The construction of dams can increase the emission of greenhouse gases (GHG), mainly methane (CH4) by the anaerobic decomposition of forest residues like twigs, branches, leaves and miscellaneous flooded. The aim of this study was to evaluate the emission of CH4 after the flooding of soil covered with residuals of forests. Experimental units were built with PVC tubes containing soil covered with different combinations of dose (0; 21.2; 42.3 and 64.1 Mg ha-1) and type (branches, leaves and miscellaneous; twigs; and original composition) of forest residues and river water. The experimental design was completely randomized with factorial arrangement and three replications. Rates of CH4 emission were monitored in 19 events during one year (February/2012 to March/2013). Approximately, 75 days after incubation of soil with residue, a significant increase in CH4 emission was observed occurring two emission peaks: at 111 and 249 days. The cumulative emission of CH4 in the first year after flooding was 200 g C m-2 in the dose zero, until above 400 g C m-2 in the 21.2 Mg ha-1 and higher doses, with no effect of type of residues, only the dose as an isolated factor.
flooded soil; biomass; anaerobic decomposition; methanogenesis; greenhouse gases
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