High rates of land cover change and deforestation in tropical peat swamp forests over the past few decades had been judged to increased peat decomposition rates and carbon (C) emissions from peatlands, yet this had been supported by little information. Our main objective was to estimate the C emission resulting from peat swamp forests (PSF) degradation into logged PSF (LPSF) and conversions into the adjacent wet shrub (WS) and oil palm plantation (OP) of the Pematang Gadung peat dome, Ketapang, Indonesia. We tested if degradation and conversion of PSF increase the peatlands' potential C emissions. C emission was measured using the C stock difference methods, comparing aboveground and belowground C stocks of LPSF, WS and OP with the PSF. PSF and LPSF have significantly higher aboveground C stocks (122 and 96 Mg C ha-1 , respectively) than WS and OP (12 and 7 Mg C ha-1 , respectively). Our results indicated that the loss of the PSF trees is a major driver of ecosystem's C loss. The significant loss of trees and other aboveground carbon stocks directed to a clear negative impact of land cover change on peatlands' role in sequestering atmospheric C. Potential CO 2 emissions of non-PSF sites were significantly higher than the PSF sites. Our study showed that PSF conversion to other land uses comes at a great cost in terms of significantly reduced function in sequestering greenhouse gas emissions. The high rates of deforestation of PSF, and subsequent high greenhouse gas emissions point to the relevance for inclusion of PSF in appropriate climate change mitigation and adaptation strategies.