28 



SHORTLEAF PINE IN VIRGINIA 



Table 10 shows the influence of density upon the cost per 

 1,000 board feet of growing shortleaf pine stumpage in old-field 

 stands, based on net returns at five per cent., taxes one per cent, in 

 addition, land value $5 an acre. 



TABLE 10. 



Influence of number" of trees, or of density of stand on cost of growing 

 1,000 board feet in old-field stands of shortleaf pine. 



At every age if thinnings are made without loss, the cost of 

 growing stumpage in fully stocked thinned stands is less than the 

 cost of growing it either in crowded or understocked stands. If 

 thinnings do not pay lor themselves the cost is higher, and if 

 they pay a profit, the cost is lower. 



Age of Cutting for Maximum Yield. The maximum annual 

 yield in board feet from trees nine inches and over in diameter 

 breasthigh is obtained from thinned stands when they are cut at 

 forty-eight years of age. At that time in such a stand, the aver- 

 age annual yield per acre is about 410 board feet, and the diameter 

 of the average-sized tree is about 9.5 inches breasthigh, or 11.5 

 inches on the stump. 



For unthinned stands, the maximum anrm-al yield is obtained 

 by cutting when about fifty-seven years old. The average dia- 

 meter of the trees in such a stand is about 8 . 2 inches at breast- 

 height or 9.8 inches on the stump. Table 11 shows the yearly 

 increment in board feet of trees nine incnes and over in diameter 

 breasthigh. 



