A MODEL OF THE GROWTH OF JUVENILE RADIATA PINE IN THE CENTRAL NORTH-ISLAND OF NEW-ZEALAND - LINKS WITH OLDER MODELS AND ROTATION-LENGTH ANALYSES OF THE EFFECTS OF SITE PREPARATION

Data from 27 site preparation experiments were used to construct a mod el that predicts growth, survival and size class distributions of radi ata pine with respect to altitude, weed control, cultivation, fertilis ation, and initial stocking during the first five years after planting . Only stand values, however, are used in this paper. The question of linking the model with existing growth and yield models for older crop s is discussed, and a theoretical structure is proposed that clarifies assumptions required if the models are jointly used to evaluate the w orth of establishment practices throughout complete crop rotations. It was found that the initial growth model generally predicted similar b asal area growth rates to those of the Pumice Plateau Model (PPM88), a growth model for older crops, in age ranges where the two models over lapped, but some of the assumptions required for rotation-length analy ses need further testing. Measurements over 8 years in a designed expe riment examining alternative site preparation strategies showed that P PM88 was insensitive to the effects of site preparation in predicting growth that occurred after the establishment phase. (C) 1997 Elsevier Science B.V.