Parameter Estimation for a Shortleaf Pine (Pinus echinata Mill.) Basal Area Growth Model

Abstract

Purpose of this study was to model basal area growth using a system of equations that accounts for tree interdependency within a plot by using seemingly unrelated regression (SUR) to estimate the parameters. A major regression assumption is that the error terms are independent. For Forestry applications, trees within a plot are not indepedent. If the independent observation assumption is violated the parameter estimates standard errors may be underestimated and the mean square error may be overestimated. Using seemingly unrelated regression to estimate the parameters of a system of equations accounts for the correlation between error terms and tree interdepency within a plot.