An annual tree survival and diameter growth model for loblolly and slash pine plantations in east Texas

摘要

An annual growth model that predicts individual tree survival and diameter growth was developed for loblolly pine (Pinus taeda) and slash pine (Pinus elliottii) trees in East Texas as a function of individual-tree diameter, plantation age, basal area per acre, dominant height, quadratic mean diameter, and presence of fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme). Data from 104,035 loblolly pine and 37,515 slash pine individual tree observations collected on a 3-year cycle from 174 loblolly pine and 80 slash pine permanent plots located in plantations throughout East Texas were used in this study. The survival equation assumes that mortality is constant across the projection length, whereas the diameter growth equation incorporates whole-stand predictions to update stand-level independent variables on an annual basis. Predictions were evaluated in terms of bias and precision, with independent observations for projection lengths from 3 to 24 years. For both survival and diameter growth, bias was lowest and precision highest for 3-year projection lengths. For survival, bias increased and precision decreased as projection length increased through 24 years. For diameter growth, bias was constant (1 in.) across all projection lengths, whereas precision decreased from 11 in. for the 3-year projection length to 2 in. for the 6 - 24 year projection lengths. A numerical example is provided that describes how to use the new model to project individual tree survival and diameter growth on an annual basis.