Judul: Dynamics of CO2 Fluxes from Oil Palm Plantations on Peatland
Abstrak: The use of peatlands for plantations has received international attention related to environmental issues, namely the release of carbon suspected to be in large quantities. The release of carbon in the form of CO2 from peatlands is also related with increasing global temperatures. The release of CO2 from the soil surface is also known as CO2 flux. The CO2 flux from oil palm plantations has so far been estimated from the results of CO2 flux measurements in the inter row, but not much from the harvesting path. In the harvesting path, the cover plants were less and more exposed when compared to inter row. This condition allows for different environmental conditions that can affect the CO2 flux. For this reason, it is also necessary to measure CO2 flux at the harvesting path to get a more precise value of CO2 flux in estimating CO2 flux from oil palm plantations. CO2 flux can be partitioned into fluxes from oil palm root respiration, litter decomposition, and peat material decomposition.Measurement of CO2 flux to separate the source of flux from oil palm root respiration and peat material decomposition is generally done by comparing the flux produced at a distance of 3.5 – 4.5 m from the oil palm trunk by plot trenching or root cutting method. At this distance, it is still possible to contribute plant root respiration to flux. Cutting roots can minimize the effect of root respiration. However, dead roots are a source of new organic matter for microbial activity, thereby contributing to the measured CO2 flux. CO2 flux measurements carried out at sites far from oil palm can minimize the influence of the contribution of plant roots to flux so that more precise data on the contribution of root respiration, litter and peat material decomposition to flux obtained. Thus, the aim of this study was to determine the spatial and temporal dynamics of CO2 flux, the contribution of root respiration and litter decomposition to flux, and their relationship to environmental factors in oil palm plantations on peatlands. The research was conducted in Pangkalan Pisang Village, Koto Gasib District, Siak Regency, Riau Province. Measurement of CO2 flux was carried out in oil palm plantations with a plant age of 14 years and bushland dominated by ferns (Nephrolepis sp). The location of the bushland in this study is still in oil palm plantations. Measurement of CO2 flux using an infrared gas analyzer (IRGA) was carried out in harvesting path, inter row and bushland. Estimation of CO2 flux from oil palm plantations is based on the value of CO2 flux from harvesting path and inter row that contain litter on the soil surface. Flux measurements without litter were also carried out to estimate the litter contribution to CO2 flux. Flux measurements were repeated every three to four days from May to September 2019. Results showed the dynamics of the CO2 fluxes spatially and temporally. The difference in flux values that occur indicates that although on the same expanse of land with plant age, air humidity, air temperature, soil temperature, and groundwater table depth are relatively
Keyword: litter decomposition, peat material, root respiration