Vegetation Changes in the Baikal Region during the Late Miocene Based on Pollen Analysis of the BDP-98-2 Core

Summary

A palynological study was conducted on samples taken from the bottom sediments of Lake Baikal. The pollen records from 600-m to 400-m depth of the BDP-98 core show that the vegetation consisted mainly of broad-leaved tree forests composed of Fagaceae, Ulmaceae, and Juglandaceae in the lower part of the core. In the middle and upper parts of the core, the vegetation consisted mainly of coniferous tree forests and deciduous broad-leaved tree forests. The coniferous tree forests were composed of Pinus and Picea accompanied by Tsuga and Larix, and the deciduous broad-leaved tree forests were mainly composed of Betula and Alnus. A major reduction in palynological diversity and abundance was found at 8.6 Ma. In addition, a drastic change in the Steppe/forest index (SFI; Traverse 1988) was detected, reflecting the intensification of dry conditions. After the change, Betula and Alnus became more important elements of the deciduous broad-leaved tree forests, suggesting that a cool continental climate prevailed.