Basal Area Growth of Individual Trees: A Model Derived from a Regional Longleaf Pine Growth Study

Abstract

Abstract An individual tree basal area increment (BAI) model for thinned, even-aged stands of naturally regenerated longleaf pine (Pinus palustris Mill.) is presented. The model is an intrinsically nonlinear equation, which is constrained so that it performs within the bounds of biologically reasonable outputs for any combination of values for the independent variables. All parameters in the equation were estimated simultaneously. This is a departure from the more traditional potential-times-modifier approach in which parameters for a potential growth function are estimated from a sample of trees exhibiting the fastest growth. Independent variables used to describe BAI are stand basal area, the competitive position of an individual tree within the stand calculated as the sum of the basal areas of all trees larger than the subject tree, mean age of dominant and codominant trees, and individual tree diameter outside-bark at breast height. Noticeably absent from the model is an independent variable that explicitly characterizes site differences. For. Sci. 40(3): 528-542.