Peat domes in Kalimantan (Indonesia) are reported to loose their dome shape as a result of disturbance such as logging and artificial drainage. The loss of the dome shape can be caused by (a combination of) two major processes: compaction and oxidation. Because natural, undisturbed peat is a major sink for atmospheric CO2, the distinction between the two processes is of utmost importance with regard to carbon storage. In case of compaction, no CO2 need to be lost to the atmosphere. In case of oxidation, either as a result of increased decomposition upon improved drainage or by burning, all CO produced goes to the atmosphere. To estimate the contribution of oxidation and compaction to the loss of peat dome shape, research was conducted in the Mawas area in Central Kalimantan. Physical and chemical parameters of an intact and collapsed dome were compared. Increased bulk densities in the collapsed peat dome showed that considerable compaction has occurred. Depending on the initial bulk density, compaction has probably caused a subsidence from 2.2 to 4.0 in. According to ash content measurements, no significant oxidation has taken place, but increased EC found at the collapsed dome can be due to oxidation of at least 2.3 cur to 46.9 cm peat, which implies an emission of respectively 4.2 to 85.9 kg CO2 m(-2) over the 6 years since collapse. Compaction appeared to be a more important factor in the loss of dome structure than oxidation based on the estimated possible ranges in peat loss. Collapse of the dome had only minor influence on its chemical parameters. Regrowth did not seem to be hindered by the collapse and its consequences, but it was less at sites that had suffered recent fires. If peat growth resumes, collapse need not be detrimental to carbon storage. (c) 2006 Elsevier B.V. All rights reserved.