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CHAPTER IV. 



THE NORMAL GROWING STOCK. 



It has been stated at page 173, that by the normal growing 

 stock is understood that present in a forest, which has a normal 

 proportion of age classes and a normal increment. This being 

 so, the forester need only see, that the age classes and incre- 

 ment are normal, and the normal growing stock will be present 

 as a natural consequence. 



It happens, however, that, as far as quantity is concerned, 

 the normal growing stock may be present, if neither the 

 normal age classes or increment have been established ; for 

 instance, if the deficit in one age class is made good by a 

 surplus in another. If, in such a case, an annually equal 

 quantity of wood were cut, it would lead to a deviation from 

 the normal final age and consequently to loss. Indeed, the 

 normal growing stock, according to quantity, might be present, 

 if the whole forest consisted of only one uniform age class of 

 about half the normal final age. In that case, no ripe w^ood at 

 all would be found in the forest, and cuttings would have to 

 be suspended for a considerable number of years. 



Under these circumstances, the normal growing stock by 

 itself is of subordinate importance in determining the yield of 

 a forest, and yet it is useful to look at its determination for 

 the following two reasons : — 



(1.) Because the yield, taken out of a forest in the course of 

 a rotation, consists partly of the growing stock, which was 

 present at the beginning of the rotation, and partly of in- 

 crement added to that growing stock during the rotation. 

 (2.) Because several methods base the calculation of the 

 yield upon the difference between the normal and real 

 growing stock. 



F.M. Q 



