Growth and yield model for Pinus halepensis Mill.: in Catalonia, north-east Spain

In this study a set of models was developed which enables tree-level distance-independent simulation of the development of Pinus halepensis stands in Catalonia. The system consists of a diameter growth model, a static height model, an ingrowth model and a survival model for the coming 10-year period. Special emphasis was placed on the logical behaviour of the growth models and site evaluation. Models for linear and non-linear diameter increment were developed and compared. A past growth index, based on increment borings from sample trees, and location characteristics such as latitude, elevation and slope were used for site description. The diameter growth models were based on 14 733 observations, the height models on 14 893 observations, the ingrowth models on 1860 observations, and the survival models on 14 588 observations. The biases of the diameter growth models were zero due to the estimators used for bias correction. The relative bias for the height model was 1.9%. Due to the fitting method applied, the biases of the ingrowth models were zero. The relative RMSE values were 50.9% for the linear diameter growth model, 50.7% for the non-linear diameter growth model, 23.7% for the height model, and 208% for ingrowth. The developed model set enabled logical long-term simulations. (C) 2004 Elsevier B.V. All rights reserved.