By integrating a variable-form differential equation for taper, a segmented-stem system of models involving a taper equation, merchantable volume equation, and total stem volume equation results. Through the constraints imposed on the coefficients of integration, the taper model is continuous at the inflection points, and all components in the system are compatible with each other. Models are derived for a bole with two inflection points, but the constant form factor model (no inflection point) and one inflection point segmented model can be obtained as special cases by substituting appropriate parameters directly into this more general model. All parameters are shared by the components in this compatible system. Simultaneous parameter estimation techniques are used so that all appropriate information is obtained from the data. Based on stem analysis data for 1,280 loblolly pine (Pinus taeda L.) trees and 871 slash pine (Pinus elliottii Engelm.) trees, improved predictions result with respect to predicting a stem profile when compared to a constant form factor model. For. Sci. 46(1):1-12.
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