A REVIEW OF CARBON-DIOXIDE GAS EMISSIONS FROM PEATLANDS TO DETERMINE THE EMISSIONS FACTOR FOR DRAINED PEATLANDS FOR OIL PALM PLANTATIONS IN INDONESIA
The C loss from peatlands through CO2 flux was derived from autotrophic (root) respiration and peat decomposition (heterotrophic respiration). The CO2 emitted into the atmosphere was determined as a net flux, showing the difference between CO2 gas released from peat surface and CO2 gas absorbed by oil palm trees and other crops. This paper aims to: (1) review the current reports concerning CO2(eq) flux or emission from oil palm plantations on drained peatlands, and (2) review the one-year research activities in relation to (i) contribution of peat decomposition to subsidence, and (ii) emission factor of peatlands drained for oil palm plantations. Based on review past reports, the emission of CO2 from peatlands drained for oil palm plantations varied from 33-95 Mg ha-1 yr-1. However, emission factor used for CPO evaluation as raw material of biodiesel was 95 Mg ha-1 yr-1, for which the use of contribution of peat decomposition to subsidence was about 92%. One-year data observation from our research showed the contribution of peat decomposition of subsidence of about 43.2%. The net-flux was measured above the canopy and the result showed the average CO2 flux was 19.0 Mg CO2 ha-1 yr-1 as CO2 emission. The flux from peat decomposition was measured at the farthest distance from the oil palm trees and the results showed the average peat CO-flux was 29.2 Mg CO2 ha-1 yr-1 as peat CO2 emissions. The contribution of peat decomposition to peat subsidence is 43.2%. From the results of those CO2 flux measurement we suggest that emission factor for peatlands drained for an oil palm plantation varied from 20 to 30 Mg CO2 ha-1 yr-1. This means emission factor used for CPO evaluation was over-estimated.