Equations for estimating loblolly pine branch and foliage weight and surface area distributions
Equations to predict foliage weight and surface area, and their vertical and horizontal distributions, within the crowns of unthinned loblolly pine (Pinus tueduL.) trees are presented. A right-truncated Weibull function was used for describing vertical foliage distributions. This function ensures that all of the foliage located between the tree tip and the foliage base is included. Foliage distribution prediction is based on actual two-dimensional foliage location. It is shown that the average time of full foliage, and hence average foliage weight or surface area prediction, is highly variable for loblolly pine and subject to considerable error. To help account for the old and new foliage differences during the approximate time of "full leaf," the prediction equations for new and old foliage weight and surface area include a day-of-year term. New equations to predict branch weight, surface area, and the vertical distributions of branch biomass and surface area were also developed. The vertical distributions of branch biomass and surface area are described with logarithmic equations constrained to equal zero when relative crown depth is equal to zero, and to equal one when relative crown depth is one.