With the increasing use of tropical peatland for agricultural development, documentation of the rate of carbon dioxide (CO 2) emissions is becoming important for national greenhouse gas inventories. The objective of this study was to evaluate soil-surface CO 2 fluxes from drained peat under different land-use systems in Riau and Jambi Provinces, Sumatra, Indonesia. Increase of CO 2 concentration was tracked in measurement chambers using an Infrared Gas Analyzer (IRGA, LI-COR 820 model). The results showed that CO 2 flux under oil palm ( Elaeis guineensis) plantations ranged from 3416 and 4525 Mg CO 2 ha -1 year -1 in two locations in Jambi province to 6625 Mg CO 2 ha -1 year -1 for a site in Riau. For adjacent plots within 3.2 km in the Kampar Peninsula, Riau, CO2 fluxes from an oil palm plantation, an Acacia plantation, a secondary forest and a rubber plantation were 6625, 5919, 6125, 5217 Mg ha -1 year -1, respectively, while on bare land sites it was between 5630 and 6724 Mg CO 2 ha -1 year -1, indicating no significant differences among the different land-use systems in the same landscape. Unexplained site variation seems to dominate over land use in influencing CO 2 flux. CO 2 fluxes varied with time of day ( p<0.001) with the noon flux as the highest, suggesting an overestimate of the mean flux values with the absence of night-time measurements. In general, CO 2 flux increased with the depth of water table, suggesting the importance of keeping the peat as wet as possible.
