A Mixed-Effects Height—Diameter Model for Individual Loblolly and Slash Pine Trees in East Texas

Abstract A new mixed-effects model was developed that predicts individual-tree total height for loblolly (Pinus taeda) and slash pine (Pinus elliottii) as a function of individual-tree diameter (in.), dominant height (ft), quadratic mean diameter (in.), and maximum stand diameter (in.). Data from 119,983 loblolly pine and 42,697 slash pine height–diameter observations collected on 185 loblolly pine and 84 slash pine permanent plots located in plantations throughout East Texas were used for model fitting. This new model is an improvement over earlier models fit with ordinary least squares, in that it can be calibrated to a new stand with observed height–diameter pairs, thus improving height prediction. An example is provided that describes how to calibrate the model to a new stand with observed data.