Preliminary site index model and individual-tree growth and mortality models for black pine (Pinus nigra Arn.) in Catalonia (Spain)

Abstract

A site index model, a distance-independent individual-tree diameter growth model, a static height model and a mortality model for Pinus nigra Arn. in Catalonia were preliminarily developed based on 2 to 7 measurements of 6 permanent sample plots established in 1964 by the Instituto Nacional de Investigaciones Agrarias (INIA). The plots ranged in site index from 9 to 15 m (dominant height at 60 years). The data for the diameter growth model consisted of 2997 observations and ranged in age from 45 to 132 years. The data for the height and mortality models consisted of 1065 and 3044 observations, respectively. A polymorphic difference equation derived from the Hossfeld function was selected to model dominant height development. This dynamic equation can compute predictions directly from any age-dominant height pair without compromising consistency of the predictions. The predictions of dynamic equations are unaffected by arbitrary changes in base-age. The relative bias for the diameter g rowth model and the height model were –0.80 and 0.13 %, respectively. The relative RMSE values for the diameter growth and height model were 67.7, 8.93 %, respectively. A logistic model for the probability of a tree to survive the coming 5-year period was prepared. The model set enables the simulation of stand development on an individual tree basis an accurately described the long-term development of sample plots of the study.