Grandes árvores da Amazônia: relações entre os estoques de biomassa, a riqueza de espécies e os estoques madeireiros.

Abstract

Large trees in tropical forests are crucial for biomass stocks and play a fundamental role in climate regulation. In this study, we used forest inventory data from 10 sites under timber management in the western region of Pará state, aiming to achieve two objectives related to large trees in the Amazon: a) finding the most appropriate allometric equation to estimate the biomass of large trees in the Amazon, and b) analyzing the importance of species richness as a predictor variable for biomass stocks, timber stocks, and basal area. Trees with a diameter at breast height equal to or greater than 50 cm (DBH≥50cm) were sampled at each studied site, totaling a sampled area of 20,449.95 hectares. To assess the fit of the allometric equations, a linear regression was performed between the estimated total tree biomass from each equation and the independently calculated biomass of the main stem, using the forest inventory data. To evaluate the importance of species richness for biomass stocks, timber stocks, and basal area, we employed mixed linear models (LMM) that included the sampled area of the plots and individual density as random factors. The results showed that the equation proposed by Réjou-Méchain et al. (2017) exhibited a slope that closely approximated the expected proportion of the main stem in relation to total tree biomass (56%), as well as a higher coefficient of determination (R² = 0.82) and an intercept closer to zero (slope = -0.02), thus considered the most suitable for estimating the biomass of large trees. Species richness was positively associated with biomass stocks (R²m = 0.52), timber stocks (R²m = 0.27), and basal area (R²m = 0.53). Our results indicate allometric equations with better fit for estimating large trees in the Amazon and suggest that species complementarity mechanisms favor higher biomass stocks and greater basal area in the region.