Species-specific or generic allometric equations: which option is better when estimating the biomass of Mexican tropical humid forests?

The aim of this study has been to compare the aboveground biomass (AGB) in six tropical forests in southeastern Mexico using generic and species-specific models at tree, species, and community levels. The dbh of 2,352 trees >= 10 cm was measured at 115 plots. AGB was estimated using Chave et al.'s generic model, with the most reliable specific equations extracted from the literature and online databases. Overall, we found 45 specific models applicable to 55.4% of the species present. In 30% of the species examined, there was a difference in AGB between the different methods used. Using specific equations at the community level, the estimate for AGB increased by 9.1% (x = 166.6 Mg ha(-1) +/- 27.5 SD) compared to the generic model alone (p < 0.04). Based on the consistency of overestimation at all sites, we concluded that for these particular tropical rainforests, applying specific models to the small proportion (<= 10%) of dominant tree species (>= 5% relative biomass) was sufficient to improve the accuracy of community level AGB estimates. This justifies increasing the number of databases of specific models particularly for highly productive rainforests. We therefore recommend that this approach be applied to provide further evidence to facilitate model choice.