Plant species determine tidal wetland methane response to sea level rise

Abstract

Abstract Blue carbon (C) ecosystems are among the most effective C sinks of the biosphere, but methane (CH 4 ) emissions can offset their climate cooling effect. Drivers of CH 4 emissions from blue C ecosystems and effects of global change are poorly understood. Here we test for the effects of sea level rise (SLR) and its interactions with elevated atmospheric CO 2 , eutrophication, and plant community composition on CH 4 emissions from an estuarine tidal wetland. Changes in CH 4 emissions with SLR are primarily mediated by shifts in plant community composition and associated plant traits that determine both the direction and magnitude of SLR effects on CH 4 emissions. We furthermore show strong stimulation of CH 4 emissions by elevated atmospheric CO 2 , whereas effects of eutrophication are not significant. Overall, our findings demonstrate a high sensitivity of CH 4 emissions to global change with important implications for modeling greenhouse-gas dynamics of blue C ecosystems.