Arid Ecosystems最新文献

The current state of a rare medicinal species, the “green-flowered” hound’s tongue (Cynoglossum viridiflorum Pall. ex Lehm.), of Uzbekistan growing in the Karakalpak part of the Ustyurt Plateau, based on the structure of its cenopopulations is examined. New data is reported with respect to the ontogeny and ontogenetic structure of cenotic populations of this rare endemic, and plant communities with its participation are characterized. In the Ustyurt conditions, the vegetation cycle of C. viridiflorum spans approximately eight months from March to October. The studied populations were shown to be normal and full-membered. The left-sided ontogenetic spectrum is characteristic of C. viridiflorum due to the high seed productivity and germination capacity. Altogether, this reflects the biological characteristics of C. viridiflorum and points to a stable state of the species population in the Ustyurt conditions.

The plant communities of the sandy massifs of the Northern Gobi Desert on the territory of the Bulgan Omnogovi aimag are considered. The classification of vegetation by the Braun–Blanquet method, first carried out for vegetation of the flat part of the Bulgan soum, revealed six vegetation associations belonging to three unions of three orders of the class Stipetea glareosae-gobicae Hilbig 2000. The flora of sandy massifs includes 108 species from 73 genera and 28 families. The species structure of genera and families reflects the specifics of the flora of this desert–steppe region within the Bulgan soum. In the spectrum of life forms of plants in sandy communities, perennial and annual and biennial grasses predominate, although in terms of participation in the structure of plant communities, the dominant phytocenotic role belongs most of all to woody plants. Dominant types of vegetation of the sandy massifs (Krascheninnikovia ceratoides, Caragana korshinskii, Haloxylon ammodendron, Psammochloa villosa, Nitraria sibirica, Brachanthemum gobicum, etc.) are natural sand fixers. At the same time, these species are for the most part well-eaten food for livestock. Consequently, grazing in such habitats must be strictly regulated.

Soil cover as a systemic formation is characterized by the formation of properties of different taxonomic levels and signs of structural organization with hierarchical subordination. As an integral natural formation, soils have resource potential, subject to the active influence of factors of the physical and geographical environment. Individual soil properties and their overall functional purpose may differ in time and space. Such properties are formed in different regions, reflecting the influence of local conditions. Typical representatives of soils with signs of salinity, excluding the implementation of production processes, are formed in arid conditions (Caspian lowland, Volga delta). The difference in the target functioning of soils in the region is expressed in the presence of a special natural combination of properties that the components of a typical soil profile do not possess (Neustruev, 1915). This is due to the fact that, when determining the classification characteristics of saline soils, processes that occur between individual horizons and are reversible in nature remain unaccounted for to date. The possibility of reversibility and restoration of physicochemical properties to the level of indicators characteristic of the climatic regime with the duration of geological periods of time remains in the shadows for many types of soils to this day (the water-soluble part of carbonates, silicates, and organic matter). We consider it appropriate to use a systematic approach when analyzing the temporal and seasonal functions of various types of soils (especially saline ones) under conditions of desertification and arid degradation.

Violation of nomadic forms of pasture use leads to vegetation degradation, periodic large-scale outbreaks of deflation and desertification, and transformation of the physicochemical properties of sandy soils in the arid zone. Practice has shown that an effective means of restoring their production potential is the creation of multi-tiered vegetation cover—forest and pasture lands. The purpose of this study is to assess the current state, feed productivity, attractiveness, and sustainability of forest pastures and to develop proposals for their optimization. This research was carried out through a comprehensive study of natural objects on temporary trial plots using standard methods of agroforestry, geobotanical and soil research, and statistical data processing. It has been established that on the thick blown sands of the Nogai steppe in forest pastures with a tree layer of Robinia pseudoacacia and Ulmus pumila, the forage yield increases to 2–3 t/ha (in terms of hay) and, depending on the seasons of the year, is 1.5–3.5 times higher than that on natural pastures. On the fine sands of the Black Lands, there are forest pastures formed by plantings of Krascheninnikovia ceratoides and Calligonum aphyllum. At the age of 30–40 years, they produce 1.5–3 t/ha of dry food, which is 1.4–2 times higher than in the surrounding steppe. On weakly and unwinnowed sands of the Astrakhan Trans-Volga region, in 20- to 60-year-old forest–pastures with protective fodder plantings of Haloxylon aphyllum, C. aphyllum, and K. ceratoides, the consumed mass of shrubs is 0.1–4 t/ha, while the grass stand is 0.3–1 t/ha, which is 20% more than in the open steppe. Pastures with tree and shrub layers attract animals and are more resistant to deflation. The functional durability of silvopastures depends on the technology of their creation, maintenance, and operation regime. The most important measures are fire protection and rationing of the pasture load.

This work is devoted to assessing the features of the distribution of spatiotemporal changes in the characteristics of the minimum 30-day winter flow of rivers in the basin of Lake Sevan. The problem of spatiotemporal changes in the minimum river flow is especially relevant for regions with insufficient and unstable moisture, like the basin of Lake Sevan, most of which is located within the steppe zone. The purpose of this work is to summarize modern ideas about the impact of climate change on the characteristics of the minimum 30-day winter river flow based on the authors’ own research, to analyze and evaluate the spatiotemporal variability of long-term fluctuations, and to identify nonstationarity in the series of minimum winter flow. The characteristics of the minimum flow have been determined, their spatiotemporal changes have been studied, and the dates of violations of homogeneity in the series of long-term runoff observations have been discovered. Using statistical parameters and difference integral curves, we assessed the representativeness of time series of minimum 30-day winter water flows at 12 sites during the period of instrumental observations. Nonstationarity in the series of minimum winter runoff in the basin of Lake Sevan has been revealed, and the dates for changes in stationary regimes have been determined. For most of the watersheds analyzed, the changes are statistically significant. Maps of the date of violation of the stationarity of the series under consideration based on information up to 2021 are presented, including a map of the distribution of the module of the minimum 30-day runoff for the winter period and maps on the nature of changes in the minimum 30-day winter flow. It is shown that changes in the minimum 30-day winter flow have a multidirectional nature, but mainly for the minimum 30-day winter flow, on average, over the territory of the lake basin. In recent decades, Lake Sevan has shown an increasing trend associated with rising air and soil surface temperatures. For some of the watersheds analyzed, the changes are statistically insignificant. On the territory of the Vardenis, Lichk, and Bakhtak river basins, on average, the minimum 30-day winter flow decreases by 20–30%, which will lead to an increase in environmental risk, requiring the adoption of appropriate measures. The obtained statistical materials will serve as the basis for scientific generalizations of research on the territory under consideration and can also be used for practical purposes in hydraulic engineering design and assessment of natural hazards and in making appropriate preventive decisions.

Information on the state of the nesting population of some species of the order Charadariiformes (Charadriiformes) based on our own expeditionary and published data obtained during the study of bird species of the marsh-near-water complex, which is the most sensitive to changes in the water regime of reservoirs in the southern European part of Russia (using the example of artificial reservoirs of the Republic of Kalmykia), due to increased anthropogenic pressure and climate change is provided. An analysis of the impact of the water factor (drainage/watering of the reservoir) on the nesting population of some representatives of the Gull family (Laridae) is given. Information is provided on the features of the nesting ecology of the most typical nesting species of this taxonomic group for the study area, and their general quantitative indicators and population dynamics for the period 2011–2015 are given. The contribution of the reservoirs of the Sarpinskaya lake system and Deed-Khulsun Lake to the preservation and enrichment of biodiversity of the region was assessed. Recommendations are given for managing their hydrological regime in order to maintain and preserve populations of rare and vulnerable bird species.

The use of background indicators for monitoring the content of nutrients in surface and groundwater in the steppe and forest–steppe zones of the Russian Plain is substantiated. Approaches to determining the background content of nutrients are proposed. The peculiarities of the formation of the runoff of nutrients during the flood period and summer–autumn and autumn–winter periods are revealed. It is advisable to use the results obtained to assess anthropogenic changes in the content of ammonium nitrogen, nitrate and nitrite nitrogen, and mineral phosphorus in the surface water and groundwater, as well as in wastewater. It is shown that it is advisable to adjust the standards for the content of nitrates and ammonium nitrogen in river and waste waters taking into account the level of the regional natural and anthropogenic background.

Mathematical modeling is considered as a method for studying the dynamics of grassland soil and plant systems in arid zones of Russia. The evolutionary development of grassland phytocenoses was modeled using the principles of nonequilibrium thermodynamics based on continuous and discrete mathematical formalisms. Examples are given, and problems of sustainable development of such systems under conditions of anthropogenic load and climate change are discussed. This study demonstrates new methodological capabilities of mathematical models of different types: in the form of systems of ordinary differential equations and discrete Markov chains. Prediction of degradation processes occurring in grasslands using these models has been studied in a comparative aspect. Differential models with constant and variable coefficients showed different results due to the nonlinearity of succession dynamics. The model with constant coefficients was refined by introducing time-dependent coefficients. The stability of the functioning of grassland ecosystems is discussed from the point of view of the formal parametric stability of solutions for a system of ordinary differential equations. Discrete modeling using the Markov chain technique showed that the degradation of soil and plant systems when the animal load is exceeded is described by a heterogeneous Markov process. Homogeneous Markov chains give adequate forecasts on one observation time interval. Prediction of the final states in the homogeneous approximation revealed that the observed nonlinearity in the dynamics of phytocenoses was caused by changes in the rate of development, ultimately leading to heterogeneity of the Markov chain. The issues of modeling nonlinear processes in the ecology of grassland soil and plant systems in the context of heterogeneous Markov processes are discussed.

The basis of Russia’s natural reserve fund consists of federal state reserves, national parks, and wildlife sanctuaries, the representativeness of which in relation to the diversity of natural complexes, including soils, is the main mechanism for protecting natural diversity. Using the method of geoinformation analysis, the areal and typological representation of the natural diversity of steppe soils in the system of specially protected natural areas (SPNAs) of the country was assessed based on vector maps: Pochvennaya karta Rossii (Soil Map of Russia) on a scale of 1 : 2 500 000 (a combined version of the Pochvennaya karta RSFSR (Soil Map of the RSFSR) and the Pochvennaya karta Kryma (Soil Map of Crimea) and the Karty pochvenno-ekologicheskogo raionirovaniya v Rossiiskoi Federatsii (Map of Soil-Ecological Zoning of the Russian Federation) on a scale of 1 : 8 000 000. The area occupied by steppe soils in Russia is 1 564 000 km² (9.4% of the total soil area of the country), of which 7.4% are soils of steppes (including forest–steppes and true steppes) and 2.0% are soils of dry steppes and semideserts. In protected areas, steppe soils occupy 11 500 km² and are found in 23 nature reserves, 14 national parks, and 13 wildlife sanctuaries. The current areal representativeness of protected steppe areas is very low: less than 0.5% for the group “Soils of the steppes” and about 2% for the group “Soils of dry steppes and semideserts. “Of the 55 steppe soils, units of the legend of the “Soil Map of Russia,” 58% are represented in federal protected areas, while reserves, which account for a fifth of the total area of steppe protected areas, provide 81% of the typological representativeness. Currently, many natural steppe soils in Russia, including the most fertile ones, are not represented in protected areas. The most significant compact array of such soils in terms of area is located in Ciscaucasia. The largest area here is occupied by southern and ordinary mycelial–carbonate chernozems (World reference base for soil resources (2014) – Calcic Сhernozems (Pachic)), their area is about 98 000 km² (7.9% of the soil area of the Russian steppes). There is a real threat of losing the last virgin examples of highly fertile soils typical of Ciscaucasia: southern and ordinary chernozems, dark chestnut, chestnut, light chestnut soils (WRB – Calcic Сhernozems (Pachic), Haplic Kastanozems, Calcic/Gypsic Kastanozems, Luvic Calcisols). Preservation of these soils in the virgin state, at least as samples for comparison with anthropogenically modified analogues, requires an inventory of all areas of their distribution and assignment of a protective status.

The state of the invasive species Dreissena polymorpha (Pallas) was studied in Ivan’kovskoe (Ivan’kovo) Water Reservoir in 2018–2022 to obtain the quantitative parameters of the mollusk development at the larval and definitive stages in all pleses (moderately wide stretches of a water body that is deeper compared to the surrounding waters) of the water reservoir during different seasons, as well as to show the interannual dynamics of their population size and spatial distribution. In the Ivan’kovo Water Reservoir, the southern invasive species Dreissena polymorpha (Pallas) has adapted rather successfully and has occurred continuously in the subsaline water conditions with a persistent lack of dissolved oxygen in summer in the near-bottom waters, which caused a shift in the mollusk niche down to a depth of 4 m; the mussel did not occur in silty biotopes. Range expansion of the southern immigrant D. polymorpha to the northern regional water bodies is influenced by climate warming, which prolongs the reproductive process of this mollusk. Currently, the end dates of mussel spawning in the Upper Volga water reservoirs approach those in southern water bodies. Eutrophication enhancement due to climate changes may pose a serious threat to Ivan’kovo Water Reservoir. Overall, the mussel population (adult mollusks + veligers) play a significant role in the process of self-purification of the water reservoir.