LAUSR

Forested peatlands are widespread in the boreal landscape, but their role as carbon (C) pools remains poorly documented. In this study, we investigated the long-term C sequestration function of boreal forested bogs in relation to fires in eastern Canada. Results show that the forested peatlands comprise substantial peat C mass reaching values similar to open peatlands. At the six studied peatland sites, the amount of C stored in peat (62–172 kg C m −2 ) exceeds substantially the aboveground tree biomass C (1.5–5.3 kg C m −2 ). The C locked up in live conifers on the peatlands corresponds only to a small fraction of the C stored in peat (1–6%). In comparison, the shallow organic layer (≤ 30 cm) in the adjacent paludifying stands store 10.8 kg C m −2 on average, which is about twice as much C as the live conifers. Long-term apparent C accumulation rates are relatively low in the studied forested bogs (mean: 15.9 g C m −2  y −1 ), suggesting that these ecosystems have lower C sequestration potential than non-forested bogs over millennia. The charcoal data suggest that past local fires reduced C sequestration rates, but these peatlands burn much less frequently than upland forests and are thus more efficient long-term C stores. This study highlights the importance of boreal forested peatlands as C reservoirs and helps understanding how fires, logging and climate change can affect their C sequestration function. These findings have important implications for ecosystem management that aims at maximizing C sequestration at the landscape level to mitigate climate change.