Quantitative reconstruction of the last interglacial vegetation and climate based on the pollen record from Lake Baikal, Russia |
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| Authors: | P Tarasov W Granoszewski E Bezrukova S Brewer M Nita A Abzaeva H Oberhänsli |
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| Institution: | (1) Institute of Geological Sciences, Palaeontology Department, Free University, Malteserstr. 74-100 Building D, Berlin, 12249, Germany;(2) Carpathian Branch, Polish Geological Institute, Skrzatow 1, Krakow, 31-560, Poland;(3) Institute of Geochemistry, Siberian Branch Russian Academy of Sciences, Favorsky street 1a, Irkutsk, 664033, Russia;(4) CEREGE CNRS/University P. Cèzanne, UMR 6635, BP80, 13545 Aix-en-Provence cedex 4, France;(5) Faculty of Earth Sciences, University of Silesia, Bedzinska 60, 41-200 Sosnowiec, Poland;(6) GeoForschungsZentrum, Potsdam, 14473, Germany |
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| Abstract: | Changes in mean temperature of the coldest (T
c) and warmest month (T
w), annual precipitation (P
ann) and moisture index (α) were reconstructed from a continuous pollen record from Lake Baikal, Russia. The pollen sequence
CON01-603-2 (53°57′N, 108°54′E) was recovered from a 386 m water depth in the Continent Ridge and dated to ca. 130–114.8 ky
BP. This time interval covers the complete last interglacial (LI), corresponding to MIS 5e. Results of pollen analysis and
pollen-based quantitative biome reconstruction show pronounced changes in the regional vegetation throughout the record. Shrubby
tundra covered the area at the beginning of MIS 5e (ca. 130–128 ky), consistent with the end of the Middle Pleistocene glaciation.
The late glacial climate was characterised by low winter and summer temperatures (T
c ~ −38 to −35°C and T
w~11–13°C) and low annual precipitation (P
ann~300 mm). However, the wide spread of tundra vegetation suggests rather moist environments associated with low temperatures
and evaporation (reconstructed α~1). Tundra was replaced by boreal conifer forest (taiga) by ca. 128 ky BP, suggesting a transition
to the interglacial. Taiga-dominant phase lasted until ca. 117.4 ky BP, e.g. about 10 ky. The most favourable climate conditions
occurred during the first half of the LI. P
ann reached 500 mm soon after 128 ky BP. However, temperature changed more gradually. Maximum values of T
c ~ −20°C and T
w~16–17°C are reconstructed from about 126 ky BP. Conditions became gradually colder after ca. 121 ky BP. T
c dropped to ~ −27°C and T
w to ~15°C by 119.5 ky BP. The reconstructed increase in continentality was accompanied by a decrease in P
ann to ~400–420 mm. However, the climate was still humid enough (α~0.9) to support growth of boreal evergreen conifers. A sharp
turn towards a dry climate is reconstructed after ca. 118 ky BP, causing retreat of forest and spread of cool grass-shrub
communities. Cool steppe dominated the vegetation in the area between ca. 117.5 ky and 114.8 ky BP, suggesting the end of
the interglacial and transition to the last glacial (MIS 5d). Shift to the new glaciation was characterised by cool and very
dry conditions with T
c ~ −28 to −30°C, T
w~14–15°C, P
ann~250 mm and α~0.5. |
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