Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)

Quaternary International xxx (2013) 1e11

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Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia) Stefanie Müller a, *, Pavel E. Tarasov a, Philipp Hoelzmann b, Elena V. Bezrukova c, d, Annette Kossler a, Sergey K. Krivonogov e a

Institute of Geological Sciences, Palaeontology, Freie Universität Berlin, Malteserstr. 74-100, Building D, 12249 Berlin, Germany Institute of Geographical Sciences, Physical Geography, Freie Universität Berlin, Malteserstr. 74-100, Building B, 12249 Berlin, Germany Institute of Archaeology and Ethnography, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia d A.P. Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk 664033, Russia e Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia b c

a r t i c l e i n f o

a b s t r a c t

Article history: Available online xxx

This paper presents a new decadal-resolution fossil pollen record from Lake Kotokel (52
470 N, 108
070 E, 458 m a.s.l.) and provides a reconstruction of the Last Glacial Maximum (LGM) vegetation and environments in the study area during this interval of globally harsh climate. Lake Kotokel is situated close to the eastern shoreline of Lake Baikal, in the boreal forest zone of southern Siberia. The analysed 190 cm long section 6 of the bottom core KTK10 (KTK10/6) consists of compact, undisturbed, greenish-grey to dark-grey, slightly laminated silty clay indicating continuous lacustrine sedimentation throughout the LGM period ca. 26.8e19.1 cal. ka BP. The age model is supported by 11 calibrated AMS dates. The results of pollen analysis and pollen-based biome reconstruction show that steppe and tundra vegetation composed of grasses and various herbs dominated ca. 26.8e19.1 cal. ka BP. Occurrence of conifer tracheids and stomata throughout the record, together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen, suggests the presence of single trees or small forest stands in the lake vicinity, most likely in the river valleys. Application of the biomisation method and the resulting numerical scores of the most characteristic biomes (steppe, tundra and cold deciduous forest) show minor fluctuations, signifying stability of the regional vegetation cover during the analysed LGM interval. In contrast to the regional biomes, the local environmental indicators demonstrate greater sensitivity of the lake system to decadal- and century-scale climate variability. The highest pollen percentages of Ranunculaceae, representing littoral/meadow vegetation communities, are registered ca. 23.8e23.4 cal. ka BP. This and an increase in coarse-grained sand particles together with slightly increased total inorganic carbon (TIC) values representing calcite in the KTK10/6 sediment provide evidence of a much shorter than present distance between the coring site and the shoreline and a reduced lake area, in line with a drier-than-present LGM climate. A general stability of the grassland vegetation in the study region ca. 26.8e19.1 cal. ka BP and relatively constant total organic carbon (TOC) values support the hypothesis that this productive vegetation could stably serve as a perennial food resource for large populations of herbivores, thus providing favourable environments for the local hunteregatherers inhabiting the Lake Baikal region during the LGM interval. Ó 2013 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction

the extreme conditions of the Last Glacial Maximum (LGM) covering the time frame from ca. 26.5 to 19 ka BP (Clark et al., 2009). Published archaeological records (e.g. Okladnikov, 1950, 1955, 1959; Weber, 1995; Weber and Katzenberg, 2002; Parzinger, 2006; Weber et al., 2010, 2013; and references therein) and environmental records (Tarasov et al., 2007, 2009; Bezrukova et al., 2013; White et al., 2013 and references therein) reveal an intriguing human habitation and environmental history in the

Southern Siberia and the Russian Far East played a key role in occupation and reoccupation by late Upper Palaeolithic groups in response to changing environmental conditions, in particular for * Corresponding author. E-mail address: [email protected] (S. Müller). 1040-6182/$ e see front matter Ó 2013 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2013.12.012

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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S. Müller et al. / Quaternary International xxx (2013) 1e11

Fig. 1. Schematic maps showing (A) location of the study area in Eurasia; (B) the vicinity of Lake Kotokel near Lake Baikal; and (C) the KTK10 coring site location.

Baikal region during the Holocene. The Holocene humaneenvironmental interactions are the focus of the Baikal-HokkaidoArchaeology Project (BHAP, http://bhap.artsrn.ualberta.ca/, Tarasov et al., 2013a; Weber et al., 2013) which aims to better understand the long-term patterns of culture change among huntere gatherer populations inhabiting these two representative regions. However, the BHAP only covers the time interval of the past ca. 9000 years, whereas the human habitation history of eastern Eurasia and the Baikal region can be traced back to late Pleistocene time (e.g. Dolukhanov et al. 2002; Vasil’ev et al., 2002; Metspalu et al., 2006; Lbova, 2009; Svendsen et al., 2010; Buvit and Terry, 2011). Though archaeological and geochronological data from western Europe show numerous evidence of human occupation during the last glacial interval, including Marine Isotope Stages (MIS) 2 and 3 (e.g. Dolukhanov et al., 2002; Conard and Bolus, 2008), results of geoarchaeological research covering the Mediterranean region suggest severe decline or even total collapse of human populations during the extreme oscillations towards a cold and arid climate, the so-called Heinrich Events (Weniger, 2008). Understanding which role climatic and environmental conditions played in the life of Palaeolithic inhabitants of southern Siberia and the Baikal region requires high-quality archaeological and palaeoenvironmental data. This work, which is still underway, is paying great attention to chronological control and time resolution of the archaeological and environmental archives. Lake Kotokel, located on the western shore of Lake Baikal, has been an important object of palaeoenvironmental studies since two sediment cores from the southern lake basin (KTK1 and KTK2) and several cores from the surrounding peat bogs revealed pronounced changes in vegetation cover and composition and lake-internal bio-productivity, caused by the longand short-term variations in temperature and atmospheric precipitation throughout the last glacial and the Holocene interval (Bezrukova et al., 2008, 2010; Shichi et al., 2009; Tarasov et al., 2009; Kostrova et al., 2013). The KTK2 sediment core retrieved in summer 2005 (Shichi et al., 2009) provided pollen, diatom and climate records, yielding a temporal resolution of ca. 200e500 years (i.e. 250 years on average) over the last glacial interval (Bezrukova et al., 2010). As demonstrated by further geophysical investigation of the lake (Zhang et al., 2013), the KTK2 core did not penetrate the whole lacustrine sediment

sequence. Moreover, the lack of material did not allow higher resolution multi-proxy analyses of the KTK2 core and showed the necessity of obtaining another core from the lake. This task was partly accomplished in 2010. In the current study we present a new pollen record from Lake Kotokel, which covers the interval between ca. 26.8 and 19.1 cal. ka BP (i.e. the LGM) with an average temporal resolution of ca. 40 years. Together with other analytical and reconstruction results from the same core, this pollen record is then used to discuss the regional environmental dynamics and terrestrial ecosystem stability in the study region during the LGM. In a final step, results are discussed along with published archaeological data from the Baikal region and compared with published contemporary results of geoarchaeological studies from other regions of Eurasia. 2. Regional setting 2.1. Site location and coring details Lake Kotokel (52
470 N, 108
070 E, 458 m a.s.l.) in southern Siberia (Fig. 1A) is a 15 km long and approximately 6 km wide basin with a water area of about 69 km2 and a catchment area of ca. 183 km2 (Kostrova et al., 2013). The lake is situated only 2 km away from the eastern shore of Lake Baikal (Fig. 1B). The bathymetric mapping performed in May 2011 shows a ca. 4 m mean water depth and an almost flat lake bottom (Zhang et al., 2013). Although Lake Kotokel has an outflow to Lake Baikal (Fig. 1C) via the rivers Istok, Kotochik and Turka (Kostrova et al., 2013 and references therein), there is no evidence that Baikal water has penetrated to Kotokel during the past ca. 47e50 ka (Shichi et al., 2009; Bezrukova et al., 2010). The sediment core KTK10 (52
47.2760 N, 108
07.4350 E) was retrieved during a coring campaign in July 2010. The Livingstontype piston corer was applied, which allowed subsequent extraction of 190 cm long sediment sections (diameter 7.6 cm) within the coring depth interval 0e770 cm, and 200 cm long sediment sections (diameter 7 cm) within the coring depth interval 770e 1370 cm. The coring site location was chosen in the southern part of the lake, ca. 1.8 km from the nearest shoreline and only a few metres apart from the sites where KTK1 and KTK2 cores were collected

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

S. Müller et al. / Quaternary International xxx (2013) 1e11

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3. Materials and methods

(Fig. 1C). The sediment stratigraphy indicates that the most suitable coring sites for palaeoenvironmental studies are located in the southern part of the basin, where almost undisturbed sediments up to a depth of ca. 50 m can be expected (Zhang et al., 2013). The recovered KTK10 core includes a section of the undisturbed LGM sediment (KTK10 Section 6, hereafter named KTK10/6), which has been selected for the purpose of the current study.

3.1. Sub-sampling strategy and radiocarbon dating The KTK10/6 core section (coring depth interval 970e1170 cm; length of the undisturbed core segment 190 cm) was cut into half for further sub-sampling and lithological description performed in the Institute of Geochemistry (Irkutsk). One half was cut into 1 cm slices, packed in plastic containers and transported to FU Berlin for storage and further analyses. Seven bulk sediment samples (1 cm thick slices) were submitted to the Poznan Radiocarbon Laboratory (Poland) for AMS age determination. The sample details and dating results are summarised in Table 1. All samples were dated using humin fraction, i.e. sediment after removal of carbonates (HCl treatment) and humic acids (NaOH treatment). For comparison with the earlier studies of the KTK1 and KTK2 cores (Tarasov et al., 2009; Bezrukova et al., 2010) all radiocarbon dates were calibrated using the online version of CalPal-2007 calibration software and the CalPal-2007-Hulu calibration curve (Danzeglocke et al., 2008; Weninger et al., 2013). All ages are expressed in cal. ka BP (1 ka ¼ 1000 years before 1950 AD).

2.2. Modern climate and vegetation The regional climate, including that of the study area, is continental with long, cold winters and short, hot summers (Alpat’ev et al., 1976). Near Lake Kotokel, the two meteorological stations of Cheremukhovo and Goryachinsk are situated less than 10 km apart, (Galaziy, 1993; Bezrukova et al., 2013). The averaged station records document a mean January temperature of 19.4
C, mean July temperature of 14.7
C, annual precipitation of ca. 375 mm, and ca. 176 days with snow cover around Lake Kotokel. The modern precipitation distribution has a well-pronounced summer maximum in July and August. During these months, westerly winds dominating through the year become weak, and southeastern cyclones

Table 1 Summary of the AMS radiocarbon dates from the KTK10/6 and KTK2 sediment cores of Lake Kotokel (Fig. 2A). Radiocarbon years before present were converted to calendar  Radiocarbon Laboratory (Poznan  , Poland). years using the CalPal Online Radiocarbon Calibration software (Danzeglocke et al., 2008). All dates were processed in the Poznan Samples representing the KTK2 core were published by Bezrukova et al. (2010). Core name

Respective core depth (cm)

Dated sediment

14

C age (years BP; 68% range)

Calibrated age (cal. years BP; 68% range)

Lab. number

KTK10/6 KTK10/6 KTK10/6 KTK10/6 KTK10/6 KTK10/6 KTK10/6 KTK2 KTK2 KTK2 KTK2

15e16 35e36 55e56 75e76 105e106 145e146 185e186 685e689 795e799 918e922 1036e1040

Dark-grey silty clay Dark-grey silty clay Dark-grey silty clay Dark-grey silty clay Dark-grey silty clay Dark-grey silty clay Dark-grey silty clay Blackish silty clay Grey silty clay Grey silty clay Grey silty clay

17,230  90 17,310  90 18,410  100 20,560  120 20,120  90 21,780  110 21,590  100 12,680  60 18,000  90 21,450  110 27,820  200

20,990e20,400 21,070e20,480 22,360e21,710 24,820e24,230 24,360e23,760 26,570e25,580 26,130e25,290 15,300e15,080 21,610e21,430 25,710e25,250 32,570e32,090

Poz-40941 Poz-40942 Poz-40944 Poz-40945 Poz-52847 Poz-52848 Poz-52849 Poz-27585 Poz-27586 Poz-27587 Poz-27589

bring warm and wet Pacific air to the region, causing heavy rainfalls at the eastern branch of the Polar front (Bezrukova et al., 2008). By contrast, the precipitation associated with the Atlantic air masses brought by the westerly winds is not abundant and mainly falls during autumn and spring. During winter, dry, cold and sunny weather often occurs, because of the stationary Siberian Anticyclone occupying the area (Tarasov et al., 2009). Related to these moderately harsh continental climatic conditions, modern vegetation of the study area east of Lake Baikal consists of boreal coniferous and deciduous forests (Galaziy, 1993). Forests are mainly composed of Pinus sylvestris (Scots pine), Larix sibirica (Siberian larch) and Betula (birch) trees, with some admixture of Populus tremula (aspen) and Alnus fruticosa (shrubby alder). Boreal evergreen conifers, including Pinus sibirica (Siberian pine), Abies sibirica (Siberian fir) and Picea obovata (Siberian spruce), grow on the mountain slopes of Ulan-Burgasy. At elevations above 1800 m the mountain taiga is replaced by cold deciduous birch and larch forests and shrubby communities with Pinus pumila, Alnus fruticosa and Betula middendorfii (Bezrukova et al., 2010). Alpine tundra occupies large areas north and northeast of Lake Baikal, whereas steppe vegetation is widespread on the Baikal’s largest island of Olkhon, northwest of Lake Kotokel, and in the semiarid depressions along the Selenga River (Fig. 1B).

3.2. Carbon determination and mineral identification For the carbon quantification 97 samples representing slices of 1 cm were analysed for every 2 cm of core depth (Fig. 3). Total carbon (TC) was analysed with the LECO Truspec Macro elemental analyser. Powdered samples of up to 150 mg were weighed into tin foil and the encapsulated sample was dropped into the primary furnace (950
C) and flushed with pure oxygen for combustion. An infrared detector measured the evolved CO2 for TC quantification. As calibration standard soils (LECO 502e309; 12.29  0.37% carbon; LECO 502e308; 3.6  0.29% carbon) were used (the RSD <2%). The total inorganic carbon (TIC) content was determined with the Woesthoff Carmhograph C16 analyser by evolving CO2 from the weighted (up to 200 mg) sample during mixing with hot (70
C) acid (H3PO4) and subsequent quantification of the evolved CO2 in 20 ml of a 0.05 N NaOH solution by conductivity. Calcite (CaCO3) was used as a calibration standard (12.01  0.14%; RSD <2%). The total organic carbon (TOC) content was calculated by subtracting TIC from TC. At 11 selected core depths qualitative and semi-quantitative mineralogical compounds were examined by X-ray powder diffraction. Powdered samples were placed in the sample holder and analysed with the RIGAKU Miniflex600 instrument at 15 mA/ 40 kV (Cu ka) from 3
to 80
(2q) with a goniometer step size of

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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S. Müller et al. / Quaternary International xxx (2013) 1e11

0.02
and a velocity of 0.5
/min. For the identification and semiquantitative mineral composition analysis the software program X-Pert HighScore Version 1.0b by PHILIPS Analytical B.V. was used. 3.3. Palynological investigation In total, 190 samples have been microscopically analysed for pollen and non-pollen palynomorphs (NPPs). Laboratory treatment of the sediment samples, including pollen extraction and microscopic analysis, was performed at FU Berlin. Pollen and spores of higher plants and other NPPs were extracted from the samples (1.5 g wet sediment) according to standard procedures (Cwynar et al., 1979; Fægri et al., 1989), including 7-mm ultrasonic finesieving, HF (hydrofluoric acid) treatment and subsequent acetolysis. One tablet of Lycopodium marker spores, each containing 18,584 spores (batch no. 177745), was added to every sediment sample prior to the chemical treatment for calculating concentrations of identified palynomorphs (Stockmarr, 1971). Water-free glycerol was used for sample storage and preparation of the microscopic slides. Pollen and spores were identified at magnifications of 400, 600, and 1000, with the aid of published pollen keys and atlases (Kupriyanova and Alyoshina, 1972, 1978; Bobrov et al., 1983; Reille, 1992, 1995, 1998; Beug, 2004) and a modern pollen reference collection stored at FU Berlin. Preservation of extracted pollen and spores was generally good; corroded grains were rarely found. Bisaccate pollen grains of Pinus and Picea were frequently broken, but easily identifiable. The pollen and spore content of the samples was sufficiently high to allow the counting of a minimum of 300 terrestrial pollen grains per sample. In addition to pollen and vascular cryptogam spores, several other palynomorphs (NPPs) were identified and counted, including fungi spores (e.g. Glomus, Thekaphora), algae colonies (e.g. Pediastrum, Botryococcus), and fragments of chironomid head capsules following van Geel et al. (1998). The chironomid analysis may provide valuable palaeoclimatic (e.g. warmest month air temperature) and palaeoenvironmental (e.g. lake water depth) information (e.g. Nazarova et al., 2013 and references therein), though precise species identification requires special sample preparation and experience. Although detailed chironomid analysis of the KTK10 core sediment and chironomid-based reconstructions are planned in the near future, these are beyond the scope of the current paper. For all analysed fossil pollen samples, calculated pollen percentages refer to the total sum of terrestrial pollen grains. For the other counted taxa, including pollen of aquatic plants, spores of ferns and mosses, algae spores, chitin remains of non-biting midge flies (chironomids) percentages were calculated using the total terrestrial pollen sum plus the sum of palynomorphs in the respective group. The Tilia/Tilia-Graph/TGView software (Grimm, 1993, 2004) was used for calculating pollen percentages and drawing the pollen diagram (Fig. 4). The biome reconstruction approach applied to the KTK1 (Tarasov et al., 2009) and KTK2 pollen record (Bezrukova et al., 2010) from Lake Kotokel was also applied to the KTK10 LGM pollen data set generated in this study. The principles of the method were first described in Prentice et al. (1996). Here, we applied two modifications to the regional biomeetaxon matrix (Tarasov et al., 2009). Both successfully resembled the plant communities in northeastern Siberia for the last 50 ka (Müller et al., 2010). These modifications affect the Betula sect. Nanae/Fruticosae and Alnus fruticosa (¼Duschekia fruticosa) taxa. Originally, both taxa were attributed to the arctic and alpine dwarf shrub PFTs (plant functional types) and consistently used to distinguish the tundra biome from the boreal forest and cool steppe biomes (Tarasov et al., 1999). However, the morphology of birch pollen proves to be variable,

making it difficult to separate shrubby and tree taxa by means of pollen analysis with a high degree of confidence. The problem can be overcome by grouping all birch taxa into one broader category, e.g. Betula undiff. (e.g. Anderson et al., 2002), which then can be attributed to tundra and boreal/temperate forest biomes (Prentice et al., 1996). According to the modified biomeetaxon matrix, Alnus fruticosa is attributed to both tundra and cold deciduous forest in line with work by Edwards et al. (2000) in northeastern Siberia. 4. Results 4.1. Sediment lithology and age determination The analysed KTK10/6 core section (Fig. 2) consists of compact homogenous dark-grey (greenish-dark-grey in the bottom part) slightly laminated silty clay (Fig. 2C). Light grey 1e2 mm thick layers were noted between 14 and 21 cm, at 31, 35, 55, 75, 76, and between 174 and 183 cm depth. Two thin layers with nonidentified plant fragments were registered at 168 and 180 cm depth. Furthermore, non-identified insect fragments were found at 9 and 156 cm depth, and non-identified plant remains were found at 13, 18, and 142 cm depth. The top and bottom quartiles contained fine sand particles, whereas coarse-grained sand was more abundant within the third quartile (94e141 cm; between ca. 24.7 and 23.1 cal. ka BP). Ostracod shells and shell fragments were visually identified along the whole analysed core segment, but were more abundant within the uppermost 50 cm. The better-preserved ostracod shells were collected and identified at FU Berlin. The results are used to interpret the LGM environments. The seven radiocarbon dates obtained on the samples from the analysed segment of the KTK10 core vary from 17,230  90 to 21,780  110 14C years BP (Table 1). After calibration these dates yield calendar ages from ca. 20.7 to ca. 26 cal. ka BP (Table 1). Comparison of the high-resolution pollen record from the KTK10/6 core (this study) with the coarse-resolution KTK2 pollen record (Bezrukova et al., 2010) using characteristic changes in the Ranunculaceae pollen percentages (Fig. 2B) helps to correlate both records (Fig. 2C) and to compare newly obtained radiocarbon dates with the published KTK2 core chronology (Bezrukova et al., 2010). The graph combining KTK2 and KTK10/6 datasets (Fig. 2A) demonstrates robustness of the published age model, which is used in the current study. When applied to the analysed KTK10/6 record, the age model points to a very detailed sedimentary and environmental archive, which covers the LGM interval between ca. 26.8 and 19.1 cal. ka BP (Fig. 2C) with a temporal resolution of ca. 32e58 years (i.e. ca. 40 years on average). On the other hand, pollen-based correlation (Fig. 2B) reveals very good correspondence for the lower and the middle Ranunculaceae peaks in the two records, but the absence of the uppermost Ranunculaceae peak in the KTK2 record. This may indicate that a ca. 3e7 cm thin layer (spanning ca. 120e300 years) of the KTK2 sediment at the border between the KTK2/6 and KTK2/7 core segments (Fig. 2B) could not be recovered during the coring campaign. The KTK10/6 data generated in this study allow this gap in the LGM record to be filled. 4.2. Carbon determination and mineralogical composition The TOC content is relatively constant throughout the investigated core and values vary between 2.02 and 4.21% (median ¼ 3.28%). The TIC values show a median of 0.71% and a maximum of 2.0% but minimum values 0.2% in the lowest part of the investigated section that are not reached elsewhere. With respect to the carbon analyses three different core sections (aec in Fig. 3) were identified that are mainly reflected by changes in the

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

S. Müller et al. / Quaternary International xxx (2013) 1e11

15

17

19

21

23

25

27

29

31

33

666

19

686

19.5

706

20

726

20.5

746 766

0

B

20

786

40

806

KTK10/6, cm (this study)

KTK2 composite depth, cm (after Bezrukova et al., 2010)

C

Age, cal. ka BP

KTK2/6

826

KTK2/7

846 866 886 906 926

KTK2 KTK10/6

946 10 20 30

966 986 1006 1026

60

21 21.5 22 22.5

80

23

100

23.5

120

24

140

24.5

160

25

180

25.5

KTK10 age, cal. ka BP (this study)

A

5

26

Ranunculaceae, % Radiocarbon dates from KTK2 (Bezrukova et al., 2010) Radiocarbon dates from KTK10 (this study) Age model (both studies)

1046

26.5 ostracod shell fragments plant macro remains insect remains light grey lamina plant macro remains layer

Fig. 2. (A) Ageedepth relationship for the KTK10 core segment, with newly obtained dates from the KTK10/6 core (squares) shown in relation to the KTK2 dates (circles) published in Bezrukova et al. (2010); (B) pollen-based correlation of the KTK2 and KTK10/6 sediments using relative percentage curves of Ranunculaceae pollen (0 cm in the KTK10/6 record is equivalent to 753.5 cm in the KTK2 record); and (C) the KTK10/6 lithology column (dark-grey slightly laminated silty clay) plotted against the age and depth scales.

TIC values. From ca. 26.8 to 25.8 cal. ka BP (core section a) the TIC is lowest 0.2% whereas the TOC content shows relatively high values between 2.97 and 4.21%. After ca. 25.8 cal. ka BP (core section b) the TIC increases to a median of 0.78% and exhibits highest values (up to 2%) at ca. 22.7 cal. ka BP. The TOC content varies between 2.0 and 4.1% (median 3.18%) and resembles that of core section a. After 22.5 cal. ka BP (core section c) the TIC values decrease slightly (median 0.62% and the highest values around 1%) and once again the TOC values vary between 2.5 and 4.18% as throughout the entire core. Increased TIC values are often also accompanied by slightly higher TOC contents as shown in core sections b and c around 23.9 cal. ka BP; 23.4 cal. ka BP; 22.7 cal. ka BP; 21.5 cal. ka BP and 20.9 cal. ka BP. The mineralogical composition is also very similar throughout the entire section and dominated by quartz (SiO2), plagioclase feldspar (albite, NaAlSi3O8), alkali feldspar (orthoclase, KAlSi3O8) and the amphibole group. As phyllosilicates muscovite (KAl2(AlSi3) O10(OH)2), chlorite ((Mg,Fe)3(Si,Al)4O10(OH)2$(Mg,Fe)3(OH)6) and kaolinite (Al2Si2O5(OH)4) were identified. These minerals are present in all samples in nearly similar amounts as the different XRDdiagrams show only minimum differences. Calcite (CaCO3) is only present in the XRD-diagrams after 25.8 cal. ka BP but then continuously occurs until 19.2 cal. ka BP. 4.3. Biological records In total, 188 of 190 samples analysed for pollen and NPPs were used to interpret the LGM environments. The two uppermost

samples showing high percentages of tree pollen, especially Pinus subgenus Diploxylon type, were excluded from the pollen data set and from further sedimentary analyses. An incursion of younger (and more fluid) sediment to the uppermost part of the sampler during the coring operation was noted when the core was opened in the laboratory. We identified 60 pollen taxa, and 70 NPPs, including fern and fungi spores. The most characteristic taxa distributions are summarised in a simplified percentage diagram (Fig. 4A). Neither pollen spectra composition nor pollen-derived scores of the most characteristic regional biomes show any substantial changes through the KTK10/6 record (Fig. 4B), thus suggesting general stability of the vegetation cover during the analysed interval. The pollen assemblage representing the LGM interval can be described as follows. Herbaceous pollen taxa absolutely predominate in the analysed pollen spectra, whereas needleleaf coniferous tree/shrub taxa and broadleaf deciduous tree/shrub taxa are sparse and do not exceed ca. 2.4% and 5.4% (159.5 cm, ca. 25.8 cal. ka BP), respectively. The shrub pollen sum contains mostly Betula sect. Nanae (0e3%), Alnus fruticosa (0e2%), and Salix pollen (0e1%). Pollen percentages of Ephedra and Ericales are low (0e1%) and restricted to the lower part of the KTK10/6 core section. Among herbaceous pollen taxa, Poaceae (grasses), Cyperaceae (sedges) and Artemisia (e.g. wormwood, sagebrush, etc.) are dominant with less abundant pollen of Asteraceae subfamily Cichorioideae (up to 8%), Caryophyllaceae (up to 6%), and Asteraceae subfamily Asteroideae (up to 6%). Ranunculaceae is constantly present in the pollen spectra, though its

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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S. Müller et al. / Quaternary International xxx (2013) 1e11 19

20

c

Age, cal. ka BP

21

22

23

b

24

resting algae cells of the Zygnemataceae family, including Spirogyra sp., are present throughout the whole sequence, but in very low percentages. Ostracod shells were rarely intact, thus hampering identification of specimens. Nevertheless, Cytherissa lacustris and valve remains of the subfamily Candoninae show almost continuous presence throughout the KTK10/6 record. Numerous fragments of chironomid larval head capsules are found in the analysed samples in remarkably high quantities (Fig. 4A). The sample from 83 cm (ca. 22.78 cal. ka BP) depth reveals head capsules of the Sergentia coracina type. Moss remains are recognized at 168 (ca. 25.53 cal. ka BP) and 180 cm levels (ca. 26.23 cal. ka BP). However, poor preservation hindered more precise identification. 5. Interpretation and discussion 5.1. The LGM vegetation and environments

25

% TIC

26

a % TOC

27 0

1

2

3

4

5

% Fig. 3. Total inorganic carbon (TIC) and total organic carbon (TOC) contents from the KTK10/6 core plotted against the age scale.

percentages vary significantly throughout the record. Three Ranunculaceae percentage maxima were identified in the lower and middle part of the core, including a less pronounced one (up to 13% at ca. 25.5 cal. ka BP), followed by a second maximum (up to 28%) at ca. 23.4 cal. ka BP and a third maximum (up to 18%) at ca. 22.3 cal. ka BP. Pollen concentrations vary from w4750 grains/gram to w51,000 grains/gram, averaging ca. 16,000 grains/gram. Monolete spores of Polypodiaceae ferns are continuously present with relatively low values (less than 2%) throughout the whole record, followed by less frequent trilete spores of Botrychium (moonworts) and even more occasional Lycopodiaceae (clubmosses), including Lycopodium annotinum, L. clavatum type, and Huperzia selago type (Fig. 4A). Spores of Glomus, an endomycorrhizal fungus that forms symbiotic relationships (mycorrhizas) with plant roots, are very abundant especially in the middle part of the core (to 11% at ca. 22.1 cal. ka BP), whereas its percentages generally do not exceed 3e 4% in the most part of the record. Spore balls of the smut fungus (Thekaphora) which is a plant-parasitic microfungus reproducing in various organs of the host plants (Vanky et al., 2008) are quasicontinuously found throughout the record, though in low percentages. Spores of Delitschia, a coprophilous fungus, and mycelia of Geumannomyces, a pathogen mainly on Carex species, have been found in a few samples (Fig. 4A). Conifer tracheids, elongated cells in the xylem of vascular plants that serve to transport water and minerals, are found in nine samples along the analysed record (Fig. 4A). Pediastrum algae colonies are highly abundant, with values up to 88% at around 22.6 cal. ka BP, the highest values being concentrated in the middle part of the record between ca. 24 and 22.5 cal. ka BP. Botryococcus colonies reach levels up to 38%; however, the highest values occur between 22.5 and 19.5 cal. ka BP, with a distinct decrease in percentages between ca. 25 and 23 cal. ka BP. The

The KTK10/6 pollen record spans the time from ca. 26.8 to 19.1 cal. ka BP, thus covering the whole interval conventionally assigned to the LGM (e.g. Clark et al., 2009). The LGM pollen spectra composition and taxa percentages reflect regional and local vegetation composition around Lake Kotokel. Previous studies in northern Eurasia (e.g. Prentice et al., 2000) and in the Lake Baikal region (Tarasov et al., 2005, 2009; Bezrukova et al., 2010) demonstrated that the main regional vegetation types (or biomes) can be reliably reconstructed by applying the biomisation approach (Prentice et al., 1996) to the late Quaternary pollen records. The pollen-based biome reconstruction (Fig. 4B) demonstrates the highest scores for steppe (ca. 20) followed by tundra (ca. 12), suggesting that herbaceous tundra and steppe vegetation predominated in the region owing to the substantially colder than present regional climate. High percentages of Artemisia, Poaceae, Cyperaceae (up to 90% of total pollen sum) and a rich variety of other herbaceous taxa point to a rather productive vegetation. Very low percentages of boreal tree and shrub pollen and consequently very low scores of the cold deciduous forest biome (0e3.3) throughout the whole record support the reconstruction of the open regional vegetation in line with generally colder and drier than present climate conditions. However, the existence of a permanent lake and the low pollen percentages of the taxa indicators of dry environments in Inner Asia (e.g. Chenopodiaceae and Ephedra) do not suggest semi-desert or desert vegetation and a corresponding climate in the region during the LGM. Our current results confirm the reconstruction of cold steppe and herbaceous tundra communities with minimal representation of woody taxa in the regional vegetation ca. 28e18 cal. ka BP based on the coarse-resolution KTK2 pollen record from Lake Kotokel (Bezrukova et al., 2010). Furthermore, the KTK2 and KTK10 LGM pollen assemblage composition, taxa diversity and relatively high pollen concentrations do not support the viewpoint of some authors (e.g. Ray and Adams, 2001) who suggested polar and alpine desert environments with less than 2% of the ground covered by vascular plants around Lake Baikal and in major parts of northern Asia during the LGM interval. The pollen concentrations in the surface samples from the Siberian tundra north of Lake Baikal usually do not exceed 1000e2000 grains/gram (Müller et al., 2010), whereas values calculated for the KTK10/6 sediment are substantially higher. Available pollen (Anderson et al., 2002; Müller et al., 2010; Andreev et al., 2011; Lozhkin and Anderson, 2011) and plant macrofossil (Kienast et al., 2005) records of the LGM interval obtained from more northern regions of eastern Siberia also indicate that productive meadow and steppe communities played an important role in the Siberian vegetation during the last glacial

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

7 Fig. 4. (A) Simplified pollen percentage diagram of KTK10/6 including percentages of the selected non-pollen palynomorphs (NPPs); and (B) pollen-derived biome scores of three characteristic regional biomes (i.e. steppe, tundra and cold deciduous forest) plotted against the depth and age scales.

S. Müller et al. / Quaternary International xxx (2013) 1e11

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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S. Müller et al. / Quaternary International xxx (2013) 1e11

interval and served as food resources for large populations of herbivores (Kienast et al., 2005). The KTK10/6 pollen spectra composition resembles (although at a less precise taxonomic level) the LGM plant macrofossil assemblages’ composition from the “Mamontovy Khayata” permafrost sequence (71
600 N, 129
250 E) on the Bykovsky Peninsula, which was interpreted as similar to modern vegetation mosaics of the Yakutian relict steppe (Kienast et al., 2005). In contrast to the LGM records from northern Yakutia (Andreev et al., 2002; Kienast et al., 2005; Müller et al., 2010; Lozhkin and Anderson, 2013) showing high concentrations of Selaginella rupestris (rock spike-moss) spores, the Lake Kotokel record reveals only a sporadic appearance of this taxon e an indicator of disturbed and dry soils or dry sparsely vegetated rocky environments (Andreev et al., 2002). Such regional differences in the floristic composition of the LGM vegetation likely indicate less continental and less arid environments in the southern part of eastern Siberia compared to the central and northern regions. Crowley (1995) reconstructed a conifer forest belt across western and central Siberia within 55e60
N during the LGM, and LGM vegetation maps compiled by Grichuk (Grichuk, 1984; Frenzel et al., 1992) show cold boreal conifer and deciduous trees in southern Siberia (e.g. in the Altai Mountains and around Lake Baikal), suggesting many scattered refugia from which tree vegetation could quickly spread as climates warmed. Although low percentages of arboreal pollen recorded in the LGM sediment from Lake Kotokel (Fig. 4A) do not support a continuous boreal forest belt, the total disappearance of cold/drought-tolerant boreal trees and shrubs from the regional vegetation cover is unlikely. Conifer tracheids and stomata are identified in the pollen spectra; together with boreal conifer and broadleaf tree and shrub taxa pollen occurring throughout the KTK10/6 record (Fig. 4A), they suggest the presence of single trees or small forest stands in the lake vicinity, likely in the stream valleys. A similar conclusion that small populations of boreal trees and shrubs were capable of surviving long periods of the harsh climate at the LGM in the Asian mid-latitudes appeared in the most recent syntheses and re-analyses of the available pollen and archaeological charcoal data (Vasil’ev et al., 2002; Brubaker et al., 2005; Tarasov et al., 2007; Williams et al., 2011). The pollen-based reconstruction of vegetation (Müller et al., 2010) and climate (Tarasov et al., 2013b) from Lake Billyakh (65
170 N, 126
470 E, 340 m a.s.l.) in the western central part of the Verkhoyansk Mountains suggests a mean July temperature of approximately 8e10
C and mean annual precipitation of about 270 mm, confirming the cool grass/shrub vegetation around Lake Billyakh during the coldest and driest phase of the last glacial between ca. 32 and ca. 15 cal. ka BP. However, modern larch distribution patterns from arctic Siberia north of Lake Billyakh demonstrate that individual larch plants can survive within a shrub and grass tundra landscape even under mean July temperatures of about 8
C (Pisaric et al., 2001). It is unlikely that last glacial environments around Lake Kotokel located about 1700 km south-west of Lake Billyakh, were as cold as in central Yakutia. Therefore, lower-than-present atmospheric precipitation and moisture availability could have been a main limiting factor for tree growth there. Comparing the LGM pollen spectra of the KTK2 core with the pollen assemblages and pollen-based climate reconstructions derived from the CON01-603-2 sediment core from Lake Baikal (Tarasov et al., 2005), Shichi et al. (2009) estimated an annual precipitation of less than 250 mm and a mean January temperature dropping down to 32
C during the LGM period. Although this interpretation by Shichi et al. (2009) can only be regarded as very preliminary and requires further proof, it demonstrates general cooling and drying of the LGM climate in the Lake Baikal region.

The regional pollen/vegetation-based interpretation of the LGM climate is further supported by other evidence from the KTK10/6 sediment. Thus, the ostracod species Cytherissa lacustris and the chironomid species Sergentia coracina are generally cold-adapted taxa (Nazarova et al., 2013) that recently occur most abundantly in the profundal zone of oligo- to mesotrophic freshwater lakes (Hofmann, 1971; Meisch, 2000). But during colder climatic phases they also occur in shallow lakes (Hofmann, 1971; Kossler, 2010); especially Cytherissa lacustris benefits from a higher content of dissolved oxygen in colder lake waters. According to Antonsson et al. (2006), the chironomid S. coracina has its optimum at mean July temperatures of 13
C. This value matches the climatic interpretation of the LGM pollen spectra from Lake Kotokel (Shichi et al., 2009) and the quantitative reconstruction of glacial climate around Lake Baikal (Tarasov et al., 2005). Mesotrophic water conditions are supported by the NPP record (e.g. Type 187B: van Geel et al., 1998), as well as by the identified algae taxa abundant in the eu- to mesotrophic freshwater shallow lakes, quickly warming up during the summer (van Geel et al., 1998; Miola et al., 2006). Plant macrofossils, e.g. decomposed moss remains, found in the core sediment likely indicate a lower-than-present surface of the LGM lake, and closer location of the KTK10 coring site to the LGM shoreline in response to the drier-than-present climate. Peaks in Ranunculaceae pollen could be also interpreted as an indicator of the littoral zone and/or meadow vegetation communities close to the KTK10 site, particularly between ca. 26 and 22 cal. ka BP. The slightly increased TIC values between 25.8 and 22.5 cal. ka BP likely represent enhanced calcite production during summer when a decreased water volume becomes additionally warmer and productivity is enhanced as shown by often associated higher TOC and TIC contents. Littoral pioneer vegetation communities, with Ranunculaceae species occupying erosive soils in the range of fluctuating water levels at shores of shallow lakes and regularly inundated depressions (Hilbig, 1995; Dierßen and Dierßen, 1996), were a characteristic part of the LGM vegetation mosaic in eastern Siberia (Kienast et al., 2005). The presence of sand in the KTK10/6 sediment supports intensified soil erosion and/or proximity to the coastal zone, whereas the increase in coarse-grained sand particles in the interval between ca. 24.7 and 23.1 cal. ka BP parallels the general increase in Ranunculaceae pollen percentages. Relatively high percentages of Glomus might also point to intensified soil erosion. In the European records, spores of this fungus, which occurs in a variety of host plants, including a number of herbaceous plant families, are reported to be especially abundant in late glacial environments with highly eroded soils (van Geel et al., 1998). As pollen analysis does not allow robust assignment of Ranunculaceae pollen grains to the species (or even genus) level, a number of interpretations involving various representatives of the Ranunculaceae family native to marshes, fens and wetlands and flourishing in a landscape inundated with snowmelt waters (e.g. Caltha palustris, Ranunculus reptans) can be suggested. However, all scenarios agree well with the smaller size of the lake and proximity of the coring site to the lake shore during the LGM. Furthermore, our interpretation of a lower lake level prior to 15 cal. ka BP is independently supported by the recent bathymetric and geophysical studies at Lake Kotokel, reporting traces of two former river channels along the northeastern coast, ca. 10 m below the present lake level (Zhang et al., 2013). Published faunal records from the study region also provide evidence for continental and cold LGM climate and open dry steppe, tundra-steppe and meadow-steppe vegetation, in line with the available plant and sedimentary records. The faunal remains of the last glacial interval are known from a number of archaeological and cave sites as well as from several natural open sections (Erbajeva et al., 2011) and show that the distribution areas of some

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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steppe dwellers such as Marmota sibirica (Tarbagan marmot), Ochotona daurica (pika) and Lasiopodomys brandti (steppe vole) were extended far beyond their present-day ranges in Mongolia towards the north (Erbajeva et al., 2011). 5.2. The LGM environments and humans Strengthening and correcting the earlier interpretations of the LGM environments in the Baikal region based on various but discontinuous proxy records (e.g. Chlachula, 2001 and references therein), the KTK10/6 sediment provides a robustly dated and continuous environmental archive of the interval between ca. 26.8 and 19.1 cal. ka BP. This environmental archive of decadalresolution demonstrates a general stability of the LGM vegetation in the Lake Kotokel region and most probably in the greater area around Lake Baikal. Additionally, sedimentological parameters such as TOC contents and mineralogical composition show that the limnic conditions within Lake Kotokel remained relatively stable throughout this period. Solely the slightly increased TIC contents e often accompanied by higher TOC values e reflect changes towards decreased water volume and higher biological productivity. Highresolution climate reconstruction gained from the Greenland ice cores demonstrates significant temperature oscillations with a magnitude of up to 7e11.3
C during the LGM interval at about 27e 19 cal. ka BP (Alley, 2000, 2004). The Antarctic EPICA Dome C record also demonstrates frequent temperature oscillations during this interval (Jouzel et al., 2007), though of much smaller magnitude (i.e. 1e2.7
C), suggesting large differences in temperature changes in the North Atlantic and more distant regions. Results of the palynological investigation presented in this paper (Fig. 4A) show numerous decadal/century/millennial scale oscillations in the taxa percentages, which likely reflect respective oscillations of the global and regional climate. However, as indicated by the relatively small changes in the calculated biome scores (Fig. 4B), these climatic fluctuations were obviously not powerful enough to destabilise the predominance of the cool steppe vegetation in the region. Results of the geoarchaeological research conducted in the Mediterranean region suggest that extreme oscillations towards a cold/dry climate (e.g. Bartov et al., 2003), most pronounced in and around the North Atlantic region (Alley, 2004), led to a major reduction of the potential living area and the collapse of human populations there during the coldest phases of the last glacial interval (Davies et al., 2003a, 2003b; Weniger, 2008 and references therein). More recently, Schmidt et al. (2012) published a major study, based on the extensive number of 152 archaeological cave sites and rock shelters, analysing the environmental impact of North Atlantic Heinrich Events (HE) on the human population on the Iberian Peninsula. Their conclusion is that “climatic deterioration during the different HE repeatedly lead to a near-complete breakdown of settlement patterns, but following each HE there was a major reorganisation in settlement patterns on the Iberian Peninsula” (Schmidt et al., 2012: 179). By contrast, the Lake Kotokel record presented in the current paper shows no noticeable change in the terrestrial pollen taxa composition (Fig. 4A) nor in the pollenderived biome scores (Fig. 4B) even during the HE2, one of the coldest episodes of the last glacial, dated to ca. 24 cal. ka BP and well pronounced in the d18O records from Greenland (Svensson et al., 2008) and from Chinese stalagmites (Wang et al., 2001). The growing body of archaeological data on the Late Palaeolithic habitation of southern Siberia and the Baikal region shows a relatively high number of sites with radiocarbon dates in the range of 25e17 ka BP (i.e. ca. 28e18.3 cal. ka BP), suggesting that environmental stress associated within the LGM interval did not cause serious difficulties to the local human population, as it did in the western regions of Eurasia (Dolukhanov et al., 2002). In an attempt

9

to explain this phenomenon, Dolukhanov et al. (2002) employed quantitative estimates of the LGM climate (Tarasov et al., 1999), which supported productive steppe plant communities and indicated very thin snow cover in central Siberia. Hence, the dry grass fodder was easily available beneath the thin snow cover and could support large herds of herbivores, which in turn were effectively exploited by the Palaeolithic hunter-gatherers (Velichko and Kurenkova, 1990). Bones of the large herbivores such as horse, woolly rhinoceros, woolly mammoth, bison, red deer, roe deer, wild sheep and Mongolian gazelle are reported in the archaeological and geological records dated to the LGM in the Baikal region (Kuzmin, 2009; Lbova, 2009 and references therein). A further argument against the considerable (or even complete) depopulation of Siberia during the LGM (e.g. Goebel, 2002) emerged as a result of a rigorous analysis of 437 radiocarbon dates from the Middle and Upper Palaeolithic archaeological sites (Kuzmin and Keates, 2005). Their analysis suggests that e in terms of the relative size of the Siberian Palaeolithic population based on the frequency of occupation episodes e population density was small until ca. 36 ka BP, and subsequently increased gradually from ca. 36 to 16 ka BP (ca. 41.3e19.1 cal. ka BP). Comparison of calibrated 14 C dates from Siberian archaeological sites with Greenland ice core records performed by Fiedel and Kuzmin (2007) does not demonstrate an easy correlation between the North Atlantic-centred climatic fluctuations and the human occupation dynamics in Siberia between ca. 36 and 12 cal. ka BP and does not indicate that cold climate created significant challenges to humans in Siberia during the LGM. 6. Conclusions The present study demonstrates the high potential of the KTK10 core sediment recovered from Lake Kotokel in 2010 for (i) gaining high-resolution palaeoenvironmental data from this region of southern Siberia and for (ii) verifying earlier published hypotheses based on the discontinuous, low resolution and/or poorly dated archaeological and sedimentary archives. The sedimentary data from the KTK10/6 section presented here covers the time interval between ca. 26.8 and 19.1 cal. ka BP conventionally termed as the Last Glacial Maximum at an average temporal resolution of ca. 40 years. It reveals the regional vegetation composition and local lake ecosystem history during the LGM. Furthermore, the KTK10/6 pollen record correlated with the KTK2 sediment proves the discontinuity of the previously published coarse-resolution LGM records and helps to fill this identified gap. The results of pollen analysis and pollen-based biome reconstruction show that steppe and tundra communities composed of grasses and various herbs predominated in the regional vegetation cover between ca. 26.8 and 19.1 cal. ka BP. Occurrence of conifer tracheids and stomata throughout the KTK10/6 record, together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen, reflects the presence of single trees or small groups of trees close to the lake, most likely in the river valleys or in the locally moist environments. Numerical scores of the most characteristic biomes (steppe, tundra and cold deciduous forest) show minor fluctuations, signifying stability of the regional vegetation cover during the whole analysed time interval. Continuous lacustrine sedimentation, little changes in sedimentological parameters and generally low contents of drought indicator taxa revealed by the KTK10/6 record do not support pronounced aridity of the LGM climate in the study region, though conditions were drier and colder than at present. In contrast to the stable regional vegetation cover and sedimentological conditions in Lake Kotokel, greater sensitivity to decadal- and century-scale climate variability is seen in the isotopic

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

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S. Müller et al. / Quaternary International xxx (2013) 1e11

records from the ice cores and cave stalagmites. The Ranunculaceae peaks in the pollen record reflect decreases in the lake surface area and expansion of the littoral and meadow vegetation communities towards the coring site. The highest pollen percentages of Ranunculaceae registered at ca. 23.8e23.4 cal. ka BP, together with an increase in coarse-grained sand particles in the KTK10/6 sediment, likely represent the lowest lake stand of the whole record. Published geoarchaeological data from the Mediterranean region suggest that major oscillations towards cold and dry climate during the last glacial could be a reason for a noticeable depopulation of this region. On the contrary, the archaeological and zooarchaeological data from the Palaeolithic sites in southern Siberia demonstrate that the cold climate did not create significant challenges to humans during the LGM. A general stability of the grassland vegetation and lake ecosystem in the study region ca. 26.8e19.1 cal. ka BP, inferred from the high-resolution KTK10/6 sedimentary record, supports the hypothesis that this productive landscape could stably serve as a perennial food resource for large populations of herbivores and provide favourable environments for the local hunter-gatherers inhabiting the Lake Baikal region during the LGM interval. Acknowledgements This work is a contribution to the “Bridging Eurasia” research programme initiated during the International Workshop at FU Berlin (April 28eMay 2, 2010) sponsored by the Russian Foundation for Basic Research (RFBR), German Research Foundation (DFG) and German Archaeological Institute. The authors acknowledge financial support from the DFG (TA 540/4, TA 540/5 and MU 3181/1), the RFBR (12-05-00476a) and FU Berlin (Innovation Fund). We are grateful to A. Shchetnikov, E. Ivanov, E. Dobretsov and O. Levina for their active participation in the coring campaign on Lake Kotokel in July 2010 and to Prof. F. Riedel for providing additional financial support for three AMS dates. We sincerely thank A. Beck (FU Berlin) for English proof reading and two anonymous reviewers for helpful and constructive comments to an earlier version of this manuscript. References Alley, R.B., 2000. The Younger Dryas cold interval as viewed from central Greenland. Quaternary Science Reviews 19, 213e226. Alley, R.B., 2004. GISP2 Ice Core Temperature and Accumulation Data. IGBP PAGES/ World Data Center for Paleoclimatology Data Contribution Series #2004-013. NOAA/NGDC Paleoclimatology Program. NOAA/NGDC, Boulder CO, USA. Alpat’ev, A.M., Arkhangel’skii, A.M., Podoplelov, N.Y., Stepanov, A.Y., 1976. Fizicheskaya geografiya SSSR (Aziatskaya chast’). Vysshaya Shkola, Moscow (in Russian). Anderson, P.M., Lozhkin, A.V., Brubaker, L.B., 2002. Implications of a 24,000-Yr palynological record for a Younger Dryas cooling and for Boreal forest development in northeastern Siberia. Quaternary Research 57, 325e333. Andreev, A.A., Schirrmeister, L., Siegert, C., Bobrov, A.A., Demske, D., Seiffert, M., Hubberten, H.-W., 2002. Paleoenvironmental changes in Northeastern Siberia during the late Quaternary e evidence from pollen records of the Bykovsky Peninsula. Polarforschung 70, 13e25. Andreev, A.A., Schirrmeister, L., Tarasov, P.E., Ganopolski, A., Brovkin, V., Siegert, C., Wetterich, S., Hubberten, H.-W., 2011. Vegetation and climate history in the Laptev Sea region (Arctic Siberia) during Late Quaternary inferred from pollen records. Quaternary Science Reviews 30, 2182e2199. Antonsson, K., Brooks, S.J., Seppä, H., Telford, R.J., Birks, H.J.B., 2006. Quantitative palaeotemperature records inferred from fossil pollen and chironomid assemblages from Lake Gilltjärnen, northern central Sweden. Journal of Quaternary Science 21 (8), 831e841. Bartov, Y., Goldstein, S.L., Stein, M., Enzel, Y., 2003. Catastrophic arid episodes in the Eastern Mediterranean linked with the North Atlantic Heinrich events. Geology 31 (5), 439e442. Beug, H.-J., 2004. Leitfaden der Pollenbestimmung für Mitteleuropa und angrenzende Gebiete. Verlag Dr. Friedrich Pfeil, München (in German). Bezrukova, E.V., Krivonogov, S.K., Takahara, H., Letunova, P.P., Shichi, K., Abzaeva, A.A., Kulagina, N.V., Zabelina, Yu, S., 2008. Lake Kotokel as a stratotype for the late glacial and Holocene in southeastern Siberia. Doklady Earth Sciences 420 (4), 658e663.

Bezrukova, E.V., Tarasov, P.E., Solovieva, N., Krivonogov, S.K., Riedel, F., 2010. Last glacialeinterglacial vegetation and environmental dynamics in southern Siberia: chronology, forcing and feedbacks. Palaeogeography, Palaeoclimatology, Palaeoecology 296, 185e198. Bezrukova, E.V., Hildebrandt, S., Letunova, P.P., Ivanov, E.V., Orlova, L.A., Müller, S., Tarasov, P.E., 2013. Vegetation dynamics around Lake Baikal since the middle Holocene reconstructed from the pollen and botanical composition analyses of peat sediments and its implication for paleoclimatic and archeological research. Quaternary International 290e291, 35e45. Bobrov, A.E., Kupriyanova, L.A., Litvintseva, M.V., Tarasevich, V.F., 1983. Spores and Pollen of Gymnosperms from the Flora of the European Part of the USSR. Nauka, Leningrad (in Russian). Brubaker, L.B., Anderson, P.M., Edwards, M.E., Lozhkin, A.V., 2005. Beringia as a glacial refugium for boreal trees and shrubs: new perspectives from mapped pollen data. Journal of Biogeography 32, 833e848. Buvit, I., Terry, K., 2011. The twilight of Paleolithic Siberia: humans and their environments east of Lake Baikal at the late-glacial/Holocene transition. Quaternary International 242, 379e400. Chlachula, J., 2001. Pleistocene climates, natural environments and palaeolithic occupation of the Altai area, West Central Siberia. In: Prokopenko, A., Catto, N., Chlachula, J. (Eds.), Lake Baikal and the Surrounding Regions. Quaternary International 80e81, 131e167. Clark, U.C., Dyke, A.S., Shakun, J.D., Carlson, A.E., Clark, J., Wohlfarth, B., Mitrovica, J.X., Hostetler, S.W., McCabe, A.M., 2009. The last glacial maximum. Science 325, 710e714. Conard, N.J., Bolus, M., 2008. Radiocarbon dating the late Middle Paleolithic and the Aurignacian of the Swabian Jura. Journal of Human Evolution 55, 886e897. Crowley, T.J., 1995. Ice-age terrestrial carbon changes revisited. Global Biogeochemical Cycles 9, 377e389. Cwynar, L.E., Burden, E., McAndrews, J.H., 1979. An inexpensive sieving method for concentrating pollen and spores from fine grained sediments. Canadian Journal of Earth Sciences 16, 1115e1120. Danzeglocke, U., Jöris, O., Weninger, B., 2008. CalPal-2007 Online. http://www. calpal-online.de (accessed 15.04.2013). Davies, W., van Andel, T.H., Weninger, B., 2003a. The human presence in Europe during the last glacial period I: human migrations and the changing climate. In: Van Andel, T.H., Davies, W. (Eds.), Neanderthals and Modern Humans in the European Landscape During the Last Glaciation. McDonald Institute for Archaeological Research, Cambridge, UK, pp. 31e56. Davies, W., Valdes, P., Ross, C., van Andel, T.H., 2003b. The human presence in Europe during the Last Glacial Period III: site clusters, regional climates and resource attractions. In: van Andel, T.H., Davies, W. (Eds.), Neanderthals and modern Humans in the European Landscape During the Last Glaciation, McDonald Institute Monographs. McDonald Institute for Archaeological Research, Cambridge, UK, pp. 191e220. Dierßen, K., Dierßen, B., 1996. Vegetation Nordeuropas. Eugen Ulmer, Stuttgart (in German). Dolukhanov, P.M., Shukurov, A.M., Tarasov, P.E., Zaitseva, G.I., 2002. Colonization of Northern Eurasia by modern humans: radiocarbon chronology and environment. Journal of Archaeological Science 29, 593e606. Edwards, M.E., Brubaker, L.B., Ager, T.A., Andreev, A.A., Bigelow, N.H., Cwynar, L.C., Eisner, W.R., Harrison, S.P., Hu, F.-S., Jolly, D., Lozhkin, A.V., MacDonald, G.M., Mock, C.J., Ritchie, J.C., Sher, A.V., Spear, R.W., Williams, J.W., Yu, G., 2000. Pollen-based biomes for Beringia 18,000, 6000 and 0 14C yr BP. Journal of Biogeography 27, 521e554. Erbajeva, M.A., Khenzykhenova, F.I., Alexeeva, N.V., 2011. Late Pleistocene and Holocene environmental peculiarity of the Baikalian region, based on mammal associations and deposits. Quaternary International 237, 39e44. Fiedel, S.J., Kuzmin, Y.V., 2007. Radiocarbon date frequency as an index of intensity of paleolithic occupation of Siberia: did humans react predictably to climate oscillations? Radiocarbon 49 (2), 741e756. Frenzel, B., Pecsi, B., Velichko, A.A., 1992. Atlas of Palaeoclimates and Palaeoenvironments of the Northern Hemisphere. INQUA/Hungarian Academy of Sciences, Budapest. Fægri, K., Kaland, P.E., Krzywinski, K., 1989. Textbook of Pollen Analysis, fourth ed. John Wiley & Sons, Chichester. Galaziy, G.I. (Ed.), 1993. Baikal Atlas. Federal Agency for Geodesy and Cartography of Russia, Moscow. Goebel, T., 2002. The “Microblade Adaption” and re-colonization of Siberia during the late Upper Pleistocene. Archeological Papers of the American Anthropological Association 12, 117e132. Grichuk, V.P., 1984. Late Pleistocene Vegetation History. In: Velichko, A.A. (Ed.), Late Quaternary Environments of the Soviet Union. University of Minnesota Press, Minneapolis, USA, pp. 155e178. Grimm, E.C., 1993. TILIA 2.0 Version b.4 (Computer Software). Illinois State Museum, Research and Collections Center, Springfield. Grimm, E.C., 2004. TGView. Illinois State Museum, Research and Collections Center, Springfield. Hilbig, W., 1995. The Vegetation of Mongolia. SPB Academic Publishing, Amsterdam. Hofmann, W., 1971. Die postglaziale Entwicklung der Chironomiden- und Chaeborus-Fauna (Dipt.) des Schöhsees. Archiv für Hydrobiologie 40 (Suppl.), 1e74. Jouzel, J., Masson-Delmotte, V., Cattani, O., Dreyfus, G., Falourd, S., Hoffmann, G., Minster, B., Nouet, J., Barnola, J.M., Chappellaz, J., Fischer, H., Gallet, J.C., Johnsen, S., Leuenberger, M., Loulergue, L., Luethi, D., Oerter, H., Parrenin, F., Raisbeck, G., Raynaud, D., Schilt, A., Schwander, J., Selmo, E., Souchez, R.,

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012

S. Müller et al. / Quaternary International xxx (2013) 1e11 Spahni, R., Stauffer, B., Steffensen, J.P., Stenni, B., Stocker, T.F., Tison, J.L., Werner, M., Wolff, E.W., 2007. Orbital and millennial Antarctic climate variability over the past 800000 years. Science 317, 793e796. Kienast, F., Schirrmeister, L., Siegert, C., Tarasov, P., 2005. Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage. Quaternary Research 63, 283e300. Kossler, A., 2010. Faunen und Floren der limnisch-telmatischen Schichtenfolge des Paddenluchs (Brandenburg, Rüdersdorf) vom ausgehenden Weichselhochglazial bis ins Holozän. Berliner Päläobiologische Abhandlungen, Band 11, p. 422 (in German with English abstract). Kostrova, S.S., Meyer, H., Chapligin, B., Kossler, A., Bezrukova, E.V., Tarasov, P.E., 2013. Holocene oxygen isotope record of diatoms from Lake Kotokel (southern Siberia, Russia) and its palaeoclimatic implications. Quaternary International 290e291, 21e34. Kupriyanova, L.A., Alyoshina, L.A., 1972. Pollen and Spores of Plants from the Flora of European Part of USSR, vol. I.. Academy of Sciences USSR, Nauka, Leningrad (in Russian). Kupriyanova, L.A., Alyoshina, L.A., 1978. Pollen and Spores of Plants from the Flora of European Part of USSR. Academy of Sciences USSR, Nauka, Leningrad (in Russian). Kuzmin, Y.V., 2009. The Middle to Upper Palaeolithic transition in Siberia: chronological and environmental aspects. Eurasian Prehistory 5 (2), 97e108. Kuzmin, Y.V., Keates, S.G., 2005. Dates are not just data: paleolithic settlement patterns in Siberia derived from radiocarbon records. American Antiquity 70 (4), 773e789. Lbova, L.V., 2009. Chronology and paleoecology of the Early Upper Paleolithic in the Transbaikal Region (Siberia). Eurasian Prehistory 5 (2), 109e114. Lozhkin, A.V., Anderson, P.M., 2011. Forest or no forest: implications of the vegetation record for climatic stability in Western Beringia during Oxygen Isotope Stage 3. Quaternary Science Reviews 30, 2160e2181. Lozhkin, A.V., Anderson, P.M., 2013. Late Quaternary lake records from the Anadyr Lowland, Central Chukotka (Russia). Quaternary Science Reviews 68, 1e16. Meisch, C., 2000. Crustacea: Ostracoda. Süßwasserfauna von Mitteleuropa 8/3. Spektrum Akademischer Verlag, Heidelberg, Berlin, 522 pp. Metspalu, M., Kivisild, T., Bandelt, H.-J., Richards, M., Villems, R., 2006. The pioneer settlement of modern humans in Asia. In: Bandelt, H.-J., Macaulay, V., Richards, M. (Eds.), Human Mitochondrial DNA and the Evolution of Homo sapiens, Nucleic Acids and Molecular Biology, vol. 18. Springer, Berlin, Heidelberg, pp. 179e197. Miola, A., Bondesan, A., Corain, L., Favaretto, S., Mozzi, P., Piovan, S., Sostizzo, I., 2006. Wetlands in the Venetian Po Plain (northeastern Italy) during the Last Glacial Maximum: interplay between vegetation, hydrology and sedimentary environment. Review of Palaeobotany and Palynology 141, 53e81. Müller, S., Tarasov, P.E., Andreev, A.A., Tütken, T., Gartz, S., Diekmann, B., 2010. Late Quaternary vegetation and environments in the Verkhoyansk Mountains region (NE Asia) reconstructed from a 50-ka fossil pollen record from Lake Billyakh. Quaternary Science Reviews 29, 2071e2086. Nazarova, L., de Hoog, V., Hoff, U., Dirksen, O., Diekmann, B., 2013. Late Holocene climate and environmental changes in Kamchatka inferred from the subfossil chironomid record. Quaternary Science Reviews 67, 81e92. Okladnikov, A.P., 1950. Neolit i bronzovyi vek Pribaikal’ya (Chasti I i II). Materialy i Issledovaniya po Arkheologii SSSR, vol. 18. Izdatel’stvo Akademii Nauk SSSR, Moscow (in Russian). Okladnikov, A.P., 1955. Neolit i bronzovyi vek Pribaikal’ya (Chast’ III). Materialy i Issledovaniya po Arkheologii SSSR, vol. 43. Izdatel’stvo Akademii Nauk SSSR, Moscow (in Russian). Okladnikov, A.P., 1959. Ancient Populations of Siberia and its Cultures. Russian Translations of the Peabody Museum of Archaeology and Ethnology. Harvard University, Cambridge. Parzinger, H., 2006. Die frühen Völker Eurasiens vom Neolithikum bis zum Mittelalter. Verlag C. H. Beck, München (in German). Pisaric, M.F.J., MacDonald, G.M., Velichko, A.A., Cwynar, L.C., 2001. The Lateglacial and Postglacial vegetation history of the northwestern limits of Beringia, based on pollen, stomate and tree stump evidence. Quaternary Science Reviews 20, 235e245. Prentice, C.I., Guiot, J., Huntley, B., Jolly, D., Cheddadi, R., 1996. Reconstructing biomes from palaeoecological data: a general method and its application to European pollen data at 0 and 6 ka. Climate Dynamics 12, 185e194. Prentice, I.C., Jolly, D., 6000 BIOME participants, 2000. Mid-Holocene and glacial maximum vegetation geography of the northern continents and Africa. Journal of Biogeography 27, 507e519. Ray, N., Adams, J.M., 2001. A GIS-based vegetation map of the World at the last glacial maximum (25,000e15,000 BP). International Archaeology 11. http:// intarch.ac.uk/journal/issue11/rayadams_toc.html. Reille, M., 1992. Pollen et spores d’Europe et d’Afrique du nord. Laboratoire de Botanique historique et Palynologie, Marseille. Reille, M., 1995. Pollen et spores d’Europe et d’Afrique du nord. Supplement 1. Laboratoire de Botanique historique et Palynologie, Marseille. Reille, M., 1998. Pollen et spores d’Europe et d’Afrique du nord. Supplement 2. Laboratoire de Botanique historique et Palynologie, Marseille. Schmidt, I., Bradtmöller, M., Kehl, M., Pastoors, A., Tafelmaier, Y., Weninger, B., Weniger, G.-C., 2012. Rapid climate change and variability of settlement patterns in Iberia during the Late Pleistocene. Quaternary International 274, 179e204.

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Shichi, K., Takahara, H., Krivonogov, S.K., Bezrukova, E.V., Kashiwaya, K., Takehara, A., Nakamura, T., 2009. Late Pleistocene and Holocene vegetation and climate records from Lake Kotokel, central Baikal region. Quaternary International 205, 98e110. Stockmarr, J., 1971. Tablets with spores used in absolute pollen analysis. Pollen et Spores 13, 614e621. Svendsen, J.I., Heggen, H.P., Hufthammer, A.K., Mangerud, J., Pavlov, P., Roebroeks, W., 2010. Geo-archaeological investigations of Palaeolithic sites along the Ural Mountains e on the northern presence of humans during the last Ice Age. Quaternary Science Reviews 29 (23e24), 3138e3156. Svensson, A., Andersen, K.K., Bigler, M., Clausen, H.B., Dahl-Jensen, D., Davies, S.M., Johnsen, S.J., Muscheler, R., Parrenin, F., Rasmussen, S.O., Rothlisberger, R., Seierstad, I., Steffensen, J.P., Vinther, B.M., 2008. A 60,000 year Greenland stratigraphic ice core chronology. Climate of the Past 4, 47e57. Tarasov, P.E., Peyron, O., Guiot, J., Brewer, S., Volkova, V.S., Bezusko, L.G., Dorofeyuk, N.I., Kvavadze, E.V., Osipova, I.M., Panova, N.K., 1999. Last Glacial Maximum climate of the Former Soviet Union and Mongolia reconstructed from pollen and plant macrofossil data. Climate Dynamics 15, 227e240. Tarasov, P., Granoszewski, W., Bezrukova, E., Brewer, S., Nita, M., Abzaeva, A., Oberhänsli, H., 2005. Quantitative reconstruction of the Last Interglacial vegetation and climate based on the pollen record from Lake Baikal, Russia. Climate Dynamics 25 (6), 625e637. Tarasov, P., Bezrukova, E., Karabanov, E., Nakagawa, T., Wagner, M., Kulagina, N., Letunova, P., Abzaeva, A., Granoszewski, W., Riedel, F., 2007. Vegetation and climate dynamics during the Holocene and Eemian interglacials derived from Lake Baikal pollen records. Palaeogeography, Palaeoclimatology, Palaeoecology 252, 440e457. Tarasov, P.E., Bezrukova, E.V., Krivonogov, S.K., 2009. Late Glacial and Holocene changes in vegetation cover and climate in southern Siberia derived from a 15 ka long pollen record from Lake Kotokel. Climate of the Past 5, 285e 295. Tarasov, P.E., White, D., Weber, A.W., 2013a. The Baikal-Hokkaido archaeology project: environmental archives, proxies and reconstruction approaches. Quaternary International 290e291, 1e2. Tarasov, P.E., Müller, S., Zech, M., Andreeva, D., Diekmann, B., Leipe, C., 2013b. Last glacial vegetation reconstructions in the extreme-continental eastern Asia: potentials of pollen and n-alkane biomarker analyses. Quaternary International 290e291, 253e263. van Geel, B., van Hoeve, M.L., Hendrikse, M. (Eds.), 1998. A Study of Non-pollen Objects in Pollen Slides. Utrecht. Vanky, K., Lutz, M., Bauer, R., 2008. About the genus Thekaphora (Glomosporiaceae) and its new synonyms. Mycological Progress 7, 31e39. Vasil’ev, S.A., Kuzmin, Y.V., Orlova, L.A., Dementiev, V.N., 2002. Radiocarbon-based chronology of the Paleolithic in Siberia and its relevance to the peopling of the New World. Radiocarbon 44 (2), 503e530. Velichko, A.A., Kurenkova, E.I., 1990. Environmental conditions and human occupation of northern Eurasia during the Valdai. In: Soffer, O., Gamble, C. (Eds.), High Latitudes, The World at 18000 BP, vol. 1. Unwin Hyman, London, pp. 255e265. Wang, Y.J., Cheng, H., Edwards, R.L., An, Z.S., Wu, J.Y., Shen, C.-C., Dorale, J.A., 2001. A high-resolution absolute-dated Late Pleistocene Monsoon record from Hulu Cave, China. Science 294, 2345e2348. Weber, A.W., 1995. The neolithic and early Bronze Age of the Lake Baikal Region, Siberia. Journal of World Prehistory 9, 99e165. Weber, A.W., Katzenberg, M.A., 2002. Hunteregatherer culture change and continuity in the middle Holocene of the Cis-Baikal, Siberia. Journal of Anthropological Archaeology 21, 230e299. Weber, A.W., Katzenberg, M.A., Schurr, T. (Eds.), 2010. Prehistoric Hunteregatherers of the Baikal Region Siberia: Bioarchaeological Studies of Past Lifeways. University of Pennsylvania Museum Press, PA, USA. Weber, A.W., Jordan, P., Kato, H., 2013. Environmental change and cultural dynamics of Holocene hunter-gatherers in Northeast Asia: comparative analyses and research potentials in Cis-Baikal (Siberia, Russia) and Hokkaido (Japan). Quaternary International 290-291, 3e20. Weniger, G.C., 2008. Wie modern waren Neandertaler? 2. Thomsen-Vorlesung. Eurasia Antiqua 14, 1e16 (in German). Weninger, B., Jöris, O., Danzeglocke, U., 2013. CalPal-2007. Cologne Radiocarbon Calibration & Palaeoclimate Research Package. http://www.calpal.de/ (accessed 15.04.2013). White, D., Preece, R.C., Shchetnikov, A.A., Dlussky, K.G., 2013. Late Glacial and Holocene environmental change reconstructed from floodplain and aeolian sediments near Burdokovo, lower Selenga River Valley (Lake Baikal region), Siberia. Quaternary International 290e291, 68e81. Williams, J.W., Tarasov, P., Brewer, S., Notaro, M., 2011. Late Quaternary variations in tree cover at the northern forest-tundra ecotone. Journal of Geophysical Research, Biogeosciences 116, G01017. http://dx.doi.org/10.1029/2010JG001458. Zhang, Y., Wünnemann, B., Bezrukova, E.V., Ivanov, E.V., Shchetnikov, A.A., Nourgaliev, D., Levina, O., 2013. Basin morphology and seismic stratigraphy of Lake Kotokel, Baikal region, Russia. Quaternary International 290e291, 57e67.

Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/ j.quaint.2013.12.012