Arid Ecosystems最新文献

The purpose of this study was to compare two methods for assessing damage from the degradation of soils and agricultural lands located in the Kalachevsky district of the Volgograd Region. The amount of damage from soil and land degradation was calculated by the “Methodology for determining the amount of damage from soil and land degradation” (1994) and the cost of restoration (reclamation) of degraded soils was determined using the SmetaWizard estimate program (version 4.1.3). It was established that the most significant contribution to the total amount of damage from soil and land degradation (175 573 000 rubles or 64 955 rubles/ha) was made by the increase in the share of exchangeable sodium in soils (147 424 528 rubles or 54 541 rubles/ha), which is due to the development of the process of alkalinization in the soils of the studied agricultural sector in the region. This degradation process, which is harmful to the agricultural use of soils and lands, was found in areas that comprise 52% of the total farm area. This indicator’s significant damage is also associated with extended periods of restoration (reclamation) work, 4 years. The cost of reclamation work amounted to 11 647 353 rubles or 4309 rub./ha. The maximum contribution (78%) to this was made by damage from soil organic matter losses (the amount of damage was 9 131 525 rubles or 3378 rubles/ha). The significant difference in the total values of the environmental and economic assessment of soil degradation and the land of the Donskoye agricultural enterprise in the Kalachevsky district, calculated in various ways, is associated with the methodological features of this assessment: the assessment of damage from degradation by the “Methodology …” (1994) is a stricter approach than estimating the cost of reclamation (restoration) measures. Thus, soils may be degraded compared with a standard (considered when assessing damage), but this degradation is “insufficient” to justify reclamation.

The problem of protecting agricultural landscapes from degradation and desertification must be solved using a systematic and adaptive landscape approach to agricultural activities. Therefore, it is necessary to radically change the approach to modern agriculture. The main task must be to prevent degradation and desertification of agricultural landscapes. The methodological basis for our research and generalizations was a system of methods used in agroforestry and related sciences. When planning and conducting experiments and analyzing the results we used statistical and genetic approaches and elements of system approaches. The studies used physical and mathematical modeling. An important stage of the adaptive landscape agricultural system is the agroforestry improvement of the land use area. Its technological process includes calculation of runoff and soil loss and distances between forest belts; classification of lands according to the degree of soil erosion and nature of their use; organization of the territory; determination of parameters and structure of runoff-regulating forest belts; and creation of a system of runoff-regulating forest belts consisting of 2–3 rows of trees and a row of low-growing shrubs in the catchment area. The developed technology for anti-erosion management of watersheds for land use helps to optimize the placement of agricultural crops and forest strips on slopes to ensure runoff regulation, erosion-safe agricultural activities, and increased yield. An important role in the system of agroforestry measures is played by runoff-regulating forest belts and other protective plantings. In combination with other anti-erosion measures, forest belts play a large role in the formation of the ecological agroforestry framework of the territory and sustainable agroecosystems.

Rapid assessment of salinity based on the electrical conductivity of the liquid phase of the soil is widely used throughout the world. However, the results of such an assessment strongly depend on the soil–water relationship, while the known salinity standards based on electrical conductivity are proposed for a soil solution in the state of soil water saturation (full moisture capacity). Thus, a serious underestimation of the degree of salinity may occur when studying water extracts (suspensions) with an obviously higher soil–water ratio compared to the state of full moisture capacity. In this regard, the purpose of the study was to compare the GOST methodology in Russia with a soil–water ratio of 1 : 5 and the classical Richards method with the assessment of the electrical conductivity of the soil solution in a water-saturated state using the example of arid soils of different genesis and dispersion of the Republic of Uzbekistan. In contrast to well-known works on the empirical assessment of the influence of the soil–water relationship on the conductometric assessment of salinity, we applied the fundamental theory of dilution to justify the reduction of the results to a standard state of water saturation and the possibility of using the international classification of soils according to the degree of salinity. The results showed satisfactory agreement between the experimental data and the theory of solution dilution in the range of electrical conductivity values up to 30–35 dS/m, that is, up to a gradation of a very strong degree of salinity according to the international classification. Deviations from the theory can be explained by the nonlinearity of the dependence of electrical conductivity on the concentration of electrolytes and the immobilization of ions by the solid phase and thin pores, as well as a higher yield of electrolytes into solution at high dilution compared to the standard state of water saturation.

The forest–steppe is considered as an integral geographical and ecological-phytocenotic zonal phenomenon of Northern Eurasia, which has its own characteristic features. The unique altitudinal zone of the forest–steppe is formed in the mountains of Siberia and occupies a certain place in the altitudinal-zonal spectra of the mountains. The structure of the oroboreal forest–steppe is considered on the basis of the ecosystem concept and an ecological–geographical approach to data interpretation. An exposed forest–steppe is a complex combination of plant communities of forests and steppes that occupy contrasting ecotopes within the same altitudinal level, forming a single indigenous altitudinal-climatic ecosystem, where its components closely interact with each other and with the surrounding natural conditions. The cenotic and biotic diversity of the forest–steppe is due to bioclimatic conditions that determine the hydrothermal areas of distribution of mountain formations and the composition of their climatypes. Characteristics of forest–steppe combinations of seven regional orobiomes of Siberia provide comparative information about the geography of mountain forest–steppe, the combination of forest and steppe communities, their composition and bioclimatic conditions of development.

The results of a survey of vegetation dynamics on fixed transects in the east of the Volga River delta are presented. Sample plots of 2 × 2 m were laid in ecotopes mainly affected by floods. They underwent inundation or a groundwater level rise during high water periods. Geobotanical relevés of 498 sample plots were compared based on the survey results of 1980, 2011, and 2013. Five groups of plant communities were identified by cluster analysis. DCA ordination was used in combination with the L.G. Ramensky’s indicator values to identify the direction of vegetation succession. It was revealed that most of the vegetation changes on the transects occurred between 1980 and 2011. Reed (Phragmites altissimus (Benth.) Nabille) and cattail (Typha angustifolia L.) thickets replaced forb marsh–meadow phytocenoses. The areas of halophytic phytocenoses sharply decreased: they were replaced by these thickets and meadow communities dominated by Elymus repens (L.) Gould. The authors consider that there are two main reasons for these phenomena. First, this is the increase in the water flow of the Volga River after 1980. Second is the end of hay harvesting on a significant part of meadow wetlands. Changes in the vegetation between 2011 and 2023 were noticeable only on the lower parts of the slopes of the Baer hills. The number of sample plots with communities of the middle-steppe humidification increased here during the last year. These moved down the slopes of the Baer hills, which could be related to changes in climatic parameters towards aridization in 2014–2022 and to a decrease in the flood height by 23 cm.

The purpose of this study was to analyze the ecogeographical distribution of poisonous plants in floristic regions of Kazakhstan and identify the effect of arid conditions on their distribution. In total, the 51 most toxic vascular plant species belonging to 34 families were identified in the republic. Cartographic analysis showed that the lesser part of these species are confined to plain floristic regions in northern deserts; while mountain steppe regions have the greater part of toxic species. The largest numbers of poisonous plant species were recorded in the following floristic regions: Western Tien Shan, Tarbagatai, and Altai; the smallest numbers, in Mangyshlak, Northern and Southern Ustyurt, and Buzachi.

The results of a study of the photosynthetic efficiency, as well as the qualitative and quantitative composition of free amino acids in dandelion (Taraxacum officinale Wigg.) plants growing in Republic of Dagestan at various altitudes are presented. These complex studies show the high adaptability of dandelions to abiotic stress factors. As the altitude zoning increases, the efficiency of the solar energy transformation (Y(II)) in plants decreases due to photoinhibition (β and Ib). An increase in the relative rate of a noncyclic electron flow in the electron transport chain allows highland plants to maintain photosynthesis at the required level, thus providing the required energy balance and bioproductivity. Sixteen free amino acids have been identified in roots of T. officinale, including six essential amino acids that possess antioxidant properties. The amount of free amino acids varies depending on the zonality: the contents of α-alanine, arginine, methionine, serine, cysteine, threonine, and proline are higher in highland specimens. Altitude-associated changes in biophysical reactions and primary metabolites of the studied plants result from the impacts of abiotic factors and have an adaptive character.

Saline soils are a huge potential resource of the soil fund of the country, which may be used in agricultural production at present and in the future, if regular collection of system data on saline and solonetzic soils is arranged. The proposals of scientists for improving the monitoring of irrigated lands are aimed at the solution of this problem. Information of this kind is relevant for the development of measures to stabilize and restore soil fertility. The problems of the organization of salinization monitoring for irrigated soils in Russia are considered. The proposed approaches to its optimization are based on the integrated use of remote and terrain data and on our own research experience in Volgograd oblast. A comparative analysis of existing approaches to monitoring of saline soils in our country and abroad is given. The term of saline soils is defined. We show which soil layer should be analyzed for the presence of easily soluble salts to assign the soils, as well as solonetzes and solonetzic soils, to saline. The terrain monitoring performed by hydrogeological and reclamation parties, counting saline and saline-solonetzic soils on irrigated lands by terrain and analytical methods, should be supplemented with annual monitoring (during the spring–summer period) based on remote information for comprehensive survey. This approach will enable us to identify irrigated, rain-fed, and fallow lands in irrigation systems by satellite images; to supplement permanent terrain survey plots with sampling sites chosen by remote information; to identify areas with secondary soil salinization by the vegetation status on irrigated lands with a critical groundwater level and to take samples in them for analysis; and to reveal areas of saline-solonetzic soils on rain-fed lands and in the fields with noncritical groundwater levels by the vegetation status. All this will expand the database and characteristics of saline and saline-solonetzic soils and supplement the information obtained by hydrogeological and reclamation parties at permanent survey sites for better accounting of these soils.

The dumps of the Moscow coal basin represent a long-term spontaneous experiment that reflects self-revegetation of a potentially acid soils by herbaceous and woody vegetation. This study investigated the biodiversity of vascular plants and the productivity of plant communities formed on coal dumps in the Tula oblast and described on 32 plots of 10 × 10 m. It was established that plant communities on the surface of the leveled areas of dumps are lower than background and sub-background meadows in both the number of species and reserves of aboveground phytomass. Meanwhile, according to the same parameters, the artificially restored vegetation formed during the reclamation of dumps have higher species richness and yielding capacity the background and sub-background meadows located outside the zones of influence of acid mine drainage from coal dumps.