Methane (CH4) as a potent greenhouse gas has doubled its concentration in the atmosphere since the Industrial Revolution; the terrestrial ecosystems have been a key player controlling the atmospheric methane concentration. The natural wetland is the largest natural source of the atmospheric methane, the changing environment has been confirmed affect land surface CH4 emission. Climate warming and elevated carbon dioxide have been shown to affect CH4 emission; while the underlying mechanisms remain under-investigated. A model-data integration approach was used to understand the methane processes in natural wetlands along the permafrost transect.
Results/Conclusions
After model parameterization and validation with the observational results at the S1 bog in Minnesota. Model simulations found that lower (<6.75C) warming stimulated while 9 C warming suppressed NPP (net primary productivity). All warming scenarios stimulated SOM (soil organic matter) mineralization. The 9C warming stimulated DOC (dissolved organic carbon) decomposition and reduced the concentrations of DOC and acetic acid. The acetoclastic and hydrogenotrophic methanogenesis went up in the first two years and went down after then. Warming led to higher CH4 flux at the surface while lower CH4 concentration in the soil profile. The elevated CO2 led to higher NPP and SOM mineralization, resulting in higher DOC and acetate concentrations. The acetoclastic and hydrogenotrophic methanogenesis went up, leading to higher CH4 concentration in soil and larger CH4 emission at the land surface. A global synthesis of warming and elevated CO2 on the C cycle in peatland confirmed our modeling results. The data-model integration across multiple scales in time, space, and biological system is a powerful approach to advance our understanding and enhance our ability to better predict the methane fluxes in natural wetlands.