Planted longleaf pine individual tree taper, volume, and green weight equations

Abstract Transforming forest inventory data into useful information about a stand requires equations to estimate tree volume and merchantable volume, or green weight. Taper equations that predict diameters at any point on the stem are essential for merchantable volume estimations. Here, we measured taper, total and merchantable volume, and green weight by destructively sampling 324 longleaf pine (Pinus palustris Mill.) trees grown on sites with differing site histories including 11 sites corresponding to former agricultural fields and 9 clearcut areas (formerly stocked with forest). We tested whether there is an effect of stand origin on taper and volume. We fit the measured data to available taper, total and merchantable volume, and green weight models published for longleaf pine plantations and developed updated models fit to the newly collected data. We assessed the updated models fit here to a pre-existing longleaf pine dataset. The best model for stem taper used the Max and Burkhart (Segmented polynomial regression applied to taper equations. For Sci 1976;22:283–9.) form [root mean square deviation (RMSD) = 0.7 cm], the best model for total volume used the generalized logarithmic equation (Abs. Bias = 4.4%), and the best total green weight equation used the Bullock and Burkhart (Equations for predicting green weight of loblolly pine trees in the south. South J Appl For 2003;27:153–9.) form (RMSD = 0.01 kg). Notably, stem taper and volume did not vary with stand origin. The models presented here for individual tree taper, volume, and green weight perform exceedingly well for planted longleaf pine stems grown on old-field and cut-over sites in Georgia.