Optimized wetland rewetting strategies can control methane, carbon dioxide, and oxygen responses to water table fluctuations

Abstract Rewetting is widely promoted as a climate mitigation strategy to preserve soil carbon in drained wetlands, although rewetting may enhance methane production and corresponding emissions. The increase in methane emissions following rewetting might be underestimated without considering near-surface methane oxidation under a fluctuating water table. Here, we refined the methane module in Lund-Potsdam-Jena General Ecosystem Simulator with high-affinity methane oxidation and oxygen parameterization involving water table fluctuations. During 2007-2023, the Danish temperate wetland site functioned as a carbon dioxide sink (−41 gC-CO 2 m -2 yr⁻ 1 ) and a methane source (0.71 gC-CH 4 m⁻ 2 yr⁻ 1 ), with significant declines in seasonal amplitudes of methane flux, net ecosystem exchange, and gross primary productivity. Scenario analysis shows maintaining a stable water table at 9 cm depth offers the optimal trade-off between carbon sequestration and methane release. Our findings reduce the uncertainty in wetland methane estimates under climate change and highlight the importance of site-specific rewetting strategies to optimize mitigation efforts.