Generalized allometric equations of total volume generated by meta-analysis for roble, raulí and coigüe in second growth forests in Chile

A modified meta-analysis was used to develop generalized allometric equations of total individual volume underbark for second growth forests of roble, raulí and coigüe. From a set of total volume equations compiled from the literature, pseudo-data were generated to fit generalized equations for each species. The meta-analysis was supplemented with an observed database, which, besides contributing data for validation was used to fit the height– diameter relationship and to model the variance of total volume. This variance was used to simulate random pseudo-data of volume with variability similar to that of the observed data, in order to avoid residual autocorrelation problems. It was also used to define weights for the fitting of volume equations. In order to determine zonal effects, volume equations compiled from the literature were assigned to agro-climatic zones defined by ODEPA (ODEPA. 2000 Oficinas De Estudios y Políticas Agrarias. Clasificación de las explotaciones agrícolas del VI censo nacional agropecuario según tipo de productor y localización geográfica. Ministerio de Agricultura. Documento de trabajo N°5. I.S.S.N. 0717-0378. Santiago, Chile. 91 p.), according to the location of the sample. In the fitting, which included dummy variables, no significant zonal effects were detected in the regression parameters in any of the species. The generalized allometric equations of total volume showed highly precision and accuracy, i.e. FI < 0.0852m tree and E < 0.0674m tree. Thus, obtained equations are considered valid for widespread use in the study zones.