values in the stand tables, particularly between the horizontal 

 values, change rapidly, interpolation is best accomplished from 

 a curve. 



It should be clearly understood that the percentages given in 

 the stand tables do not hold for any stands that are not normally 

 stocked. That too absolute a reliance should not be placed on 

 the tables even in normal stands is suggested by the fact that 

 the tables give data for 2-inch intervals only. 



DEFINITION AND EXPLANATION OF TERMS^USED 



GENERAL TERMS. 



Age. — The average age of the dominant trees in a stand is 

 taken as the age of the stand. Average age is based on ring 

 counts made on several dominant trees covering a good range of 

 sizes. 



Ring counts may be made on stumps or by taking increment 

 cores at breastheight. In figuring total age, 3 years must be 

 added to the breastheight age of loblolly, shortleaf, and slash 

 and 7 years to that of longleaf . If age determinations are made 

 at a stump height of 1 foot, 2 years is added for total age of 

 loblolly, shortleaf, and slash and 5 years for total age of longleaf. 



Average diameter, breast high. — The breast-high diameter of the 

 tree of average basal area. 



Average dominant tree. — Dominant trees include the codomi- 

 nants also. The average dominant is a tree having a basal area 

 equal to the average basal area of the dominant stand. 



Cords. — Cords are of 4-foot wood. Converting factors from 

 cubic feet to cords are given for trees of different diameters in 

 Table 171. 



Diameter class. — Each inch-class includes diameters 0.4 inch 

 or less below and 0.5 inch or less above the even inch; for example, 

 the 9-inch class comprises all trees 8.6 to 9.5 inches, inclusive. 



Height, total. — Total height is reckoned to the extreme tip of 

 the tallest branch, not simply to the upper limit of utilization. 



One and one-fourth logs. — The smallest tree considered in this 

 bulletin to have a board-foot volume contains one 16-foot log to 

 the top diameter specified (5 inches inside the bark in the inter- 

 national tables, 6 inches in the Scribner tables, and 7 inches in 

 the Doyle tables). Since all 1-log trees would have the same 

 volume, regardless of diameter at breastheight, the shortest trees 

 for which volumes are given contain 1J4 logs. This value is the 

 midpoint between 1 and l}i logs; V-/i logs is the lower limit of the 

 2-log class. Volumes for trees intermediate in log length between 

 those shown in the tables may of course be obtained by interpo- 

 lation. 



Site index. — Sites are designated by the height attained on each 

 by the average dominant tree in a 50-year-old stand; this height 



15 



