Global warming potential from soils in tropical peatland of Sarawak, Malaysia

Tropical peatlands are important sources and sinks of atmospheric methane (CH4) and major sources of carbon dioxide (CO2) and nitrous oxide (N2O). Recently, large areas of tropical peatland have been developed for agriculture plantations in Southeast Asia whereby drainage is a prerequisite, which can increase greenhouse gas (GHG) emissions substantially and therefore, global warming potential (GWP). Despite this, there is still a paucity of knowledge on GHG emissions from different ecosystems on tropical peatland and their roles and contribution to the global gas budget. Thus, three ecosystems from tropical peatland of Sarawak, Malaysia, mixed peatswamp forest, oil palm (Elaeis guineensis) plantation and sago (Metroxylon sagu) plantation, were chosen for the study of GHG emissions from the soils to determine their contribution towards GWP. The GHG emissions were measured monthly over 12 months using a closed chamber technique. GWP from forest soils was higher (7850 9 CO2 m(-2) y(-1)) compared with oil palm ecosystem (5706 9 CO2 m(-2) y(-1)) and sago ecosystem (4233 g CO2 m(-2) y(-1)). A high GWP in forest ecosystem was due to its high soil respiration rate of 7817 9 CO2 m(-2) y(-1). Soil respiration rates for sago and oil palm were 4074 g CO2 m(-2) y(-1) and 5652 g CO2 m(-2) y(-1) respectively. About 4 % of GWP from peat soils in sago ecosystem was due to CH4 (5.5 9 CO2 m(-2) y(-1)) and N2O (153.4 g CO2 m(-2) y(-1)) emissions, which were negligible in forest and oil palm ecosystems. Thus, the GWP of the soils in the three ecosystems on tropical peatland were mainly dominated by CO2 fluxes from the soil implying that tropical peatlands may function as a source for atmospheric CO2 on a global scale.