Short-term predictions of growth of Pinus radiata with models incorporating indices of annual climatic variation

Data for Pinus radiata D. Don grown in the Australian Capital Territory (AC T) are used to show that annual indices of growth potential can be successf ully incorporated into Schumacher projection models of stand basal area gro wth. A Monte Carlo method is used to avoid problems arising from correlated errors in repeated measures data and to compare predictions made with the various models. Incorporation of climatic indices into the Schumacher model increases bias in the predictions. This is not statistically significant f or predictions over a I-year period, but can become significant as the pred iction period increases to 5 years. The effect of bias in the model can be successfully reduced by correction with a ratio estimator derived from the sample. Predictions of annual basal area increment made with models contain ing climatic indices after correction for bias in the model were less biase d and more accurate (23%) than those obtained with the basic Schumacher mod el. The magnitude of this advantage declines as the prediction period is ex tended to 5 years. The new models improve the descriptive power of the Schu macher model and open up new avenues for forest modelling. They are particu larly applicable for making short-term updates of forest inventories. (C) 2 001 Elsevier Science B.V. All rights reserved.