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Ecosystem context modulates salinization impacts on diffusive greenhouse gas fluxes in coastal wetland soils
Journal article   Open access   Peer reviewed

Ecosystem context modulates salinization impacts on diffusive greenhouse gas fluxes in coastal wetland soils

Yi Liu, Dehong Hu, Tao Bao, Lifei Su, Ting Wang, Xiangling Zhou, Shijia Liu, Siqi Zheng, Yuanbin Cai, Shihua Li, …
Geoderma, Vol.472, pp.1-12
08/2026
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Published (Version of record) Open CC BY V4.0

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Abstract

Coastal wetlands Ecosystem context Mangroves Salinization Soil diffusive GHG fluxes Tidal marshes
Saltwater intrusion is accelerating salinization in coastal wetlands, altering soil ionic strength and sulfate availability with potential consequences for soil diffusive greenhouse gas (GHG) fluxes. Despite numerous local studies, large-scale response patterns and associated mechanisms remain insufficiently resolved. Here, we combined a global meta-analysis of chamber-based soil diffusive GHG fluxes (76 studies; 813 paired observations) with a year-long mesocosm experiment to quantify salinization effects on soil diffusive CO2, CH4, and N2O fluxes. In tidal marshes, salinization suppressed CO2 and CH4 fluxes more strongly than in mangroves, by 31% and 42%, respectively, whereas N2O declined modestly by 14%. In mangroves, suppression was dominated by N2O, which declined by 38%, with smaller reductions in CO2 (7%) and CH4 (10%). Across studies, CO2 and CH4 responses were associated mainly with ambient salinity and temperature seasonality, whereas N2O responses were more closely associated with tidal range. By contrast, Δsalinity, the magnitude of salinity change, showed weaker explanatory power for soil diffusive GHG responses. The mesocosm experiment provided process-related support for these patterns. In Cyperus-planted mesocosms, salinization reduced labile carbon pools and acetate availability and was associated with lower functional potential for organic matter breakdown (cex, cdh, xylA) and methanogenesis (mcrA, acsB), consistent with lower soil diffusive CO2 and CH4 fluxes. In Kandelia-planted mesocosms, salinization reduced dissolved inorganic nitrogen availability, increased C:N ratios, and was associated with lower functional potential for nitrogen fixation, nitrification, and denitrification (nifH, amoA, narG, nirS), consistent with stronger N2O suppression. These findings suggest that salinization effects on coastal-wetland soil diffusive GHG fluxes are shaped by environmental gradients and soil biogeochemical conditions rather than by Δsalinity alone. Incorporating ecosystem context into process-based models may improve predictions of short- to medium-term GHG responses to salinization in coastal wetland soils.

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