Ecosystem-scale CH4 budgets in tropical peat swamp forests in Indonesia have not yet been reported, although these peatlands have the potential to emit CH4. We observed 1-year variations in the ecosystem-scale CH4 flux in an undrained secondary peat swamp forest in central Kalimantan, Indonesia, using the eddy covariance method.
We found that the peat swamp forest switched from being a CH4 sink during the dry season to a source of CH4 during the wet season depending on changes in the groundwater level (GWL). The annual CH4 budget was a small source (0.09 – 0.17 g C m−2 year−1). We found that CH4 fluxes had almost no effect on the global warming gas budget of the peat swamp forest, and values were only a few percent less than the CO2 fluxes. In addition, we conducted anaerobic soil incubation experiments to examine the effect of land-use change on CH4 production. The results indicated much higher CH4 production potential in undrained forest soil than in drained or drained and burned ex-forest soils. Although CH4 production decreased in drained soils relative to undrained soils, conserving pristine peat swamp forests with high GWLs is important to suppress global warming because CO2 emissions increase in drained peatlands.