Postglacial Vegetation and Climate History of the Oka Plateau (East Sayan Mountains, South Siberia)

Abstract

The first results of palynological analysis of the bottom deposits of Kaskadnoe Lake and a reconstruction of vegetation and climate on the Oka Plateau over the last 14.2 ky are reported. It is shown that approximately 1.2–12.9 cal ka BP (GI-1) the regional climate was sufficiently warm and humid to allow the development of a forb–shrub tundra with spruce and larch stands. Cooling at approximately 12.9–11.5 cal ka BP (GS-1) led to the predominance of the forb–shrub tundra in the lake basin. Siberian pine settled on the Oka Plateau in a moderate–cold and humid climate at approximately 11.5–9.0 cal ka BP. The warmer and drier climate, which prevailed in the Middle Holocene approximately 9.0–4.5 cal ka BP, resulted in the retreat of dark-coniferous forests from the Kaskadnoe Lake basin. The spreading of larch and Siberian pine coincided with the onset of Neoglacial conditions in the Late Holocene. It was established that the environmental conditions on the Oka Plateau in the Late Glacial Period and Holocene were generally controlled by the interaction of the western atmospheric transport and the East Asian summer monsoon, the temperature variations caused by the insolation level, and the specific features of regional atmospheric circulation.