Climate change and fires drive mire development in central Siberian permafrost areas over the past century

Permafrost mires are very sensitive to climate variations and can potentially release considerable amounts of carbon to the atmosphere due to permafrost degradation. On the other hand, permafrost degradation may promote mires development, leading to atmospheric carbon sequestration in the form of peat. In order to understand the dynamics of mire development in a continuous permafrost region, we used a multi-proxy paleoecological reconstruction based on 120-year-old peat deposit from Central Siberia. At the initial stages, a waterlogged forest at the border of a permafrost mire was subjected to burning that resulted in further waterlogging leading to a quick transition from waterlogged forest to a poor fen over ca. 15 years. Further accelerated mire development and corresponding rapid peat accumulation coincided with climate warming and were associated with a post-fire succession on the surrounding area. This resulted in a formation of a dry forested oligotrophic mire. Overall, our findings demonstrate a substantial potential for permafrost mires to develop in the marginal zone after forest disturbance with the subsequent establishment of a new equilibrium between forests and mires in accordance with the climatic conditions.