Peatlands are a significant global carbon store, which can be compromised by drainage and afforestation. We measured the peat decomposition under a 30-year-old drained forest plantation: 115 ± 16 g C m⁻² yr⁻¹, ca. 40 % of total soil respiration. Considering input of litter from trees, our results indicate that the soils in these 30-year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil as organic matter than is decomposed heterotrophically.