SHORTLEAF PINE IN VIRGINIA 



21 



Table 2 shows for two stands about forty-five years old the 

 effect of thinning in increased board yield and in the distribu- 

 tion of diameter classes. One is a crowded stand which has never 

 been thinned; the other has been thinned for fifteen years in a 

 desultory manner. Had the thinnings been systematically made, 

 better results would have followed. The large number of trees 

 between ten and fifteen inches in diameter in the thinned stand is 

 noteworthy. 



TABLE 2. 



Effect of thinning on board-foot yield of shortleaf pine and the distribit- 

 tion of diameter classes (two stands about forty-five years old). 



Table 3 shows the average height of the trees in stands at 

 different ages, and the average diameter of all trees in unthinned 

 and irregularly thinned stands: 



