CHAPTER XVIII. 



ESTIMATION OF INCREMENT ON CROPS OF TIMBER. 



IT is a matter of the very greatest importance, for those 

 responsible for the management of woodland areas, to be 

 able to correctly gauge the increment or increase in value of 

 the timber crops under their charge. For, an accurate know- 

 ledge of the increment that is taking place in any crop, in any 

 given year, or that is likely to take place during the next few 

 years, affords, when compared with the present capital repre- 

 sented by that crop, the only data which can show, for the 

 time being, the financial return that is being obtained from 

 the invested capital. Whenever this increment in value falls 

 short of the returns that could reasonably be obtained by 

 investing the capital elsewhere, it will seldom be in accordance 

 with the true principles of forestry, to allow the crop to con- 

 tinue growing in its present condition. In many cases it will 

 indicate that the whole crop should be clear felled ; in other 

 cases, perhaps, a partial clearance of the crop will be indicated, 

 in order to admit of an increased increment on the trees left, 

 which may prove very remunerative. 



The increment in value of any crop may be expressed as 

 the sum of the increment in cubic contents and the increment 

 in the price per cubic foot. 



1. Increment in Cubic Contents. 



One method of ascertaining this increment is to accurately 

 measure the total contents of any crop at two different 



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