Arctic permafrost regions contain the largest terrestrial carbon stocks on the globe. Thermokarst wetlands are increasingly forming in these Arctic systems due to ground subsidence caused by permafrost thaw, necessitating understanding of how these changing landscapes function and their feedback with global change and carbon cycling. We evaluated how the above- and belowground plant traits of dominant Arctic tundra sedge Eriophorum vaginatum impacted soil chemistry and trace gas fluxes in a greenhouse rhizobox experiment, using planted and unplanted treatments. Plants and soils used in this experiment were collected from a thermokarst wetland in the Arctic. We simultaneously quantified in situ soil chemistry and root growth dynamics, linking these belowground dynamics to aboveground fluxes of trace plant-soil gas fluxes of carbon dioxide (CO2) and methane (CH4) to improve our understanding of how shifting landscape and aboveground plant community will alter belowground biogeochemistry. Our results indicate how a single species of Arctic sedge shifts bulk soil chemistry over a single growing season. For example, spectroscopic techniques showed that porewater amino acid-like compounds were correlated with root production over time, indicating increased rhizodeposition with belowground growth over a simulated growing season. These exudates are partially responsible for increased CO2 flux in plant treatments. These findings indicate that rhizodeposition is a significant pathway in which an Arctic graminoid shapes the biogeochemical conditions within thermokarst-affected soils. These findings underscore how rapid environmental and landform change may alter elemental cycles in the Arctic.
