Methane fluxes from three ecosystems in tropical peatland of Sarawak, Malaysia

Methane fluxes were measured monthly over a year from tropical peatland of Sarawak, Malaysia using a closed-chamber technique. The CH4 fluxes in forest ecosystem ranged from -4.53 to 8.40 mu g C m(-2) h(-1), in the oil palm ecosystem from -32.78 to 4.17 mu g C m(-2) h(-1) and in the sago ecosystem from -7.44 to 102.06 mu g C m(-2) h(-1). A regression tree approach showed that CH4 fluxes in each ecosystem were related to different underlying environmental factors. They were relative humidity for forest and water table for both sago and oil palm ecosystems. On an annual basis, both forest and sago were CH4 source with an emission of 18.34 mg C m(-2) yr(-1) for forest and 180 mg C m(-2) yr(-1) for sago. Only oil palm ecosystem was a CH4 sink with an uptake rate of -15.14 mg C m(-2) yr(-1). These results suggest that different dominant underlying environmental factors among the studied ecosystems affected the exchange of CH4 between tropical peatland and the atmosphere. (c) 2005 Elsevier Ltd. All rights reserved.