Testate amoebae are unicellular eukaryotic organisms covered with an external skeleton called a shell. They are an important component of many terrestrial ecosystems, especially peatlands, where they can be preserved in peat deposits and used as a proxy of surface wetness in paleoecological reconstructions. Here, we represent a database from a vast but poorly studied region of the Western Siberia Lowland containing information on TA occurrences in relation to substrate moisture and WTD. The dataset includes 88 species from 32 genera, with 2181 incidences and 21,562 counted individuals. All samples were collected in oligotrophic peatlands and prepared using the method of wet sieving with a subsequent sedimentation of aqueous suspensions. This database contributes to the understanding of the distribution of testate amoebae and can be further used in large-scale investigations.

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.