Representing methane emissions from wet tropical forest soils using microbial functional groups constrained by soil diffusivity

Abstract. Tropical ecosystems contribute significantly to global emissions of methane (CH4), and landscape topography influences the rate CH4 from wet tropical forest soils. However, extreme events such as drought can alter normal topographic patterns emissions. Here we explain dynamics during conditions across a catena in Luquillo Experimental Forest, Puerto Rico. Valley soils served major source precipitation year (2016), but recovery 2015 resulted dramatic pulses all positions. Geochemical parameters including (i) dissolved organic carbon (C), acetate, soil pH (ii) hydrological like moisture oxygen (O2) concentrations varied catena. During drought, decreased slope ridge, O2 increased valley. We simulated with Microbial Model for Methane Dynamics-Dual Arrhenius Michaelis–Menten (M3D-DAMM), which couples microbial functional group model diffusivity module solute gas transport within microsites. Contrasting moisture, O2, associated changes regulated emissions, were also altered by rate-limited diffusion Changes available substrate production (acetate, CO2, H2) oxidation (O2 CH4) predicted biomass methanotrophs event methanogens recovery, turn affected net CH4. A variance-based sensitivity analysis suggested that related aceticlastic methanogenesis methanotrophy most critical simulate This study enhanced predictive capability complex