Abstract :
[en] Tropical forests are one of the largest carbon pools on the planet and one of the largest remaining uncertainties in the global carbon budget, challenging the development of accurate climate projections and adapted conservation actions. Although climate, topography, and soil are recognized as key drivers of diversity and dynamics of tropical forests, their direct impact on biomass and carbon stocks remains unclear. The crux lies in shifting away from the idea that forest biomass is a singular entity to considering it as an aggregated property shaped by multiple attributes of the forest stand, such as basal area, canopy height, quadratic mean diameter, stem density, and average wood density, each responding independently to environmental factors. Gathering tropical forest inventory data from over 2,000 plots across the tropics, we demonstrate that there is no straightforward relationship between climate (mean annual temperature, total annual precipitation, and precipitation seasonality) and aboveground biomass, whether at the pantropical or continental scale. Our results indicate that this link is indirect, mediated through compensatory effects among structural attributes along climatic gradients. These compensations vary significantly between continents, offering new perspectives to understand the contrast in forest structural attributes across the tropics. Furthermore, by considering multiple climate datasets, we provide a robust assessment that highlights the importance of accounting for variability in climate data sources when evaluating forest dynamics in tropical regions. These results provide a new understanding of the spatial distribution of forest biomass in the tropics and open promising avenues for reducing uncertainties in the global carbon budget and modelling forest response to global change.
