Based on the data obtained during a detailed palynological study of Pleistocene deposits of multilayered paleolithic sites in Northwestern Altai, the sequences of climatic, floristic, and phytocenotic changes that occurred during the interglacial and cold stages of the Pleistocene in the low-mountain part of the Altai Mountains, during the periods of Paleolithic man's habitation here, are reconstructed. Paleogeographic features of the optima of the studied Neo-Pleistocene interglacial epochs and pessimums of glacial-grade cooling periods in this territory are established.

Key words: Neo-Pleistocene, palynology, paleogeography, natural environment, plant formations, structure of natural complexes.

Introduction

The incompleteness of the Pleistocene geological record in most of Northern Eurasia makes it necessary to identify the features of spatial and temporal patterns of flora, vegetation, and climate development in order to solve the issues of detailed dissection of recent deposits, periodization and correlation of climate-related paleogeographic events, as well as to determine the geological age of Paleolithic objects and reconstruct the living conditions of primitive man. Materials on the history of vegetation cover are among the most important paleogeographic evidence, on the basis of which K. K. Markov concluded that the main regularities of changes in the natural environment are direction, rhythm and metachronism (local individuality) [1960]. The accumulation and synthesis of new analytical data in the course of subsequent paleogeographic studies made it possible to make significant adjustments to the understanding of the features of the three spatiotemporal patterns of development of flora, vegetation, and climate of the Pleistocene (Bolikhovskaya, 2005, 2007).

Based on detailed reconstructions of floristic, phytocenotic, and climatic successions created for a number of stratoregions in Eastern Europe that have different histories of paleogeographic development, the structure of climatic rhythmicity - the number of interglacial and glacial rhythms within the Neo - Pleistocene-and features of climatorrhythmics within warm and cold epochs are refined. It is established that changes in the natural environment during the Brunes chrono were caused by changes in 15 global climatic rhythms - 8 interglacials and 7 glacial cooling periods.

The study was carried out within the framework of the RFBR project N 13 - 06 - 12002.

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rank. Within the glacial and interglacial stages, more fractional climatostratigraphic units are distinguished: endothermal cooling, thermoxerotic and thermohygrotic stages are traced in interglacial climatic rhythms, and stadials are traced in cold rhythms of glacial rank. interstadials, interphases, cryohygrotic and cryoxerotic stages.

Detailed palynological records have significantly expanded our knowledge of the specifics of spatial differentiation of vegetation cover in interglacial and glacial epochs. The spatial differentiation of periglacial vegetation, i.e. vegetation of the Neo-Pleistocene glacial periods, was more significant than the spatial differentiation of the vegetation cover of interglacial epochs. The diversity of zonal and subzonal vegetation types in cold periods was greater than the diversity of zonal and subzonal vegetation types in interglacial epochs (Bolikhovskaya, 2005).

The obtained data also significantly changed the understanding of the course of directed development of flora and vegetation in the Pleistocene. They supported only the ubiquitous pattern of directed depletion of the entire set of interglacial floras of one Pleistocene link, compared with the integral interglacial floras of the subsequent link, established by the results of studies of Late Cenozoic floras of higher plants in all the studied areas of Northern Eurasia. However, they did not confirm the prevailing view that each subsequent interglacial epoch should be characterized by a flora poorer in exotic elements than the flora of the previous interglacial period. According to the results obtained, the process of impoverishment of interglacial floras by exotic elements in some interglacial epochs of the early and Middle Neo-Pleistocene, which was growing in the Late Cenozoic, was disrupted by the appearance of floras with a more diverse composition of taxa and a richer set of Neogene relics than the flora of the previous Interglacial period (Bolikhovskaya, 2007).

In addition, another pattern in the history of vegetation and climate of the Neo-Pleistocene is established. Two long cycles of changes in the flora, vegetation, and climate of the East European Plain in the Neo-Pleistocene, which determined the natural features of all interglacial and cold stages, were determined by a comparative analysis of the almost continuous sequence of climate-phytocenotic and floristic successions. Each of these cycles spanned four interglacial and four glacial epochs (Bolikhovskaya, 2005).

Data on the absolute chronology of warm and cold epochs allowed us to determine the age range of each such cycle. To determine the age and duration of the reconstructed warm and cold stages of the Neo-Pleistocene, the continental sediments and paleoclimatic events of the extraglacial and glacial-periglacial zones of the East European Plain were correlated with warm climatic rhythms reconstructed on the basis of EPR analysis of marine mollusk shells from transgressive sediments of the paleoshelf zone of Northern Eurasia, and with the oxygen isotope scale [Bolikhovskaya, Molodkov, 2002; Bolikhovskaya and Molodkov, 2006; Molodkov and Bolikhovskaya, 2006]. According to these chronostratigraphic data, the duration of the established cycles in the development of the natural environment was approximately 450 thousand years. Each of the interglacial or glacial stages of the younger 450-millennial cycle had its own paleogeographic counterpart in the previous cycle. The discovery of this regularity brought to a new level the prospects of palino-climatostratigraphic research in solving the problems of stratigraphy and paleogeography of the Pleistocene not only in lowlands, but also in mountainous regions.

One of the most studied mountain regions of Northern Eurasia in this respect is the territory of the Russian Altai, which is part of the Eurasian steppe zone. At the same time, the northern part of Altai is zonally located in the subzone of the northern forest-steppe, connected through the forests of the Kuznetsk Alatau with the southern taiga, and the southern part adjoins the zone of the northern deserts of Central Asia. In addition, the florophytic-cenotic specialization of this region is also due to the fact that Altai is part of the vast contact zone of the Boreal (relatively humid) and Central Asian (arid) regions of the Holarctic (Tolmachev, 1974). The Altai territory is bordered by two sectors of Northern Asia: the boreal West Siberian-Central Asian-Himalayan and the extreme continental Central Siberian-Central Asian-Indochina (Kamelin, 2005). These patterns of latitudinal zoning and sectorality leave an imprint on the features of the modern vertical belt of the Northwestern Altai, where communities of four high-altitude belts are now widespread: high-mountain (with alpine-meadow and mountain-tundra associations); mountain-taiga; transitional mountain-forest-steppe, combining mountain-steppe and mountain-taiga associations; mountain-steppe (Ogureeva, 1980).

It should be noted that at present there are no broad-leaved and coniferous-broad-leaved forest formations in the Altai vegetation. Moreover, almost all Nemo's are not represented here-

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natural wood-shrub plants, autochthonous pollen of which is found in Pleistocene deposits of this mountainous country. Of all the broad-leaved species included in the fossil Pleistocene dendroflora of the research area, only the Siberian linden Tilia sibirica is found in the north-east of Altai. At the same time, in the south-west and north-east of Altai, there are areas with a fairly high average annual precipitation (from 1,000 to 2,000 mm), which have preserved in the modern vegetation cover grassy relics - satellites of broad - leaved forests and even formations-derivatives of coniferous-broad-leaved forests of the Pliocene (Kuminova, 1957). On their territory were the main Altai refugia of non-moral forest formations, which did not cease to exist during the most unfavorable climatic periods of the Pleistocene.

The current paleobotanical information available for individual regions of the Altai varies in volume. The most representative climatoflorophytocenotic records, which allow identifying specific features of changes in Pleistocene flora and vegetation, were obtained for the northwestern part of the Altai Mountains (Prirodnaya Sreda..., 2003). Thanks to long-term interdisciplinary studies of multilayered Paleolithic sites located in the valley of the Anui River-Karama, Denisova Cave, Ust-Karakol, Anui-2, etc. 1), constantly updated geological, paleosoil, paleobotanical, paleofaunal, geochronological and other analytical data necessary to substantiate the age and climate of the stratigraphic division of Pleistocene deposits, reconstruct the history of the natural environment and the living conditions of primitive man.

Paleobotanical studies of recent deposits in this area have been carried out since the early 1990s. In 1992-1997, E. M. Malaeva performed a detailed spore-pollen study of the neo-Pleistocene strata of the Paleolithic sites Denisova Cave, Ust-Karakol, Anui-2, and the Lower Kara-kol and Black Anui sections, now located in the mountain taiga belt. A thorough historical and floristic analysis of the studied Pleistocene palynoflora was carried out and vegetation and climate changes during the period from the Tobolsk Interglacial to the Holocene were reconstructed in detail (Malaeva, 1995, 1998; Derevyanko, Malaeva, and Shunkov, 1998, 2000). In addition, E. M. Malaeva evaluated two warm stages of the dominance of forest and forest-steppe phytocenoses in the Early Pleistocene (Derevyanko et al., 1992).

Since 1998, N. S. Bolikhovskaya has been conducting palynological studies of Pleistocene deposits in the Northwestern Altai. To date, based on the results of spore-pollen analysis of sections of the Karama, Kaminnaya Cave sites, etc. vegetation and climate changes that occurred during two interglacial and two cold epochs of the early Pleistocene were reconstructed and correlated with marine isotope stages 16-19 of the warm Karginsky stage, the Sartan pessimum, and the late glacial Sartan stadials and interstadials (Bolikhovskaya and Markin, 2002; Bolikhovskaya and Shunkov, 2005; Derevyanko et al., 2000; Bolikhovskaya, Derevyanko, Shunkov, 2006].

Lower Neo-Pleistocene

Materials on climate stratigraphy and florophytocenotic reconstructions obtained for the Lower Pleistocene stages of the development of the natural environment of the Northwestern Altai are of great importance for establishing patterns of vegetation and climate change not only in Altai, but also in the entire southern territory of North Asia.

Lower Pleistocene sediments in the Anuya Valley were first studied in the Black Anuya and Lower Karakol sections,

1. Reference Paleolithic complexes in the Anui River basin, Northwestern Altai.

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located within the modern mountain-forest belt at absolute altitudes of 740-750 m (Derevyanko et al., 1992). The spore-pollen spectra of these sections characterize the vegetation of two early neo-Pleistocene warm epochs, in which dendroflora, along with edifiers of modern forests, grew exotics: Betula sect. Costatae, Juglans cf. mandshurica, Carpinus betulus, Quercus, Ulmus cf. laevis, Tilia sibirica, Acer, Alnus, Corylus avellana. During the first Interglacial period, forest-steppes were developed in the vicinity of the Cherny Anuy section with the dominance of birch forests and the participation of scots pine, Siberian cedar and broad-leaved species. The subsequent cold snap with an increase in water availability led to the dominance of forest communities from Pinus sylvestris, P. sibirica, Abies, and Picea. The second Interglacial epoch is reflected in the palynospectra of the Lower Karakol section. During this era, first forests dominated, then forest-steppes, and later the participation of forest communities increased markedly again. In the optimal phases, as well as during the first warming, birch forests with broad-leaved and coniferous trees prevailed.

More complete and detailed palynological data describing not only warm but also cold epochs of the Lower Neo-Pleistocene were obtained by studying the section of the Early Paleolithic Karama site, located at an absolute altitude of about 630 m. Judging by the geobotanical descriptions of the Altai vegetation cover (Ogureeva, 1980, p.5) and the structure of phytocenoses in the vicinity of the site, it is currently located in the transition zone from the mountain-forest to the mountain-forest-steppe belt.

The Karama excavation revealed a thickness of sediments with a total thickness of approx. 12 m, which, according to the nature of occurrence, sediment structure, and dynamics of palynospectres, consists of three strata and has significant sedimentation breaks (Stoyanka..., 2005). Detailed spore-pollen analysis of the exposed sediments allowed us to clarify their geological age, reconstruct the landscape and climatic conditions of Early Paleolithic man, and describe in detail the changes in flora and vegetation that occurred during the oldest interglacial and glacial epochs of the Neo-Pleistocene (Bolikhovskaya and Shunkov, 2005; Bolikhovskaya, Derevyanko, Shunkov, 2006).

В целом в составе автохтонной палинофлоры трех проанализированных толщ Карамы отмечено более 130 таксонов разного ранга. На приведенной ниже спорово-пыльцевой диаграмме (рис. 2) большинство определенных до вида таксонов объединены и показаны в составе родов и семейств. Определена пыльца 45 родов и видов деревьев и кустарников, а также 56 видов, родов и семейств травяно-кустарничковых растений. Группу высших споровых растений (мхов, папоротников, плаунов, хвоща и др.) представляют 30 таксонов.

The palynoflora of the lower (layers 13 - 9) and middle (layers 8 and 7) strata of the Karama section is significantly richer than the flora of the previously studied coeval deposits of the Cherny Anuy and Lower Karakol sections, which contained only 25 genera and species of tree and shrub taxa. However, in terms of the generic and specific composition of dendroflora, as well as the structure of paleophytocenoses, the periods of accumulation of these deposits are relatively close to the ancient interglacial epochs reconstructed for the Karama section.

The palynospectrs of layers 7, 8, and 10-13 of Karama include a significant number of boreal elements that are exotic for modern dendroflora: Picea sect. Omorica, Pinus sect. Strobus, Pinus cf. koraiensis, Betula sect. Costatae and non-moral European, Far Eastern and other taxa: Juglans mandshurica, Carpinus betulus, C cordata, C. orientalis, Ostrya sp., Quercus robur, Tilia cordata, T. amurensis, T. mandshurica, Ulmus pumila, Corylus avellana, Alnus glutinosa, A. incana, Morus sp. etc. Many of them were first recorded in the palynospectra of the Middle and Early Pleistocene deposits of the Anuya Valley.

The presence of layers 7, 8, and 10-13 of the Pinus sect in the palynoflora. Strobus, Carpinus cordata, С. orientalis, Ostrya sp., Quercus robur, Tilia cordata, T. amurensis, T. mandshurica, Alnus glutinosa, A. incana, Corylus avellana, Juglans mandshurica, Carpinus betulus, Ulmus pumila, Morus sp. et al., as well as the ecological and coenotic features of all the discovered exotic taxa, the results of the analysis of geographical groups of dendroflora genera, and other data indicate the Early Pleistocene age of this section. For example, hmelegrab Ostrya sp. and mulberry Morus sp., belonging to the group of American-Mediterranean-Asian genera, are indicators of the Early Neo-Pleistocene age of the host sediments of the Southern Baikal and Upper Amur regions (Makhova, 1978; Grichuk, 1982).

Interglacial Karama palynoflora significantly differ from the Eopleistocene floras of the Eastern Altai, southern Western Siberia, and other mountain and lowland regions of Southern Siberia and the Far East (Giterman et al., 1968; Volkova, 1977; Golubeva and Kara-ulova, 1983; Belova, 1985; Arkhipov and Volkova, 1994). They do not contain pollen grains of subtropical broadleaf species: Pterocarya, Carya, Zelkova, Celtis, Ilex, Tsuga and other exotic taxa of the pine family typical of thermophilic Eopleistocene floras of these regions. This circumstance does not give grounds to assume an Eopleistocene age for Karama deposits (Bolikhovskaya and Shunkov, 2005). However, some is-

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2. Spore-pollen diagram of the Karama site sediments (analyst N. S. Bolikhovskaya). 1 - lithological layer; 2 - pollen content less than 1 %; 3 - presence of spores in a small group (without counting percentages).

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Investigators believe that the Eopleistocene age cannot be excluded for the lower Karama sequence (Zykin et al., 2005). This assumption is based on paleomagnetic testing of the section, which showed direct magnetization for the entire sediment thickness, as well as the presence in the structure of the lower part of the section of a pedocomplex consisting of two slithozem soils that were previously known only in Pliocene deposits of Western and Central Siberia, which, according to V. S. Zykin and his colleagues, allows for a correlation of the lower Karaminsky section with the Barnaul layers of the Eopleistocene and, accordingly, with the Olduvei subchron. However, it is difficult to agree with this assumption, since the Early Pleistocene interglacial epochs reconstructed from Karama's palynological data differ markedly in floristic, phytocenotic, and paleoclimatic characteristics from the period of formation of the Barnaul layers in the south of Western Siberia (Istoriya..., 1970). If deposits with the Barnaul flora accumulated in forest-steppes and steppes with a climate close to the present [Volkova and Kulkova, 1999], the interglacial flora of Karama existed in much warmer and less continental climatic conditions than modern ones.

The Karama spore-pollen spectra from the bottom up of the section reflect a significant dynamics in the composition and percentage of taxa, indicating repeated changes in zonal vegetation types in the Anuya Valley and rearrangements of plant formations in the vicinity of the site, due to global climatic fluctuations of the four reconstructed large stages of the Brunes crone.

The time of the first interglacial recorded in the section corresponds to the period of accumulation of layers 13 - 10. This epoch is correlated with the marine isotope stage (MIS) 19, or the Gremyachyevsky interglacial stage of the East European Plain, which, according to correlation calculations, dates back to the interval of 790-760 Ka BP (Bolikhovskaya, 2005; Molodkov and Bolikhovskaya, 2009). At that time, the warmer climate than today was dominated by forest-steppe and forest landscapes. Seven phases were reconstructed that reflect the transformations of the communities that made up them - steppe areas, broad-leaved forests from Tilia cordata and T. sibirica, Quercus robur, Q. mongolica Fisch. ex Ledeb., Carpinus cordata, Juglans mandshurica, Ulmus, Morus, birch and coniferous forests. Phase 1 (palynozone 1.1) - dominance of pine-birch and birch-pine forests from Betula pendula, B. pubescens, Pinus sylvestris with spruce admixture, Betula sect. Costatae, oak and linden Tilia cordata, T. sibirica, with Corylus avellana in the undergrowth. Pollen of thermophilic elements of dendroflora totals 3.5-7.9 %. Phase 2 (palynozone 1.2) is dominated by forest-steppe. The share of pollen from non-moral dendroflora species increased to 9.2 %. Under the conditions of climate warming, the total area of forests decreased, but the role of broad-leaved species in their composition increased: Carpinus cordata, Quercus robur, Tilia cordata, T. sibirica, Ulmus pumila, Morus, etc. Steppe biotopes were first dominated by grasses and mixed grasses, and then by haze-sagebrush and aster-sagebrush communities. Phase 3 (Palinozone 1.3) corresponds to endothermal (intraglacial) cooling, during which forest-steppes still dominated. The decrease in heat supply is indicated by a sharp drop (up to 1.4 %) in the role of broad-leaved pollen, represented only by Tilia sibirica. Poaceae, Asteraceae, and Artemisia began to prevail in steppe groups. Phase 4 (palynozone 1.4) reflects an increase in climate humidity and the dominance of forest landscapes - the content of tree pollen increased to 70 %. Pine and birch forests dominated. Due to relative warming and increased water availability, Abies, Pinus cf.koraiensis, Betula sect. Costatae, Juglans mandshurica, Quercus. Phase 5 (palynozone 1.5) - prevalence of cedar-pine and birch-oak-lime-hornbeam forests. Phase 6 (palynozone 1.6) is characterized by further transformation of forest vegetation with a noticeable decrease in heat and moisture supply during the second endothermic. The role of broadleaf species has been reduced, hornbeam and oak have disappeared. Birch-pine forests with the participation of spruce, Pinus cf. prevailed. koraiensis, Tilia cordata, T. sibirica. A shrubby birch tree appeared in the undergrowth. Phase 7 (palynozone 1.7) corresponds to the Interglacial thermohyrotic maximum. The total pollen content of thermophilic dendroflora species increased to 14 %. Broad-leaved forests of Quercus sp., Carpinus cordata, Tilia cordata, T. sibirica, and Ulmus sp dominated. with the participation of Alnus glutinosa. They were accompanied by coniferous-birch stands of spruce, Pinus sylvestris, Pinus cf. koraiensis and birch trees.

The formation of sediments of layer 9 (Palynozone 2) occurred during the cold epoch associated with MIS 18, or the Devitsky glacial stage of the East European Plain (760-710 KA BP). At this time, periglacial landscapes were developed. In the coldest periods, birch-pine forests and shrub communities from the Betula sect dominated here. Fruticosae, B. fruticosa, B. sect. Nanae, Alnaster fruticosus, Juniperus, etc., meadow and meadow-marsh coenoses. Single pollen samples of Siberian linden and alder in the palynospectra from the bottom and roof of layer 9 show that these rocks enter the subphases that transition from the previous thermochron to cooling and from it to the next interglacial period.-

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They were included in valley stands in the most favorable habitats for them.

The deluvial-proluvial sediments of layer 8 and most of Layer 7 accumulated during the next interglacial period (Palinozones 3.1 - 3.6), which was compared to MIS 17 or the Semiluk Interglacial stage (710-660 Ka BP). Climatically, it was warmer and drier than the previous interglacial period. For this thermochron, six phases in the development of the dominant steppes and forest steppes were reconstructed. In the first phase (palynozone 3.1), forest-steppes prevailed, combining areas of mixed grass and grass steppes, broad-leaved forests from Carpinus betulus, C. cordata, Quereus sp., Tilia mandshurica, etc., pine-birch forests and alders from Alnus glutinosa and A. incana. In the second phase (palynozone 3.2), steppes dominated, and the role of broad-leaved species significantly increased in the composition of forest areas. At first, hornbeam from Carpinus cordata and C. orientalis and pine-birch communities prevailed. Then the water supply increased and the importance of Carpinus cordata, Tilia mandshurica, T. sibirica and dark coniferous species increased. Pinus sect has been added. Strobus, P. cf. koraiensis. The third phase (palynozone 3.3) was dominated by steppes of mixed grasses and sagebrush communities, as well as valley hornbeam forests of Carpinus cordata and C. orientalis with an admixture of Juglans mandshurica, Tilia mandshurica, and Alnus glutinosa.

The second half of this interglacial period is associated with the most significant dispersal of thermophilic elements of dendroflora (the share of their pollen in the spectra is 27-33%). In the fourth phase (palynozone 3.4), forest-steppes dominated, where the main areas were occupied by mixed grass and grass steppes and park hornbeam forests of Carpinus betulus, C. cordata, and C. orientalis with an admixture of oak, elm, and alder. Birch pegs were of limited use. The fifth phase (palynozone 3.5) was characterized by forest-steppe landscapes with a predominance of lime-hornbeam communities from Carpinus cordata, Tilia cordata, and T. mandshurica in the dominant broad-leaved forests. In the sixth phase (palynozone 3.6), significant changes in the composition of forest vegetation occurred in the forest-steppes. The dominant species is dark coniferous, including Picea sect. Omorica. Hornbeam and some linden species have disappeared. The main areas were occupied by broad-leaved-fir-spruce forests with Tilia mandshurica, Ostrya sp. with an admixture of alder and birch Betula sect. Costatae, B. pendula, B. pubescens.

Sediments of the upper part of Layer 7 accumulated during the next cold epoch (Palynozone 4), which was compared with MIS 16 or the Don glaciation (660-610 KA BP). At this time, the climate was significantly cooled by periglacial steppes with small areas of coniferous woodlands. Broad-leaved species have disappeared from forest habitats. Larch, pine, and cedar-spruce rare coniferous forests from Larix sibirica, Pinus sylvestris, and Pinus cf predominated. koraiensis and spruce. Grass, mixed grass, sagebrush, and meadow cluster communities prevailed in the grass-shrub cover.

Middle Neo-Pleistocene

The climatic and phytocenotic conditions of human habitation in the Anuya Valley during the warm and cold epochs of the Middle Neo-Pleistocene were reconstructed in detail from palynological data from Denisova Cave deposits (Fig. 3) (Derevyanko, Malaeva, and Shunkov, 2000). In the Tobolsk Interglacial period (MIS 9, Chekala Interglacial period of the Russian Plain, 340 - 280 thousand years AGO), the warm and moderately humid climate was dominated by forest communities - birch and pine-birch forests with an admixture of Manchurian walnut, common hornbeam, Siberian linden, oak, maple, smooth elm, hazel, as well as valley alder forests with spruce trees. Mountain-steppe grass-shrub groups were confined to the southern slopes of the valley. The upper tier of the northern slopes was occupied by birch and pine-birch forests with dark coniferous species and larch.

During the cold snap of the Samara glacial stage (MIS 8, Kaluga cold snap of the Russian Plain, 280 - 240 thousand years ago), the area of woodlands significantly decreased, the share of dark coniferous species increased, and the role of steppe, nival, and boreal species increased. In the final phase, xerophytic and meadow steppe groups prevailed, and small forest areas were represented by pine-birch associations with fir, spruce, cedar and larch, as well as isolated inclusions of hornbeam, maple and hazel.

Vegetation of the Shirta Interglacial period (MIS 7, Cherepet Interglacial period of the Russian Plain, 240-205 thousand years AGO) was characterized by the predominance of massifs of pine-birch forests with an admixture of spruce, alder, and broad-leaved species. At the same time, the role of the latter significantly increased at the final stage in warm and moderately humid climates.

The vegetation cover of the final phase of the Taz cold snap (MIS 6, Dnieper/Moscow glaciation of the Russian Plain, 205 - 145 KA BP) was dominated by steppe and meadow communities of wormwood, grasses, and asteraceae. Small woodlands included birch-pine associations with admixture of alder, spruce, cedar and single broad-leaved species-oak, linden and elm.

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3. Spore-pollen diagram of the lower part of Pleistocene deposits of Denisova Cave (analyst E. M. Malaeva).

1 - lithological layer; 2-pollen content less than 1%.

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Upper Pleistocene

During the Upper Pleistocene, the role of forest biota gradually decreased in the vicinity of Denisova Cave and the Ust-Karakol and Anui-2 sites, as well as the area of forests shrinking and the areas occupied by open herbaceous and herbaceous-shrub communities expanded [Prirodnaya Sreda..., 2003, pp. 330-349]. In the evolution of the vegetation cover of the Kazantsev interglacial period, which is traditionally compared with the MIS 5e substage, three phases were reconstructed from palynospectras from layer 20 and the lower part of layer 19 in Denisova Cave (Fig. 4). In the first phase, pine-birch forests with maple, elm and linden dominated, in the second-birch-pine forests with an admixture of linden, oak and maple, and in the optimal phase of the interglacial period in the dominant forests, birch and pine were coedifiers, while alder, spruce and broad-leaved species such as Manchurian walnut, common hornbeam, Siberian linden, smooth elm, oak and hazel took a more noticeable part in the stand.

According to the climatochronostratigraphic studies of N. S. Bolikhovskaya and A. N. Molodkov, based on the results of EPR and IR OSL dating and palynological analysis of continental and marine deposits of the Pleistocene, most of the MIS 5 stage is characterized by an interglacial climate, and the age of the last interglacial period, which had at least three climatic maxima and two endothermal cooling periods, is estimated in the range from 145-140 to 70 Ka BP (Molodkov and Bolikhovskaya, 2011; Molodkov and Bolikhovskaya, 2006, 2009). Therefore, N. S. Bolikhovskaya does not exclude that layers 19 (upper part), 17 and 14 in the Denisova Cave and layers 17-14 of the Ust-Karakol site (Fig. 5), previously assigned to the climatic phase transitioning to the Ermakov cooling (substages of MIS 5a-d) [Prirodnaya Sreda..., 2003, pp. 264-270], could have been formed during the Kazantsev interglacial, since the composition of palynospectra from these layers showed a rather high content of pollen from birch, scots pine, alder and broad-leaved species.

The relatively cold Ermakov time (MIS 4) in the sections of Pleistocene deposits of the Anuya Valley includes layers 13-12 in the Denisova Cave (see Fig. 4) and at the Ust-Karakol parking lot (see Fig. 5). During the formation of these deposits, three phases of the natural environment were observed. The first phase reflects the most unfavorable climatic interval. According to palynological indicators, at this time there was a significant cooling and aridization of the climate, which caused the expansion of steppe areas with a predominance of sagebrush-grass and mixed-grass-sagebrush-grass communities in the grass-shrub cover, a reduction in the area of forest stations and a decrease in the taxonomic diversity of broad-leaved trees in their composition. The next phase, characterized by a cold and humid climate, is characterized by deposits with a high content of coniferous pollen - spruce and cedar, a small proportion of birch pollen, and the absence of pollen from broad-leaved plants. At the final stage of the Yermakov period, the general improvement of the climate situation took place in a drier and warmer climate - massifs of spruce taiga were noticeably reduced, and areas of birch forests with alder and hazel trees were restored.

For the Karginsky time (MIS 3), represented by layer 11 in the Denisova cave and layers 11 - 8 of the Ust-Karakol section, the conditions of a relatively cool and humid climate are established. At this time, the Anuya Valley was dominated by spruce forests with the participation of cedar. At optimal intervals in the composition of forests, the role of birch increased, elm, linden and hazel appeared.

In the section of the Karama site, the Karginsky time corresponds to the fossil soil lying in the thickness of sub-aerial cover deposits. Palynospectra from buried soil (see Fig. 2) indicate that during its formation, dense spruce forests grew in the vicinity of the site, i.e. dark coniferous taiga formations in the Anuya Valley descended to the modern upper boundary of the mountain-forest-steppe belt.

In the periglacial conditions of the Sartan Ice Age (MIS 2) in the Karama section (see Fig. 2) sedimentation of loess-like cover loams occurred. At this time, forest areas were significantly reduced, and tundra and steppe coenoses began to play a dominant role. At the early Sartan stage, sparse pine-larch-spruce associations prevailed among the forest formations. Significant areas were occupied by cryophytic Betula sect shrubs. Nanae, steppe and meadow communities. At the late stage, tundra-steppe landscapes dominated in the conditions of increased cryoaridization of the climate. The plant cover was richly represented by cryophytes: Alnaster fruticosus (Duschekia fruticosa). Betula sect. Nanae, B. sect. Fruticosae, Diphazium alpinum and xerophytes: Artemisia subgenus Dracunculus, Seriphidium. Small forest areas consisted of Pinus sylvestris pine and P. sibirica cedar.

The vegetation cover of the Sartan cold snap in the vicinity of Denisova Cave is reflected in the palynospectrs from layer 9 in the central hall of the cave, layers 4-2 of the Ust-Karakol site, and layers 12-5 of the Anui-2 site (Fig. 6). For most of the Sartan time, under cold and dry climate conditions, open landscapes prevailed grass-shrub and shrub communities. Dynamics of edifiers in small areas

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4. Spore-pollen diagram of the upper part of Pleistocene deposits of Denisova Cave (analyst E. M. Malaeva). 1 - lithological layer; 2 - pollen content less than 1%; 3 - presence of spores in a small group (without counting percentages).

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5. Spore-pollen diagram of the Ust-Karakol site sediments (analyst E. M. Malaeva). 1 - lithological layer; 2-pollen content less than 1 %.

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6. Spore-pollen diagram of the Anui-2 site sediments (analyst E. M. Malaeva). 1-lithological layer; 2-14 C-dates; 3-pollen content less than 1 %; 4 - presence of spores in a small group (without counting percentages); 5 - Rhododendron dahuricum: 6 - Hippophae rhamnoides.

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forest vegetation is characterized by the development of woodlands of different composition-spruce-cedar, spruce, pine, pine-birch with the participation of spruce, Siberian cedar and larch. In relatively favorable climatic intervals, the role of pine-birch forests with alder and broad-leaved species became noticeable.

Detailed characterization of changes in the natural environment during the final stage of the Sartan cold snap was compiled based on palynological studies of deposits in Kaminnaya Cave (Fig. 7), located in the mid-mountain zone of the Karakol River Valley, a left tributary of the Anui River (Derevyanko et al., 2000; Bolikhovskaya and Markin, 2002).

During the inter - stage period preceding the Early Dryas, 15.3-13.3 Ka BP, the cave area was dominated by mountain-steppe and mountain-meadow landscapes with a predominance of grass-mixed communities. Siberian cedar, spruce, fir, pine and birch formed the basis of the forest stand of the nearest woodlands. Near-valley willows and shrubby thickets of birch bark, viburnum, honeysuckle, etc. were widely developed.

In the second half of the Belling (12.2 - 12.0 KA BP), steppe areas dominated in this area, which belonged to the belt of periglacial forest-steppes, represented by mixed grass-grass and haze-wormwood communities. Expositionally or edaphically, these areas were combined in moist areas with woodlands, and on rocky outcrops and stone placers-with dry stony steppes. The most humid slopes and valley sections were occupied by spruce-cedar and pine forests with larch and birch. In the floodplain forests, willows played a significant role. The shrub layer consisted of juniper, elderberry, viburnum, buckthorn, etc., at higher hypsometric levels - juniper, shrub birch Betula fruticosa, B. rotundifolia, etc.

In the Middle Dryas (12.0 - 11.8 Ka BP), periglacial steppes dominated in the vicinity of the cave, in which the leading role was played by grass-grass, sagebrush and shrub coenoses consisting of Juniperus sp., Betula fruticosa, B. rotundifolia, Salix sp., Sambucus sp., Lonicera sp., Viburnum sp. etc. In the valleys, rare forest areas are preserved, represented by park larch-pine-spruce associations.

The Allered period (11.8-10.8 thousand years ago) is characterized by the most favorable climatic conditions. Linden, elm and alder trees constantly participated in the composition of the forests. In the thermoxerotic sub-stage, steppe vegetation with sagebrush and grass-mixed groups dominated, small areas of forests were occupied by spruce-cedar and birch-pine formations. In the thermohygrotic sub-stage, the area of woodlands in the dominant forest steppes increased, and the role of cedar, linden, and elm trees increased. Grass-mixed associations prevailed among steppe coenoses.

During the cryohygrotic sub - stage of the Late Dryas (10.8-10.4 Ka BP), this area was occupied by periglacial mountain-forest landscapes. The forests were represented by associations of coniferous species - larch, cedar and pine. Shrub formations of juniper and alder, shrub species of birch and willow were widely developed. There were sedimented grass-mixed and haze-sagebrush areas, as well as slightly blackened substrates and stony placers with Ephedra sp., Goniolimon speciosum, Cryptogramma sp. etc. The relatively harsh climate of this interval is indicated by the presence of species Alnaster fruticosus, Betula fruticosa, B. sect. Nanae, Botrychium boreale.

During the cryoxerotic sub-stage of the Late Dryassic (10.4-10.0 KA BP), a periglacial mountain semidesert developed in the cave area with sagebrush and grass-mixed sagebrush communities, in which ephedra, haze plants (Chenopodium polyspermum, Suaeda cf. physophora, and representatives of Asteraceae, Cichoriaceae, Zygophyllaceae, etc.) played a significant role. Presence in the pollen spectra of Alnaster fruticosus, B. sect. Nanae, Claytonia sp. indicates a cold and dry climate.

According to palynological data, at the final stage of the Sartan period, the middle mountain region of the Anuya basin was repeatedly located in the zone of distribution and subsequent migration of the steppe, forest-steppe and forest belts. Arcto-boreal species-Betula sect. Fruticosae, B. sect. Nanae, Alnaster fruticosus, Botrychium boreale, etc. - they constantly participated in the flora of both stadial and interstadial intervals, but tundra, tundra-steppe or tundra-forest-steppe periglacial formations as zonal formations, most likely, did not penetrate this territory. The combined presence in autochthonous palynospectres of Alnus glutinosa pollen and microthermal broadleaf species, such as Siberian linden Tilia sibirica and smooth elm Ulmus cf. laevis, which do not currently grow in this region and are similar in preservation to cryophyte microstates, confirms the conclusions of geobotanists about the refugial nature of the vegetation cover of Northwestern Altai.

Conclusion

A detailed palynological study of the deposits of layered Paleolithic sites in the Northwestern Altai allowed us to reconstruct

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7. Spore-pollen diagram of Pleistocene deposits in the Kaminnaya cave (analyst N. S. Bolikhovskaya). H1 - Holocene; LDR-late Dryasian; AL - allerated; MDR-Middle Dryasian; BO - belling; YDR - ancient Dryasian; AP - tree and shrub pollen; NAP - grass and shrub pollen; SP - spores.

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the process of vegetation cover development in the interglacial and cold stages of the Pleistocene, during the periods of primitive man's habitation here. During the interglacial epochs of the lower Neo-Pleistocene within the low mountains of the Northwestern Altai, steppe, forest-steppe, and forest landscapes, along with coniferous and birch formations, included broad-leaved forests. During the climatic optima of the Lower Pleistocene Interglacial periods, this territory was part of the transcontinental belt of non-moral forest and forest-steppe formations that occupied the southern regions of Northern Eurasia. One feature of the Altai non-moral forest communities of the lower Pleistocene is the joint growth of tree species that currently live in far-flung centers of non-moral flora - in the regions of Eastern Europe, the Caucasus, the Crimea, and the southern Far East. Another important feature of the Lower Pleistocene forests of the Anui Valley was the composition of edifiers-Juglans mandshurica walnut, European and Manchurian hornbeam species Carpinus betulus, C. cordata, C. orientalis, and linden trees Tilia cordata, T. amurensis, T. mandshurica, and T. sibirica. In contrast, in modern European and Far Eastern broad-leaved and coniferous-broad-leaved forests, the main forest-forming role is played by various oak species: Quercus robur, Q. petraea, Q. pubescens, Q. macranthera, etc. - in Eastern Europe, the Crimea and the Caucasus, Quercus mongolica, Q. dentata, Q. crispula, etc. - in the south of the Far East.

During the cold epochs of the lower Neo-Pleistocene, periglacial steppes, birch, coniferous, and coniferous-birch woodlands, and microthermal shrub formations dominated in the vicinity of the Karama site, which is currently located in the transition zone from the mountain-forest to the mountain-forest-steppe belt. During the Sartan cold snap, tundra-steppe communities dominated here.

In the modern mountain-forest belt near Denisova Cave, the climatic and phytocenotic features of the interglacial and cold epochs of the Middle and Upper Neo-Pleistocene were significantly different. During periods of cold weather, the overall moisture content increased and the areas of dark coniferous spruce and cedar forests, which previously occupied the upper tiers of mountain slopes, significantly expanded. Interglacial stages were characterized by relatively dry climatic conditions and a wide distribution of forest or forest-steppe zonal vegetation types, within which birch and pine-birch stands with a significant participation of broad-leaved trees predominated in forest communities. The development of broad-leaved forest formations on the territory of the Northwestern Altai during these interglacial periods was not recorded.

Analysis of the spore-pollen diagrams and paleorastivity characteristics compiled from them indicate that in the interstadial and transition intervals of the cold epochs in the Anuya basin, in the conditions of dissected topography and fragmentary distribution of permafrost rocks, along with typically periglacial biotopes, there were areas with favorable edaphic and mesoclimatic conditions, where birch-pine and birch-tree forests grew within the low mountains.- pine park forests with an admixture of broad-leaved species-oak, linden, elm, hazel, and in the middle mountains, where the Fireplace Cave is located, - spruce-cedar and birch-pine formations with the participation of Siberian linden and elm.

The composition of palynoflora from the Middle and Upper Pleistocene sediments shows a tendency to reduce the role of broad-leaved species in the forest biomes of the Anuya Valley and gradually disappear by the beginning of the Holocene. It has been established that black alder Alnus glutinosa and broad-leaved tree species - Manchurian walnut Juglans mandshurica, common hornbeam Carpinus betulus, Quercus oak, Siberian linden Tilia sibirica, smooth elm Ulmus cf. laevis, Acer maple and hazel Corylus avellaea-constantly participated in the forests of the Northwestern Altai during the Neo-Pleistocene.

Reconstructions of the vegetation of the Northwestern Altai during the interglacial and cold stages of the neo-Pleistocene indicate that the degree of zonal and formational differentiation of vegetation cover in the landscapes of cold intervals was not inferior to the landscapes formed in the interglacial climate.

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The article was submitted to the Editorial Board on 14.02.14, in the final version-on 18.02.14.

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