Climatic implications of Late Quaternary plant macrofossil assemblages from the Taymyr Peninsula, Siberia

Plant macrofossil investigations were carried out on Late-Quaternary deposits at Cape Sabler (NW shore of Lake Taymyr, Siberia). Four dated samples (three Late Pleistocene, one Holocene) rich in plant macrofossils were analysed with respect to their floristic composition. The flora of the Holocene sample is similar to the recent plant cover in the study area and is mainly characterized by subarctic and high arctic dwarf-shrubs and hydrophytes. The Pleistocene samples, radiocarbon dated to ca. 30, 27 and 18 ka BP, reflect a species-rich vegetation. The high proportion of pioneer plants within these samples indicates frequent disturbances of the vegetation cover. Furthermore, an almost complete absence of hydrophytes and swamp plants and the dominance of xerophytes, respectively, are typical for the Pleistocene vegetation from the Cape Sabler section. The presence of the tundra-steppe Crassulaceae Orostachys spinosa gives evidence for extremely cryoxeric climatic conditions in the Central Taymyr Peninsula during the Late Pleistocene. The species composition of the Pleistocene samples thus proves the predominance of a continental climate during the Weichselian, which was characterized by a decreased cloud cover, and thus increased direct solar radiation reaching the ground and extreme annual temperature variations. That would have entailed higher summer temperatures, lower precipitation, and longer vegetation periods (due to shorter snowmelt), thus, better conditions than today for the growth of plants in the study area. The higher species diversity in the Weichselian samples confirms this assumption. All these factors caused mainly aerobic soil environments and favourable conditions for seasonal heating of soils. (C) 2001 Elsevier Science B.V. All rights reserved.