On filamentous fungi in polar regions and boreal peatlands

Summary

Estimates suggest that more than 40-50% of the area of the northern hemisphere of our planet is covered by Sphagnum bogs, which act as a reservoir for storing planetary carbon stocks in peat, with polar and high mountain regions underlain by permafrost. In the boreal zone, permafrost also underlies some of the peatlands. Both the cold polar and high mountain regions, as well as the acidic flooded Sphagnum bogs, represent polyextreme conditions for existence. However, even in these ecotopes, actively functioning microorganisms (bacteria, archaea, protists, and fungi) are known. In this work, I focused on studying the mycelial fungi of boreal peatlands, the Arctic, and Antarctica. In peatlands, fungi mainly play an important role as decomposers of recalcitrant tissues of Sphagnum mosses, initiating this process. Fungi break down the most complex phenolic components into simpler ones, making them available to bacterial enzymes. Being mostly aerobic organisms, fungi are predominantly active in the upper aerated layers of peat, while in deeper peat deposits, the main role of decomposers shifts to anaerobic prokaryotic organisms. With global warming, the thawing of permafrost is occurring, resulting in the expansion of the area of boreal peatlands. This process is accompanied by the loss of thriving fungal species in permafrost and the activation of species that are preserved in frozen substrate as spores. At the same time, the upper layers of boreal peatlands are heating up and drying out, enhancing the activity of resident fungi. These transformations affect the intensity of global biogeochemical cycles, and therefore, the rate of peat accumulation and greenhouse gas emissions. Currently, the description of fungal communities in peatlands and permafrost soils is lacking. Furthermore, the issue with current understanding of fungal communities in permafrost and peat is that it is unknown which of the detected fungi are active and which are present as spores. Without information on the species composition of fungi in these locations and the extent of their activity, it is impossible to predict changes in the functioning of fungal communities and substance cycling under the impact of global warming. The objectives of my dissertation were to describe the diversity of fungi in Sphagnum bogs located in the Arctic region on the coast of the White Sea, compare the obtained fungal communities with the fungal community of three Sphagnum bogs in the temperate zone, and analyze the existing literature on terrestrial mycelial fungi in the Arctic and Antarctica.