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The results of continuous monitoring of the Naroch lakes system, which includes eutrophic Lake Batorino, mesotrophic Lake Myastro and oligo-mesotrophic Lake Naroch, were used to study the question of what factors most affect the long-term dynamics of the state of the lake ecosystem that is under variable load of biogenic elements. The set of continuous series of seasonal mean values of eight parameters of each ecosystem for 1978-2015 was analyzed by methods of singular spectrum analysis (SSA) and principal component analysis (PCA). The third principal component (F3) which contributed 8,2 %, 9,8 % and 13,3 % respectively to the dynamics of ecosystems of Lake Batorino, Myastro and Naroch turned out to be connected with biomasses of phyto- and zooplankton, as well as with the parameters characterizing processes of destruction and biochemical decomposition of organic matter. Comparison of statistical relationships and periods of the dominant cyclic components of the principal components F3 and associated parameters of ecosystems allowed us to conclude that the interpretation of the third main factor under conditions of variable load of biogenic elements depends on the characteristics of a particular ecosystem. For ecosystems that are not deficient in nutrients, it can be interpreted as the transfer of created primary organic matter to consumers of the next trophic level, related to the structure of the food chain in the ecosystem. For an ecosystem in which the process of primary production formation is limited by the available amount of nutrients, it is this available amount of nutrients that is the third main factor affecting its long-term dynamics.

The succession of bird communities in the hemiboreal forests of the Eastern upper Volga region was traced by the method of multidimensional nonmetric scaling (nMDS).Comparison of data on the species composition and bird population density of managed forests, intact forests, and forest reserves. Analysis of the impact of natural and anthropogenic disturbances of various intensity on common and rare species, as well on the stability of hemiboreal ornithocenoses in space and time.

The population of spiders in the intermontane depressions of Southeastern Altai and Tuva was studied using a numerical approach. It has been established that the population is very small in number and taxonomically poor. On the catenas of the Chuya Hollow, subarid species predominated, while in the Kurai Hollow, located in the valley of the large Chuya River, polyzonal species predominated. In Tuva, the driest conditions of the catena on the Tannu-Ola ridge (Uvs-Nur depression, western sector) determined the predominance of subarid faunal elements, as in the Chuya depression. For the same reason, these two catenas were distinguished by the largest proportion of representatives of the Central Palaearctic fauna. On the catenas near lakes Khadyn (Ulug-Khem depression) and Tore-Khol (Uvs-Nur depression, eastern sector), where accumulative positions were characterized by high humidity, the share of subboreal humid species was high. Western Palaearctic species predominated on the catenas in the Kurai steppe and near Lake Khadyn. On the catena near Lake Tore-Khol, there is no dominance of species with any one longitudinal type of range. The dynamic density of spiders was usually highest in the lower catena positions. Under extremely arid conditions, at all catena positions in the Chuya and Uvs-Nur (Tannu-Ola) depressions, the maximum dynamic density was noted at the uppermost positions. The spiders belonging to the families Lycosidae and Gnaphosidae are the most numerous and diverse in the population of spiders in the mountain basins of Southeastern Altai and Tuva. In the isolated conditions of individual hollows, specific spider faunas are formed. Only the transit and accumulative positions on the catena in the Kurai depression are similar in terms of population structure.

The effect of PEG‑induced drought on the growth, the efficiency of photosystems I and II, and the
accumulation of proline, sodium and potassium ions in plant shoots of two populations of the intermediate
C3-C4 xerohalophyte Sedobassia sedoides was studied. The heterogeneity of plant response to osmotic stress
was revealed, both between populations and within each of them. The relationshi ps between the factors involved
in the adaptive mechanisms of plants from different populations under osmotic stress was determined.
Presumably, the intraspecific variability of S. sedoides plants in the mechanisms of drought tolerance is
associated with the different expression of the C4 photosynthetic syndrome in different populations and soil
conditions, in particular, with the water-salt balance of soil.

This study was conducted to examine the diversity and community structure of saproxylic beetles inhabiting silver birch ( Betula pendula Roth) in the State Nature Reserve “Voroninsky”. Beetles were caught using interception traps that were located on the trunks of birch trees in different decomposition stages. The result of this study showed that a total 1806 individuals of saproxylic beetles, belonging to 96 species and 37 families were sampled. The largest number of species is found in the families Staphylinidae, Tenebrionidae and Mycetophagidae. The largest number of specimens is found in the families Throscidae, Tenebrionidae, Staphylinidae, Lycidae, and Pyrochroidae. Most of the species are facultative inhabitants of the birch tree and are able to develop on other types of trees. More than a third of all the collected specimens belong to six species Lygistopterus sanguineus , Aulonothroscus brevicollis , Schizotus pectinicornis , Mycetochara flavipes , Trixagus dermestoides and Mesosa myops . The species composition and trophic structure of the complex of beetles at different stages of wood decomposition in the surveyed habitat is characterized by high similarity, but the distribution of species and quantitative abundance at different destruction stages differ. In general, complexes of saproxylic beetles at decomposition stages II and III are more taxonomically diverse, which shows the importance of dead wood for maintaining the species diversity of forest communities. Almost all trophic groups were observed at all decomposition stages, only necrophagous ones were found at decomposition stage III. In terms of species and number abundance, mycetophagous ones prevail at all decomposition stages, saproxylophagous ones take a noticeable part in the composition of the complex at the last decomposition stages. The dominant complex includes both mycetophages and saproxylophages ones. The composition of the dominant complexes of different habitats differs at stage I of wood destruction. The analysis reveals connectedness in time to certain stages of wood destruction in 37 species and 5 families. The least pronounced connectedness is at decomposition stage I; the subsequent decomposition stages are preferred by a greater number of species.

Comparative analysis of the size-mass and biochemical parameters (total lipid content and their fractional and fatty acid composition) of eggs of wild and cultured producers of the Ob muksun showed significant differences between them. Wild eggs is characterized by smaller size (by 7 %) and weight (by 15 %), higher fat content (by 13 %) and the level of diacylglycerols (by 33 %), and lower phospholipid content (by 30 %) in comparison with factory eggs. At the same time, factory eggs differs from wild eggs by a higher level of physiologically significant docosahexaenoic 22:6n-3 (1.8 times) and linoleic 18:2n-6 (7.1 times) acids, but a relatively lower level of eicosapentaenoic 20:5n-3 (in 1.5 times) and arachidonic 20:4n-6 (4.2 times), respectively. Such changes in the fatty acid status led to a decrease in the commercial eggs of n-3/n-6 ratio (by 52 %), palmitic 16:0/ oleic 18:1n-9 (32 %) and α-linolenic 18:3n-3/18:2n-6 (by 45 %), and to an increase of 22:6n-3/20:5n-3 (by 63 %). In addition, in the eggs of factory muksun, 68 % of the total lipids are 4 acids - 16:0, 18:1n-9, 22:6n-3 and 18:2n-6, in wild eggs the share of these acids was 47 %. The established differences in the size-mass parameters, the total lipid content and their fractional and fatty acid composition of wild and hatchery eggs of the Ob muksun are most likely associated with a different diet and habitat conditions of the sexually mature fish in captivity and nature.

Trophic position of fish is one of the most important factors controlling the accumulation of potentially toxic elements and compounds in fish tissues, primarily via the spectrum of fish nutrition. In this study, the content of potentially toxic transition metals (Cu, Zn, Mn, Pb, Cd) and radiocesium (¹³⁷Cs) in the edible tissues (muscles and liver) of two representatives of the fish-eating ichthyofauna of the Yenisei River, northern pike ( Esox lucius ) and burbot ( Lota lota ), have been comparatively studied relatively to the size of the fish. A significant decrease in the content of radiocesium and zinc in the muscles of pike, and zinc in the liver of pike with an increase in body size was recorded in juvenile pikes with a body weight ( W ) of less than 0.35 kg. For larger sexually mature pikes, no significant size dependences of the accumulation of metals in tissues were found. A positive correlation was found between the content of ¹³⁷Cs, Cu, Zn and Mn in muscles and the size of burbot in the W range from 0.42 to 1.62 kg. The tissues of one-sized burbots and pikes significantly ( p < 0.05) differed in the concentration of metals in their tissues: concentrations of Zn and Mn were 1.6-2.2 times higher in muscle of burbot; concentration of Pb was 1.8 times higher in muscle of pike; Cu was twice higher in liver of burbot; Zn and Mn were 4.7 and 1.6 times higher in liver of pike, respectively. The revealed differences may be due to the differing food spectra of pike and burbot. Concentrations of Cu, Zn, and Mn in liver of pike were 3-7 times higher than in muscle; concentration of Cu in liver of burbot was 5 times higher than in muscle. Pb and Cd tended to be higher in liver than muscle for both fish species. Despite the revealed size-dependences, the concentrations of potentially toxic metals and radiocesium in the muscles and liver of fish were below the permissible concentrations for food. The results obtained can be used to assess environmental risks for the population consuming fish, as well as to plan long-term environmental monitoring of rivers using representatives of fish-eating fish fauna.

On the example of the Volga basin, based on the materials of large-scale landscape surveys, predictive empirical-statistical modeling of the carbon balance of boreal and nemoral forest biomes was carried out. One of the types of predictive ecological models is presented - within the framework of experimental landscape ecology. Methods for calculating and mapping the volumes of absorption/emission of greenhouse gases by forests under predicted climate changes are discussed. Based on global climate models, predictive estimates of the components of the carbon balance of forest ecosystems as integral formations and their influence on the carbon exchange of the earth’s surface with the atmosphere are given. For two climatic forecast scenarios: moderate and extreme, quantitative indicators of adsorption and emission of СО₂ in various local and zonal-regional conditions of the East European subcontinent are given. It has been established that boreal forest ecosystems predominantly carry out cumulative regulation of the carbon cycle, which mitigates warming, while nemoral forests regulate emission regulation. The general softening effect of the forest cover of the Volga basin on climatic changes with the strengthening of the hydrothermal signal was revealed. It is shown that the process of thermal arid transformation of forest ecosystems leads to a general decrease in carbon accumulation in most groups of forest formations. The maps of the carbon content and the projected carbon balance of the main forest formations of the Volga basin for

The capsule review of the scientific editor for the thematic issue of the Siberian Journal of Forest Science, 2021, number 5 is done, dedicated to the Siberian silkworm problems.

Every year, hundreds of forest fires occur on the territory of the Siberia. It is established that in recent decades there has been an increase in the number and area of forest fires, respectively, the volume of pyrogenic emissions increases too. During fires gas-aerosol emissions are released the volume of which is determined by the intensity of the fire and the burnt forest combustible materials. The paper presents calculations of greenhouse gas emissions from fires in light coniferous forests of the Lower Angara region for 2014-2019. Using data on the amount of forest combustible materials burned in a fire, the mass of greenhouse gases released during fires is calculated, depending on the type of fire, the type of forest and weather conditions that affect the drying of combustible materials., The estimated greenhouse gas emission from fires in light coniferous forests ranges from 5.9 to 37.5 ton/ha, depending on the type of fire and the type of forest. Each year, in the light coniferous forests of the Lower Angara region, greenhouse gas emissions from fires vary from 160 to 5649 thousand tons, on average more than 2300 thousand ton/ha per year. In total, during the period under review, according to the calculated data, more than 16 million tons of greenhouse gases were released during forest fires, with a predominance of CO-CO₂. It is revealed that unfavorable conditions of dispersion of emissions from forest fires are formed in the summer months, characterized by a high frequency of calm, surface inversions and radiation fogs. Relatively favorable weather conditions in the presence of pollution factors for self-cleaning the atmosphere from fire emissions are observed in spring and autumn, when the greatest number of windy days is recorded.