This article summarizes the results of long-term integrated research performed by the Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences (SIPPВ SB RAS), to study the composition, structure, and dynamics of biodiversity in Siberia and adjacent regions at the level of populations, species, biocoenoses, and ecosystems and reveal the responses of organisms and their coenoses to changes in environmental conditions caused by natural and anthropogenic factors. The sequestration of carbon dioxide by conifer forests growing on the territory of Baikal Natural Region (BNR) is estimated. Forest fires in Transbaikalia are reconstructed on the basis of tree-ring chronology with an annual resolution of 351 years. The concept of paragenesis is justified, as it characterizes the formation of phytocoenoses that, in regards to their structural–dynamic organization, are not related to a zonal type (or altitudinal belt) of vegetation. The data can serve as an information base while determining basic vectors of regional ecological policy, and they are important for assessing the present state of biodiversity in Baikal Siberia and its changes under the conditions of anthropogenic pressure, as well as for developing measures for its protection.

The article establishes the tendencies of forest formation in fallow lands of different ages, currently used as rangelands, in postagricultural areas of Western Transbaikalia. Assessments of the nature of the restorative dynamics of forests in fallow lands extensively reference the typological and species composition of phytocenoses of the surrounding areas that have never been used for tilling. It is established that herbaceous communities currently emerging in fallow lands and steppe areas include tree species such as Scots pine (Pinus sylvestris L.), more rarely Siberian larch (Larix sibirica Ledeb.), and sometimes Siberian elm (Ulmus pumila L.). It has been determined that, once removed from intensive pasture rotation, plant communities gradually restore a layered structure and show an increase in the species diversity of plants and in their abundance in communities. At the same time, it is noted that pine is actively advancing into herbaceous (steppe) communities of plant species typical of the forest–steppe and steppe. It has been found that the age composition of pine specimen varies from 2–5-year-old individuals to 20–25-year-old trees growing in isolated groups in fallow lands throughout the study area. It is noted that areas of fallow lands that are adjacent to a closed forest stand tend to have a fairly closed undergrowth, regardless of orographic features of the territory. The ground cover of such groupings is noted to have a significant presence of plant species characteristic of zonal light coniferous forests. That is likely to indicate an early stage of formation of zonal-type light coniferous taiga. A restraining factor in the development of forests in fallow and steppe lands in the study region is the potential increase in anthropogenic influences, mainly grazing regimes, due to an increased number of farms. Human activity in the area often involves periodic anthropogenic fires deliberately set in order to preserve rangelands. Pine undergrowth is also simply felled, both on fallow lands and in adjacent territories. That is, in many respects, a crucial factor for the possibility of formation and development of forests on postagricultural territories in the near future.

Wood formation (xylogenesis) in trees depends on two main factors providing growth processes with assimilates and energy, photosynthesis and respiration. Temperature and precipitation affect photosynthesis and respiration and, consequently, growth processes in wood. The aim of our study was to characterise the relationship of growth processes (cambium activity and biomass deposition) in Pinus sylvestris L. (Scotch pine) trunks with crown photosynthetic activity and trunk respiration in years with contrasting summer-weather conditions. Formation of xylem and phloem cells, accumulation of cell wall biomass, photosynthetic productivity and trunk respiration were studied in P. sylvestris trees growing in Eastern Siberia (Russia). We estimated the number of cells in differentiation zones and morphological parameters of cells produced by cambium, determined cambium activity, accumulation of biomass in tracheid walls and their relationship with crown photosynthetic productivity and stem respiration costs at certain stages of annual ring wood formation. It turned out that cambium cell division towards xylem or phloem depends on the combination of temperature and precipitation in some periods of the season, as well as on the reaction of photosynthesis and respiration to these factors. Biomass accumulation had a bimodal character with maxima in June (early wood development) and predominantly in August (development of thick-walled late tracheids). This corresponded to an optimum combination of air temperature and humidity, providing sufficient assimilate influx and low respiration consumption. We also showed that cambial activity and biomass accumulation in the cell walls of annual wood rings depend on the cumulative effect of temperature and precipitation on photosynthesis and stem respiration during the growing season. Fluctuations in external factors changes the balance between the inflow of photoassimilates and their utilization. As a result, photoassimilates are utilised not only for synthesis of cell wall biomass, but also partially converted into reserve substances, particularly starch. Our study expands the understanding of plant development processes that lead to wood formation under the influence of external factors.

Обобщаются результаты многолетних комплексных исследований, проводимых СИФИБР СО РАН по изучению состава, структуры, динамики биоразнообразия Сибири и сопредельных регионов на уровне популяций, видов, биоценозов, экосистем и выявлению ответных реакций организмов и их сообществ на изменение условий среды при воздействии природных и антропогенных факторов. Оценена секвестеризация диоксида углерода хвойными лесами, произрастающими на территории Байкальского природного региона. Произведена реконструкция лесных пожаров в Забайкалье на основе древесно-кольцевой хронологии с ежегодным разрешением в 351 год. Обосновано понятие парагенеза, которое понимается как развитие растительных сообществ, по структурно-динамической организации не относящихся к зональному типу (или высотному поясу) растительности. Полученные данные могут служить информационной базой при определении основных направлений региональной экологической политики, имеют значение для оценки современного состояния биоразнообразия Байкальской Сибири, его изменений в условиях пресса антропогенных факторов, разработки мер его сохранения. This article summarizes the results of long-term integrated research performed by SIPPВ of SB RAS studying composition, structure and dynamics of biodiversity in Siberia and adjacent regions at the level of populations, species, biocoenoses, and ecosystems and revealing of responses of organisms and their coenoses to changes in environmental conditions caused by natural and anthropogenic factors. The sequestration of carbon dioxide by conifer forests growing on the territory of Baikal Natural Region was estimated. Forest fires in Transbaikalia were reconstructed on the basis of tree-ring chronology with an annual resolution of 351 years. The concept of paragenesis was justified as it characterizes the formation of phytocoenoses which by their structural-dynamic organization are not related to a zonal type (or altitudinal belt) of vegetation. The data obtained can serve as an information base while determining basic vectors of regional ecological policy, and they are important for the assessment of the present state of biodiversity in Baikalian Siberia and its changes under the conditions of anthropogenic factor press as well as for development of measures for its protection.

Установлены тенденции формирования лесов на залежах разных лет, выступающих в настоящее время в качестве пастбищных угодий, на постаграрных территориях Западного Забайкалья. При оценке характера восстановительной динамики лесов на залежах был максимально учтен типологический и видовой составы фитоценозов окружающих территорий, не использованных ранее под распашку. В формирующихся травянистых сообществах на залежах и степных участках установлено присутствие древесных пород - сосны обыкновенной (Pinus sylvestris L.), редко лиственницы сибирской (Larix sibirica Ledeb.), иногда присутствует ильм низкий (Ulmus pumila L.). Определено, что в растительных сообществах, выведенных из интенсивного пастбищного оборота, наблюдается постепенное восстановление ярусности, увеличение видового разнообразия растений и их обилия в сообществах. Наряду с этим отмечено активное внедрение сосны в травянистые (степные) сообщества, состоящие из видов растений, характерных для лесостепи и степей. Установлено, что возрастной состав деревьев сосны варьирует от 2-5-летних экземпляров, до 20-25-летних деревьев, представленных отдельными группами повсеместно на залежах. Отмечено, что на участках залежей, близко примыкающих к сомкнутому древостою, наблюдается достаточно сомкнутый подрост, независимо от орографических особенностей территории. В напочвенном покрове таких группировок выявлено существенное присутствие видов растений, характерных для зональных светлохвойных лесов. Вероятно, это связано с началом этапа формирования светлохвойной тайги зонального типа. Сдерживающим фактором развития лесов на залежах и степных участках в районе исследований следует считать возможное усиление антропогенных воздействий, главным образом пастбищных режимов, за счет становления фермерских хозяйств. Часто имеют место периодические, вызванные деятельностью человека, пожары («палы») в целях сохранения пастбищных угодий. Отмечены и простые вырубки подроста сосны как на залежах, так и на примыкающих территориях. Во многом это имеет определяющее значение для возможности формирования и развития лесов на постаграрных территориях в ближайшей перспективе. The tendencies of forest formation on fallow lands of different years, currently acting as rangelands, in post-agrarian areas of Western Transbaikalia have been established. When assessing the nature of the restorative dynamics of forests on fallow lands, the typological and species composition of phytocenoses of the surrounding areas, not previously used for plowing, was taken into account as much as possible. In the forming herbaceous communities on fallow lands and steppe plots, the presence of woody species such as Scots pine (Pinus sylvestris L.), more rarely Siberian larch (Larix sibirica Ledeb.), and sometimes dwarf elm (Ulmus pumila L.) was established. It was determined that in plant communities removed from intensive pasture turnover, there occur a gradual restoration of layering, and an increase in species diversity of plants and in their abundance in communities. At the same time, an active introduction of pine to herbaceous (steppe) communities, consisting of plant species characteristic of the forest-steppe and steppe, was noted. It was found that the age composition of pine varies from 2-5-year-old individuals to 20-25-year-old trees represented by separate groups everywhere on fallow lands. It was noted that in the plots of fallows adjacent to a closed forest stand, there is a fairly closed undergrowth, regardless of the orographic features of the territory. A significant presence of plant species characteristic of zonal light coniferous forests was detected in the ground cover of such groupings. This is probably due to the early stage of formation of light coniferous taiga of zonal type. A restraining factor in the development of forests on fallow and steppe plots in the study area should be attributed to a possible increase in anthropogenic influences, mainly grazing regimes, due to the formation of farms. There are often periodic human-induced fires (“deliberate fires”) in order to preserve rangelands. Simple felling of pine undergrowth has also been noted, both in fallow lands and in adjacent territories. In many respects, this is of decisive importance for the possibility of formation and development of forests on post-agrarian territories in the near future.

This article presents the results of a study of the structural and dynamic organization of forests located in basins of large rivers influent into Lake Baikal that have considerable influence on changes in the hydrologic regimes of the lake. It is known that the annual river flow significantly depends on the state of the forests growing in the river basins. The stable hydrologic regimes of the rivers responsible for most water runoff into the lake are directly dependent on the functional properties of forests. Maintaining the functions of environmental conservation and water regulation of forests contributes to the stable functioning of river basins, ensuring the general sustainability of the lake as an integrated ecosystem within the Lake Baikal basin. It is noted that the combination of centuries-spanning dynamics of forests associated with the succession of forest-forming species (typical for zonal types of vegetation) and the influence of climate change facilitates the formation of polydominant dark–light coniferous and light coniferous forests and, additionally, influences the hydrologic regimes of rivers in the study areas. The structural and dynamic organization of forest communities of different physical and geographical conditions is established, as are the characteristics of their formation. This information is then used to forecast the vector of possible development of forests growing within the Lake Baikal drainage basin. It is shown that changes in the structure, dynamics, and spatial organization of forests within the drainage basin of the lake, associated with the intensification of fires over the last several decades and recent industrial logging, affect river flows and, consequently, lead to relatively severe fluctuations in lake water levels across years. It is established that trends in forest formation within basins of rivers influent into Baikal determine the relationships in the “forest structure–river volume” systems, which can influence the optimization of forest use within the Lake Baikal basin as a whole.

This work is dedicated to analysing of the nature of the relationship between the radial growth of trees and remote sensing data. The calculations performed showed that there are certain connections between the satellite data and the values of the first differences in the widths of tree rings, but the strength of these correlations depends on the uniformity of the plantation trees’ radial growth processes. The less synchronous in time are the series of the first differences in the widths of the tree rings (FD WTR), the weaker are the connections between the remote sensing data and the radial increment. Another factor influencing the nature of the relationship between the satellite data and the radial growth is damage to trees. Thus, weak or lacking links between satellite and field data can still be observed and the reason for this is the heterogeneity in growth processes periods of different trees in the stand.

Аннотация.Проведены комплексные исследования причин и масштабов усыхания темнохвойных лесов в геосистемах северного макросклона хр.Хамар-Дабан с 2006 по 2020 гг

This article presents the results of a large-scale soil-geobotanical profiling (1 : 10 000–1 : 100 000 scale) of plant communities in the Baikal region under conditions of contact with different environments. Data characterizing spatial stratigraphy and trends in the formation of vegetation at the regional level of its organization is obtained. The pattern of alternation of forest and steppe communities under conditions of extrazonality of steppes in the central part of the western shores of Lake Baikal (Priolkhonie) and in the middle part of the bottom of the Barguzinskaya depression is determined. It is established that the studied vegetation has no clear floristic or cenotic dependencies on edaphic conditions; both steppe and forest communities occur on the same soils. The widespread afforestation of territories occupied by steppe communities is observed. Vegetation that forms where the forest steppe meets the zonal steppe (Selenga River basin) is characterized by the alternation of forest and steppe communities in correspondence with topographic features and with a clearly pronounced connection with types of soils characteristic for areas of contact between the forest steppe and zonal steppe. The afforestation of steppe territories occurs within zonal forest-steppe areas, and tree species encroach on the zonal steppe in the course of spatial expansion of the interzonal ecotone. Unswe conditions of altitudinal zonality (the vicinity of the Davan Pass, Baikal Ridge), a gradual transition from one altitudinal belt to another—forest to subgolets and subgolets to mountain tundra—due to the invasion of tree species into communities of areas of contact of the zones (interbelt ecotones), is observed. Communities form on the same soil. This kind of study can serve as a methodological basis for indicating vegetation development in the Baikal region as a whole.

Abstract. This article presents new data on the study of preserved wood from flooded forests in the Muya-Kuanda Basin, Eastern Siberia. On the basis of the stratigraphic position of a buried tree stump horizon, the analysis of the associated alluvial deposits and a new programme of radiocarbon dating, the chronology of formation and collapse for a Late Pleistocene pal eolake in the Muya-Kuanda Basin can be precisely determined. The accuracy of dating of geological events with the radiocarbon method and the possibility of linking them to calendrical dates is discussed. As a result of this research it is possible to connect the geochronology of the lake with archaeological sites in the Vitim Basin, both upstream and downstream along the river. The reasons for the periodic formation of substantial bodies of water in the Muya-Kuanda Basin are also discussed, with implications for decision making with regard to the modern economic development of the region.

The potential for the assessment of the tree state based on remote-sensing data has been studied. The integral indicators of seasonal dynamics of the vegetation-index (NDVI) were used. The values for in 2003–2017 were compared for control (unharmed) and damaged test plots in the Khamar-Daban zone near the coast of Lake Baikal (Irkutsk oblast). It is shown that the use of the proposed integral indicators of the seasonal NDVI dynamics makes it possible to classify the test plots according to the tree state.

According to data of dendrochronological investigations of larch trees that had grown on the Patom crater (Irkutsk oblast, Bodaibinskii district) and near its base, the initial period of the formation of the crater can be dated back to the late 15th‒early 16th centuries. In 1841‒1842, the trees under investigation recorded in annual rings a catastrophic event which caused a disturbance to their root systems, damage to tree stems, and the formation of compression wood. It is obvious that the event is associated with the time of formation of the late stage ring swell on which sparse larch trees are 93‒101 years of age, and on the central mound emerging upon completion of the formation of the Patom crater the age of the oldest tree is 7 years. Thus dendrochronological investigations confirm a long-lasting and multievent formation of the Patoma crater. In some periods, the deposition cone was evolving with a different intensity, sometime showing an explosive character. X-ray fluorescent analysis revealed a double Sr enrichment of larch wood at the time of significant activity of crater formation (1852‒1859) when plutonic fluids from the igneous source were able to enter the upper horizons of the Earth’s crust at the time of magma intrusion into water-containing rocks. The fluids were enriched with CO2 and transported significant amounts of Sr, as a result of which the 87Sr/86Sr ratios in carbonate and terrigenous rocks assumed higher values in sandstone and schists on the early stage ring swell of the Patoma crater. The findings, coupled with geological data, suggest that the Patom crater emerged as a result of a phreatic explosion that occurred either at the time of magma intrusion into water-containing rocks or as a consequence of the fault and decompression of heated water-containing rocks.

Dendrochronology and radiocarbon dating, with reference to remote sensing, digital elevation modeling, geological, and geomorphological data, provide new age constraints for the Jombolok lava field in the East Sayan Mountains (Siberia). The Jombolok lava field originated in the latest Late Pleistocene and underwent at least four phases of volcanic activity recorded in lava flows. Two earliest phases followed shortly one after another more than 13 kyr ago. The third phase corresponding to eruptions of Kropotkin volcano can be timed only relatively. The fourth phase has been dated by dendrochronology and AMS C-14 of well-preserved wood buried under the youngest lava which occurs among older lavas near the Jombolok River mouth. The age of this activity is bracketed between the death of trees caused by eruptions 1268-928 years ago and the beginning of new tree growth on the surface of the most recent lavas 900 years ago. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Dendrochronology and radiocarbon dating, with reference to remote sensing, digital elevation modeling, geological, and geomorphological data, provide new age constraints for the Jombolok lava field in the East Sayan Mountains (Siberia). The Jombolok lava field originated in the latest Late Pleistocene and underwent at least four phases of volcanic activity recorded in lava flows. Two earliest phases followed shortly one after another more than 13 kyr ago. The third phase corresponding to eruptions of Kropotkin volcano can be timed only relatively. The fourth phase has been dated by dendrochronology and AMS C of well-preserved wood buried under the youngest lava which occurs among older lavas near the Jombolok River mouth. The age of this activity is bracketed between the death of trees caused by eruptions 1268–928 years ago and the beginning of new tree growth on the surface of the most recent lavas 900 years ago. Полный текст статьи доступен по ссылке: http://www.sciencedirect.com/science/article/pii/S1 068797116302577 The Activation and Cessation of Late Cenozoic Extensionin the Lithosphere at the Margin of the Baikal Rift Zone: Alternating Sources of Volcanism in the Vitim Upland I. S. Chuvashovaa, S. V. Rasskazov, T. A. Yasnygina, N. A. Rudneva Abstract. A comparative analysis of the concentrations of major oxides, trace elements, and the Nd/Nd ratios in representative sequences of volcanic and subvolcanic rocks in the western and eastern Vitim Upland has revealed petrogenetic groups with different relationships among components from lithosphere and sublithosphere sources. A comparative analysis of the concentrations of major oxides, trace elements, and the Nd/Nd ratios in representative sequences of volcanic and subvolcanic rocks in the western and eastern Vitim Upland has revealed petrogenetic groups with different relationships among components from lithosphere and sublithosphere sources. It is hypothesized that the initial 16–14-Ma eruptions of picrobasalts and Mg basanites in the east of the upland resulted from high-temperature melting, hence, the melting of sublithospheric peridotite and lithospheric Mg-pyroxenite mantle material with mildly and strongly depleted isotope compositions of Nd relative to the value in the primitive mantle

Studies of spatial-temporal variability of the upper boundary of the forest on the north-western coast of Lake Baikal (Baikal and Upper Angara Ridges) are performed on the base of the analysis of forests renewal processes and of the dynamics of larch radial increment in the ecotone of the forest upper boundary and out of it. The presence of a large amount of well-developed uplands and circuses with considerable heights drops in the structure of mountain system favours formation of interrupted boundary between forest and subgoltsy belt. The timber stand of the upper forest boundary in the studied area is represented by Daurian larch. Three tree-ring chronologies of larch are obtained. The longest chronology is obtained for mountain taiga belt of Baikal Ridge and is as long as 460 years. Since 1980ies, a sustainable trend of increase of radial trees growth is observed. It is observed the most distinctly in trees of the upper forest boundary on the Baikal Ridge. There is advancing of trees species into subgoltsy belt and into mountain tundra, which depends, respectively, on slopes heights, exposition and tilting, on sites of growth of concrete cenoses. Modern peculiarity of the vegetation of the studied area is presence of abundant viable larch undergrowth (from 2–3 to 25 y.o.) and fir in the ecotone of upper forest boundary and in subgoltsy belt, as well as appearing of single specimens of spruce. Main undergrowth mass (2/3) is presented by trees aged in average 15–25 y.o., i.e., they appeared in late 1980ies. Due to increase of snow cover thickness in winter, the trees young growth obtained great protection from freezing resulting in the increase of ability of young growth to live up to elder age.

This study presents new data on one of the most recent (historical) volcanic eruptions in Central Asia. The Jombolok lava field located in the East Sayan Mountains (Southern Siberia) was formed during Late Pleistocene and Holocene times. At least four phases of volcanic activity have been identified and evidences associated with the last phase have been found in the upper reaches of the Khi-Gol valley and in the Oka-Jombolok basin. The volcanic activity is represented by young basaltic lava located among older lavas. Live and dead trees have been sampled in the young lava field. Nine fragments of wood have been found embedded in lavas of the latest eruption. Dendrochronological analysis, radiocarbon dating and the analysis of historical chronicles have shown that the latest eruption occurred during the period 682-792 CE. The volcanic activity possibly triggered the migration of Mongolian tribes out of the locality known in historical chronicles as Ergune-Kun towards the Onon River, which, 400 years later, became the place of birth and rise of Chinggis Khaan. (C) 2016 Elsevier Ltd. All rights reserved.