Role of Scirpus mariqueter on Methane Emission from an Intertidal Saltmarsh of Yangtze Estuary

The role of wetland plant ( Scirpus mariqueter ) on methane (CH 4 ) emissions from a subtropical tidal saltmarsh of Yangtze estuary was investigated over a year. Monthly CH 4 flux and pore-water CH 4 concentration were characterized using static closed chamber technique and pore-water extraction. Measured chamber CH 4 fluxes indicated that saltmarsh of the Yangtze estuary acted as a net source of atmospheric CH 4 with annual average flux of 24.0 mgCH 4 ·m −2 ·day −1 . The maximum chamber CH 4 flux was in August (91.2 mgCH 4 ·m −2 ·day −1 ), whereas the minimum was observed in March (2.30 mgCH 4 ·m −2 ·day −1 ). Calculated diffusion CH 4 fluxes were generally less than 6% of the chamber fluxes. Significant correlations were observed between the chamber CH 4 flux and rhizospheric pore-water CH 4 concentration (11–15 cm: p < 0.05, R = 0.732; 16–20 cm: p < 0.05, R = 0.777). In addition, chamber CH 4 fluxes from July to September constituted more than 80% of the total annual emission and were closely correlated with aboveground biomass yield of S. mariqueter . The results indicated that S. mariqueter transportation was the dominant CH 4 emission pathway and it provided an efficient route for the belowground CH 4 to escape into the atmosphere while avoiding oxidation, leading to CH 4 emissions.