Differentiation of phytocenoses of the swamps of the southern tundra in the Holocene in northern Western Siberia (Tazovsky District)

In the region of hypoarctic southern tundra, polygonal peatlands formed during the Holocene are widespread. These peatlands are characterized by changes in plant communities, buried at the site of growth, and store information about the natural conditions of the Holocene. The aim of the study was to establish the differentiation of phytocenoses of the southern tundra during the Holocene based on the botanical composition and properties of peatlands in Western Siberia. From 2016 to 2020, peat sections were studied in the hastyriyas near (clearing V7-17) and far from the settlement of Gaz-Sale (clearing V8-17 and borehole C3-20), and 23 peat samples were collected for laboratory research. The botanical composition, properties, and age of the Holocene bogs of the southern tundra in Western Siberia were determined in the peat samples. The species composition of peat-forming plants was identified using a microscopic method with the help of identification atlases. The degree of decomposition was established according to GOST 10650-2013, and ash content according to GOST 11306-2013. The radiocarbon age of the peat was determined using a spectrometer-radiometer. The layer-by-layer radiocarbon age, ash content, degree of decomposition, and species composition of peat from typical peatlands of the southern hypoarctic tundra in Western Siberia and their spatial differentiation were determined. It was established that peat accumulation began in the pre-boreal period of the Holocene and depended on the spatial location of lowlands. Near the settlement of Gaz-Sale, peat was actively accumulating during the boreal period and is mainly represented by sphagnum communities. At a distance from the settlement—in the Atlantic period—it shows greater diversity of peat-forming plants. The floristic composition and physicochemical properties of the peat reflect the conditions of peat accumulation: nutrient type, thaw-freeze conditions of the deposits, and local swamp conditions. The mosaic nature of the phytocenoses of the bogs in the southern tundra during the Holocene is determined by biotic and abiotic factors that influence the dynamics of plant communities.