Abstract
Three whole stand equations were evaluated for best prediction performance of loblolly pine volume and green weight in three physiographic regions of the Western Gulf through age 15 using remeasured permanent research plots from a spacing study. The equations evaluated are two nonlinear forms of the Schumacher yield equation that predict yield from dominant height, stand basal area, and age with or without stand tree density, and a logistic parameterization of the Chapman–Richards equation that uses only basal area and age. The nonlinear form of the Schumacher yield equations (Equations 2 and 3) performed better than the Chapman–Richards model (Equation 4), indicating a more appropriate mathematical model to describe forest yield. The sixfold cross-validation residual standard error for volume prediction in the Lower Coastal Plain, Upper Coastal Plain, and Interior Flatwoods was 109, 179, and 71 cubic feet per acre, respectively. The residual standard error of green weight prediction for the Lower Coastal Plain, Upper Coastal Plain, and Interior Flatwoods was 4, 2, and 3 tons per acre, respectively. The presented whole stand yield models provide physiographic region-specific estimates of yield for genetically improved loblolly pine under intensive management regimes.