Generalized Tree Volume Equations for Eucalyptus Genotypes under Contrasting Irrigation

Abstract

Tree volume equations for Eucalyptus plantations are essential to estimate productivity, generalize equations that consider different genotypes and low-bias water regimes, and simplify plantation management. Our study evaluated the possibility of a generalized tree volume equation for eight Eucalyptus genotypes under contrasting irrigation regimens. We evaluated a seven-year-old plantation with eight Eucalyptus genotypes in two contrasting irrigation regimens (summer-irrigated vs. non-irrigated conditions). Diameter (DBH) and total height (H) measurements were considered in the tree equations (Schumacher and Hall (1933), Honer (1967), and Clutter et al. (1983)). The equation with the best fit considered the coefficient of determination, mean square error, and AIC and BIC parameters. The results showed that it is possible to use a generalized tree volume equation; the genotype, irrigation regime, and their interaction were not statistically significant for all equations. The best tree volume equation was Schumacher and Hall (1933), which showed the best fit and minor bias, with a small trend of underestimating the total volume in trees with a DBH >18.3 cm. These results suggest that it is possible to use a generalized tree volume equation to simplify plantation productivity projections while maintaining a good fit and low bias.

Keywords

• model
• water availability
• allometric
• tree improvement