Ratio estimators and simultaneous regression estimators for biomass in mixed plantation of Pinus elliottii Engelm. and Pinus taeda L.
2026
Ornélio P. E. Nhaduco | Alexandre Behling | Sylvio Péllico-Netto | Ana P. Dalla-Corte | Carlos R. Sanquetta | Franciele A. da Silva | Jonathan W. Trautenmüller
Aim of study: To evaluate the performance and biological consistency of ratio estimators for estimating the biomass of Pinus elliottii Engelm. and Pinus taeda L. and to compare the results obtained by this method with those generated by the nonlinear seemingly unrelated regression (NSUR) method in its weighted version (WNSUR), a procedure that was considered as a control. Area of study: The study was carried out in the state of Paraná, in southern Brazil. Material and methods: Data were collected on the following variables: diameter at 1.30 m height aboveground (D), total height (H), crown diameter (dc), crown height (hc), and the biomass of the following parts was quantified: roots, stem, bark, branches, needles, and total. The ratio model used for each part was obtained by the ratio between the biomass of the mth part (dependent variable) and the estimated stem volume (independent variable). Nonlinear allometric models were fitted simultaneously by the NSUR and WNSUR methods. Main results: The ratio estimators did not require additional procedures to achieve additivity and, in general, became more accurate for total aboveground biomass and its parts than regression estimators (WNSUR). Research highlights: Due to its simplicity of application and because it meets the premise of additivity of the biomass parts in a natural way, the ratio estimators constitute an appropriate and promising procedure for compatible estimates of tree biomass.
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