THE HOLOCENE DYNAMICS OF VEGETATION IN BURYATIA

Abstract

Bottom deposits of four lakes in the central part of Buryatia (51-54°N, 106-112°E) were subjected to the pollen and radiocarbon analyses. The data obtained elucidate development of regional and local Holocene vegetation in response to climatic changes. As far as 10600-10000 years ago, the Kotokel' Lake depression was covered by the forest tundra and cryophilic forest-steppe vegetation. The summer temperature rise and some increase in aridity 10000-9000 years ago widened steppe areas, which were replaced by forests 9000 years ago. The interval of 8500-8000 years ago was characterized by the distribution maximum of spruce forests in Buryatia. Birch and spruce were widespread in forest communities till 6000 year ago. The dispersal of spruce suggests a more humid and less continental climate of the mid-Holocene time. Climatic conditions optimal for fir growth on the ridge slopes facing the Lake Baikal existed 3000-6000 years ago. The pine and larch forests, which became dominant in the vegetation cover during the last 3000 years, characterize the period of less humid and more continental climate in the region.