Modeling Methane Emissions from Amazon Floodplain Ecosystems

A new process-based simulation model to estimate methane emissions from Amazon floodplain ecosystems is described and evaluated in comparison to independent measurements of methane fluxes. The model's three major components are 1) types of wetland vegetation and the changes in water level, temperature and dissolved oxygen of flooded areas, 2) plant production, biomass accumulation, and litterfall decay in soils and sediments, and 3) methane production and transport pathways through the water column and into the atmosphere. Ecological and limnological data from Lake Calado, a well-studied site in the central Amazon basin, were used to develop the model. One set of model simulations were generated for floating macrophytes. Predicted rates of CH4 emission to the atmosphere by all simulated transfer pathways were typically in the range of 0.25 to 0.33 g C m(-2) day(-1). Simulated CH4 emissions from flooded forests were predicted to be around 0.25 g m(-2) day(-1), nearly all by ebullition. These rates compare favorably to rates measured in Amazon floodplain habitats.