Vegetation and climate changes in northwestern Russia during the Lateglacial and Holocene inferred from the Lake Ladoga pollen record

The new pollen record from the upper 12.75m of a sediment core obtained in Lake Ladoga documents regional vegetation and climate changes in northwestern Russia over the last 13.9cal. ka. The Lateglacial chronostratigraphy is based on varve chronology, while the Holocene stratigraphy is based on AMS C-14 and OSL dates, supported by comparison with regional pollen records. During the Lateglacial (c.13.9-11.2cal. ka BP), the Lake Ladoga region experienced several climatic fluctuations as reflected in vegetation changes. Shrub and grass communities dominated between c.13.9 and 13.2cal. ka BP. The increase in Picea pollen at c.13.2cal. ka BPprobably reflects the appearance of spruce in the southern Ladoga region at the beginning of the AllerOd interstadial. After c.12.6cal. ka BP, the Younger Dryas cooling caused a significant decrease in spruce and increase in Artemisia with other herbs, indicative of tundra- and steppe-like vegetation. A sharp transition from tundra-steppe habitats to sparse birch forests characterizes the onset of Holocene warming c.11.2cal. ka BP. Pine forests dominated in the region from c.9.0 to 8.1cal. ka BP. The most favourable climatic conditions for deciduous broad-leaved taxa existed between c.8.1 and 5.5cal. ka BP. Alder experiences an abrupt increase in the local vegetation c.7.8cal. ka BP. The decrease in tree pollen taxa (especially Picea) and the increase in herbs (mainly Poaceae) probably reflect human activity during the last 2.2cal. ka. Pine forests have dominated the region since that time. Secale and other Cerealia pollen as well as ruderal herbs are permanently recorded since c. 0.8cal. ka BP.