Massive methane emission from tree stems and pneumatophores in a subtropical mangrove wetland

• Published in: Plant and soil 2022-04, Vol.473 (1-2), p.489-505
• Main Authors: Zhang, Changwei, Zhang, Yuxue, Luo, Min, Tan, Ji, Chen, Xin, Tan, Fengfeng, Huang, Jiafang
• Format: Article
• Language: English
• Subjects: Agriculture; Analysis; Aquatic ecosystems; Atmosphere; Biomedical and Life Sciences; Dormancy; Ecology; Ecosystems; Emission; Emission measurements; Emissions; Emissions (Pollution); Fluxes; Identification and classification; Life Sciences; Mangrove plants; Mangroves; Measurement; Methane; Plant Physiology; Plant Sciences; Regular Article; Seasonal variations; Seasons; Soil Science & Conservation; Soils; Stems; Trees; Wetlands
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-022-05300-z

Purpose Increasing evidence indicates that trees could emit methane (CH 4 ) from soils into the atmosphere. However, inter-species and seasonal variations in the magnitude of tree-mediated CH 4 fluxes within coastal mangrove wetlands have not yet been clarified. Methods We measured CH 4 emission fluxes in three independent mangrove communities, Avicennia marina , Aegiceras corniculatum , and Kandelia obovata , within a subtropical mangrove wetland during tree dormancy and growth seasons using static chambers. Tree-stem, pneumatophore, and soil–atmosphere-interface CH 4 fluxes were simultaneously measured, thus enabling an estimate of the contributions from each pathway to ecosystem CH 4 fluxes. Results Pneumatophore and tree-stem CH 4 fluxes were much higher than the soil–atmosphere-interface CH 4 flux. In mangrove communities with pneumatophores ( A. marina ), the pneumatophore CH 4 fluxes accounted for 84% of the ecosystem CH 4 flux, whereas tree-stem and soil–atmosphere-interface CH 4 fluxes accounted for 9% and 7%, respectively. In contrast, in mangrove communities without pneumatophores ( A. corniculatum and K. obovata ), the tree-stem CH 4 fluxes dominated (75–79%) the ecosystem CH 4 fluxes, whereas the soil–atmosphere-interface CH 4 fluxes accounted for 21–25%. Ecosystem CH 4 fluxes, as well as pneumatophore, tree-stem, and soil–atmosphere-interface CH 4 fluxes were higher during the growth season than the dormancy season. However, the partitioning of ecosystem CH 4 fluxes did not significantly change between the two seasons. Conclusion Tree stems and pneumatophores are important conduits for CH 4 emissions in mangrove wetlands. Ecosystem CH 4 emissions may offset 53% (with pneumatophores) or 10–13% (without pneumatophores) of the total C burial rates in global mangrove wetlands.