Kimiyasu Kawamuro

Radiocarbon chronology of the late Pleistocene-Holocene paleogeographic events in lake Baikal region (Siberia)

New radiocarbon dates obtained from Late Pleistocene and Holocene deposits of the southern, eastern, and northern shores of Lake Baikal in 1995-2001 are presented, and the most important results of paleoenvironmental studies based on (super 14) C data are discussed. The following paleogeographic events were verified with the help of (super 14) C dating: 1) first Late Pleistocene glaciation (Early Zyryan); 2) Middle Zyryan interstadial; 3) loess formation during the Late Zyryan (Sartan) deglaciation; 4) warm and cold events in the Late Glacial; and 5) vegetation changes and forest successions during the Late Glacial and Holocene.

Pollen Record from the Chivyrkui Bay Outcrop on the Eastern Shore of Lake Baikal since the Late Glacial

Bogs have formed on the shore of Chivyrkui Bay near Svyatoy Nose Peninsula on the eastern shore of Lake Baikal. Two sediment columns were taken from the outcrop of one of bogs (53°39′N, 109°12′E) to investigate the vegetation history of the eastern shore area of Lake Baikal. The forests around the bog are composed mainly of Pinus sylvestris, Pinus sibirica, Larix sibirica, and Abies sibirica. The results of a palynological study of the cores with 14 radio-carbon dates revealed the following vegetation history since the late glacial. The late glacial and early Holocene vegetation from 12000 to 9000 14C years BP was a shrub tundra with spruce and birch trees, thickets of dwarf birch and alder, and herbs such as Gramineae and Artemisia. Between 9000 and 8000 14C years BP, spruce forests expanded in the area, accompanied by some fir and pine, indicating the initial development of the dark taiga. Pine trees gradually increased after 8000 14C years BP and then started a dramatic increase, to become dominant in 6000 14C years BP in the dark taiga forests. The vegetation from 6000 14C years BP to the present was mainly composed of pines (Pinus sylvestris and P. sibirica) and birch, accompanied by spruce, fir, and larch.

Forest-desert alternation history revealed by the pollen-record in lake baikal over the past 5 million years

Publisher Summary The watershed of Lake Baikal constitutes the southern portion of the Siberian taiga and the northern part of the Mongolian steppe, and it is located at a high-latitude (51–56 N), far from the ocean. The paleoclimatic history of the Baikal region sensitively reflects past global changes, such as warm-cold and dry-moist oscillations of climate. Paleovegetational reconstruction of the region is indispensable to understanding how the Siberian taiga forest responded in timing and magnitude to past global changes. However, there are few palynological studies for paleovegetational reconstruction of the past million years in the region. This chapter presents a palynological study on the BDP96 Hole 1 core drilled by a Russian scientific drilling team in 1996. The results obtained in this study prove that the forest-desert alternations are closely related to global glacial–interglacial cycles during the Pleistocene. Considerable forest retreats are visible for relatively long periods during the late Pliocene, and a remarkable desert prevailing period during the early and middle Pliocene preceded the forest dominant period. The work in the Baikal area has also shown that these forest-desert alternations are more sensitive to global paleoclimate changes than those found in other continental region records.

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

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.