Effect of plant-mediated oxygen supply and drainage on greenhouse gas emission from a tropical peatland in Central Kalimantan, Indonesia

To evaluate the hypothesis that plant-mediated oxygen supplies decrease methane (CH4) production and total global warming potential (GWP) in a tropical peatland, the authors compared the fluxes and dissolved concentrations of greenhouse gases [GHGs; CH4, carbon dioxide (CO2) and nitrous oxide (N2O)] and dissolved oxygen (DO) at multiple peatland ecosystems in Central Kalimantan, Indonesia. Study ecosystems included tropical peat swamp forest and degraded peatland areas that were burned and/or drained during the rainy season. CH4 fluxes were significantly influenced by land use and drainage, which were highest in the flooded burnt sites (5.75 +/- 6.66 mg C m(-2) h(-1)) followed by the flooded forest sites (1.37 +/- 2.03 mg C m(-2) h(-1)), the drained burnt site (0.220 +/- 0.143 mg C m(-2) h(-1)), and the drained forest site (0.0084 +/- 0.0321 mg C m(-2) h(-1)). Dissolved CH4 concentrations were also significantly affected by land use and drainage, which were highest in the flooded burnt sites (124 +/- 84 mu mol L-1) followed by the drained burnt site (45.2 +/- 29.8 mu mol L-1), the flooded forest sites (1.15 +/- 1.38 mu mol L-1) and the drained forest site (0.860 +/- 0.819 mu mol L-1). DO concentrations were influenced by land use only, which were significantly higher in the forest sites (6.9 +/- 5.6 mu mol L-1) compared to the burnt sites (4.0 +/- 2.9 mu mol L-1). These results suggest that CH4 produced in the peat might be oxidized by plant-mediated oxygen supply in the forest sites. CO2 fluxes were significantly higher in the drained forest site (340 +/- 250 mg C m(-2) h(-1) with a water table level of -20 to -60 cm) than in the drained burnt site (108 +/- 115 mg C m(-2) h(-1) with a water table level of -15 to +10 cm). Dissolved CO2 concentrations were 0.6-3.5 mmol L-1, also highest in the drained forest site. These results suggested enhanced CO2 emission by aerobic peat decomposition and plant respiration in the drained forest site. N2O fluxes ranged from -2.4 t