Arid Ecosystems最新文献

Under the influence of pollution by petroleum hydrocarbons, soils from different natural zones have different physical, chemical, and biological indicators of the soil condition. Biological indicators are the most sensitive to soil pollution and changes in the ecological state. Arid zone soils, compared to other types of soils, due to the soil formation conditions and the physical and biological properties, are very unstable to pollution by petroleum hydrocarbons. In this regard, it is important to standardize the content of petroleum hydrocarbons taking into account the response of enzyme activity and microbiological indicators, and an assessment of soil phytotoxicity. Such standards serve as parameters for the health of soils in a region when contaminated with oil and oil products. The aim of this study is to assess the environmental health standards of arid soils in southern Russia when contaminated with oil and oil products. It has been established that, with an increase in the concentration of oil and oil products, the biological indicators of soils are suppressed. The ecological standard for oil in brown semi-desert soil (0.1%) is the lowest compared to solonchak (1.0%) and chestnut soil (0.2%). The permissible content of fuel oil in chestnut soil (0.4%) is less than in solonchak (1.0%) and brown semi-desert soil (0.5%). The content of diesel fuel in chestnut and brown semi-desert soils is the same (0.2%), and in solonchak it is three times higher (0.6%). The maximum difference in standards among the studied soil types was established for oil: between solonchak and chestnut and brown semi-desert soils, it is five and ten times. Chestnut and brown semi-desert soils are more sensitive to oil pollution than saline soils. Among the biological indicators, the greatest sensitivity to pollution by oil and oil products is the abundance of bacteria of the genus Azotobacter and the total number of bacteria, and the lowest, the activity of catalase and dehydrogenases and the length of roots. The most informative indicators for contamination of arid soils with oil and oil products are the activity of catalase and dehydrogenases and the length of roots, while the least informative indicators are the total number of bacteria and the activity of urease. The most resistant soil to pollution by petroleum hydrocarbons is the salt marsh, and the least resistant are brown semi-desert (oil and diesel fuel) and chestnut (fuel oil and gasoline) soils. The results of this study can be used in the development of environmental standards for the health of arid soils contaminated with oil and oil products.

A study of soils of winter pastures with different intensities of grazing in the north of the Terek-Kuma Lowland was conducted. Based on the results of a survey of the soil cover of three key areas located at different distances from the watering hole, it was established that, in the zone of intensive cattle traffic, the proportion of solonetz soils increases in the structure of the soil cover. The largest proportion of solonetz soils is found in the 200-meter zone. Solonetz soils are associated with cattle trails and elongated micro-depressions of erosional origin. No salt licks were found at a distance of 500 m from the watering place. It has been shown that the development of the solonetz process under the influence of cattle grazing is a consequence of the reduction of vegetation cover and soil compaction. This leads to a decrease in desiccation and intense heating of open areas, resulting in an increase in the salt content in the middle part of the profile. Subsequently, with periodic moistening and drying of the upper horizons, sodium salts enter them with capillary-suspended solutions and the share of exchangeable sodium increases to 20–30% of the cation exchange capacity. Subsequent evolutionary transformations of solonetz soils are associated with a reduction in the thickness of the SEL horizon up to its complete loss as a result of erosion and deflation and the complete destruction of the vegetation cover. The desiccative–exudative water regime is replaced periodically by an exudative one; degradation of solonetzic features occurs due to surface salinization. Thus, there is a pasture evolution of chestnut soils into solonetz and then into post-solonetz salt marsh abrazems, which form large areas of “badlands” near farms and watering places.

Electric fish barriers of various systems have long been successfully used to protect fish from entering water intake structures, especially under conditions that make it difficult to use other types of fish protection devices and structures. Strong electric fields created by electric fish barriers can affect the survival, physiological state and injury rate of juvenile and adult fish. At the same time, the sensitivity of fish to such impacts is largely determined by their size. In this regard, we have carried out a complex study to examine the biological safety of electric fields generated by the electronic programmable complex fish-protecting facility of electrical action (EPS IFPEI) on mass fish species from the coastal zone of the Caspian Sea and separate estuaries of its tributary rivers. Behavior and distribution of fish of different size groups (juveniles and adults) at different levels of electric impact from the fish barrier were tested. Survival and injury rates of fish at prolonged maximum voltage of electric fish barrier were evaluated. As a result of the experiments, the modes and parameters of the electric fish barrier (EPS IFPEI) effectively causing behavioral avoidance response in fish were established. Significant differences in survival of individuals from the intact (control) and electrically exposed (experimental) groups of fish were not revealed.

Reconstruction of paleoecological conditions on the territory of the Kamensky district of Rostov region, in the Middle Bronze Age yamnaya–catacomb culture border, has been carried out. The work based on results of soil investigations of kurgan 1, archaeological object “Malaya Kamenka VI” group. It was set up that paleochernozems and modern surface soils are clay loam and loamy, thin and having medium humus content and formed on loess-like loams. Values of pH in upper soil horizons are almost neutral. Increasing of pH in humus horizons of paleosols are of smooth character (from 7.0 to 7.3), which indicates carbonate formations surface upliftment. The content of Cl^–-ions in the genetic horizons of paleosols are in the values 0.15–0.30%, ({text{SO}}_{4}^{{2 - }})—0.04–0.09%, and Mg²⁺—0.007–0.020%, that higher comparing to modern surface soil. It can be an indicator of more arid paleoecological conditions. Short soil profile of paleosol, the footmarks of huge soil animals activity, traces of phytomass burned, a higher soil mass boiling point in paleosols are indicators of the arid climatic phase. In paleosol the low content of pollen from woody and shrubby plants in pollen spectra (up to 6.5%) and a large proportion of pollen from xerophilic species: wormwood (up to 17%), other the Asteraceae family plants (up to 20%), Ephedra pollen finds (up to 2%), indicates an increase of arid conditions. Vegetation was similar a dry steppe with the part of xerophilic grasses. The modern surface soil characteristics (traces of leaching of carbonates from the topsoil, the absence of salinity in the profile) and significant part of motley grass in pollen spectra reflect more humid and favorable conditions at present.

The application of camera traps to study the fauna and population of terrestrial vertebrates of the mountain wastelands of the Zeiskii State Nature Reserve, which occupies the eastern part of the Tukuringra Ridge, is described. An original method of counting mammals using camera traps was used, where the final indicator is the load on the area of the photo–video recording zone per unit of time, expressed as the number of individuals per unit area (Podolsky et al., 2020). Extreme habitat conditions (lack of moisture during the growing season, frequent storm winds, etc.), along with seasonal migrations and periodic food concentrations, determine the characteristics of the animal population of mountain wastelands and the difficulties of studying it; the use of standard observation methods is insufficient. Nine cameras were installed: eight in mountain tundra with clumps of dwarf pine, and one in the subalpine Ayan spruce forest, at the intersection of animal trails. For mammals, population densities estimated from camera trap data were compared with multi-day censuses and other standard methods to assess the feasibility of using the method for censuses of different species. It has been shown that, in mountain wasteland conditions, it is optimal for recording the main parameters (population density, timing) of summer–autumn food concentrations of brown bears (Ursus arctos) and is also applicable for recording several other species of animals: the white hare (Lepus timidus), lynxes, and probably wolverines. The proposed method of accounting on bare mountains is not applicable to sable (Martes zibellina), the red squirrel (Sciurus vulgaris), and the Asian chipmunk (Eutamias sibiricus). The population density of the mentioned species, calculated using camera trap data, turned out to be several orders of magnitude lower than that obtained using standard methods. The described method is also not suitable for determining the number of birds. At the same time, the analysis of the footage from the installed cameras allowed us to expand the list of bird species regularly visiting the mountain wastelands, as well as to supplement the list of the avifauna of the Zeiskii Reserve: the Eurasian whimbrel (Numenius phaeopus) and the Asian rosy finch (Leucosticte arctoa) were noted for the first time. The natural features of the upper altitude zones of the Tukringra ridge, the specifics of organizing research in extreme conditions, the technical capabilities of modern automatic cameras, and the developed census methodology determine the significant prospects for using camera traps to study the fauna and population of animals and birds of the mountain wastelands of the Zeiskii State Nature Reserve.

Dendrochronological and dendroclimatic analyses of radial growth of trees in shelterbelts of the dry-steppe subzone are presented. In dry steppe conditions, trees of shelterbelts are very sensitive to climate change and are forced to adapt to extreme conditions, which directly affects their annual increment. The radial growth of trees and their response to climatic factors are determined by their species composition and geographical location within the dry steppe. The rates of radial growth vary significantly among species. Poplars show the highest increment. Larch chronologies are characterized by the lowest rates of radial growth. Birch chronologies are the most sensitive to climatic fluctuations, and pine chronologies are the least sensitive. A statistically significant relationship with precipitation, temperature, area moisture index (with the Selyaninov hydrothermal coefficient), and the Palmer Drought Severity Index (sc-PDSI) is noted. A deficiency of precipitation and increased air temperature most often cause a decrease in the wood increment. A large number of narrow, wedging, and missing reference rings were noted. The analysis of the age structure of the studied trees of shelterbelts showed that they are moving into the senile stage of development. Further increase in climate aridization will inevitably affect the growth of trees of shelterbelts and create additional risks for their existence.

The territory of the basin of Lake Baikal is a complex mosaic of oroecosystems, in which anthropogenic and natural processes lead to significant and often difficult-to-predict changes in the structure of both individual ecosystems and the entire complex. The aim of this work was a spatiotemporal analysis of some climatic parameters as the primary link in energy and mass exchange, which sets the general trend in the development of ecosystems: average values of the air temperature, precipitation, and aridity index. For the period from 1975 to 2019, climate data were obtained on the average daily air temperature from 84 weather stations and on the amount of precipitation from 72 weather stations. The obtained climate data were divided into five-year periods and processed in ArcMap 10.7 and Qgis 3.16 GIS; statistical preparation was carried out in the Python 3.10 programming environment. The construction of precipitation and temperature distribution rasters was carried out using the Spline interpolation method. We have constructed a series of maps of the distribution of the average air temperature values, total precipitation, and the Morton aridity index, as well as a series of large-scale maps of the distribution of average air temperature values, taking into account the morphometric features of the Earth’s surface. It is noted that the most stable directional changes in annual air temperature are observed in the Russian part of the basin, and the highest rate of transformation of the temperature field in annual values is characteristic of the mountainous regions of the Mongolian part (the spurs of Khangai and Khentii). The main share of the increase in the annual air temperature values occurs during the warm period, and it is formed due to the Mongolian part of the basin. The greatest variability in the amount of precipitation during the warm period corresponds to the mountainous regions of Khangai (the southwestern part of the basin, the Zavkhan aimag, and the southwestern part of the Khuvsgol aimag), as well as the valley complex of the Orkhon–Selenga interfluve. There are strong differences in the temporal dynamics of precipitation of the cold period between the northern and southern parts of the basin. Thus, for the period 1975–2019, the increase in precipitation in the Russian part was only 4%, while in the Mongolian part, it was about 40% of the average value of precipitation during the cold period of 1975–2019. The territory is characterized by multidirectional changes in the values of the aridity index. Two large areas of increasing aridity have been identified: the southern and central parts of the Bulgan aimag, together with the eastern end of the Arkhangai aimag, represent the Mongolian area of increasing aridity, and the central part of the Republic of Buryatia is the Russian area of aridity. Details of the methodology for constructing rasters and for processing the initial data are located in the database GIS Ecosystems of the Lake

According to remote sensing (space image decoding), the Darkhat Basin of Northern Mongolia is a sparsely populated cattle-breeding territory, which was an area of developed agriculture in the past. Quite numerous land plots are recognized at the end spills of rivers flowing from its mountainous frame, lake and river terraces, floodplains, and deluvial–proluvial slopes, at absolute elevations from 1535 to 1700 meters a.s.l. or more. Among the wide soil range, here are fertile chernozems, chestnut, and dark chestnut soils. The geological position of the region and its confinement to the southwestern periphery of the Baikal rift contributed to both the formation of the basin and its modern seismic activity, manifestations of basaltoid volcanism, as well as the emergence of a “regional thermal anomaly” (Vilor et al., 2019). The basin also belongs to the Khubsugul Upper Riphean–Cambrian phosphorite-bearing basin, where deposits and numerous manifestations of phosphorites, the basis of mineral fertilizers, are known (Il’in, 1973). The long history of the formation of the relief of the Darkhat Basin led to the enrichment to a greater or lesser extent of its Quaternary deposits with phosphorus compounds useful for agricultural practices. Modern volcanism and continental rifting processes contributed to the emergence of thermal springs in this area; nitrogen baths, which are a kind of liquid nitrogen fertilizer, are known here (Mongol’skaya..., 1990). The combination of the following features: fertile soils, the thermal anomaly of the Baikal rift, and the presence of nitrogen thermal springs, as well as deposits and manifestations of phosphorites, products of their destruction, enriching the soil, contributed to the development of agriculture here. Manifestations of Cenozoic basaltoid volcanism, causing the presence of fertile volcanic ash, as well as processes of medieval volcanic activation (Arzhannikov et al., 2017), played a possible role in the development of agricultural practices on this territory. Social and political events are also important reasons. According to an earlier analysis of ancient agriculture in the arid territories of Central Asia (Prudnikova, 2020), its maximum development in the Darkhat Basin occurred in the early Middle Ages, a time attributed to the small climatic optimum.

The problem of changes, and especially deterioration of the quality of water in functioning reservoirs, is extremely relevant at the present time. In arid regions, the possibility of using reservoirs is limited by the increase in mineralization, but this issue has been practically unstudied and not covered in the scientific literature. The results presented in this article are original and for the first time characterize the features of quantitative changes in the spatial and seasonal transformation of water mineralization in reservoirs in arid regions over a long period of operation. The data were obtained as a result of long-term observations for the spring–autumn period from 2001 to 2023 at five reservoirs with different purposes and water regimes and located in the southern part of the steppe zone and in the northern part of the desert zone in the Republic of Kalmykia. In all reservoirs, the water mineralization was higher than the waters that feed them. In the Krasinskoye and Chograyskoye reservoirs, used for drinking water supply and filled with river waters from large rivers of other regions (Volga, Terek, and Kuma), the average value of water mineralization in the spring and autumn seasons was minimal (0.5 and 0.8 g/dm³; 1.6 and 2.0 g/dm³, respectively) in comparison with other reservoirs. The highest water mineralization was in the Tsagan-Nur and Deed-Khulsun reservoirs (5.8 and 32.0 g/dm³; 9.1 and 12.9 g/dm³, respectively), serving as reservoirs for the drainage and discharge waters of the Sarpinskaya and Chernozemelskaya irrigation and water supply systems. At the Arshan-Zelmen reservoir, created for irrigation and formed by the waters of local river runoff (2.9 g/dm³) and springs (0.4 g/dm³), the average mineralization value for the entire observation period was 5.3 and 19 g/dm³ in the spring and autumn seasons. It has been established that the mineralization of water in reservoirs with attracted runoff is not geographically determined. In reservoirs located in the desert zone (Krasinskoye and Deed-Khulsun), the mineralization value turned out to be lower than in reservoirs located in the steppe zone and having a similar purpose (Chograyskoye and Tsagan-Nur). The seasonal variability of the mineralization of water in all reservoirs is similar in that in the autumn period the values are higher than in the spring. Minimal changes were noted in drinking water reservoirs (Krasinskoye and Chograyskoye). The spatial variability of the difference in mineralization in different parts of the reservoirs is due to the fact that newly incoming waters have a lower mineralization than in the reservoir. The differences in water mineralization values between different sections of the same reservoir and between seasons are smaller than the lower mineralization value of its waters. At Krasinskii and Chograiskii, it does not exceed 0.3 g/dm³; on Tsagan-Nur, the re