Resumo

HERNANDEZ-RAMOS, Jonathan et al. Eucalyptus urophylla merchantable volume estimation with total volume and ratio models. Agrociencia [online]. 2017, vol.51, n.5, pp.561-580. ISSN 2521-9766.

The functional relationships between diameter at breast height (dn) and height (A) with the total volume (Vt) of a tree is essential for the technical management and exploitation of commercial forest plantations (PFC), along with the rate of different commercial heights (Ai) or minimum diameters (di) along the bole with the merchantable volume (Vc). Based on the hypothesis that with such mathematically-expressed relationships it is possible to accurately estimate Vt and Vc, the objective was to propose a tool to quantify the Vt and Vc in Eucalyptus urophylla PFCs from seed and clones in southeastern Mexico, by means of volume-ratio functions (r). Six Vt models -fitted and corrected for heteroscedasticity taking variance into consideration- and ten ratio models -correcting autocorrelation with an autoregressive structure- were evaluated using dasometric information from 175 clone trees measured in 2007 (P1), 93 in 2014 (P2), and 459 in 2007 (P3); the third group was grown from seeds. The Schumacher-Hall model -which includes dichotomous variables- showed that populations are statistically different. The best Vt models were: Schumacher-Hall for P1 and P3, and Spurr for P2. The best r models -which consider the diameter at different heights- were: Burkhart for P1 and P2, and Cao for P3. When bole height models are used, Zepeda’s was the most appropriate for the three populations. With these Vt and r models, each population’s Vc was determined at any given di or Ai, which accounted for more than 94 % of the variability. The slenderness ratio was 114, 122, and 118 cm cm-1 and the form factor was 0.45, 0.34, and 0.34 for P1, P2 and P3, respectively.

Palavras-chave : stem profile; taper; forest plantations; product distribution; Eucalyptus urophylla.

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