Competition indexes for individual Pinus taeda L. trees in non-thinned commercial stands

Abstract

The competition process in a forest plantation originates from the dispute for resources, which are essential for growth. Several indexes were proposed to assess competition for different species, but such studies for pine trees are scarce in the country. These competition indices are essential in the forest modelling process. Thus, the aim of this study was to assess competition indexes for a non-thinned Pinus taeda L. stand. Data from permanent sampling units in the Telêmaco Borba region, Paraná, Brazil, were used, and tree ages ranged from 3.4 to 21.4 years. Eight indexes were assessed with a Spearman correlation matrix with dendrometric and stand variables. Moreover, for each site class, the average trend of competition indexes by class diameter and age was analysed. There was no single index that correlated the most with all variables. For diameter, height and probability of mortality variables, the most correlated indexes were Glover and Hool, Lorimer, and Stage, respectively. The competition indexes have satisfactorily shown the average behaviour of competition in relation to age and site classes. The selection of a single index will depend on its use, being necessary specific tests according to purpose.