9 - Vegetation history of the southeastern and eastern coasts of Lake Baikal from bog sediments since the last interstade

Abstract

This chapter describes the geology and vegetation around the study sites and the regional vegetation history in the southeastern and eastern coastal areas of Lake Baikal. Various paleoecological studies of mire sediments from the coastal areas of Lake Baikal were conducted and sediment samples from the last glacial and the Holocene are taken from eight bogs and two outcrops of peat sediment on the southeastern and eastern coasts of Lake Baikal and examined for fossil pollen, plant macrofossils, and charcoal fragments. The chronology of each deposit is based on radiocarbon dating. The results of these studies reveal the vegetation history of the taiga around Lake Baikal since the last glacial period. During the last interstade (approximately 35–30000 y BP), forests on the southeastern coast consisted mainly of spruce and birch, with Gramineae and Artemisia. Herbaceous plants such as Gramineae and Artemisia and shrubs such as willow, birch, and alder characterized the vegetation of the last glacial maximum. Between 12000 and 11000 y BP, spruce expanded again in the coastal areas. The changes in spruce suggest that the Lake Baikal area is a glacial refugia of dark coniferous taiga. In the early Holocene, the spruce was replaced by fir and pine on the southeastern coast. On the eastern coast, the forests contained both spruce and fir. Diploxylon and Haploxylon pine forests shared large areas with birch since 6000 y BP. In some sites on the southeastern coast, the concentration of charcoal fragments, which indicates fires, increases sharply in the upper sediments. This increase in charcoal probably reflects forest fires caused by human activity.