192 



Studies in Forestry 



[CHAP. IX. 



On area II to 4-48 inches, or an average diametral increment 

 of 0-48 inches. 



On area III to 4-72 inches, or an average diametral increment 

 of 0-52 inches. 



The actual average increment in basal area was found to be 

 per annum per acre 



Comparing the average annual increment with the total basal 

 area at the middle of the period of five years, the percentage 

 of annual basal increment was found to be 



The obvious conclusions from these data seem to be that 

 in plantations, in which from the very outset each individual 

 plant has a fixed amount of growing-space, the natural process 

 of selection proceeds so much more rapidly than otherwise 

 that 



I. There is less risk of any overcrowding of the leaf-canopy. 



II. Despite the smaller number of stems per acre, the total 



