TRANSFORMATION OF PLANT COMMUNITIES AT THE TURN OF THE PLEISTOCENE AND HOLOCENE IN THE ROSTOV LOWLAND (YAROSLAVL REGION)¹

The article presents the results of a multiproxy study of a sedimentary sequence located on the lacustrine-alluvial plain west of Lake Nero (Yaroslavl region). The investigated 2 m-long core made it possible to reconstruct environmental changes since the Allerød to the Late Holocene. Previously poorly studied Preboreal deposits in this area have a significant thickness in the core (0.4 m). The obtained materials help fill the gap in understanding of the vegetation history in the Rostov lowland at the turn of the Late Glacial and Holocene and during the Early Holocene. The study is based on several paleogeographic methods: spore-pollen analysis, botanical composition analysis of peat, diatom analysis, loss-on-ignition, and radiocarbon dating. It was found that after 14.3 cal. ka BP sparse spruce-birch forests were widespread, open spaces were occupied by herbaceous communities. Since 13.7 cal. ka BP, as a result of a significant cooling, the open areas expanded, sparse birch forests dominated in combination with steppe and tundra associations. About 12.1 cal. ka BP a lowland reed wetland began to form at the site. It transformed into a reed-sedge wetland after 10.9 cal. ka BP. During the interval of 12.1–11.5 cal. ka BP, the landscapes of the periglacial forest-steppe were gradually replaced by pine-birch forests. The climate was colder than today, but with the tendency to warming compared to the Late Glacial stage. Short-term cooling 11.5–11.2 cal. ka BP led to a new expansion of open herbaceous communities, but the spread of forests continued after 11.2 cal. ka BP. Starting from 9.8 cal. ka BP, the role of broadleaf species increased in the woods; mixed pine-birch forests with oak, elm, and linden dominated in the surrounding area. In the interval 7.9–5.2 cal. ka BP, climate conditions were warmer than modern ones. This led to the spread of spruce-pine forests with birch and thermophilous deciduous trees. After 5.2 cal. ka BP the vegetation cover was dominated by spruce forests with pine, birch, and broadleaf species.