Abstract
Mangroves are recognized globally as important blue carbon ecosystems for mitigating climate change due to their remarkable carbon sequestration potential. However, methane emissions from these ecosystems can partially offset their net carbon burial capacity. Although methane oxidation within soils can minimize these emissions, the contribution of methane released directly through mangrove tree stems remains underexplored. Emerging evidence indicates that wetland trees may serve as conduits for soil-derived methane, potentially constituting a poorly quantified component of mangrove carbon cycling. Here we present a global quantification of methane emissions mediated by trees, leveraging field measurements, global datasets and machine learning-driven upscaling. Our analysis reveals that annual stem methane emissions total approximately 730.60 (95% CI: 586.09–876.93) gigagrams per year, offsetting sediment carbon burial by ~16.9%. When combined with soil methane emissions, stem fluxes increase the total methane budget, offsetting approximately 27.5% of blue carbon sequestration. Stem methane emissions were closely related to wood density, soil organic carbon content, salinity and soil methane flux, indicating that emissions originate primarily from mangrove sediments, with higher emissions correlated to lower wood density, lower salinity and greater wood water content. Our findings underscore the need to incorporate stem-mediated fluxes into blue carbon budgets and climate mitigation strategies.
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Data availability
All datasets and analysis files generated in this study have been deposited in the Data Center of the South China National Botanical Garden and are publicly available at https://doi.org/10.57841/casdc.0004245 (ref. 77). Source data are provided with this paper.
Code availability
The code used to process and analyse the data in this study has been deposited in the Data Center of the South China National Botanical Garden and is publicly available at https://doi.org/10.57841/casdc.0004245 (ref. 77).
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Acknowledgements
We are grateful to G. Yu, S. Ye, J. Chen and W. He for their assistance with field measurements. This study was funded by the National Natural Science Foundation of China (42471067 and U2106209), National Key R&D Program of China (2023YFE0113100, 2023YFF1304500, the CAS Project for Young Scientists in Basic Research (YSBR-037), Key Special Project for Marine Environmental Security and Sustainable Development of Coral Reefs 2021-400), the MOST Ocean Negative Carbon Emissions project, the Alliance of National and International Science Organizations for the Belt and Road Regions (ANSO-CR-KP-2022-11), Guangdong Basic and Applied Basic Research Foundation (2023A1515010946), the CAS Youth Innovation Promotion Association (2021347), the National Forestry and Grassland Administration Youth Talent Support Program (2020BJ003), Guangdong S&T Program (2022B1111230001), Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (SML2024SP022, SML2024SP002), Guangdong Science and Technology Plan Project (2023B1212060046), Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden (2023B1212060046), Natural Science Foundation of Guangdong Province (2024A1515010722) and Guangdong Basic and Applied Basic Research Foundation (2023A1515110277).
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F.W. and G.Q. conceived and supervised the project. G.Q., Z.L., J. Zhang, S.G., J. Zhou, X.H., H.H., M.Y. and H.L. conducted the fieldwork and data collection. C.S. and P.I.M. contributed to the revision of the manuscript. G.Q. and F.W. analysed the data and wrote the manuscript, with input from all authors. All authors discussed the results and contributed to the final version of the manuscript.
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Qin, G., Lu, Z., Sanders, C. et al. Mangrove sediment carbon burial offset by methane emissions from mangrove tree stems. Nat. Geosci. 18, 1224–1231 (2025). https://doi.org/10.1038/s41561-025-01848-4
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DOI: https://doi.org/10.1038/s41561-025-01848-4


