Predictive Ability of Mixed-Effects Height-Diameter Models Fit Using One Species but Calibrated for Another Species

Mixed-effects individual tree height-diameter models are presented for important pines in the Western Gulf, USA. Equations are presented for plantations of loblolly (Pious taeda L), longleaf (Pious palustris P Mill.), shortleaf (Pinus echinata Mill.), and slash (Pinus elliottii Engelm.) pine. To produce localized individual tree height estimates, these models can be calibrated after obtaining height-diameter measurements from a plot/stand of interest. These equations can help answer an interesting question of whether a model fit for one species can be calibrated to produce reasonable height estimates of another species. In situations where mixed-effects models have not been developed for a particular species, perhaps an equation from another species can be used. This question was addressed by calibrating these models using independent data of loblolly, longleaf, and slash pine plantations located in South Carolina. For each calibration species, in addition to the models developed described above, previously published models, but of the same model form, fit using other species from across the USA were examined. Results show that models of a variety of species can be calibrated to provide reasonable predictions for a particular species. Predictions using this particular model form indicate that model calibration is more important than species-specific height-diameter relations.