Spatial Patterns and Climatic Drivers of Biomass Carbon Turnover in Amazonian Forests

Tropical forests store more than 60% of the world’s vegetation biomass and are among the most important ecosystems for regulating the global carbon cycle and stabilizing climate. The carbon sink capacity of forests depends not only on vegetation productivity, but also on how long carbon remains stored in biomass. Biomass carbon turnover time refers to the average residence time of carbon in the vegetation biomass pool, and it is a key determinant of the long-term carbon sink potential and stability of forest ecosystems. However, previous studies have largely focused on site-level observations. Given the high complexity and spatial heterogeneity of tropical forest ecosystems, limited field plots cannot fully capture the large-scale spatial patterns and environmental drivers of biomass carbon turnover.

To address this challenge, the research team focused on the Amazon rainforest. By integrating satellite remote sensing with long-term forest plot observations, the researchers developed a remote-sensing based approach to scale up tree mortality estimates and mapped the spatial patterns of tree mortality across Amazonian forests. Building on a nonequilibrium carbon cycle framework, they further produced a spatially explicit map of biomass carbon turnover time across the region. The team then applied interpretable machine-learning models to systematically evaluate the influence of environmental factors on biomass carbon turnover time.

The study found that biomass carbon turnover time in Amazonian forests exhibits pronounced spatial heterogeneity and responds to environmental factors in strongly nonlinear ways. Importantly, the researchers identified convective storms—extreme weather events often accompanied by short-duration heavy rainfall and strong winds—as a key climatic regulator of biomass carbon turnover time in Amazonian forests. Their influence was found to be greater than that of drought-stress related indicators. The study also projected that by the end of this century, biomass carbon turnover time in Amazonian forests will decline by about 3% on average under a low-emissions scenario, and by as much as 15% under a high-emissions scenario. These results suggest that, as atmospheric drying intensifies and convective storm activity increases, the residence time of carbon in Amazonian vegetation will continue to shorten, thereby weakening the long-term carbon storage capacity of these forests.

Corresponding author Dr. WU Donghai noted that current research on tropical forest carbon sinks has focused on vegetation productivity, while tree mortality and biomass carbon turnover have received relatively less attention. This study shows that convective storms and drought stress can profoundly shape present and future carbon cycling in Amazonian forests by altering biomass turnover processes. The findings not only deepen understanding of the mechanisms underlying tropical forest carbon sink stability, but also provide important scientific support for improving the representation of biomass carbon turnover processes in Earth system models.

The South China Botanical Garden, Chinese Academy of Sciences, in collaboration with Cornell University and several international research institutions, has made important progress in understanding biomass carbon turnover in tropical forests and its response to climate change. The study, entitled “Increasing atmospheric dryness and storms accelerates biomass turnover in Amazonian forests” was recently published in Nature Climate Change. Article link： https://doi.org/10.1038/s41558-026-02639-4

Fig. 1. Spatial patterns of Amazonian biomass turnover time and its environmental drivers.（Image by WU et al.）