Arid Ecosystems最新文献

The results of studies conducted in 2020–2023 in Astrakhan oblast on the basis of the Caspian Agrarian Federal Scientific Center, Russian Academy of Sciences, are presented. The purpose of these experiments is to develop the most environmentally friendly and resource-saving method of growing planting material of the leafless juzgun (Calligonum aphyllum (Pall.) Gürke) for use in phytomelioration of arid degraded pasture ecosystems and the creation of protective forest plantations in the arid zone of the Northern Caspian Sea. The objectives of this research were to study various methods of planting leafless juzgun (seedlings, cuttings, and seeds) and to identify a more effective one for light chestnut soils of Astrakhan oblast; to determine the optimal seeding rate and soil moisture (% of the lowest moisture capacity) for growing juzgun planting material; and to conduct an assessment of planting material during the growing season, including susceptibility to pests and diseases, crop condition (visual assessment), and biometric indicators according to experimental options. The studies carried out used the methodology of B.A. Dospehov (2011); Technical Specifications OST 56-98-93 (1994) were used to determine the compliance of planting material with the standard. Based on the results of our research, we found that the optimal way to plant leafless juzgun on the light chestnut soils of Astrakhan oblast is to plant seedlings. In addition, in these soil and climatic conditions, elements of the technology for growing leafless juzgun seedlings were developed, including the seeding rate of 250 kg/ha, soil moisture during the sowing–germination growing season at 60–70% of the lowest moisture capacity, and maintaining soil moisture during the growing season at 20–25% of the lowest moisture capacity.

Research was carried out on changes in the moisture supply of the territory in the dry steppe subzone of the southern part of Western Siberia (geographic coordinates 50.5°–54.5° N, 77.5°–83.0° E) for the period 1980–2050. The hydrothermal humidification coefficient of G.T. Selyaninov is used as the main indicator of the level of moisture supply in the region. The information basis for this study is the results of six climate models of the CMIP6 family, obtained for the modern period 1980–2015, as well as within the framework of scenarios SSP2-4.5 and SSP5-8.5 of the possible evolution of the global climate system for 2015–2050. The long-term dynamics, boundaries of variations, and trends of the hydrothermal coefficient for the southern part of Western Siberia have been established. An analysis of the influence of the total amount of precipitation and the surface air temperature on the nature and rate of change in the level of moisture supply in the region was carried out. The spatial distribution of moisture supply in the region and the rate of its change for the period under study have been established.

In the steppe zone of the Southern Ural region (Russia, Republic of Bashkortostan), an abrupt change in the hydrological regime due to drainage melioration triggered alteration of the set of soil properties, potentially leading to soil degradation. Drainage of the Berkazan-Kamysh nature area resulted in a development of a number of adverse effects, of which the major ones included mineralization of peat organic matter and soil salinization as strong as the formation of meadow solonchaks entirely devoid of vegetation. As illustrated by the example of the Serek-Kul’ nature area, rewetting after drainage has not triggered degradation of the soils and appears to be the most effective practice in restoration of bog ecosystems.

The common hawthorn (Crataegus rhipidophylla Gand.) is a typical representative of arid woodland species of Piedmont Dagestan. It grows in the lower, middle, and upper mountain zones. Identification of patterns of intraspecific and interpopulation diversity, including quantitative traits of annual shoots and their adaptive manifestations under conditions of introduction, makes it possible to determine the optimum of the species and the adaptive potential to specific arid growing conditions. The results of an ecological–geographical experiment on the altitudinal gradient of common hawthorn using the example of an annual shoot are presented. This study was carried out using a unique research assembly “System of experimental bases located along an altitude gradient (1100 and 1700 m above sea level).” Plants grown from seeds collected in different conditions of arid areas were studied. To study adaptive changes using the example of an annual shoot under introduction conditions, ten quantitative traits and one qualitative trait (hairs) of the shoot and leaf were studied. The research results were processed and evaluated using descriptive statistics, correlation, cluster, and two-factor analysis of variance. The degree and structure of variability in the quantitative traits of the annual shoot and leaf were revealed, and the presence of population–geographic differentiation was established based on the traits of “shoot length,” “number of leaves,” and “number of thorns” depending on the germination conditions of the samples. Differences between the samples in terms of the quantitative and qualitative characteristics were determined; with growing altitude above sea level, the increase in the “number of thorns” and hairs on the shoot and leaf can be considered as one of the adaptive mechanisms of vegetative organs to the abiotic factors of the arid climate in mountain conditions.

Research on the Caspian region has been conducted for over 20 years under the auspices of the Framework Convention for the Protection of the Marine Environment of the Caspian Sea (Tehran Convention). It aims to protect not only the water area of the Caspian Sea, but also areas of land located directly adjacent to it from negative impacts. For the first time, based on the concept of Land Degradation Neutrality (LDN), this work presents the results of a comparative assessment of land conditions for the coastal areas of five states: the Republic of Azerbaijan, the Islamic Republic of Iran, the Republic of Kazakhstan, the Russian Federation, and Turkmenistan. The approach implemented made it possible to identify the main trends in land dynamics in the region under consideration, including for individual countries and regions for different periods of observation. The results are presented in cartographic form. It has been established that most regions of the Caspian region are characterized by a deterioration of the current situation associated with the intensification of degradation processes, and the main “hot spots” of desertification are described. At the same time, the dynamics of land degradation in the Caspian region are multidirectional in individual regions and observation periods. Selecting different comparison periods and baselines can help track changes in land conditions over time and identify peaks of improvement and deterioration.

A negative dependence of the digestibility of grassland vegetation on the amount of grasses in the feed consumed, which is in turn associated with an increased content of silicon compounds in grasses, is found. Using the example of four species of herbivores (Przewalski’s horse, American bison, Bactrian camel, and saiga), which differ in the specifics of digestion, the selectivity of their nutrition was studied in relation to two groups of plants differing in digestibility—grasses and forbs. Saigas, like other obviously highly selective consumers of easily digestible food, strictly select forbs with a low silicon content and high digestibility. With the dominance of low-digestible grasses on the grassland and their forced consumption, the saiga population is not viable. Horses and bison, like other representatives of equines and large ruminants, due to the characteristics of the digestive system, are able to assimilate low-digestible grass feeds successfully and are highly specialized in feeding on grasses. The exclusion of forbs from the diet of horses and bison is associated with the increased toxicity of this group of plants. Camels do not discriminate in the choice of grasses and forbs of different nutritional value and currently actively use fallow areas (on former arable land) dominated by weedy plants, which are avoided by other herbivores. Different specialization in the choice of forage plants when different species of animals graze together causes their division in the use of grassland feed resources, eliminates competition between them, and acts as a necessary factor in preserving the species diversity of grassland vegetation.

The various dune fixation works carried out at the level of the dune belt are extremely useful, on the one hand to fight against desertification via the creation of a microclimate which ensures the ecological sustainability of fragile ecosystems, and on the other hand, to improving the way of life of rural populations. In this context, carry out a diachronic study, with the aim of quantifying the floristic diversity after 31 years of planting. Also, the application of Factorial Correspondence Analysis (FCA) and CAH to 118 statements and 74 species revealed 4 plant groups. The main factors that determine them are: slope (Axis 1), soil humidity (Axis 2). The analysis of the results of the diachronic study shows that the overall percentage of vegetation increases in line with the altitudinal gradient, it occupies the lowest topographies of the dune where soil humidity is high and the action of the wind is minimal; windward topographies are generally difficult to colonize; they are drier and more exposed to the prevailing wind (SW), on the other hand the leeward topographies which are in shelter are cooler and therefore easily colonizable. Each fixing species occupies the dune differently as well: Retama retam Webb., grows across the entire dune at different topographies and exposures. Tamarix gallica L. colonizes all the topographies of the dune except the summits at high altitudes exposed to the wind. Tamarix aphylla (L.) Karst and Eleagnus angustifolia L. colonize the lower slopes and inter-dune spaces. Lycium arabica Boiss., recorded a success rate of less than 10%, especially in topographic position facing the wind.

An assessment is given of the hydrogeological potential of the Terek-Kuma sands of the Western Caspian region, the strata of which contain significant reserves of underground water (artesian, ground water) of the Caspian lowland, which are located near the feeding glaciers of the Greater Caucasus. In terms of their chemical composition, they are suitable for irrigating woody and herbaceous ameliorant crops, as evidenced by the long-term scientific and experimental experience of the Achikulak Research Forestry Experimental Station of the All-Union Scientific Research Institute of Agroforestry Reclamation (now the North Caucasus Branch of the Federal Scientific Center for Agroecology, Integrated Land Reclamation, and Protective Afforestation, Russian Academy of Sciences) on the sands of the Bazhigan massif, which provides a wide potential for the use of self-pressure (artesian) and free-flow (ground) underground water in oasis irrigation of sandy lands. Compared to the capital-intensive model of preliminary reservoir accumulation of self-flowing artesian waters for irrigating pastures, the project of using ground water for irrigating fodder phytocenoses directly from wells, by pulsed sprinkling using renewable energy sources (sun, wind energy), appears to be more profitable and faster to pay for itself. According to forecast estimates, the potential of the region’s underground water is sufficient for hydromelioration of more than 100 000 ha of sandy lands in an arid territory.

This study is concerned with a conjugate analysis of the productivity of herbaceous and woody plants from various landscape communities, such as the typical steppe, salinized, woody, and agricultural, in arid conditions of southwestern Siberia performed using different methods; specifically, remote sensing (analysis of the vegetation indices NDVI) and dendrochronological (analysis of the stem growth increment in width in Scotch pine (Punus sylvestris L.) from extrazonal ribbon coniferous forests (bors)). Climate factors were established that govern the dynamics of NDVI and the radial growth increment in trees of the steppe zone, which include the limiting impact of summer temperature and the positive effect of atmospheric precipitation of the previous winter and current summer seasons. Analysis of the vegetation indices and the radial growth increment in trees showed the occurrence of a moderate relationship between them, in that NDVI of May and July of the herbaceous communities (Stipa spp.-Volga fescue and arable lands) correlate with a width of annual rings in trees. The width of the pine radial growth increment in the arid steppe was found to depend on the NDVI value of the crown of tree stands in May from two years before.

On the territory of the Kazakh small hills, boreal plant species have been preserved, growing far beyond the boundaries of their typical taiga ecosystems since the widespread expansion of coniferous forests during the Pleistocene period. These species are an important component of the region’s phytodiversity and require comprehensive study. In the course of this study, based on field observation data and analyses of literary sources, information was obtained on the taxonomic composition of this group of species, their coenotic occurrence, and the ecological and geographical characteristics. In the composition of the plant communities of the Kazakh small hills, 30 species of vascular plants were identified that belong to the boreal ecological–coenotic group of plants, differing in ecology and coenotic affiliation from plants of zonal steppe vegetation. In conditions of a sharply continental arid climate, the studied boreal species grow in special habitats—in mountain forest–steppe landscapes and moist habitats along rivers and along the shores of lakes. The largest number grows on the slopes of hills with granite outcrops as part of island pine forests. In places of increased moisture at the foot of the slopes and in depressions, which are associated with azonal forest communities, mainly small-leaved plants of this group are also found. In addition, finds of boreal plants were noted in the intrazonal meadow and swamp cenoses and on rocky slopes. As an analysis of the distribution across the territory of the small hills has shown, the maximum diversity of boreal species is concentrated in the Kokshetau and Karkaraly floristic regions, where 23 and 29 species of these plants grow, respectively. Three species of boreal plants are included in the Red Book of the Republic of Kazakhstan (2006) due to the small number and vulnerability of their populations; however, as the study showed, a number of other boreal species also require protection. The main threats to the conservation of populations of boreal plant species are excessive recreation and fires. Thoughtful measures are needed to preserve rare and vulnerable plant communities, including plant species growing at the border of the range.