Palynological study of Lake Kotokel’ bottom sediments ( Lake Baikal region)

Abstract

Pollen and AMS 14C analyses of bottom sediments from the upper nine meters of the Lake Kotokel’ section were carried out. The regional climate and landscape dynamics during the Late Glacial and Holocene has been reconstructed with an average time resolution of ∼120 years. It is shown that the climatic conditions in the Kotokel’ basin during Termination I (∼15.5–11 ka) were characterized by short drastic changes resulting in the reorganization of landscapes and vegetation. Five short (400–1200 years) intervals have been recognized: 15.5–14.7, 14.7–14.3, 14.3–13.2, 13.2–12.5, and 12.5–11.7 ka. In the early Holocene (∼11 ka), the climate became less continental and stayed such till ∼7 ka. Later on, it again became more continental, which led to a significant decrease in average annual precipitation and winter temperatures and an increase in average summer temperatures. The pollen record from Lake Kotokel’ agrees with the general climatic trend for the Northern Hemisphere. The amplitude of vegetation and climatic variations during the Late Glacial is best expressed as compared with the previous regional pollen records. This is probably because the ecosystem of the small lake localized deep inside the continent, at the boundary of two large ecotones (forest and steppe), is highly sensitive to moisture deficit. The new dated detailed pollen record from the Lake Kotokel’ bottom sediments might be regarded as a key section for the reconstruction of variations in regional vegetation and climatic dynamics for the last 15–15.5 kyr. The results obtained refined the kind of changes in regional vegetation, and the reliable age model permitted intra- and interregional correlations of environmental changes.