Identity of hypsometric models for eucalyptus clones in the eastern region of Paraguay

In Paraguay, the development of the forestry sector is relatively recent and is based on hybrid Eucalyptus spp. plantations. As such, no information about the adjustment of hypsometric relationship models is available, which is essential for volume calculation. Thus, the present study aims to evaluate hypsometric relationship models for different eucalypt genotypes in Eastern Paraguay and determine the possibility of a single equation for the hypsometric relationship through an identity test. The evaluated plantation areas were located in Hernandarias (Location 1) and San Juan Nepomuceno (Location 2), with 13 clones evaluated in Location 1 and 10 clones in Location 2. In the plantation areas, permanent inventory plots of 1,000 m(2) were measured to evaluate the plantations from 12- to 93-months after planting, including annual remeasurement of diameter at breast height (DBH) and total tree height. For the collected data, models developed by Curtis, Prodan (modified), Nogueira, and Campos were adjusted. The results showed adjusted coefficient of determination (R-adj(2)) varying from 0.96 to 0.98, and standard error of estimate in percentage (S-yx%) ranging from 5.4 and 11.2%. In Location 1, the Nogueira and Campos models presented the best adjustment, whereas in Location 2 the Campos model presented better results. For both locations, the Campos model showed better residual distribution and was therefore selected for the identity test. The identity test indicated that the use of a single equation among genotypes in each location and between locations was not possible. Therefore, the Campos model, with the independent variables of age, dominant height, and DBH, must be adjusted for genotype and location, but offers good performance to estimate the total height of different genotypes of eucalypts.