Modeling methane dynamics in three wetlands in Northeastern China by using the CLM-Microbe model

Wetlands account for up to 70%of the natural source of methane(CH_(4))in terrestrial ecosystems on a global scale.Soil microbes are the ultimate producers and biological consumers of CH_(4)in wetlands.Therefore,simulating microbial mechanisms of CH_(4)production and consumptionwould improve the predictability of CH_(4)flux in wetland ecosystems.In this study,we applied a microbial-explicit model,the CLM-Microbe,to simulate CH_(4)flux in three major natural wetlands in northeastern China.The CLM-Microbe model was able to capture the seasonal variation of gross primary productivity(GPP),dissolved organic carbon(DOC),and CH_(4)flux.The CLM-Microbe model explained more than 40%of the variation in GPP and CH_(4)flux across sites.Marsh wetlands had higher CH_(4)flux than mountain peatlands.Ebullition dominated the CH_(4)transport pathway in all three wetlands.The methanogenesis dominates while methanotroph makes a minor contribution to the CH_(4)flux,making all wetlands a CH_(4)source.Sensitivity analysis indicated that microbial growth and death rates are the key factors governing CH_(4)emission and vegetation physiological properties(flnr)and maintenance respiration predominate GPP variation.Explicitly simulating microbial processes allows genomic information to be incorporated,laying a foundation for better predicting CH_(4)dynamics under the changing environment.