Vegetation dynamics around Lake Baikal since the middle Holocene reconstructed from the pollen and botanical composition analyses of peat sediments: Implications for paleoclimatic and archeological research

摘要

The present paper summarizes the current evidence of natural changes in the forest and forest-steppe areas of the Lake Baikal Region (LBR) since ca. 7 cal ka BP, covering the period from the late Neolithic to the present time. To reconstruct local to small-regional scale vegetation changes and their probable causes during this period, pollen content and peat botanical composition were analyzed from three radiocarbon-dated peat sections, located near Lake Baikal. For better understanding of the local and regional environmental history and climate variability during the middle and late Holocene, the results are compared with published environmental records from lacustrine and mire sediments from the LBR and from elsewhere. The comparison confirms the earlier interpretations that the middle and late Holocene vegetation dynamics in the LBR was primarily driven by natural forcing and likely was associated with large-scale circulation processes controlling the regional water balance rather than with human activities. Some synchronous changes in environmental and archeological data likely point to a possible causal link between past climate changes and the cultural history of the region. The Kuchelga (53°00'57"N, 106°44'49"E), Ochkovoe (51°26'05"N, 104°38'57"E) and Cheremushka (52°45'09"N, 108°05'50"E) peat records represent three different climatic regions around Lake Baikal and demonstrate that the environments and vegetation of the drier western coast were more sensitive to the climate oscillations of the middle and late Holocene in comparison to the more humid areas east, and particularly south of Baikal. Therefore, it could be expected that environmental impact on early human societies was strongest in the arid region to the west of Lake Baikal. To test this hypothesis, however, accurately dated multi-proxy records of the Holocene climate and environments from this so far poorly studied region are absolutely necessary.