CHAPTER X. 



GROWTH OF TREES AND FORESTS. 



The study of the growth of trees and forests is, perhaps, the 

 most difficult one in forestry and it is not proposed to attempt 

 any complete presentation of the subject here. Several tech- 

 nical works, ^ in English and in other languages, can be con- 

 sulted for detailed information. The purpose of this chapter 

 is rather to indicate the various kinds of growth and the general 

 methods of study. For convenience the chapter is divided into 

 two sections: A. Growth of trees; B. Growth of stands. A 

 knowledge of the latter must rest upon a knowledge of the 

 former. 



For scientific purposes foresters speak of increase in volume 

 of a tree or stand as "increment"; and the increase in diam- 

 eter, sectional area, or height, as "accretion"; but ordinarily 

 "growth" is used to cover both terms. The growth of a tree 

 or stand may be the growth of a specific year, when it is called 

 "current annual growth"; or of a specified period of years, 

 called "periodic growth." By dividing the total volume by 

 the age the "mean annual growth" is obtained. 



A. GROWTH OF TREES. 



There are many incentives for the study of tree growth, the 

 chief being to establish a basis for forest-growth studies. For 

 the forester to have a knowledge of the relative rates of growth 

 of the more important species with which he deals is not only 

 interesting, but very necessary. It is also advisable to know 

 something of the relative growth of the same species under 

 different conditions. Height growth is the best indication of 



^ The most important .\merican book dealing with this subject is, "Forest 

 Mensuration," by Graves. Wiley & Sons. 



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