B048-0014
Modeling the effects of nitrogen and hydroperiod on greenhouse gas emissions in Great Lakes coastal wetlands

Thursday, 10 December 2020
Poster
Ye Yuan, University of Michigan Ann Arbor, School for Environment and Sustainability, Ann Arbor, MI, United States, Kenneth J. Elgersma, University of Northern Iowa, Department of Biology, Cedar Falls, IA, United States, Jason Philip Martina, Texas State University, Department of Biology, San Marcos, TX, United States, Sean J. Sharp, University of Michigan Ann Arbor, School for Environment and Sustainability, Ann Arbor, United States and William S. Currie, University of Michigan, School of Natural Resources and Environment, Ann Arbor, MI, United States
Abstract:
Wetlands impact global warming potential by regulating the exchange of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). These three key greenhouse gases (hereafter GHG) contribute to the anthropogenic greenhouse effect and global warming. Few studies have investigated the interactive effects of different environmental factors, such as water residence time and nutrient inflows, on GHG emissions. Here we investigate GHG emission in Great Lakes coastal wetlands across various hydrology, temperature, and N inflow regimes using a process-based simulation model Mondrian. We found the emission of CH4, N2O and sequestration of C (i.e. negative NEE) all increased with increasing water residence time and N inflow, primarily driven by increased plant productivity and N uptake, which indicated greater C and N cycling rates. The total comprehensive global warming potential (i.e. sum GWP of CH4, N2O, and NEE) of wetlands on 20-year and 100-year time horizons were both primarily driven by CH4 emissions. Under most conditions, the global warming potential of NEE was negative, meaning wetlands were net sinks of carbon as wetland plants assimilated atmospheric CO2 and plant litter becomes accreted in underlying anaerobic soil. Negative GWP of NEE partially offset the GWP of measured CH4 and made the comprehensive GWP less than the GWP of CH4 alone. GWP of N2O was negligible even though N2O has high radiative forcing because the amount of N2O emitted from these simulated wetlands was very small. The comprehensive global warming potential mainly depended on how much global warming potential of CH4 could be offset by negative global warming potential of NEE (CO2). Water level scenarios also had an effect on GHG exchanges by modulating conditions between aerobic and anaerobic states. Higher temperature promoted higher global warming potential but due to the modest range of temperature increases expected by the midcentury, compared to other factors, its effects were minimal.
<< Previous Abstract | Next Abstract >>