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The vast areas of permafrost peatlands in the West Siberian Lowland (WSL) hold a significant amount of carbon currently at risk due to human-caused global warming. The rapid thawing of about 20–60% of the frozen soils of Western Siberia adds to the destruction of the region's signature palsa landscape and the development of thermokarst lakes or fens. Due to the complex interactions between climate and the ecosystem that shape its formation and degradation, permafrost reacts in different ways to environmental changes. Understanding recent changes in Western Siberia requires knowledge of previous environmental transitions, which needs to be enhanced further. This study, aimed to create a hydrological testate amoebae (TA) transfer function (TF) from the Khanymei area in the WSL to reconstruct past hydrological conditions in permafrost peatlands. In addition, this research intended to examine the influence of TA communities living in lichens (genus Cladonia) on the performance of TF by integrating these data with a calibration data set. In the summer of 2019, 76 modern samples of Sphagnum , Cladonia , and vascular plants from permafrost and non-permafrost sites were collected. Moreover, one peat core was extracted from the same area to reconstruct the depth to water table (DWT) quantitatively. The Shannon's diversity index, a quantitative measure of species richness, was calculated for each sample to estimate the TA species diversity in a community. Non-metric multidimensional scaling ordination was applied to the dataset to explore the similarities in TA communities between samples and determine whether the DWT controls the TA community structure. Results showed that the typical transition of TA species along the microtopographic (wet–dry) gradient is influenced by the presence of lichens on the surface of the peatland. Statistical analysis confirmed that TA communities in Cladonia are less affected by DWT. Therefore, the TF was constructed on the entire dataset (n = 75) and the dataset with Cladonia excluded (n = 55). Both these TFs showed satisfactory results. Even though the TF constructed on the entire dataset showed fewer predictive abilities, it provided a complete picture of the current vegetation conditions of Khanymei peatlands, where lichens are an essential element of the ecosystem. Therefore, it is assumed that TF with local environment traits may be more suitable for quantitative reconstruction, particularly in the newly explored permafrost area of Western Siberia. • New hydrological testate amoebae transfer function for permafrost peatlands. • Better capture of local conditions and trends in water level changes. • First use of data on testate amoebae communities in Cladonia in the training set. • Influence of depth to water table on testate amoebae depends on the vegetation type. • Testate amoebae communities in Cladonia are less affected by depth to water table. [ABSTRACT FROM AUTHOR]

Siberian peatlands provide records of past changes in the continental climate of Eurasia. We analyzed a core from Mukhrino mire in western Siberia to reconstruct environmental change in this region over the last 1300 years. The pollen analysis revealed little variation of local pine-birch forests. A testate amoebae transfer function was used to generate a quantitative water-table reconstruction; pollen, plant macrofossils, and charcoal were analyzed to reconstruct changes in vegetation and fire activity. The study revealed that Mukhrino mire was wet until the Little Ice Age (LIA), when drought was recorded. Dry conditions during the LIA are consistent with other studies from central and eastern Europe, and with the pattern of carbon accumulation across the Northern Hemisphere. A significant increase in fire activity between ca. AD 1975 and 1990 may be associated with the development of the nearby city of Khanty-Mansiysk, as well as with the prevailing positive Arctic Oscillation. [ABSTRACT FROM AUTHOR]

In northern peatlands, reduction of Sphagnum dominance in favour of vascular vegetation is likely to influence biogeochemical processes. Such vegetation changes occur as the water table lowers and temperatures rise. To test which of these factors has a significant influence on peatland vegetation, we conducted a 3‐year manipulative field experiment in Linje mire (northern Poland). We manipulated the peatland water table level (wet, intermediate and dry; on average the depth of the water table was 17.4, 21.2 and 25.3 cm respectively), and we used open‐top chambers (OTCs) to create warmer conditions (on average increase of 1.2°C in OTC plots compared to control plots). Peat drying through water table lowering at this local scale had a larger effect than OTC warming treatment per see on Sphagnum mosses and vascular plants. In particular, ericoid shrubs increased with a lower water table level, while Sphagnum decreased. Microclimatic measurements at the plot scale indicated that both water‐level and temperature, represented by heating degree days (HDDs), can have significant effects on the vegetation. In a large‐scale complementary vegetation gradient survey replicated in three peatlands positioned along a transitional oceanic–continental and temperate–boreal (subarctic) gradient (France–Poland–Western Siberia), an increase in ericoid shrubs was marked by an increase in phenols in peat pore water, resulting from higher phenol concentrations in vascular plant biomass. Our results suggest a shift in functioning from a mineral‐N‐driven to a fungi‐mediated organic‐N nutrient acquisition with shrub encroachment. Both ericoid shrub encroachment and higher mean annual temperature in the three sites triggered greater vascular plant biomass and consequently the dominance of decomposers (especially fungi), which led to a feeding community dominated by nematodes. This contributed to lower enzymatic multifunctionality. Our findings illustrate mechanisms by which plants influence ecosystem responses to climate change, through their effect on microbial trophic interactions. [ABSTRACT FROM AUTHOR]