Diameter-Distribution Yield-Prediction System for Unthinned Loblolly and Slash Pine Plantations on Non-Old-Fields in East Texas

Abstract

Abstract Procedures and methods for a diameter-distribution yield-prediction system for young (4-20 years old) unthinned loblolly (Pinus taeda L.) and slash pine (Pinus elliotti Englem.) plantations on non-old-fields in East Texas are presented. Average height and number of trees are predictors of minimum diameter, arithmetic mean diameter, and quadratic mean diameter. The three measures of diameter are then used to determine the parameters of a Weibull probability density function. After obtaining the function, the number of trees by diameter class can be calculated, and by using individual tree content equations, expected yield by diameter class can be computed. An evaluation of the system indicated that on the average, loblolly pine plantation yields were underestimated by 5.3% and slash pine plantation yields were underestimated by 8.1%. Computer programs written in FORTRAN and BASIC are available from the author for the diameter-distribution yield-prediction system. South. J. App. For. 12(4):239-242