Stratification in the adjustment of hypsometric relationship models in forest fragment

Abstract

The objective of this study was to find a hypsometric relationship model capable of estimating the height of trees in unequal forest fragment, testing the efficiency of stratification by species, ecological group and diametric class. In the unequal forest fragment (2.2 ha) belonging to the Federal Rural University of Rio de Janeiro, Seropédica / RJ, a census was carried out, botanical identification of trees with a diameter ≥ 5 cm, being this variable measured, as well as their respective height total. The data were stratified into ecological group, species and diametric class, and then ten traditional models of hypsometric relation were adjusted for the general database and for each stratum. The significance of the models was evaluated by the F test and the t test, with 95% probability. Trends of the estimates were verified with graphical analysis of the residues, being also observed the coefficient of determination (R2 aj.) and standard error of the estimate in percentage (Syx%). By means of the regression parameters, the Graybill models identity test was subsidized. The Trorey model was chosen and it was observed that the stratification by species and ecological group made the adjustment more efficient. Stratification in diametric class showed no gain.