186 



STUDIES OF TREES 



how fast the trees in a forest grow, both in height and 

 diameter, he will know how much wood, in cubic feet, the 

 forest produces in a year, and he can then determine how 

 much he may cut without decreasing the capital stock. 

 The rate of growth is determined in this way: A tree is 



FIG. 126. Bottom Lands Buried in Waste from Deforested Mountains. 

 Wu-t'ai-shan, Shan-si Province, China. 



cut and the rings on the cross-section surface are counted 

 and measured; see -Fig. 124. Each ring represents one 

 year's growth. The total number of rings will show the 

 age of the tree. By a study of the rings of the various 

 species of trees on a given plot, the rate of growth of each 

 species in that location can be ascertained and, by knowing 

 the approximate number of trees of each species on the 



