Plant responses to warming, salinity, and inundation regulate methane fluxes in coastal systems

The Greenhouse gas Exchange NeXus or GENX aims to understand the biogeochemical processes that regulate methane emissions. Located in the Smithsonian Environmental Research Center's Global Change Research Wetland (GCReW), GENX aims to understand interactions between ecology and biogeochemistry using a methane autochamber system. With this system, GENX can monitor methane emissions at a high temporal frequency to capture ebullition events, tease apart contributions from plants and microbes, and understand the interacting effects of warming, salinity, and inundation. With these data, we can improve our mechanistic representation of methane fluxes in coastal environments.

Building on redox networks developed in the reactive transport model, PFLOTRAN, for saltmarshes located at GCReW, we incorporated the role of diurnal cycles (tides, night/day) to account for changes in plant-mediated transport associated with shifts in photosynthesis, respiration and/or transpiration based on auto-chamber data. Preliminary results indicate that the indirect effects of warming, salinity, and inundation on plant responses can have a greater effect on methane emissions than the direct effects on soil processes. By accounting for these daily cycles, we can improve representation of methane dynamics and develop ways to account for the system's heterogeneity in response to environmental shifts.