E.V. Bezrukova1, A.A. Abzaeva1, P.P. Letunova1, N.V. Kulagina2, and L.A. Orlova3 EVIDENCE of ENVIRONMENTAL INSTABILITY of the LA

PALEOENVIRONMENT. THE STONE AGE 17

E.V. Bezrukova1, A.A. Abzaeva1, P.P. Letunova1, N.V. Kulagina2, and L.A. Orlova3 1Laboratory of Archaeology and Paleoecology, Irkutsk State University, K. Marxa 1, Irkutsk, 664003, Russia E-mail: [email protected] 2Institute of the Earth’s Crust, Siberian Branch, Russian Academy of Sciences, Lermontova 128, Irkutsk, 664033, Russia E-mail: [email protected] 3Laboratory of Cenozoic Geology and Paleoclimatology, Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Akademika Koptyuga 3, Novosibirsk, 630090, Russia E-mail: [email protected]

EVIDENCE OF ENVIRONMENTAL INSTABILITY OF THE LAKE BAIKAL AREA AFTER THE LAST GLACIATION (BASED ON POLLEN RECORDS FROM PEATLANDS)*

Pollen analysis of two dated sedimentary cores from lacustrine-boggy sediments in various parts of the Lake Baikal area yielded the fi rst complete record of deep changes in the lake catchment area during the Late Glacial and Early Holocene. The Early Middle Holocene record shows an optimum – a humid and mild climate with warm winters between ca 10,000 and 7000 BP. During the Late Holocene, the climate grew more and more continental, and dark coniferous forests were replaced by light coniferous ones. Comparison of variation ranges of paleogeographic events in the Late Pleistocene and Holocene recorded in our samples with previously known records for the Lake Baikal area and other regions of Eurasia indicated that major changes of vegetation and climate mostly correlate with the global ice retreat, solar radiation level, and the concentration of carbon dioxide in the atmosphere. Less signifi cant short-term fl uctuations of vegetation and climate recorded in our archives can be regarded as regional ecosystem responses to solar activity changes of a quasi-millenary scale. Regional pollen records demonstrate a distinct relationship with the climate of the Northern Hemisphere as a whole. The amplitude of these changes is higher in the northeastern Lake Baikal area than in its southern part. Key words: Pollen analysis, paleoclimate, paleoecology, Late Glacial, Holocene, Lake Baikal catchment area.

Introduction evolution of the climate during the Late Glacial and in the Holocene (Rind, Overpeek, 1993). Before the natural To evaluate the anthropogenic climatic changes and dynamics of the recent past, i.e. of Termination 1 and their relationship with natural environmental changes, of the Holocene, universally represented by sediments, one must first of all assess the directionality of the has been adequately described and interpreted, it will be impossible to evaluate the magnitude of the *This study was supported by the Russian Foundation anthropogenic impact on the environment and climate. for Basic Research (Project 09-05-00123-а) and the Baikal Our knowledge of the recent geological past is limited. Archaeological Project. Currently, the most reliable oxygen-isotopic record

17 18 of temperature changes in the Late Glacial and in the thousand years (Kataoka et al., 2003; Bezrukova, Holocene, based on the ice core from Greenland, contains Krivonogov, Abzaeva et al., 2005; Bezrukova, Belov, signals of sharp short-lived climatic fl uctuations during Abzaeva et al., 2006; Bezrukova, Belov, Letunova et al., the Late Glacial and evidences a relatively stable climate 2008; Bezrukova, Krivonogov, Takahara et al., 2008). in the Holocene (GRIP Members, 1995). However, data As the study of these records has demonstrated, climatic concerning the geochemical admixture in the same core fl uctuations in the Holocene had a larger amplitude and attest to climatic instability and the irregularity of the higher frequency than previously believed, although the Holocene characteristics at least in Greenland (Mayewski range was lower than during the Late Glacial. et al., 1997). Climatic fluctuations in the Holocene The objective of the present article is to develop have been demonstrated in many regions (Enzel et al., a high-resolution reconstruction of Late Glacial and 1999; Wurster, Patterson, 2001; Zhao et al., 2007), and Holocene environmental changes in the Lake Baikal various mechanisms explaining these fl uctuations have area using dated pollen records from marsh systems, been suggested (Bond et al., 2001; Visbeek, 2002). It which today are situated in areas with different biological is impossible to reconstruct the temporal and spatial and climatic parameters – those in the southern and variation of the Late Glacial and Holocene climate and the northeastern shores of the lake. Before the mid- environment without information from various regions 17th century, neither area was subjected to a signifi cant of the planet, especially those where the environment is anthropogenic impact. Therefore the sedimentation particularly sensitive to climatic changes. Earlier studies records from these ecosystems will hopefully refl ect the have shown that geochemical and diatom records from the natural environmental changes. bottom sediments of Lake Baikal meet this requirement (Uchastniki..., 1998; Khursevich et al., 2001; BDP-99..., 2005; and others). However, earlier reconstructions of Study areas climate in these studies are based on averaged signals from deep-water cores. Meanwhile, the Lake Baikal basin Duguldzera. The core was taken at the eastern Baikal spans nearly four degrees of latitude and, because its shore (Fig. 1), in the forest ecosystem of the middle southern and northern parts display climatic differences mountain zone. Larch, Scots and Siberian pines dominate at the present, such differences must have existed in the this ecosystem. Forests composed of larch, Siberian pine, past as well. The relevant information can be obtained and spruce occupy more elevated areas on mountain from peatland ecosystems, where a thick layer of organic slopes and in valleys. Open Siberian pine and fi r forests sediments contains a continuous record of environmental of a primarily valley type grow higher. This region changes with a high time resolution over the last 15 is characterized by an extreme continental climate. According to data of the nearest weather station at Davsha, mean January and July temperatures are –22 ºС and +14 ºС, respectively; the mean annual temperature equals –3.3 ºС. Mean annual precipitation ranges from 350 to 400 mm. Insular permafrost occurs in this region (Baikal..., 1993). Dulikha. The peat bog is located on the southern 1 shore of Baikal (Fig. 1), where southern Siberian taiga composed of Siberian pine and fi r predominates. Larch trees are rare in marshlands. Birches form secondary forests, replacing dark coniferous forests in felling areas and fi re-sites. The climate is moderate continental (Ibid.). Mean July, January, and annual temperatures are +14.4, – 17.7, and –0.7 oC, respectively. Mean annual precipitation is 600–650 mm. Thus, the temperatures in the two areas differ by 4–5 oC in January, by 2 oC in July, and by approx. 2.5 oC on average, whereas the difference between mean 3 annual precipitation levels is nearly 250 mm.

2 Materials and methods Fig. 1. Map showing the location of the core sites. 1 – Duguldzera; 2 – Dulikha; 3 – VER93-2 bottom sediments, station The Duguldzera core is 400 cm long. The upper 330 24 GC. cm are represented by peat of various composition; 19 the lower 70 cm are formed by lacustrine gyttja with of the present article, the diagrams themselves are less an admixture of clay mineral particles. Every fourth important than the indices of environmental changes centimeter was subjected to pollen analysis; therefore based on these diagrams. Duguldzera is designated Dz the temporal resolution of the record is 150–200 years. and Dulikha is labeled Dl. The chronological model of the section is based on seven radiocarbon dates. The depth of Late Glacial and Holocene peat sediments Results and interpretation in the Dulikha core is 500 cm (Bezrukova, Krivonogov, Abzaeva et al., 2005). Every fourth centimeter of the Four zones have been recognized in the Duguldzera pollen core was treated with pollen analysis. The average diagram (Fig. 2). They are described from bottom to top. temporal resolution of the record is 100–150 years. The The zones are characterized by the most signiﬁ cant pollen chronological model of this core is based on three dates taxa for paleoenvironmental reconstructions. (Table). Dz4: Artemisia – Betula alba-type – Picea; > 16,000 Chronological limits of pollen zones were estimated BP; depth 400–385 cm. Sediments are represented by by linear interpolation between the dates. To evaluate mineralized gyttja. Spore-pollen spectra (hereafter, SPS) the possible mechanisms behind the vegetation changes evidence the first maxima of pollen of spruce (Picea and to correlate the temporal limits of these changes with obovata) and birches of both sections (Betula sect. those for the Northern Hemisphere, radiocarbon dates Albae and Betula sect. Nanae). The herbaceous group is were calibrated using CalPal software (Danzeglocke, dominated by Artemisia pollen. Jöris, Weninger, 2008). Age estimates in pollen diagrams Dz3д: Artemisia – Salix – Betula alba-type; meadow- are calibrated. steppe motley grassland; ~16,000–14,700 BP; depth 385– The classiﬁ cation of pollen taxa used for the calculation 355 cm. SPS formed in lacustrine gyttja. Tall birch pollen of pollen indices of temperature and moisture corresponds prevails along with pollen of shrub birch, willow, and to the taxa grouping applied in the biome reconstruction mesoxerophytic herbs. method (Prentice et al., 1996; Tarasov et al., 2000; Dz3г: Betula alba-type – Cyperaceae – Salix; Demske et al., 2005). ~14,700–14,000 BP; depth 355–345 cm. Birch and Pollen diagrams are presented here in the most general willow pollen dominate SPS; sedge pollen occurs in large form for several reasons: (1) the complete diagram quantities. of the Dulikha section has already been published Dz3в: Duschekia – Picea – Larix – Betula alba-type – (Bezrukova et al., 2005), although dates were given Equisetum; ~14,000–13,200 BP; depth 345–325 cm. SPS in conditional uncalibrated 14C values and no pollen were accumulated in gyttja. Spruce pollen appears again; indices of temperature or moisture were provided; (2) the amount of alder pollen increases. the complete diagram of the Duguldzera section was Dz3б: Larix – Betula alba-type – Duschekia; ~13,200– published by Abzaeva et al. (2008); (3) for the purpose 12,800 BP; depth 325–315 cm. SPS are characterized by

Results of radiocarbon dating of sediments

Interval in the core Radiocarbon age, Laboratory code Calibrated age, years Dated material (cm from the surface) years Duguldzera 0–2 240 ± 45 SO AN-5705 275 ± 114 Peat 25–30 1485 ± 50 SO AN-5706 1391 ± 55 » 90 4515 ± 40 АА-37969* 5179 ± 92 Wood 94–96 4805 ± 65 SO AN-5707 5531 ± 66 Peat 193 8020 ± 45 SO AN-37970* 8893 ± 93 Seeds 323 11,295 ± 55 АА-37971* 13,194 ± 101 Gyttja 378 12,950 ± 90 АА-37972* 15,767 ± 422 » Dulikha 300 7620 ± 115 NUTA-5615* 8425 ± 32 Seeds 399 9185 ± 55 AA-37974* 10,362 ± 79 Peat 475 11,110 ± 120 NUTA-6038* 13,010 ± 128 »

*Dated by the accelerator mass spectrometry technique at the Nagoya University Center for Chronological Research. 20

Fig. 2. Pollen diagram of Duguldzera sediments. In Fig. 2 and 3, the thick line in the column “Pollen indices” shows changes of the temperature index, and the thin line shows those of the moisture index. the second major spruce pollen maximum. Sediments birch pollen and by a high amount of arboreal birch pollen represent a gyttja to peat transition. and sphagnous moss spores. Dz3а: Picea – Duschekia – Betula alba-type; Four zones are recognizable in the Dulikha pollen ~12,800–11,300 BP; 315–265 cm. SPS were formed in diagram (Fig. 3). They are described from bottom to top. peat sediments. They are characterized by the greatest Dl4: Larix – Picea – Salix – Betula nana-type – Betula amounts of birch and alder pollen. alba-type; > 13,200 BP; depth 500–480 cm. Shrub and Dz2б: Larix – Betula alba-type – Picea – herb pollen dominates SPS. Pollen of spruce, larch, and Polypodiophyta; ~11,300–10 000 BP; depth 265– birch of both sections prevails in the group of arboreal 225 cm. SPS abound in larch and birch pollen; the ﬁ rst plants. fern spores and sedge pollen maxima are recorded. Dl3: Artemisia – Larix – Picea – Betula nana-type The amount of spruce pollen constantly varies. A – Betula alba-type – Cyperaceae – Polypodiophyta; maximum of pollen representing hygrophytic plants ~13,200–10 600 BP; depth 480–405 cm. Shrub and of Potamogeton and Typha can be observed in the herb pollen is still predominant in PSS. Birch and larch beginning of the zone. pollen dominates the group of arboreal plants. The share Dz2а: Abies – Larix – Picea – Betula; ~10,000–6000 of mesoxerophytic herbs, gramineous plants, sedge, and BP; depth 225–110 cm. Fir pollen continually presents, fern increases while the amount of spruce pollen decreases. Small Dl2в: Abies – Picea – Betula alba-type; ~10,600– quantities of Siberian pine pollen are constantly recorded. 10,000 BP; depth 405–370 cm. Arboreal pollen becomes The content of sedge pollen and that of fern and horsetail more abundant. The pollen of Siberian pine, Scots pine, spores is high. and Siberian dwarf pine appears in spectra. Dz1б: Pinus sylvestris – Pinus sibirica – Pinus pumila, Dl2б: Pinus sibirica – Betula alba-type – Abies; ~6000–2500 BP; depth 110–55 cm. Pollen of all the ~10,000–9200 BP; depth 370–330 cm. Fir pollen mentioned pine species dominates SPS. dominates SPS; the amount of pollen of both Siberian and Dz1a: Larix – Pinus sylvestris – Pinus sibirica – Pinus Scots pine increases. pumila – Betula nana-type; ~2500 – 0 BP; depth 55–0 cm. Dl2а: Abies – Pinus sibirica – Betula alba-type; SPS are characterized by the second maximum of shrub ~9200–6200 BP; depth 330–215 cm. The share of ﬁ r pollen 21

Fig. 3. Pollen diagram of Dulikha sediments. constantly decreases, while that of Siberian and Scots pine conditions under which mineralized gyttja formed in continues to rise. The amount of birch pollen is stable. the peat bog near the vegetated lake. At that time, the Dl1: Pinus pumila – Betula – Pinus sylvestris – Pinus northeastern shore was covered with forest and tundra sibirica; ~6200–0 BP; depth 215–0 cm. vegetation composed of larch, birch, spruce, and tundra herbs and shrubs. Vegetation of this type currently occurs in the Pechora River delta characterized by a cold climate Discussion: with an average annual temperature of –4 °С, an average Reconstruction of the paleoenvironment July temperature of approx. 13 °С, and an average annual precipitation of approx. 400 mm (Valiranta, Kaakinen, Pollen records and results of radiocarbon dating of Kuhry, 2003). The time period of this vegetation existence lacustrine and marsh sediments make it possible to coincided with the beginning of deglaciation after ~17,000 reconstruct climate and vegetation evolution and to BP (Bowen et al., 2002) and relative climatic warming. partially trace changes of the hydrological regime on the Temperature and moisture indices suggest that the climate southern and northeastern Baikal shores after the last was cold (especially in the winter) and humid. Judging by glacial maximum. the vegetation composition, the humidity index diagnoses a high soil moisture level caused by melting permafrost and lower summer temperatures rather than high atmospheric Vegetation and climate precipitation. Almost a complete disappearance of spruce of the last glacial period pollen and decrease in the amount of arboreal pollen in the spectra formed in the mineralized gyttja ~16,000– The Duguldzera pollen record encompasses a longer 14,700 years ago, on the one hand, and dominance of time period than the Dulikha record. The pollen analysis pollen of birch, willow, and mesoxerophytic herbs, on of the Duguldzera core provided a base for the first the other hand, testify to deterioration of conditions for reconstruction of vegetation and climate changes of the forest vegetation growth (Dz3д). This could possibly be entire Lake Baikal record for the transitional period from determined by a general climate worsening during one of the last glaciation to the modern interglacial. the stadials of Termination 1, whose minimum occurred The lowest section of the Duguldzera pollen record ~15,500 years ago (Wehrli, Tinner, 2007). Temperature (up to 16,000 BP, Dz4) reflects the environmental and moisture indices suggest a lowering level of warmth 22 and moisture accessible to plants. The warmth level rose the humid optimum terminated gradually from ~9200 to slightly ~14,700–14,000 years ago (Dz3г) and coincided ~6800 BP (Dl2а). On the northeastern shore, the humid with the fi rst signifi cant warming of Termination 1, while maximum manifested itself in a different way. It started the humidity level continued to drop. The vegetation after 10,000 BP and reached its maximum ~7000–6000 BP was dominated by shrubby yernik and willow tundra (the highest amount of fi r pollen). However, despite such a with patches of open birch forests. The fi rst recorded late onset of the humid optimum on the northeastern shore, significant maximum of sedge pollen suggests the it terminated there between 7000 and 6000 BP, as on the beginning of local bog formation. Between ~14,000 and southern shore. Quantitative characteristics of the humid 13,200 BP (Dz3в), forest-tundra vegetation with larch optimum reconstructed previously on the basis of the and later on with spruce, birch, and alder spread in the pollen record from the Baikal bottom sediments (VER93- lake environs. At the same time (before ~13,200 BP), the 2, station 24 GC (Fig. 1)) have shown that ~9500–6500 southern Baikal shore was dominated by open birch and years ago, mean annual precipitation exceeded modern spruce forests with larch. This represented a shift toward values by 80–100 mm; mean winter temperatures were milder climatic conditions of the interstadial warming that 2–4 °С higher than nowadays. Mean July temperatures, corresponded to the Allerøed. A short-term culmination however, could be close to those of today (Tarasov et al., of warm and humid conditions that occurred ~13,200– 2007). A combination of mild, snowy winters, absence of 12,800 years ago (Dz3б) entailed expansion of spruce in spring frosts, and cool and moist summer seasons favored the Duguldzera region. At that time, spruce forest-tundra the development of fi r forests. Pollen indices demonstrate prevailed on the southern shore. a steady tendency toward decrease of humidity and A new period of warmth level lowering occurred increase of warmth ca 10,000–6000 BP in the northeast between 12,800 and 11,300 BP (Dz3а). At that time, and 10,500–7000 BP in the southern part of the lake. the humidity was unstable. Spruce-birch forest-tundra When temperature and humidity levels became close to and alder tundra prevailed on the northeastern shore. modern ones, fi r taiga ceased to be predominant. Conditions unfavorable for forest vegetation probably The Holocene optimum is a very important period as resulted from climate deterioration synchronous with the it may be used for modeling future climatic changes. The Younger Dryas (Dansgaard et al., 1993). Approximately optimum is usually believed to coincide with the period of at the same time period, on the southern shore, the climate the postglacial thermal maximum (Winkler, Wang, 1993). became more continental; it favored the development of In Northern Europe this period is characterized by a warm birch-larch forest tundra with spruce and of herb-shrubby and generally moist climate. However, in China, as in the tundra (Dl3). Pollen indices attest to the coldest and the Baikal basin, the Holocene optimum is defi ned as a period most humid climate over the entire period examined. of maximal precipitation values rather than as a thermal Vegetation character points to a high soil moisture level maximum (Xiaoqiang Li et al., 2004; Porter, Weijian, (melting permafrost) due to lower summer temperatures 2006). A less continental climate and the predomination of (lower evaporation rate). In the southern Baikal area, this fi r forest in the Baikal area might have been a consequence period was longer: it lasted almost to 10,600 BP. of a greater thermal gradient between the ocean and the land, which resulted in a greater transport of moist air masses to the continent. Having attained the lake area, Vegetation and climate these masses caused a greater convective rainfall. Various of the Holocene humid optimum paleoclimatic records contain evidence of the Holocene optimum characterized by wet and cool conditions almost At the onset of the Holocene (~11,300–10,000 BP all over the Northern Hemisphere (Herzschuh et al., 2005; (Dz2б)), a lowland sedge marsh formed in the place of Blyakharchuk et al., 2004; Mudie et al., 2007). New the vegetated lake in the northwestern Baikal area. Larch facts suggesting the highest atmospheric precipitation and spruce became more abundant in the surroundings and temperate continental climate with cool summers of the Duguldzera marsh. On the southern shore, on and warm winters that existed ca 11,000–7000 years the contrary, areas vegetated by larch diminished, ago have been recently obtained for the western Trans- while territories covered by spruce expanded rapidly. Baikal region, too (Bezrukova, Krivonogov, Takahara et Such shifts in plant composition suggest that the al., 2008). climate became less extreme continental; total annual precipitation values and mean winter temperatures increased. These changes marked the beginning of Vegetation and climate expansion of humid fir taiga and thus the onset of of the post-optimum period of the Holocene the Holocene humid optimum on the southern shore. The maximum of the fi r taiga development occurred During the ~7000–6000 BP interval in the south and ~10,000–9200 years ago (Dl2б). On the southern shore, after ~6000 BP in the northeast of Lake Baikal, drastic 23 changes in the composition of forest vegetation occurred: Conclusions Siberian and Scots pine replaced fi r and spruce. This shift occurred under the conditions of a signifi cant lowering Results of pollen and radiocarbon studies of lacustrine of humidity and increasing heat supply. Eco-edaphic and boggy ecosystems on various shores of Lake requirements of these new forest elements presuppose Baikal, and the comparison of these results with dated increasing continentality of the climate due to lowering records of respective changes in adjacent regions led to atmospheric humidity, drop of winter temperatures, and the elaboration of a detailed record of environmental rise of summer temperatures (Tarasov et al., 2007). The evolution in the Baikal area since the end of the last termination of the humid optimum in the Baikal basin glaciation (17,000–16,000 BP). Considerable changes in coincided with the onset of neoglaciation on the Loess atmospheric circulation in the Northern Hemisphere in Plateau (Porter, Weijian, 2006) and with the documented the beginning of the deglaciation contributed to warmer ice-rafted debris peak in the North Atlantic ca 6000 BP and dry summers 16,000–12,000 years ago in Siberia (Bond et al., 2001). At about the same time (ca 5500 (Schirrmeister et al., 2002). This was the time when peat BP), the relatively cool and moist “green” period in deposits began forming on the southern and northeastern Northern Africa, which contributed to the existence shores of Baikal (at 13,000 and 11,500 BP, respectively). of numerous lakes in what is now the Sahara, came Generally, high-resolution pollen records presented in to an end (Renssen et al., 2006). The transition to a this article attest to profound changes of vegetation considerably more continental climate all over Eurasia and climate of the lake catchment area during the Late meant that the underlying mechanisms were global. Glacial and in the Early Holocene, and to a high climatic The Baikal landscapes responded to these global variability during the modern interglacial period. Pollen changes by radical restructuring: the dark coniferous records demonstrate instability of landscapes and forest of the Early and Middle Holocene was replaced climate in the Late Glacial and Early Holocene, resulting by a light coniferous and more xerophytic vegetation in frequent changes of plant associations. The probable of the Late Holocene. Beginning from ca 6000 BP, reason behind this interchange was the melting of ice the level of moisture available to plants demonstrates sheets and mountain glaciers, leading to the instability a stable reduction with minor fl uctuations, whereas of the ocean–atmosphere–cryosphere system. Pollen relative temperature level demonstrates short-term records confirm the beginning of a long period of small fl uctuations around the modern mean (see pollen Holocene optimum with a moist and mild climate and indices in Fig. 2 and 3). Consequently, temperature and warm winters at ca 11,000–10,000 BP, characterized moisture levels did not remain permanent, evidencing by the predominance of fi r, spruce, and pine forests in climatic instability in the Late Holocene. The frequency various areas of the Lake Baikal catchment area under and range of these fluctuations requires additional increased insolation in high latitudes of the Northern study, although the available records make it clear that Hemisphere. The optimal period ended about 7000– the climatic changes affected the landscapes of the 6000 BP, when insolation decreased and the world ocean Baikal ecosystem. The changes, however, were mostly attained its modern level. The optimum was followed expressed in the local landscapes. In the Late Holocene by a period when the climate became progressively (ca 2400–2500 BP), cooling resulted in changes of the more continental, atmospheric precipitation decreased, hydrological regime of the marshland on the southern the winter became colder, and summer became warmer. shore of the lake. After 2400 BP, yernik associations As a result, dark coniferous forests gave way to light began to expand. The process was even more marked coniferous ones. The principal factors behind the on the northeastern shore of Baikal at about 2500 climatic changes of such magnitude were variability BP. A distinct pollen signal of climate deterioration in insolation and concentration of carbon dioxide in followed by the distribution of yernik associations the atmosphere. Lesser and short-term fl uctuations of which has been obtained for Lake Kotokel basin as vegetation and climate in the Holocene (ca 2500–2400, well (Bezrukova, Krivonogov, Takahara et al., 2008) 1600–1200, and 500–400 BP) evidenced by our pollen suggests that an adequate response of the entire Baikal records may be viewed as responses of the regional ecosystem to the decrease of solar radiation occurred ecosystem to quasi-millennium changes of insolation after 2700 BP, when the climate deteriorated in both (Meeker, Mayewski, 2002). Records from the Dulikha hemispheres (Swindles, Plunkett, Roe, 2007). Even and Duguldzera cores demonstrate a marked correlation shorter fl uctuations of the landscape and climate in the with climatic fl uctuations in the Northern Hemisphere Lake Baikal area, coinciding with well-known events as a whole. The range of these changes is higher on the such as the Medieval Warm Period and the Little Ice northeastern shore of Lake Baikal than on its southern Age, are registered by pollen records from the northern shore. In addition to climate, local factors such as shore of the lake (Bezrukova, Belov, Abzayeva et al., geological and geomorphological structure, vegetation, 2006). changing level of ground waters, thickness and depth of 24 permafrost, may have been important in the evolution of Bowen D.Q., Phillips F.M., McCabe A.M., the Lake Baikal environment. 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