Table of contents

The conference proceedings contain the selected papers presented at the 5th International Conference "Ecosystem dynamics in the Holocene". This conference is a multidisciplinary scientific meeting, which is organized every 3 years in different scientific centers across Russia since 2004. It was held in Moscow, 11-15 November 2019, and dedicated to the 100th anniversary of L.G. Dinesman, the famous Russian biologist and palaeoecologist. The conference was organized by the Institute of Geography of the Russian Academy of Science (RAS), the Geological Institute of RAS, A.N. Severtsov Institute of Ecology and Evolution of RAS and the Environmental Evolution Commission of the International Geographical Union.

The conference was focused on the long-term studies of ecosystem dynamics, climate changes and human activity in different geographical regions during the Holocene (the last 11700 years) as well as on new methods and approaches for reconstructions of the past environmental changes. It provided unique opportunities for scientists to introduce novel ideas and studies in the following topics:

• Dynamics of marine, fresh water and terrestrial ecosystems in the Holocene;

• Holocene landscape and climate changes;

• Natural and anthropogenic factors in the Holocene ecosystem dynamics;

• Environment condition and human occupation in the Holocene;

• Ecological modeling and forecasting; and

• Methods of ecosystem studies.

More than 100 oral and poster presentations were made at the sessions of the conference. The present special issue of IOP Conference Series: Earth and Environmental Science contains the results of 27 specially selected reports focused of the most important problems of modern palaeogeography, palaeoecology and palaeoclimatology.

The papers demonstrate that the expertise of the modern state of natural ecosystems and projections of their future changes is quite impossible without comprehensive understanding of the past environment and climate dynamics and ecosystem functioning including its adaptation to human impact. The papers relate to different scientific areas and introduce new results of the experimental and theoretical studies that are based on detailed palaeoecological information (pollen, plant macrofossil, diatoms, testate amoebae, etc), radiocarbon dates, evidence about beginning of human activities and archeological findings. The special attention in the Special Issue is given to the studies of the land surface - atmosphere interaction using various experimental and modeling approaches in order to provide a better understanding of the response of terrestrial vegetation to climate variability in past epochs.

The Organizing Committee expresses deep gratitude to all organizers and participants of the conference for their active participation, interest and discussion on the Holocene ecosystem dynamics, climate changes and human activity in different regions which is a significant contribution to the development of palaeoecology. The Organizing Committee thanks the Russian Foundation for Basic Research (project No. 19-05-20072) and the Environment Evolution Commission of the International Geographical Union for provided financial support.

Editors

Dr.Sc. Elena Novenko, the chair of the Organizing Committee

Prof. Dr. Alexander Olchev

List of Organizing committee, Scientific committee are available in this pdf.

Conference photographs available in this pdf.

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Paleozoological study of archaeological findings from the excavations of Vologda settlement (12^th–15^th centuries) revealed information about trade and trade links between Vologda and the Arctic region. The existence of such links in the Middle Ages and the Modern Age is also confirmed by museum collections and written sources that contain information about the participation of residents Vologda in long-distance marine expeditions to the Arctic region.

During the Holocene, interfluvial landscapes of European plains have experienced alternating periods of relative stability and significant shifts in climate, soil and geomorphological development. Assumed to be an arena of major transformation their evolutionary model is not entirely resolved yet. Based on lithostratigraphic, geomorphologic and soil survey, new results on the Holocene dynamics of fluvial and related processes including landscape stabilization phases for one of the gully catchments draining the Borisoglebsk Upland northeastern slope towards the Nero Lake are presented. Common absence of the early Holocene deposits can be explained by generally negative sediment budget of the catchment. Nevertheless, continuous erosion was not likely whether rare climatic extremes probably were the case. A series of middle Holocene dates obtained by analyzing total organic carbon from organic-accumulative layers of buried soils, lake gyttja and peats highlights strong evidence of the synchronous phase of landscape stabilization in both upper and lower parts of the Puzhbol catchment accompanied by active infilling of small erosion cuts in its middle part. The upper part of the Puzhbol Gully fan sediment shows clear evidence of synchronous accumulation of agrogenic colluvium and gully alluvium since XIIth Century on top of the lake terrace deposits.

Reconstructions of the vegetation in the eastern part of the Khanka Plain have been performed for the time interval at the transition from the Late Pleistocene cryochron (MIS 2) to the Holocene. New evidence of considerable changes in the vegetation structure were provided by the palynological studies supplemented with radiocarbon dates on wood fragments and plant detritus recovered from alluvial, lacustrine and mires sediments. It has been found that at the glacial stage MIS 2 the Khanka Plain was dominated by open birch forests with larch and spruce, alternating with Sphagnum mires with shrub birch. Later, at the interstadial, formations typical of southern boreal dark coniferous (needle-leaved) taiga became widely spread. The Early Holocene was marked by wide expansion of broadleaf trees (and first of all, elm and Mongolian oak) in the Khanka Plain ecosystems. Mixed forests with Korean pine became widely spread in the mountains surrounding the lowland. Mires, patches of dark coniferous forests, and open forests of larch persisted on the plains adjoining the lake and on swampy valley floors.

Global climate change at the end of the Pleistocene led to extinction across the huge territories of the Northern Hemisphere of indicator species of large mammals of the mammoth fauna. Undoubtedly, in some more densely populated regions, the mammoth fauna underwent pressure from Upper Paleolithic humans hunting activity. Previously it was thought that the megafauna of the "Mammoth complex" had become extinct in the territory of Yakutia by the beginning of the Holocene. However, the latest data indicate that extinction of the mammoth fauna was significantly delayed in the north of Eastern Siberia. Radiocarbon data show that wild horses inhabited the north of Yakutia during 5300–2200 cal yr BP. Musk oxen lived here about 3400 – 2600 cal yr BP. Some bison remains from Yakutia belong to the early Holocene. The following circumstances could have facilitated the survival of representatives of the mammoth fauna in Yakutia. The cool, dry climate in this region is favorable to steppe associations, the habitats of these mammals. The small number of Stone Age hunting tribes in the northern part of Yakutia was probably another factor that contributed to the survival of some mammoth fauna representatives.

Contemporary (corresponding to the modern state of ecosystems and land use) and prehistoric (for hypothetic intact natural ecosystems similar to modern virgin ecosystems) stocks of organic carbon were assessed for model regions of southern taiga, forest-steppe and steppe in European Russia. The comparison of these stocks enabled an assessment of the integral result of the multidirectional changes in land use that occurred in the studied regions over the historical period. The carbon stocks were determined using a unified cartographic basis, data on taxonomy and texture of soil units, modern land use types and the type and age structure of reconstructed and contemporary vegetation. The results obtained indicate that the modern carbon pool has reduced by 24% compared to the potential prehistoric one in the Kostroma Region and Rostov Region (southern taiga and steppe zones, respectively) and by 37% in the Kursk Region (forest-steppe zone). It was also demonstrated that the contribution of soil to the total organic carbon stock increases southwards, from southern taiga to dry steppe, from 51 to 95% during the prehistoric period and from 62 to 96% currently. The study results show that forestry and agriculture increase the contribution of soil to maintaining the region's carbon budget.

The Herakleian Peninsula has a unique geographical location and a long history of development. The methods of historical and geographical research of this territory have been considered. The historical landscapes development dynamics research of the Peninsula has been conducted with the use of cartographic material, satellite images interpretation and a field observations of the territory within the selected time slices. Map analysis of the economic subsystem of the anthropogenic landscapes of the Herakleian Peninsula has been made. Areas of the South -Western and North-Eastern parts of the Peninsula which preserve the historical features of the modern land use formation have been singled out with regard to the specifics of the arrangement of land allotments (klers) in the ancient system of agriculture.

The first results of paleogeographic study at estuary of the Katynka river allow to reconstruct the dynamics of vegetation in this part of the Dnieper floodplain for about 5 millennia and identify some traces of Neolithic, Early Iron Age and Medieval human activity. The most prominent anthropogenic transformation of landscapes (signs of slash-and-burn agriculture) was associated with the late Holocene «Gnezdovo» buried soil dated 2-5 centuries AD.

Estimates of probable change in water balance parameters of the Black and Azov Seas drainage basin under the global warming by 1°C were obtained. A steady-state hydrological model has been developed for evaluation of river runoff and evaporation. The paleoclimatic reconstruction for global warming on 1°C has been used as empirical scenario. This scale of climate change corresponds to the warm epoch of the past, considered as an analogue of the future climate: the Holocene Thermal Maximum (7-6 ka BP). The estimates indicate possible increase in the total river inflow into the Black and Azov Seas by about 17 km³ per year and increase of the mean annual evaporation by 27 mm per year relative to the period of 1961-1990 years. Estimation was made notwithstanding water consumption.

The diatom algae from sediments of a paleolake serve as records of changes to environments over the last 7500 cal yr. The lagoon lake formed when the sea level approximately corresponded to the present-day position. Evolution of the paleolake was controlled by sea-level oscillations and humidity changes. Eight stages have been distinguished. During a dry episode in 7330–7090 cal yr BP the lake size decreased. The salinity reached maximal values at the Holocene transgression peak. Three stages of a higher salinity are recognized (6750–6500, 6080–5830, 5420–5090 cal yr BP). A severe flood occurred in 6080–6000 cal yr BP. The brackish-water lake existed in ∼5090 cal yr BP and the freshwater lake in ∼4090 cal yr BP. A prolonged phase of decreasing humidity, associated with a weakening of summer monsoons, led to a drop in sedimentation rates in ∼3510 cal yr BP. Peat accumulation started at the Little Ice Age. The lake was transformed into a swamp during drop in precipitations in ∼270 cal yr BP. Presence of marine diatoms typical in bay and deep-water forms are evidence of influence of extreme storms and tsunami. The age of the paleotsunami coincides well with the regional data.

The paper considers the Holocene paludification process in West Siberian Plain; peat increase for the entire Holocene according to radiocarbon dating of peat deposits. The comparison of results by peat accumulation activity with the climate of Western Siberia in the Holocene is carried out, and the forecast of the natural evolution of mires is given. To determine the contemporary accumulation rate and linear peat increment, we used the model of peat and carbon accumulation process, and the field studies of carbon balance parameters of oligotrophic bog catena as an example. The modern rates of carbon accumulation and the linear peat increment of some types of mires were determined. The field studies of carbon balance parameters on the example of oligotrophic bog catena showed, in years with different climatic conditions, the NPP values varied from 206 to 337 g Cm⁻² year⁻¹. Most of the carbon losses are the carbon dioxide emission (an average is 61.3 g Cm⁻² year⁻¹, or 23.5 % NPP). The carbon flux, determined by the model of the removal chemicals, is 3.0% NPP with a mean value 7.9 g Cm⁻² year⁻¹. The calculations of the carbon balance indicate the progression of the paludification process in the studied area.

Herein we report the first decadal to centennial–scale resolution data on foraminiferal and dinocyst assemblages from core AMK-5454 collected in the hard-to-reach Cambridge Strait, Franz Josef Land, and on corresponding paleoenvironments over the last 9.2 ka. The dinocyst and foraminiferal assemblages from the core are rather diverse through the Holocene and represented by 24 and 33 taxa, respectively. The most active hydrodynamics and probably Atlantic Water (AW) inflow are suggested by the enhanced values of autotrophic dinocysts and epibenthic species, as well as Melonis barleeanus, from 9.2 to 6.3 cal ka BP. Specific benthic assemblages indicate high-productivity frontal conditions at site location from 6.3 to 4.1 cal ka BP. AW influx from the Franz Victoria Trough to the Cambridge Strait in subsurface to bottom layer, below the very cold Arctic Water and dense sea ice, is documented by enhanced % Cassidulina teretis over the last 4.5 ka.

Variation of the insolation is one of the global factors which determine the Earth's climate. Multi-periodic variations of the insolation determine the cyclicity of the Earth's climate. The aim of the investigation is the estimation of the insolation variations influence on vegetations of the Urals and West Siberia subarctic during the Holocene. The calculation of insolation in the Eurasian Subarctic for the Holocene is carried out based on the solution La2004 for the long-period evolution of the Earth's orbit. We have estimated the insolation for the latitudes from 55° to 70° N. We have considered the mean daily and mean monthly insolation over 12 ka BP. We assess changes of the insolation in the Eurasian subarctic under the influence of such factor as the topography evolution. The surface topography was analyzed for the recent period (in the Urals and West Siberia) and the Pliocene epoch (in West Siberia). An assessment of the difference in the corresponding digital elevation models showed that the subsidence of the crust took place in West Siberia (the median value of the difference between the digital elevation models was 230.7 m above sea level). The intensity of erosion processes increased in a southerly direction. We have shown that an increase in the number of autumn's months with high insolation correlates with the taiga biome 4 thousand years ago to wider territories than 8 thousand years ago.

The paper presents the results of a comprehensive palaeobotanical research of lacustrine and peat deposits of archaeological Mesolithic sites discovered at the Gorbunovo peat bog (Middle Urals). Pollen and plant macrofossil data, as well as a biome model were used to describe the vegetation changes in the study area in the Early Holocene. It was found out that in the second half of the Pre-Boreal and the first half of the Boreal periods of the Early Holocene (approximately to 9,800–9,600 cal BP), the vicinity of the Gorbunovo peat bog was dominated by cold deciduous forests. Larch, spruce-larch and birch forests and meadow communities with periglacial elements were widespread. Various aquatic plants could be found in the pond, though it started to turn into swamp. In the second half of the Boreal period (approximately at 9,600–9,500 cal BP), the taiga biome, including pine and birch-pine forests with occurrence of spruce started to prevail. Periglacial communities became degraded. Aggressive water logging led to the formation of a peat bog.

A sedimentary diatom record of Lake Goluboye, Karelian Isthmus (NW Russia) revealed two transgressive stages of the Baltic: the Ancylus Lake and the Litorina Sea, followed by two "small-lake" stages. During the Ancylus Lake transgression, a shallow bay of the Ancylus Lake existed in the Lake Goluboye basin, and species-rich benthic-dominated diatom assemblages formed in oligotrophic, low-mineralisation environments. The isolation from the Ancylus basin took place after ca. 9800 cal. yrs BP, when a small nutrient-rich lake formed in the basin. Two Litorina Sea transgressive phases were inferred from the diatom record of Lake Goluboye, both characterised with similar low-salinity environments. Such a weak signal of the marine transgression, compared with the other coastal sites in the Karelian Isthmus, might have resulted from the sheltered position of the lake. Our data also suppose that the maximum transgression level in the study area was lower than has previously been suggested. With the termination of the Litorina transgression shallow-water conditions with extensive macrophytes growth was established in the lake. Before ca. 4800 cal. yrs BP nutrient-rich small-lake conditions, similar to the post-Ancylus stage, became established.

The results of malacofauna-based palaeoenvironment reconstructions for the Late Holocene in the valleys of Bazaikha and Tartat rivers (Krasnoyarsk depression) are presented. Palynological analyses of the flood-plain deposits and radiocarbon dating complemented malacofaunal analysis. Biodiversity of malacofauna is represented by 7 freshwater species and 15 land species. Species belonging to the Valloniidae Morse, 1864 and Lymnaeidae Rafinesque, 1815 families are dominant in the fossil assemblages. The finding of Gastrocopta theeli shell in the Late Holocene deposits of the Bazaikha section is the first one in the territory of Krasnoyarsk depression. This finding supports the relic, spotted character of the geographic range of this species. Emploting malacofauna proxies and the Eleneva Cave reference section palynological record enabled reconstructing Late Holocene palaeoenvironmental conditions in the area. Malacofauna in the valleys of Bazaikha and Tartat rivers developed under the conditions of gradual increase in heat availability and decreasing annual precipitation and warm-period precipitation during the last 2500 years. A reduction of malacofauna diversity 950 years ago was caused by a change in the precipitation regime.

This paper includes information on mammalian faunas from eight localities investigated in the Kulikovo Pole region – the place at the confluence of the Nepryadva and Don River where the famous battle between Tartars and Russians occurred in 1380. The oldest faunal assemblages were recovered from the natural outcrops in the upper floodplains of these streams where only steppe and tundra species from the periglacial interval were encountered. The distribution of Middle Holocene forest-steppe landscapes in the Upper Don basin are correlated with mammalian species that indicate major environmental changes. Mammals identified at several medieval sites reflect steppe, forest and hydrogenous species, and remains of domesticated species (cattle, horse, pig, sheep, goat and dog) reveal the impact of human activities during this time. Thus, the study of mammalian faunas associated with the last ∼14 thousand years BP demonstrates significant environmental and climatic changes from the cold periglacial tundra-steppe conditions at the end of the last glaciation to the establishment of forest-steppe habitats during the Middle and the Late Holocene.

Climate change projected for the 21^st century is expected to affect different forest ecosystems with corresponding ecological, economic, and social impacts. Modeling is extensively used to estimate the impacts of climate change on tree species distributions, but only several studies produced tree growth projections based on climate change scenarios. However, those studies have been based on multiple regression models without considering the basic principles of dendroclimatology – principle of limiting factors and uniformitarian principle. Here we describe the methodology for tree growth projections that takes advantage of the process-based forward model of tree growth, VS-Lite, calibrated and independently validated on tree-ring data and driven by climate projections. We further use this methodology for spruce growth projections on Solovetskiye islands according to two extreme greenhouse gases emissions scenarios. Even according to the conservative one, which is peak-and-decayscenario, tree growth is projected to be significantly higher throughout the 21^st century, than in the 20^th century. These results are crucial for the strategies of Arctic region development in the near and remote future.

The paper presents the first results of pollen and macrofossil analysis of a peat bog located near the Moscow city within the territory of the Losiny Ostrov National Park. Macrofossil data demonstrate that the bog development started from the stage of a spring calcetrophic fen at the very beginning of the Holocene. After 9.9 ka BP it became a meso-oligotrophic herbaceous-sphagnum bog. Pollen data manifest early spread of spruce in the Moscow region (before 10.2 ka BP). Predominance of broad-leaved temperate deciduous forests is characteristic of the Holocene thermal optimum (8.5-4.8 ka BP). The new spread of spruce forests began after 4.8 ka BP. The first signs of deforestation for agriculture date back to 1.8-1.7 ka BP (Early Iron Age). The next massive deforestation for agriculture was recorded 0.7-0.4 ka BP (Middle Age). After the 17th century, anthropogenic activity decreased, as a result of the establishment of the reserve status.

Lake Chaika is the only major water body present in the sand barriers of the entire territory of South-Eastern Baltic shoreline. The article provides new insights into the formation of Lake Chaika, based on data acquired through a lithological investigation of the lake sediment core combined with an organic matter content analysis, a macrofossil analysis, a radiocarbon AMS-dating and a bathymetric survey. The study revealed that Lake Chaika was formed around 500 years ago. The kettle of the lake appears to have not been submerged during the Littorina transgressions. During the mid-late Holocene, the kettle of the lake was occupied by the peat-forming ecosystems of alder carrs and sedge fens with scattered alder. The accumulation of ligneous and sedge peat occurred. The sand horizon, separating the gyttja layer from peat deposits, is considered to be a time marker for the so-called "sand disaster", which began in the study site 200-250 years earlier than in the main territory of the Curonian Spit. There are three main formation phases of the lake's ecosystem: the period of carrs (5390–510 cal. yr BP), the "sand disaster" period (≈550–500 cal. yr BP) and the proper lake period (500 cal. yr BP – present time).

This paper is focused on environment conditions during the Medieval warm period and human impact on the broadleaved forests in central European Russia. The study area is located in the "Kaluzhskiye Zaseki" Nature Reserve, one of the unique remnants of primary Eastern European broadleaved forests. Here, we present new high-resolution pollen and plant macrofossil records and radiocarbon dating from the sediment sequences in the outcrop of the right bank of Vytebet' River (a tributary of Oka River) in the northern part of the Reserve. The obtained results have shown no clear evidence of vegetation changes in the region in response to the climatic amelioration during the Medieval time. The pronounced changes of forest ecosystems were caused by anthropogenic disturbance since the 13th century AD.

A modeling approach to reconstruct the annual land surface evapotranspiration from palaeoecological data was suggested. It is based on assumption that the actual evapotranspiration is proportional to potential surface evapotranspiration and to some decoupling factor characterizing the surface moisture conditions. It was described in our study as a function of the climate moisture index (CMI). The potential evapotranspiration rate was derived using palaeoecological data about past land use and land cover, forest coverage, plant species composition and mean annual air temperature. The value of unknown decoupling factor was approximated using the results of evapotranspiration measurements at selected FLUXNET experimental sites located in the areas with different (ranged from extremely wet to moderately dry) moisture conditions. Comparisons of modeled evapotranspiration rates with results of the field flux measurements showed their good agreement for various forest, shrubland and grassland ecosystems in different geographical regions.

The paper presents the first results of comprehensive studies of the multi-layer settlement Kurilovka 2 (Kursk region, Russia). It is located on a remnant of a low terrace above the floodplain of the Sudzha River (tributary of the Psel River – tributary of the Dnieper). The site contains archaeological materials of two main periods: proto- and early Slavonic (2^nd – 8^th centuries) and the Modern Period (end of the 17^th – 20^th century). The mail attention is paid to the results of archaeological, pedological, palynological, phytolith, anthracological study of the soil profile/archaeological pit 10/2016, located within the boundaries of the habitation zone. The data obtained allow us to reconstruct the history of the site development and dynamics of the site-encasing ecosystems over the past two thousand years. The area was initially forested and cleared for shifting agriculture, probably by the proto- and early Slavonic population. At the end of the 1^st millennium AD the settlement was abandoned. The site was reforested and cleared again in the Modern Period. Now the arable land is not farmed, the site is covered with the herbaceous vegetation.

This paper presents some conclusions of a study of a long-term lake sequence in the southwestern part of the Western Siberian Plain. Environment changes in the Holocene were identified according to geochemical indices, accumulation rate, plant macrofossils, and pollen data of sediment in Lake Kyrtyma. As a result, we firstly obtained the data on climatically conditioned changes of the sedimentation in the flat part of Western Siberia over at least the last 15 thousand years. Geochemical changes in the sediment properties clearly revealed climate change over the Late Glacial and the Holocene. Changes in the composition of macrophytes gave little independent information, while the pollen data are perfectly combined with the sedimentation features and serve as a reliable source for the reconstruction of vegetation changes and landscape. The transition to the Holocene was marked at about ∼12–11.2 ka BP, subsequent ongoing warming led to the aridest Holocene phase at ∼7.1–5.5 ka BP. Cooling and the resulting decrease in vaporation began at ∼5.5–4.9 ka BP, but a cardinal shift in sedimentation due to a gradual increase in precipitation was at ∼4.9–2.8 ka BP. The most significant increase in humidification and a cooling began at 2.8 ka BP.

Dagestan (North-Eastern part of the Caucasus) is characterized by a unique historical and environment development, however, there is little, if no, data on nature changes throughout the Holocene history of the region. In contrast to the much-studied neighboring Caucasus regions, Dagestan remains mostly unexplored from the standpoint of paleoecology. In 2017, we investigated a detailed radiocarbon-dated 185 cm peat sequence from the Shotota swamp located in the mountainous zone of Dagestan. Peat and soil deposits span most of the Holocene (about 9000 years), and they let us study vegetation history of the Eastern Caucasus for the first time. The results of the study show significant discrepancies in the timing and sequence of the expansion of tree species in the Holocene in comparison with Transcaucasia and the Western Caucasus. The second key study, an examination of a 270 cm peat sequence from Arkida swamp, formed in the second half of the Holocene, also provided new paleoenvironmental data on the south of the Caspian lowland. The vegetation of the flat parts of Dagestan, adjacent to the mountainous zone, has been dry and treeless for the last four thousand years, however, humidification fluctuations and vegetation changes were distinguished.

An ecosystem of a relic petrophytic steppe was studied in the Lower Kolyma River region. The soils of the steppe area significantly differed from those of the surrounding open larch forests in the following features: the presence of humus-accumulative horizons with a high content of roots; low moisture content; high heat supply; an extremely contrasting temperature regime; neutral reaction; decreased potential acidity; higher humification of organic matter; accumulation of exchangeable bases, soluble salts and organic nitrogen; and the presence of carbonate neoformations in the form of cutans on pebbly units. They also had a high microorganism saturation of the soil profile, a high share of actinomycetes in the microbial community, as is typical for arid soils, and a shift in the ratio of potential enzyme activities toward oxidoreductases, which reflects a deeper destruction of plant residues and more intensive humus formation. The petrophytic steppe had high bioproductivity. The growth rate of the aboveground phytomass (ANP) was closer to the true steppes of Central Asia than to the zonal tundras of the Arctic and Subarctic; such communities can serve as models for paleoreconstructions and study of the Late Pleistocene cold steppes - mammoth fauna large grazing mammals habitats.

Over the last 30–40 years, climate changes have resulted in environmental changes within the Upper Volga basin. In this study, an attempt to analyze the soil record of recent climate changes was made. An example of soil evolution induced by climate change was studied on hydromorphic saline soils in the nature reserve of the Varnicy Saline Spring. In a humid climate, soil salinization occurring in discharge areas can quickly change in response to the changed hydrothermal regime because of close relationships between climatic conditions and groundwater systems. In a poorly drained depression, we could observe an increasing soil salinity and developing hydrogenic accumulation of salts, whereas the groundwater salinity was stable.

Integrated paleogeographic studies have been performed on the loess and soil sequence in the lower reaches of the Orkhon R., northern Mongolia. The samples were taken continuously through the sequence and studied using a broad assortment of field and laboratory analyses. There are five paleosols exposed in the section under study crowned with the present-day soil and separated from each other by loess horizons or proluvial-deluvial deposits. The dating by radiocarbon proved the soil development beginning from the early Holocene. The two lower soils (PS4 and PS5) formed at that interval are noted for the minimum salinity and a considerable content of carbonates. The soils dated to the middle Holocene (PS3 and PS2) contain the least proportion of organic matter and increased salinity, which may be attributed to a dryer climate (even at optimum intervals) than in the early and late Holocene. In common with the present-day soil, the PS1 buried soil is characterized by negligible (or absent) salinity, and a noticeable accumulation of organic matter and carbonates indicative of favorable warm and relatively wet conditions. All the pollen assemblages indicate the dominance of grass vegetation; it may be safely suggested that open meadow and steppe landscapes, occasionally replaced by semi-deserts, prevailed in the considered region during the Holocene.