Late Pleistocene-Holocene paleolimnology of three north-western Russian lakes

The vegetation history and development of three different types of lakes, l akes Valday, Kubenskoye and Vishnevskoye (northwest of the East European Pl ain) were reconstructed using paleolimnological techniques. Watershed veget ation demonstrates a close connection with climate fluctuations: gradual ex pansion of the southern broad-leaved trees to the North during the Holocene with the maximum extent during the climate optimum (8000-5000 BP); and the ir subsequent retreat afterwards; followed by the extension of spruce durin g the cold and dry Subboreal time; and dominance of pine-spruce-birch fores ts in the Subatlantic time. The Late Pleistocene and Holocene climate chang es resulted in lake-level fluctuations and other ecosystem changes. Valday Lake was formed ca. 12,500 BP as an oligotrophic, deep water basin. The lak e level decreased during the dry Boreal, then increased again during the hu mid Atlantic period. The large shallow Kubenskoye Lake was formerly a part of an ice margin lake, which was then separated (ca. 13,000 BP) and develop ed into the Sukhona Basin with an outflow to the northwest. During the Atla ntic, the outflow direction changed to the east. As a result, the ancient S ukhona Lake disappeared and Kubenskoye Lake formed in its modern size and s hape. Vishnevskoye Lake, on the Karelian Isthmus, was formed at the beginni ng of the Preboreal after the disappearance of the Baltic Ice Lake. It was flooded by waters of the Boreal Ancylus transgression of the Baltic Basin a nd had become a small eutrophic lake by the time.