Developing a new testate amoeba hydrological transfer function for permafrost peatlands of NW Siberia

Abstract

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.