Thermokarst Formation and Vegetation Dynamics Inferred from A Palynological Study in Central Yakutia, Eastern Siberia, Russia

Abstract

ABSTRACT Thermokarst formation and vegetation change in central Yakutia, eastern Siberia, were reconstructed based on newly obtained AMS radiocarbon data and pollen records from four typical thermokarst depressions (alases). Radiocarbon ages of wood fragments, which are good indicators of the development of thermokarst depressions, suggest that they formed during the early Holocene. The result of dating at various locations implies that thermokarst in central Yakutia developed synchronously, at a time that regional paleoclimate records indicate warm and moist conditions prevailed. Major trends in pollen records from the four thermokarst deposits were similar. The predominant vegetation type during the thermokarst active phase was open larch and birch forest with herbaceous taxa. Grassland developed on areas exposed by a decrease in water levels of thermokarst lakes during the late Holocene.