182 INTERMEDIATE CUTTINGS THINNINGS 



reached and are strictly intermediate cuttings intended pri- 

 marily for application in evenaged stands. The overtopped 

 stand serves as a protective cover which among other pur- 

 poses has the effect of preventing the establishment of re- 

 production under any large openings created in the upper 

 canopy. 



It is estimated that from 10 to 40 per cent of the volume in 

 board feet of the stand can be removed in a selection thinning. 

 The tendency should be to cut lightly rather than heavily. A 

 high percentage of the volume in board feet should never be 

 removed except in stands where only a few of the larger 

 trees have reached sawable size. In such a stand a light 

 cutting might properly remove a considerable part of the 

 board feet volume. 



Borggreve's method has distinct advantages and disad- 

 vantages as contrasted with the other two methods. 



The advantages are: 



1. The thinning returns a greater profit because the trees 

 cut in the main stand are the largest and ordinarily at that 

 moment the most salable trees in the stand. Lumber may 

 be the chief product as compared with cordwood under other 

 methods. 



2. A better quality of timber is produced, because only 

 clean boled, small limbed trees are allowed to remain until 

 the end of the rotation. 



Among the disadvantages may be mentioned: 

 i. The rotation must be lengthened to secure timber of a 

 given size. Since the larger individuals are removed hi the 

 thinnings and trees at one time in the lower crown classes are 

 developed into the trees for the final harvest, it is evident that 

 a longer time will be needed to produce given dimensions. 

 The average rate of growth of the final harvest trees will be 

 slower than under either the ordinary or French method. An 



