Evaluation of methods of site index curve ajustment in thinned eucalypt stands

The objective of this study was to compare the efficiency of the methods guide-curve, difference equation and parameter prediction to build site index curves in stands of thinned eucalypts. Data came from a thinning experiment belonging to the Copener Florestal, enterprise, Bahia, Brazil. Seven measurements (at 27, 40, 50, 61, 76, 87, and 101 months) from 48 plots with mean area of 2,600m² each, were used to adjust the models. The methods were analyzed individually through the determination and correlation coefficients, percentage mean errors, and graphical analysis of the site index curves. The identity among methods was tested according to Leite e Oliveira (2002). To perform the test, the guide-curve method was chosen as the standard for comparison with the other two methods. In the single analysis, the three methods fitted in the criterion adopted for the efficiency evaluation to build the site index curves, but the guide-curve method presented the best adjustment. The results of the model identity showed that the estimation of site index obtained by the alternative methods differed statistically from the standard method, in other words, the identity among the tested methods was not confirmed. Therefore, the guide-curve method was considered to be the most suitable to build site index curves for thinned eucalypt stands.

Guide-curve method; identity test; difference equation and parameter prediction

Sociedade de Investigações Florestais Universidade Federal de Viçosa, CEP: 36570-900 - Viçosa - Minas Gerais - Brazil, Tel: (55 31) 3612-3959 - Viçosa - MG - Brazil
E-mail: rarvore@sif.org.br