The characteristics of climatic, lithological and geomorphological conditions of formation of sandy soils of Transbaikalia (Barguzin basin) is given. It has been established that the main soil-forming processes are cryo- and light-humus, accumulative-carbonate and pale-metamorphic. In the soils of deposits, the processes of stratification and abrasion are expressed. Moving sands are not affected by soil formation, but with partial fixation of herbaceous and/or shrub vegetation on them, embryonic underdeveloped soils (layered-eolian, humus psammozems) begin to develop. For the first time, the results of the material composition of the rocks of the Angara-Vitim batholith, soil-forming sand, as well as the composition of minerals of fractions <1.1–5 and >5 µm of cryohumus and light humus soils are presented. It has been determined that the regional features of soil-forming sands are carbonation, alkalinity, and polymineral content, which is inherited from calc-alkaline rocks. The sandy and silty soil fractions have a similar mineralogical composition, which are characterized by a high content of plagioclases and K-feldspars and a low content of quartz. The composition of the silty fraction consists of a mixed-layer phase of illite-smectites interbedded with single chlorite packets, di-trioctadridic illite, ferruginous chlorite, and kaolinite. Modern soil formation is characterized by a low degree of chemical weathering (CWC, CWI, and GM) and weak profile differentiation. A feature of the material composition of sandy soils is an increased content of potassium and sodium. According to the values of total alkalinity, the studied soils are highly alkaline soils. There is a clearly pronounced division of the soil profile according to biological activity. It was revealed that during arable use, sandy soils are potential centers of desertification: in the studied area, all arable lands and fallows located on them are deflated to varying degrees. At the same time, it was found that more than 70% belong to very strongly deflated and strongly deflated types. In such areas, humus soil layers are blown out and carbonate horizons and even soil-forming sands are exposed. The exposed middle horizons and sands do not possess elements of effective fertility. The yield of agricultural crops on such arable lands is very low, the process of natural restoration of vegetation cover on fallow lands is extremely difficult, and deflation ulcers practically do not overgrow. The inhibition of the processes of restoration of natural cenoses is largely due to the alkalinity and carbonation of soil-forming sands.

A study was made of the features of the soil cover of solonetz complexes in different parts of the pasture of an average sheep farm in the dry steppe zone in the Manych river basin in the conditions of dissected relief. It has been established that several types of soil cover can be distinguished on the territory of the pasture that differ in the degree of transformation of the profile of different components of the solonetz complex under the influence of intensive grazing. It is shown that the heterogeneity of the soil cover is due to the uneven impact of grazing, which, in turn, is determined both by the degree of remoteness from the farm and by the characteristics of the vegetation cover in different parts of the pasture. The areas with a well-pronounced complexity of the soil cover and a high proportion of solonetzes, dominated by grass-wormwood associations, are subject to the greatest pasture load. A tendency to a reduction in the thickness of the AJ and SEL horizons of light chestnut soils and solonetzes was noted as the pasture load increased. In the soil cover of feather grass areas of pastures, the share of solonetzes is much lower, which can be associated with a short-term pasture load on these soils.

Bivalve mollusks are an important component of the ecosystems of many natural and artificial reservoirs. However, the ecological role of some of them is very ambiguous, especially if we talk about invasive species that have spread widely beyond their natural habitats over the past 100 years. The present study aims to obtain quantitative estimates of the distribution of a southern invasive species, the zebra mussel bivalve mollusk, over the water area of the Ivankovo reservoir and to assess the contribution of its filtration capacity to water self-purification.

Mathematical methods for description of the processes of evaporation from the soil surface under conditions of the sub-arid zone of the south of Russia are discussed. Theoretical studies in this area and the results of their practical application have been analyzed. Natural observations are explained using mathematical modeling. Mathematical models of evaporation from the soil surface are divided into two types: physico-mathematical, which are based on the interaction between the water and the soil carcass, and phenomenological, which are based on balance ratios. The data on the evaporation from the surfaces of light soils have been analyzed with allowance for the diffusive and film transfer of moisture within the pore space. The cumulative evaporation from extended areas has been analyzed using a semi-empirical model, which connected evaporation intensity with the precipitation and the hydrophysical state of the soil moisture in the aeration zone. Good agreement between the theory of the capillary transfer of moisture and the data on the evaporation from the surface of open sandy soils has been revealed. A nonlinear relationship between the evaporation rate and the depth of the underlying surface, as well as the capillary-sorption pressure, has been revealed. The amount of annual precipitation in the south of Russia and the cumulative evaporation are associated with each other via a power dependence indicating the capillary-sorption nature of the evaporation.

This work carried out comprehensive studies of the structure, mineralogical composition, and main indicators of silt sediment from the treatment facilities of the city of Volzhsky. Analysis of the data shows that the silt sediment is characterized by a complex mineralogical composition and has high fertilizing properties; it contains nitrogen, phosphorus, and potassium (3.30; 4.27; 0.31%, respectively), as well as organic matter (32%). Using the methods of scanning electron microscopy, IR spectroscopy, and X-ray phase analysis, the studied sludge was found to have the ability to absorb and retain water, which is an important property for fertilizers used in areas where there is no artificial irrigation. This article discusses the features of using silt sludge as a soil ameliorant in dry farming in the Volgograd region based on the example of safflower cultivation. To increase the microbiological activity of the soil, as well as the yield of dye safflower, it is recommended to apply sludge as an ameliorant at a dose of 10 t ha–1 with the use of deep chisel tillage by the Rancho working body.

Modern manifestation of desertification stages and of arid degradation and the dynamics of the development of these processes depending on soil fertility under arid conditions are analyzed based on the example of some areas of the Western Caspian Sea Region: the Terek-Kuma Lowland and the Terek River delta. There are two stages of the development of degradation processes, which strongly differ in their combination and area distribution. The first stage, natural degradation, starts from the development of soil-forming processes in the Holocene as one of the obligatory elements of the functioning of living organisms on the Earth surface. The natural dynamics of degradation processes results in the formation of an equilibrium status of formation of soils of particular types with a complete profile structure. Depending on soil-forming conditions typical for degradation (salinization, pollution, solonetzicity of soils at different stages of their evolution), solonchaks, solonetzes, and sand and clay deserts are formed. These soil properties continue to develop under natural conditions at the present time and their evolution that started in the Holocene goes on (Akaev, 1996). At the second stage, the dynamics of arid degradation and desertification is caused by the anthropogenic impact and radically differs from the natural degradation. As a result of the increased anthropogenic load, the natural soil cover is replaced by an unstable secondary one under man-made conditions. The development of new directions of soil formation is favored by the expansion of irrigated lands in the Terek River delta, the Terek-Kuma Lowland, and other regions and by the subject of cultivated soils to salinization, wind erosion, and degradation.

This study was aimed at assessing the state of reproductive function according to the fish-breeding, hematological, and morphophysiological parameters of the female paddlefish Polyodonspathula (Walbaum, 1792), which have repeatedly matured and spawned for food and fish breeding purposes. The work was carried out in 2019–2020 at the BIOS experimental aquaculture complex in the Astrakhan region. It has been shown that the age of the fish, the number of maturations, and the interspawning periods are the most important factors that made it possible to compare the fish-breeding and biological parameters of paddlefish females that matured and spawned in 2020. The stability of the coefficient of fatness explains the degree of activity of the reproductive function of female paddlefish. Significant differences in morphophysiological parameters between age groups, as well as between females from which caviar for various purposes was obtained, have not been shown. The leukocyte formula of the blood of the studied paddlefish females showed a lymphoid character and viscoelastic properties of leukocytes, as well as the cell agglutination noted during the separation of individual blood components. The distribution of leukocyte types differed slightly depending on the age composition (CV = 35.55 and 35.23%, P < 0.05; CV = 23.96 and 30.92%, P < 0.05, 23, and 18 years, respectively). The results of hematological studies showed that the younger generation (18 years old) of female paddlefish, from which caviar was obtained for food purposes, is better adapted than the older generation (23 years old), and the development of reproductive function is less susceptible to stress factors during maturation. A different picture is observed for fish that have spawned for fish breeding purposes.

The rapid increase in the rarity of species is an alarming threat that the world is facing today. Like other mountainous regions of the world, fragile mountains in the Himalayas are facing tremendous pressure for species extinction. The studied data at the locality site-specific level in comparison to the global and country-level status has realized us to analyze the extinction rate for monitoring. By realizing the importance, criteria based survey analysis of each species on various habitats, distribution range patterns, population size, use pattern, extraction trend, native and endemic species were evaluated. A total of 255 threatened species (20 critical endangered, 30 endangered, 60 vulnerable, and 144 near-threaten) were identified from the Lahaul valley in parts of the Cold desert north-western Himalaya, India. The studies themselves suggest the occurrence of maximum biotic and abiotic pressures with limited diversity. The altitudinal zone 2800–3800 m AMSL; habitats (forest, shady moist, dry, rocky, bouldery, and grassland); and communities of trees (Cedrus deodara-Acer cappadocicum mixed, Juglans regia-Ulmus wallichiana-Acer acuminatum mixed, Salix fragilis-Fraxinus xanthoxyloides mixed, Abies pindrow-Pinus wallichiana mixed and Crataegus songarica), shrubs (Juniperus indica, Juniperus communis-Rosa webbiana mixed, Spiraea canescens, Salix pycnostachya, Lonicera obovata, Cassiope fastigiata, Juniperus communis-Lonicera obovata mixed, Hippophae rhamnoides ssp. turkestanica and Rhododendron anthopogon-Salix lindleyana mixed), and herbs (Waldheimia glabra-Leontopodium himalayanum-Rhodiola heterodontata-Agrostis stolonifera mixed and Leontopodium brachyactis-Saxifraga jacquemontiana-S. brunonis mixed) showed maximum conservation prioritization index value of threatened species, which requires monitoring attention for future conservation. The information is useful for the site-specific mapping of rare plants, communities, and habitats for quick planning and implementation program.

The paper considers long-term trends in changes in river flow of spring floods, hydroecological and hydroeconomic consequences of climate change in the upstream of the Arpa River. The study uses data on average daily water consumption and water temperature in the Jermuk River section of the Arpa River, and data on the main meteorological elements at the Jermuk weather station located in the upstream flow of the Arpa River basin. It is presented that maximum water flow during the passage of the spring flood is one of the most important characteristics of the flood. The absolute maximum flows vary from 8.26 to 199 m3/s, and average maximum flows from 1.86 to 116 m3/s. The interannual changes of the dates of the beginning, termination, duration and volume of spring flood runoff, as well as temperatures of the surface air layer and precipitations in December–February and April–June, maximum water reserve in snow, and water temperature in April–June are have been considered and evaluated. It is shown that over the past 28 years, the volume of floods and their duration is being reduced, the terms are shifted towards earlier dates, and maximum water discharges during the flood period are reduced. It was also established that winter and spring–summer (in April–June) average air temperatures, precipitation in the winter period is increased, and maximum water reserve in snow becomes less. As a consequence of modern changes in the hydrological regime of the spring flood, multiple hydroecological and hydroeconomic problems are manifested that require increased attention and consideration. With interannual fluctuations, a change in the flow volume of the spring flood in the early to mid-1990s is clearly visible, after what a period of their significant and steady decrease started. The rate of change in flood volumes in the second period (1993–2020) was –17.9 million m3/10 years and –13.2 million m3/10 years. In the first period (1957–1992) there was an increase in flood runoff, the rate of change thereof was +9.63 million m3/10 years and +4.07 million m3/10 years, respectively. Over the past two–three decades, the volume of spring flood runoff has decreased by almost 50.1 million m3, while the runoff in April–June has decreased by almost 37.0 million m3. This trend is due to an increase in winter air temperatures and increase in the number and duration of thaws, which leads to a decrease in pre-spring water reserves. It is noted that in the upstream of the Arpa River basin, current climate changes are leading to significant degradation of the flood as a phase of the water regime: increase of the surface air temperature in the winter season is the main reason for the decrease in water content in the spring in the upstream of the Arpa River. Correlations were obtained between the values of the volumes of the spring flood in the upstream of the Arpa River, calculated from April to June and from the beginning of the flood to its end. This relationship can be used to estimate, calculate, and check the volume of spring floods, given the volume of runoff in April–June.

Soil microflora is one of the first to feel a negative impact and can serve as a biological indicator of changes in the soil structure and the degree of impact on the soil ecosystem. In 2020, studies were carried out at two sites located in the Shamshy Gorge in the Chui region of the Kyrgyz Republic. One of the plots was withdrawn from pasture use for one year in 2020 and two years in 2019 as compared to the actively used control option. The microbiological diversity was studied with conventional methods of microbiology. The micromycetes of the studied soils were represented in the dominance of species resistant to adverse environmental factors, Trichoderma, Cladosporium, and Alternaria, i.e., the species diversity was insignificant, with a predominance of representatives of dominant species. A decrease in the anthropogenic load in the studied areas has led to the activation of microbiological processes and a significant increase in soil microbiodiversity, which is indicative of improvement in the enzymatic properties and an acceleration of the soil self-healing process. Studies have also shown that soils in the regime of unregulated overgrazing are significantly susceptible to drying and trampling, which leads to a decrease in microbiological diversity in the soil ecosystem and the dominance of microorganism forms that are resistant to adverse environmental factors. The obtained data suggest that overgrazing affects the structure of soil microbiocenosis, replacing it with more drought-resistant species. Thus, the microbiological diversity of soils subjected to varying degrees of anthropogenic pressure can serve as a biological indicator of the state of the soil ecosystem. It is also necessary to resolve the issue of the regulation of the rotational grazing of livestock, which can also ensure the preservation of pasture productivity and contribute to the conservation of the biological diversity of flora and fauna of pastures, respectively.