Soil carbon dioxide and methane emissions from three vegetation communities incubated under varying salinity and moisture conditions, Yukon-Kuskokwim Delta, Alaska, 2022-2023

The Yukon-Kuskokwim Delta in western Alaska is one of the world’s largest high latitude wetland ecosystems, and the low topographic relief of this region makes it especially vulnerable to increased flooding and saltwater intrusion. To investigate the effects of changing moisture and salinity on carbon dioxide (CO2) and methane (CH4) fluxes from this landscape, an 11-week incubation experiment was conducted on soil from three different plant communities with differing tidal inundation frequencies: a lowland wetland that experiences tidal inundation multiple times per year, an upland wetland that experiences tidal inundation infrequently, and an upland tundra community that only inundates during large storm events. Soil mesocosms from each community were exposed to a factorial combination of one of three moisture levels (40%, 70%, or 100% saturation) at one of four salinity levels (freshwater, 3, 6, or 12 parts per thousand (ppt)). CO2 and CH4 concentrations were sampled weekly and fluxes for each mesocosm.