The role of Eriophorum vaginatum in CH4 flux from an ombrotrophic peatland

Vegetation composition was found to be an important factor controlling CH4 emission from an ombrotrophic peatland in the UK, with significantly greater (P < 0.01) CH4 released from areas containing both Eriophorum vaginatum L. and Sphagnum, than from similar areas without E. vaginatum. Positive correlations were observed between the amount of E. vaginatum and CH4 emission, with the best predictor of flux being the amount of below-ground biomass of this species (r(2) = 0.93). A cutting experiment revealed that there was no significant difference (P > 0.05) in CH4 flux between plots with E. vaginatum stems cut above the water table and plots with intact vegetation, yet there was a 56% mean reduction in CH4 efflux where stems were cut below the water table (P < 0.05). The effect of E. vaginatum on CH4 release was mimicked by the presence of inert glass tubes. These findings suggest that the main short-term role of E. vaginatum in the ecosystem is simply as a conduit for CH4 release. The longer-term importance of E. vaginatum in controlling CH4 fluxes through C substrate input was suggested by the positive correlation between the night-time CO2 and CH4 fluxes (r(2) = 0.70), which only occurred when the vegetation was not senescent.