178 



CHAPTER I. 



THE INCREMENT. 



EVERY tree or wood may lay on three different kinds of 

 increment, namely : 



1. Quantity or volume increment. 



2. Quality increment. 



3. Price increment. 



SECTION I. QUANTITY INCREMENT. 



By quantity increment is understood the increase in the 

 volume caused by the growth of a tree or a wood. It is 

 measured by the cubic foot solid, or the cubic foot stacked. 

 The different kinds of quantity increment and the modes of 

 measuring them have been explained 'in Forest Mensuration, 

 p. 82. For the purpose of working plans it must be added 

 that for short periods, say 5-10 years, the periodic mean annual 

 increment can be put equal to the current annual increment, 

 without any appreciable error. 



The calculations of increment may refer to the final yield 

 only, or to the intermediate yields, or to both together. 



In the tables at pages 188 to 191, the various classes of in- 

 crement have been calculated separately for final, intermediate, 

 and both yields together. 



1. Progress of Volume Increment. 



a. Of Single Trees. 



The volume increment is produced by an annual elongation 

 of the crown and roots, and by the laying on of a new layer 



