Fire Impacts and Carbon Release on Tropical Peatlands in Central Kalimantan, Indonesia

During 1997 and 1998 intensive land irrigation and clearance activities in Indonesia, combined with a greatly extended ENSO-related dry season, created conditions for several months of forest fires. Fires were particularly intense in the lowland peatlands of Kalimantan and Sumatra where both forest and peat fires occurred. A 24,910 km (2.491 MHa) study area in Central Kalimantan has been used to investigate the consequences of fire on peat swamp forest using LANDSAT TM/ETM and ERS-1/2 radar satellite images. By combining data from remote sensed images with GIS and field measurements, it has been possible to determine fire impact, carbon storage in the peatlands and carbon emission by fire. Results indicate that 32% of the study area has been fire affected (796,901 ha); the largest scars are in areas impacted by logging, forest clearance and peatland drainage. Systematic peat drillings showed that huge amounts of carbon are stored in this tropicl peatland (average peat thickness approx. 2.5m) suggesting that the contribution of tropical peat to the global resource is much greater than thought previously and could be as much as 20-30% of the total. Using GIS interpolation algorithms a 3 dimensional volume model was calculated showing that more then 9 Billion m peat are stored in Block C of the 1 Mio ha rice project area (4400 km). Field survey of burn scars revealed a loss of surface peat from a minimum of 0.20 m to a maximum of 1.50 m. A conservative overall estimate suggests that the thickness of peat lost by combustion during the fires averaged 0.40 m over the extensive peatland areas of Central Kalimantan resulting in approx. 3 Gm of burned peat calculated for Block C. Total carbon losses from the 1997 peatland fires in the study area are estimated to be in the range 0.218 to 0.491 Gt C, with the greatest contribution to emissions of atmospheric CO2 derived from peat rather than forest combustion.