SHORTLEAF PINE IN VIRGINIA 



27 



as farm needs required. Some of these thinned stands were evi- 

 dently somewhat understocked; some were still too crowded; and 

 others, at the time the measurements were made, had not had time 

 to respond fully to the thinnings. It is probable that by sys- 

 tematic thinnings of the kind recommended the yield shown in the 

 tables could be further increased ten or even twenty per cent. 



Table 9 shows the yield of stands which have different 

 numbers of trees to the acre; in other words the yield is of under- 

 stocked, thinned, and crowded stands. The yield is based on cut- 

 ting to nine inches in diameter breasthigh, which is equivalent 

 to about eleven inches on the stump. In the understocked stands 

 the crown cover is practically as complete as in the thinned and 

 crowded ones, but all the trees are low and short-bodied and few 

 slender or dead trees are present. (Plate III). 



TABLE 9. 



Yield of stands of shortleaf pine having different numbers of trees per acre, 

 (influence of density of stands upon yield of saw timber). 



The yield of an understocked stand when more than thirty 

 years old is only about one-half of that obtainable from a fully 

 stocked stand of the same age, after thinning. Many of the trees 

 in open, understocked stands attain a diameter of nine or more 

 inches sooner than do trees in crowded stands, for in crowded 

 stands the continued competition retards the diameter growth of 

 the individual trees. This explains why crowded stands thirty 

 years old are not producing merchantable timber. 



In the average understocked stand the cost of growing the 

 timber is far in excess of its present stumpage price. This is 

 largely due to the small yield. If sold at $2 per thousand board 

 feet, timber from understocked stands pays less than two per cent, 

 on the assumed investment of $5 an acre. 



