Comparison of Prediction Equations for Estimating Inside Bark Diameters for Yellow-Poplar, Red Maple, and Red Pine in West Virginia

Abstract

Abstract The ability to predict inside bark diameters was investigated using taper data for red maple, red pine and yellow-poplar from several stands in West Virginia. Inside bark estimates were based on Grosenbaugh's STX prediction equations, a segmented polynomial taper function fitted to inside bark diameter data, an existing polynomial prediction equation published for several hardwood species in this region and a nonlinear prediction equation fitted to the taper data. Grosenbaugh's STX is a computer program for processing tree measurements and includes three equations to allow flexibility and greater accuracy in predicting inside bark upper stem diameters. The nonlinear equation had the smallest overall prediction error in almost all cases investigated. The taper function had the largest error but does not require knowledge of the specific upper stem outside bark diameter. No single STX bark option was found to be optimal for all species or for a single species from two different geographic regions.