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 article presents the historical stages of the formation of agroforestry in the steppe and semi–desert regions of Russia, as well as international cooperation and projects aimed at combating drought, degradation and its extreme degree of development - desertification. The post-war years of drought and famine (1946–1947) became significant. In 1948, the Government of the USSR adopted and began to implement the “Plan for the Transformation of Nature”, which allowed to create a solid base for crop production and animal husbandry. The aggravation of droughts, degradation and desertification of farmland, in which territories become risky for agricultural production, gave impulses to the development of international cooperation and joint actions to prevent and eliminate these phenomena. The most productive in this sense was the period 1995–2000. Within the framework of the UNEP project “Support for activities to combat desertification in the CIS countries”, 6 subregional national action programs to combat desertification (NPCD) were funded in the amount of more than 600 thousand dollars, an assessment of the environmental, socio-economic consequences of desertification was given. The measures of the “General Scheme to combat desertification of Black Lands and Kizlyar pastures” in 1986–2001 carried out phytomeliorative work on an area of about 720 thousand hectares and prevented the formation of 700 thousand hectares of floating sands.

The study of the shrub status in the South-East of the European Russia is relevant due to the need to maintain the necessary material for protective afforestation. The study of their cover plant communities provides valuable information about the ecological aspects of the introduction and successful adaptation of shrubs in a place of mass planting. The aim of the study was to assess the condition of Caragana arborescens, imported from Eastern Siberia and planted in the arid territories of the Volgograd Oblast, as well as the ecological characteristics of its cover herbaceous plant communities. In the study area we selected two groups of plants, those growing on ordinary soil and on soil with a high content of salts, zinc, and a low content of manganese. In the latter case, C. arborescens had a relatively smaller size, a rarer crown, a reduced ability to generate shoots and resistance to diseases and pests. C. arborescens are sensitive to the anthropogenic stress, but within the analyzed territory this is not accompanied by progressive succession of the ecosystem. Under the crown of C. arborescens at various sites and sites, we found in various phenophases from 8–10 to 24 species of higher sapiens with a predominance of one- and two-year-old forms. Nine species have consistently claimed the role of dominant and subdominant of plant communities, most often representatives of the Asteraceae and Mareaceae families. The discovered communities showed clear signs of anthropogenic impact, but without the development of progressive ecosystem succession.

This paper reviews the historical use of agro-ameliorative and protective afforestation to combat drought and desertification in agricultural lands. It shows the current state of forest plantations in the arid zone of the Russian Federation and problems associated with wind erosion on pastures. Russia is facing a major ecological and economic challenge due to a growing intensity of development of recurring droughts, dry winds, erosion, wind erosion, and the level of protective afforestation as a branch of the national economy overall and a subdiscipline of science, in particular. This requires adequate public policy decisions, which are stated in the "Strategy for Development of Protective Afforestation in Russia until 2025." The Strategy determines their direction, as well as volumes and types of the plantations for the period until 2025 and a longer-term perspective on lands from the forest ameliorative fund. This review considers the causes of agro-landscape desertification associated with climate and anthropogenic factors and outlines the countermeasures and technologies for combating this phenomenon.

Common hazel is valuable for its nutritional and medicinal properties and its ability to provide soil conservation functions. However, the morphological characteristics of this plant have not been studied sufficiently. The research purpose is to identify features of significant morphological characteristics of crowns of nut-bearing hazel plants, to assess the biological diversity of these characteristics at different heights, under the forest canopy and on the glades for further detection of forestry and ecological functions of this plant, and to select ornamental and other economically valuable forms. The nut-bearing hazel plants growing in the mountain forests of the North-Western Caucasus at the altitude of 450–600 and 1,300–1,500 m above the sea level under the forest canopy and on the glades were the objects of the research. We studied the diameters of the central and three largest trunks, the crown and the base of the bush, its height, the number of shoots up to 4 years old and older, the total number of shoots in the bush, the density and shape of the crown. We examined 200 ramets that had entered the fruiting stage. The diversity index was calculated according to the authors’ method (Sukhorukikh-Biganova). At the altitudes of 1,300–1,500 m above the sea level, under better humidification compared to the sites located at the altitude of 450–600 m, hazel has statistically reliable better development of average diameters of the central and three main trunks and crown, higher total number of shoots up to 4 years old and older. Hazel trees have superior crown and bush base diameters, greater number of shoots up to 4 years old and older, the total number of shoots in the bush on the glades in conditions of good light compared to those under the forest canopy. Here the plants are more likely to form bushes with a spreading and thick crown. The upper sites showed a significantly higher diversity index for the average diameter of the three largest trunks of the hazel bush and the highest number of shoots older than 4 years. There is a significantly superior difference in the morphological diversity index for the average diameter of the bush base, the number of shoots up to 4 years old and older, the total number of shoots, and crown density on the glades compared to the sites under the forest canopy. In terms of crown shape, the diversity index is higher under the forest canopy than on the glade. The generalized indices of diversity of quantitative, qualitative and general morphological characteristics of hazel bushes did not differ significantly at different heights, under forest canopy and on the glades.

Remote monitoring and landscape–environmental profiling of the Archeda–Don sand massif made it possible to assess the state of the soil–vegetation cover and to determine the groundwater level and inclination. The degrees of soil salinity were identified for various sand types. The salinization of chernozem-like soils reaches 0.05%. The salinization of sand massifs with large amounts of litterfall is 0.05–0.07%. In open sands that formed in depressions as a result of blowing, the salinity does not exceed 0.001%. Pine outliers and planted stands are widespread throughout the sand massif. Natural forest stands consist of the following species: Betula pendula, Alnus glutinosa, Quercus robur, Populus tremula, and Salix spp. (S. fragilis, S. reptans, S. carpea, and S. rosmarinifolia). Pinus sylvestris plantings were introduced in the 19th century. The large number of forest sites and their outlier-based distribution are determined by the proximity of groundwaters. Black alder (Alnus glutinosa) stands reach the maximum productivity with a timber volume of up to 500 m3/ha. In areas with stagnant groundwaters, their height is 12–15 m. Birch (Betula pendula) outliers are located in depressions. Sparse European oak (Quercus robur) standing 8–12 m high occur on clayey sites. It is shown that Pinus sylvestris grows optimally on chernozem-like sandy loam soils and on single-phase, overgrown sands with thick, sod–steppe soils. Five dominant types of sands have been distinguished. The total area of forage lands within the sand massif is 171 536 ha; their herbage productivity is 370 700 t. The total area of forest sites is 50 584 ha. Overgrown hummocky–ridgy sands predominate. Overgrown closed depressions and ancient watercourses feature the highest productivity (3.0 t/ha). The results are essential for the development of a conceptual model for the optimal use of sandy lands.

Water balance studies have been carried out in the territory of sand massifs in the Don River Basin. The studies were mostly focused on the water-regime plots in Kalachevsko-Golubinskie and Archedinsko-Donskie sands. The area under study was divided into zones according to sand types based on land relief, the conditions of the soil cover, vegetation, and phreatic-water mineralization and level. Water-balance parameters and the characteristics of water regime were evaluated for individual types of sands. The volume of gravity flow of precipitation into the Don river system was determined. The study suggests the important role of sand massifs in water-resources protection, which consists in water freshening and maintaining river discharges.

In this work, we, for the first time, manufactured a plasma-chemical reactor operating at a frequency of 0.11 MHz. The reactor allows for the activation of large volumes of liquids in a short time. The physicochemical properties of activated liquids (concentration of hydrogen peroxide, nitrate anions, redox potential, electrical conductivity, pH, concentration of dissolved gases) are characterized in detail. Antifungal activity of aqueous solutions activated by a glow discharge has been investigated. It was shown that aqueous solutions activated by a glow discharge significantly reduce the degree of presence of phytopathogens and their effect on the germination of such seeds. Seeds of cereals (sorghum and barley) and fruit (strawberries) crops were studied. The greatest positive effect was found in the treatment of sorghum seeds. Moreover, laboratory tests have shown a significant increase in sorghum drought tolerance. The effectiveness of the use of glow-discharge-activated aqueous solutions was shown during a field experiment, which was set up in the saline semi-desert of the Northern Caspian region. Thus, the technology developed by us makes it possible to carry out the activation of aqueous solutions on an industrial scale. Water activated by a glow discharge exhibits antifungicidal activity and significantly accelerates the development of the grain and fruit crops we studied. In the case of sorghum culture, glow-discharge-activated water significantly increases drought resistance.

In the semi-desert and desert regions of the planet, where the traditional type of land use is pasture animal husbandry, the successful development of the economy and the well-being of the population fully depend on the state of pasture ecosystems.In modern conditions of aridization of the climate and the development of desertification processes, in order to maintain and increase the productivity of arid pastures, it is necessary to carry out phyto-reclamation works, including the creation of reclamationfodder forest plantations (RFFP).In this regard, the aim of the research was to determine the role of reclamation-fodder forest plantations in arid pasture ecosystems and those factors that influenced changes in the semi-desert phytocenoses of the Northern Precaspian region.According to the results of the studies carried out with the forest plantations of Tamarix ramosissima and Eurotia ceratoides, it was revealed: RFFP of the openwork structure has a significant effect on changes in amelioration factors on the adjacent forage lands, including the distribution of snow cover on pastures with tamarix had a significant length of the leeward plume up to 10 m, and upwind -up to 5 m, teresken had almost no effect on the distribution of snow over the pasture, because the reliable range of its influence was limited to 2 m on both sides.Also, on pastures with tamarix RFFP, more favorable conditions are created for animals to rest during the summer heat, since in the zero zone (plantation) the temperature of the surface layer was 5 % lower than the control values, and during the cooling period at a distance of 5-20 m from them -5-10 % higher.RFFP of teresken does not create such conditions in the summer period, but in the cold off-season they give an increase in air temperature above the soil within 1-2 m from plantings to 5-7 %.The presence of RFFP makes the adjacent forage lands more productive in comparison with natural semi-desert pastures, including with tamarix by 42 %, and with teresken -by 96 %.Изучение факторов влияния мелиоративно-кормовых лесных насаждений на аридные пастбищные экосистемы

The sandy lands of the Northern Caspian Sea region are a vulnerable natural landscape. Intensification of anthropogenic pressure leads to the soil cover degradation. The first mass plantations in the Caspian lowland began in the mid-19th century. However, due to the lack of knowledge about the reclamation conditions the results were unsatisfactory. Progress was made only at the end of the 19th century. In some parts of the sands (Tugai-Khuduk) individual trees have survived up to the present day. The work of forest-meliorators in the Soviet period fixed more than 200 thousand hectares of sands in the region, and also to create more than 50 thousand hectares of deflation-resistant shrub pastures. Forest is an azonal form of vegetation for this area. Based on the data obtained on water consumption by trees and shrubs, we gave an assessment of grazing protective forest strips, tree “umbrellas”, farm and reclamation forage plantations, conservation forest bioregions, boundary forest strips and sand-fortified plantations. They perform various functions. Unvegetated sands have the ability to store a freshwater lens that is no longer fed at the overgrown areas due to evaporation and transpiration costs. One hectare of open sands in the Caspian Sea can accumulate 1000-1500 m 3 of water per year. The whole complex of forest-reclamation plantations on pastures in Astrakhan region occupies an area of 151 thousand hectares. Financially supported reforestation programs should be adopted at regional and possibly federal level, due to the importance of planting in many spheres of life in the area.

Analysis of the dynamics of modern desertification of the Northwestern Caspian with the use of geoinformation technologies and aerospace data showed that the area of degraded and desertified lands in the region increases due to an increase in the anthropogenic factor (pasture load). With a relatively stable number of animals, the role of climatic factors increases, which leads to an increase in the speed and amplitude of changes in the area of desertification foci, both in the direction of a decrease with sufficient moisture and an increase in dry years. A significant influence is exerted by fires, which lead not only to a decrease in projective cover but also to a depletion of the species composition of vegetation. The study and mapping of the relief made it possible to establish spatially defined geomorphological features of the territory as a factor affecting local moisture and, accordingly, the stability of ecosystems and the possibility of phytomelioration.

The work was performed in accordance with the program of Fundamental scientific research of the state academies of Sciences of the Russian Federation for 2013-2020 in the direction X 10.3 Land reclamation, water and forestry, section 147. Theory and principles of creating agroforestry and forestry complexes in order

The article presents comparative studies of two types of protective pasture plantations from tamarix and teresken.According to the results, it was revealed that tamarix, as a higher shrub, better protects pasture from dry winds and retains moisture in the soil than teresken, but having a lot of salt in its leaves, is a poorly eaten plant and negatively affects the creation of humus in the soil.

This paper reviews the main historical stages of the development and implementation of the largest environmental project of the late 20th century—the “General Plan to Combat Desertification of Black Lands and Kizlyar Pastures.” The goal of this project was to implement a scientifically grounded set of measures to stop desertification processes, improve the economic state of pastures, increase their fertility, and protect lands. The implementation of the general plan has led to the performance of agroforestry works in an area of more than 7000 km2, the fixing of more than 4000 km2 of mobile sands, and the restoration of more than 2500 km2 of pastures. According to the forecasts, if all of the measures stipulated by the general plan were observed, the area of the ecological disaster zone would decrease and then completely disappear. A study conducted with Landsat satellite images showed that this forecast has partially come true: the area of open sands that was recorded in the test plot in 2016 (27.3 km2) is only 1% of the open sands area recorded in 1975, which is a consequence of the implementation of the general plan, a number of environmental measures, and favorable climate fluctuations.

The modern steppe zone of Eurasia is an active arena for the blowing of mineral matter out of the land surface and for its incorporation to the global process of exchange of matter and energy. The ploughed soil of the steppe zone used in agriculture annually loses tens of tons of fine earth from each hectare. This reduces the natural fertility of lands and quickens the general degradation of steppe ecosystems. This occurs especially intensively during blocking processes, when a strong anticyclone sets in over southeastern Europe. In this case, the energy wind load on the soil surface increases by one or two orders of magnitude as compared to the normal, and its destruction becomes catastrophic. In the zone where airflows converge in the steppes of the Lower Volga, Caspian region, and Ciscaucasia, wind-blown mineral substances are transported in the storm zone for a distance of 2000 km and are accumulated on the land surface in Central and northwestern Europe.