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Holocene vegetational and climatic changes in the forest zone of Western Siberia according to pollen records from the extrazonal palsa bog BugristoyeTomsk State University, Department of Botany, Lenina 36, 634050 Tomsk
Geological Institute RAS, Pyzhevsky 7, Moscow 109017, Russia Pollen stratigraphy of an extrazonal palsa bog in the middle taiga of the West Siberian Plain is dated by radiocarbon at five levels. Local pollen assemblage zones (LPAZ) are the basis for palaeogeographical reconstructions. Tundra-steppe plant communities with shrub birch (Betula nana) dominated in the latest Pleistocene. Warming after 10 000 14C yr BP caused the local thawing of permafrost, forming shallow lakes. Larixand then Picea spread along river valleys and depressions. Steppe plant communities existed on the dry interfluves. Further climatic warming and drying caused Picea to retreat, and Betula forest-steppe dominated 95008900 yr BP. Dense Pinus sylvestris and Pinus sibirica forests then spread over the whole area, and steppe communities decreased about 8300 yr BP. The Holocene climatic optimum (60005000 yr BP) was characterized by warm and wet conditions and Abies was widespread. Cooling then caused retreat of Abiesforests to the south and the expansion of Pinus sibirica forests on clay soils and Pinus sylvestris forests on sandy soils. Cooling about 4300 yr BP caused the peat to freeze and the palsa to form by bulging. Peat accumulation on the Bugristoye bog stopped at this time.
Key Words: Palaeoecology palaeoclimate palsa bog Western Siberia
The Holocene, Vol. 9, No. 5,
621-628 (1999) This article has been cited by other articles:
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