VOLUME INCREMENT. 



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increment, than it would have in a free position, the increment 

 of a fairly crowded wood can have, and generally has, a larger 

 increment per unit of area than an open wood, because the 

 total increment is equal to the mean increment per tree 

 multiplied by the number of trees. What degree of density 

 of a wood gives the maximum increment is a question which 

 awaits solution. In the meantime it must not be forgotten, 

 that a fairly crowded condition encourages height growth, 

 decreases the tapering of the stems, and kills off the lower 

 branches, thus producing most valuable trunks. 



While the loss of material is very small in trees grown in 

 the open, it becomes considerable in the case of fully stocked 

 woods. Not only do all the lower branches die off, but the 

 greater number of the trees, of which the wood originally 

 consisted, must be removed by degrees, because they are 

 gradually overtopped, suppressed and finally killed ; these 

 form, ordinarily, the material of which the thinnings consist. 



In fully stocked woods, especially in those treated as high 

 forest, a distinction must be made between the dominant and 

 suppressed trees ; the former may be called the major or 

 primary part of the growing stock and the latter the minor or 

 secondary part. Not only the latter, but also a consideraljle 

 portion of the former will be removed in the thinnings, in 



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