A COMPATIBLE VOLUME-TAPER MODEL-BASED ON THE SCHUMACHER AND HALL GENERALIZED CONSTANT FORM-FACTOR VOLUME EQUATION

The generalized constant form factor volume equation fitted in logarit hmic form by Schumacher and Hall (1933) has a logical basis in solid g eometry. By extension of this rationale to a consideration of stem tip volume above a specified top diameter, compatible models for inside- and outside-bark variable-top volume and stem taper are derived and fi tted with data from 872 plantation grown slash pine trees. The volume equations predict total volume when upper diameter is zero and always predict nonnegative volumes for any upper diameter. The taper curves h ave inflection points near dbh and are constrained to diameters of 0, dbh, and stump diameter when merchantable height equals total height, 4.5 ft and stump height, respectively. Statistics of fit on an indepen dent subset of the data suggest that the outside-bark model compares f avorably to a recently published compatible taper and volume model bas ed on polynomials.