fall within a comparatively narrow range. Thus in 

 Maine it is readily seen that the average diameter limit 

 of spruce will be somewhere between 8 and 14 inches. 

 Accordingly, a computation of growth is made on the 

 basis of cutting to 8, 10, 12 and 14 inches. The limit 

 which shows the most satisfactory returns in volume or 

 in interest on the investment, according to the owner's 

 wishes, is selected as the guide for the cutting. 



This limit may be modified slightly by special sil- 

 vicultural considerations, such as danger from windfall, 

 reproduction, etc. These points have usually a greater 

 bearing on the actual selection of the trees than on the 

 fixing of the average limit. A limitation of cut, based 

 on this method of study, maintains the rate of growth 

 of the forest and guarantees succeeding cuts at short 

 intervals. 



Sometimes it is necessary to begin cuttings before an 

 adequate study of growth can be made. This happens 

 very commonly in the National Forests when time, 

 money, or men have been lacking to make the investiga- 

 tions, and the sales of timber cannot wait for possible 

 later appropriations for such work. In this event the 

 forester aims to cut onlv those mature trees which are 



