Elevated Carbon Dioxide (CO2) Growth Chamber Experiment - Utqiagvik, Alaska, 07/2023

Wet sedge-dominated tundra exhibits particularly high rates of methane (CH4) flux due to the presence of aerenchyma and therefore, plant-mediated transport of CH4. Yet the response of CH4 to future carbon dioxide (CO2) concentrations is still largely uncertain. Model predictions assumed that elevated CO2 (eCO2) will increase primary production and, as a result, CH4 emissions, but this has been poorly tested given the challenges of conducting eCO2 experiments in the Arctic. To address this knowledge gap, we tested the response of CH4 fluxes in soil and vegetation cores from Utqiagvik, Alaska to eCO2. The soil cores collected during the peak season in July were subject to ambient and elevated levels of CO2 in a growth chamber experiment. CO2 and CH4 fluxes from the cores were measured intermittently. The shoot biomass of various vegetation functional groups were extracted and weighed at the end of the study.