SILVICULTURAL NOTES. 



35 



Table No. 11. — Per cent of sapwood in the merchantable contents of Shortleaf and 

 Loblolly Pine, for diameters from 24 to 32 inches, breasthigh. 



The growth of the Loblolly Pine can best be understood by a study 

 of the curves of the various diagrams. Most of these will be found in 

 the figures already given for Shortleaf Pine. The curves for both 

 species are shown on the same diagram, that the two may be more 

 readily compared. 



Relation of age to diameter. — (See fig. 5.) The curve for Loblolly 

 Pine here shows a much more rapid growth than that of the Shortleaf. 

 For the first one hundred years the average time required to grow 1 

 inch is four and one-half years. If the cutting limit be placed at 12 

 inches, it will be seen that Loblolly reaches a merchantable size when 

 44 years old. or eighteen years earlier than the Shortleaf. 



Relation of age to height. — (See fig. 6.) The height growth for 

 Loblolly is rapid and very uniform for nearly forty years. After this 

 age the rate gradually diminishes. For the first one hundred years 

 the yearly average growth in height is 1.04 feet. As can be seen from 

 the two curves, there is very little difference in the height growth of 

 the two species tor the first twenty year-. 



Relation of age to merchantable contents. — (See fig. 7.) The volume 

 curve here given for Loblolly Pine is seen to be very nearly a straight 

 line. The rate of increase in merchantable contents is remarkably 

 uniform. The upper portion of this line is dotted, because so very few 

 Loblollies over 160 years of age were analyzed that the results can 

 not be accepted as conclusive. It is probable that in practice the 

 actual contents of the older trees would be somewhat less than is here 

 shown. Between the ages of 44 (when the Loblolly reaches a diameter 

 of 12 inches) and loo years, the average yearly increase m merchant- 

 able contents is 9.28 board feet per tree. 



Relation between diameter, total height, merchantaHt length, crown 

 length, and clear length. — (See fig. 9.) In trees from 15 to 30 inches 

 in diameter the merchantable length increases quite rcgularlv as the 

 diameter becomes larger, but in trees above 30 inches the length of 



