USING RESISTOGRAPHY METHOD FOR PREDICTION OF WOOD BASIC DENSITY IN STANDING TREES OF Pinus radiata

The objective of this research was to develop models for estimation of the basic density of wood at full tree level and at different heights of Pinus radiata standing trees, measured from the wood resistance using the resistography at DBH level. A sample of 29 trees of 15 years old was used for the experiment. The trees were selected in a clonal field test established in the Bio-Bio Region, Chile. For each tree, 174 measurements were made with the resistograph and wood disks were obtained to determine the wood resistance and the basic density at six different relative heights of the stem. As a result, a significant decrease of the basic density and resistance of the wood was observed, from the base to the apex of the trees, with values of 16,8% and 38,5% of decrease, respectively for each variable. The average for the resistance values determined at DBH varied between 11% and 19% among the measured trees. A prediction model was generated to estimate the basic density at the tree level using the average resistance of the wood measured to the DBH. The adjustment parameters of the model was a root mean square error value of 11,9 kg/m(3), which did not decrease when other variables of tree (DBH or total height) were incorporated. As a main conclusion, a new method to estimate the wood basic density at different sections of the tree was generated using the adjusted model.