Energy balance of a tropical peat swamp forest in Central Kalimantan, Indonesia

Tropical peat swamp forests grow over tropical peatlands, which are widely distributed in flat lowlands in Southeast Asia. Recently, however, deforestation and drainage are in progress on a large scale because of growing demands for timber and farmland. In addition, the El Nino drought and its consequent fires are accelerating the forest devastation. The forest devastation alters energy balance and will influence regional climate. Thus, we have measured eddy energy fluxes above a tropical peat swamp forest left in a devastated peatland in Central Kalimantan, Indonesia since November 2001. Both in the rainy and dry seasons, latent heat flux (lE) considerably exceeded sensible heat flux (H). Net radiation (R-n) was mainly used by evapotranspiration (ET). The El Nino event occurred in 2002, and the consequent drought caused large-scale peatland fires in Central Kalimantan. A large amount of smoke emitted from the fires decreased Rn from mid-August through October. Bowen ratio (H/lE) decreased gradually from January through July in the range of 0.20-0.35. Although Bowen ratio decreased to a minimum of 0.15 in late September, it continued to increase during the late fire period and was high at 0.35-0.45 after the fires. ET accounted for 67% of precipitation (1856 mm) on an annual basis in 2002. Annual mean daily ET was 3.4 mm d(-1).