Partition of Carbon Losses on CO2 Emission and Peat Subsidence in an Open-Drained Tropical Peatlands: A Consideration for Agroforestry Practices

Open-abandoned peatland commonly were not hydrologically well-managed in West Kalimantan causing continuous degradation of peat ecosystems, due to peat drying. This condition damage the carbon balance and function of tropical peatlands, result in significant greenhouse gas emissions. Tropical peat in the Kubu Raya District of West Kalimantan, which has a relatively large area of peat, has been degraded due to uncontrolled drainage and land firescaused by lack of management post the landcover changes. This study aims to clarify the partition of carbon loss in open peatlands due to the heterotrophic respiration (CO2 emission) process, which is part of the declining peat layer due to subsidence. The CO2 emission and subsidence assessments were accomplished for two years. The results show an increase in peat CO2 emissions to ~300% when groundwater level (GWL) lowered from ~0-5cm to >80cm. The trendis similar to the subsidence process due to changes in GWL. Carbon dioxide emissions range from 55,8 to 58,9% of peat layer losses, dependent on GWL. In undrained peatland, the CO2 emission was the lowest among others yet mainly loss in CO2 emission. The results of this studycan provide considerations on smallholder agroforestry or other agricultural practices which wide-spread developed recently in this area. It is explaining the part of the subsidence that impactsthe sources of CO2 emissions and practices to manage GWL to mitigate CO2 emission from open-drained peatlands.