Arid Ecosystems最新文献

The significant volumes of hydrocarbons and associated pollutants released into the environment during the development of oil and gas resources mean that this type of pollution is becoming a priority for many oil production areas. In the Republic of Kalmykia, the soil cover is particularly strongly affected by oil pollution. The aim of this study is to determine changes in the biological properties of brown semi-desert soil, light chestnut soil, and the southern chernozem depending on the nature of the pollutant and its concentration in the soil. Zonal soils of Kalmykia were selected as objects of study. Laboratory and analytical studies, as well as sampling, were carried out using methods generally accepted in biology and soil science. The petroleum products used were commercial and crude oil, as well as fuel oil, kerosene, and gasoline. As a result of this study, it was established that the most informative soil enzymes regarding pollution by oil products are catalase and urease, the activity of which is significantly reduced and depends on the concentration of the pollutant. Phosphatase activity also decreases when contaminated with oil products, but not as significantly; invertase activity is stimulated by low concentrations of oil products and inhibited by high ones. All soils contaminated with petroleum products exhibit high phytotoxicity towards test plants, but the exception is brown semi-desert soil, in which, when contaminated with low concentrations of fuel oil and kerosene, the length of shoots and roots increases.

The results of research work conducted at the Caspian Federal Agricultural Research Center, Russian Academy of Sciences, in Astrakhan oblast in 2024 are reported. The aim of this work was to identify climate changes and to determine their trend in the region. The quantitative climate indices were calculated based on the datasets containing average monthly air temperatures and monthly sums of precipitation for the period of 1978–2023. The evaporative capacity was calculated according to the methods of A.I. Budagovskii, G.T. Selyaninov, and N.A. Shumova. As a result of this study, a negative trend in the Selyaninov hydrothermal coefficient and the Vysotskii–Ivanov moisture coefficient was revealed. The analysis of the meteorological data for 46 years showed that the region is experiencing actual climate change leading to arid warming.

In natural biological systems, living organisms function as a system responsible for soil, botanical, climatic, and hydrological changes, as well as for the conditions created by the organisms themselves. Today, when the climate is changing and human activity is intensified, while biological resources are severely depleted, arid ecosystems are unable to regulate the contradictions in the relationships between natural and anthropogenic factors using their own resources. The dynamic escalation of these emerging contradictions results in increasing deviations from the background level with a significantly expanding range of these changes. According to our evaluation, the common system of soil cover indicators for the tree plantations of the Botanical Garden of Dagestan State University is represented by two zones: (1) the zone of a suppressed state with the beginning of a mitigated aridization process and (2) the zone of the destabilization of drought-resistant tree species, such as the English oak and tillet. The start of the negative influence of aridization stages is mainly associated with a deficiency of moisture and nutrients. One can state that the beginning of the desertification process represents mitigated desiccation of the soil profile, when the moisture content in the root-inhabited layer has decreased to 18–20% and the content of hydrolysable nitrogen is 25–30 mg/100 g of soil. Due to changes in the existing tree cultivation technology, mineral fertilizers are applied in insufficient volumes and with a lack of periodic irrigation.

A map of ecosystems, reflecting the spatial patterns and diversity of the soil–plant cover within the boundaries of landscape units, has been compiled for a test plot of the Caspian Lowland located at the contact of the Early Khvalyn and the Late Khvalyn sea plains. The heterogeneity of the plant and soil cover of this area is related to the microrelief, conditions of soil moisture, and soil salinity, which results in the formation of a complex pattern. The distribution of ecosystems in the Ural River valley is determined by the distance from the riverbed, the relief, and the moisture regime: groups of willow and poplar shoots are replaced by woodreed–poplar floodplain forests and forbs meadows. Vegetation undergoes anthropogenic transformation. The impact of fires is the strongest with respect to the affected area, and technogenically disturbed lands occupy a smaller area. Overgrazing areas are allocated to wells and wintering places. Regardless of the transformation factors, weedy vegetation (of annual saltwort and ephemerals) is formed in disturbed areas.

Unfavorable hydrothermal conditions and irrational use of agricultural land, including excessive grazing pressure, lead to the degradation of steppe and desert landscapes up to the complete loss of vegetation and upper soil horizons. This serves as a prerequisite for the intensification of deflation processes and the emergence of dust storms, which provoke further growth in the area of open (moving, blowing) sands and areas devoid of vegetation. Remote sensing data, including spectral vegetation indices obtained on their basis, are widely used to monitor the prerequisites and consequences of intensive deflation processes. This study aims to assess the information content of 45 different vegetation indices calculated using Sentinel-2 and Landsat satellite data for mapping open sands in the Northwestern Caspian region, where degradation processes of pastures on sandy and sandy loam soils have intensified in the last decade. As a result of comparison with aerial survey data on three test sites with a total area of 23.1 hectares, which was carried out three times during 2023, the most informative vegetation indices were established. For Sentinel-2 data with a spatial resolution of 10 m, NDVI and spectral radiance coefficients in the visible range are recommended, and for data with a resolution of 20 m and Landsat, vegetation indices based on the visible and shortwave infrared ranges (NDSAI, BUI, NBR2, BAEI) are recommended. The results of this study can be used in mapping open sands using satellite remote sensing data and developing automated methods for their classification, including those based on machine learning.

Data on the current state of white saxaul pastures (Haloxylon persicum Bunge), widespread in Northwestern Kyzylkum (in the southern part of the Karakalpak Republic, Uzbekistan), are given. The pasture vegetation was studied by conventional methods of terrain geobotanical and floristic research at experimental stations and during route surveys used for studying and monitoring pastures and vegetation mapping. Three varieties of white saxaul pastures were analyzed during the terrain research in 2023. We determined their area, soil cover pattern, the total projective cover of the plant community, the species composition of plants, the yield of the forage mass, and the nutritional value of the forage. The calculated yield of the eaten part, nutritional forage value, and feed reserves show that all three varieties may be recommended for year-round use. The destruction of saxaul stands as a result of diverse human activities causes the destruction of natural ecosystems, soil compaction, an increase in the areas of drift sands, and a decrease in the species composition of flora and fauna. Therefore, there is a need for regular comprehensive geobotanical studies to assess the state of white saxaul pastures and for elaboration of measures to improve and restore them in modern environmental management conditions. The preservation of arid pastures in Uzbekistan is a complex problem that requires joint efforts by the state, farmers, and the population. Sustainable development and preservation of the unique ecosystems of arid zones may be achieved only by a systematic approach to this problem.

Fifteen juvenile greater spotted eagles (Clanga clanga) in the central regions of European Russia and the Middle Volga region were tagged with GPS–GSM trackers, which made it possible to determine the length of migration routes (passing through arid regions and abroad) and the duration of autumn and spring migrations, to analyze the spatial distribution within these routes, to identify the locations and duration of migration stops, and to determine the mortality rate and also the dates of the beginning of departure. It has been established that the duration of migration, which varies greatly among individuals, depends on the distance of wintering areas from the birthplaces of the birds and on the presence and duration of migratory stops. The location of migration routes varies significantly not only among birds from the same population, but also among individuals born in the same nesting area, and even among chicks from the same brood. The most significant factors influencing the start dates of autumn migration are the transition of the average daily temperature through 10°C and a sharp decrease in night temperatures. First-year birds begin their migration later than birds older than one year old. The patterns of use of the territories where long-term migratory stops of the two individuals were recorded differed significantly. Mortality rates for the greater spotted eagles are highest during the first autumn migration.

In this work, field surveys, carried out over 30 years (1986–2016) in three Algerian geographical regions during the desert truffle fruiting seasons, allowed us to locate 61 desert truffles producing sites spread over several bioclimatic zones, to determine the pedoclimatic characteristics of sites and to identify the desert truffle species, their host plants and their natural mycorrhizal associations. This study complements our previous work on the characterization by macro- and micromorphological studies and molecular phylogeny of desert truffle samples collected throughout Algeria. Results revealed that natural production of these desert truffle species is irregular from year to year and closely related to rainfall intensity and distribution, temperature and storm frequency during the fruiting seasons. Nine desert truffle species grow on sandy-loam soils and form endomycorrhizae with Helianthemum spp. on calcareous soils and mantle-free ectomycorrhizae with Tuberaria guttata on acidic soils.

The highlands of Tokinsko-Stanovoi National Park (established at the end of 2019 with an area of 257 000 hectares in the northern part of Amur oblast at the junction of its borders with Yakutia and Khabarovsk krai) are extremely important for preserving the population of the Okhotsk snow sheep (Ovis nivicola alleni Matschie, 1907), a rare and poorly studied subspecies of snow sheep or bighorn sheep, listed in the Red Books of Amur oblast (2020) and Yakutia (2003). This animal is the primary edificator of the mountain heaths of the Stanovoi Range, which are characterized by a moisture deficit. In Amur oblast, snow sheep inhabit a relatively narrow strip of the Tokinsko-Stanovoi highlands (the eastern section of the Stanovoi Range) 5–15 km wide, stretching along the northern border of Amur oblast from the headwaters of the Okonon River in the west to the headwaters of the Maya River in the east. In addition, they are regularly observed in some areas of Dzhugdyr ridge. The bulk of the population in this region is concentrated in the territory of the national park. The data on the spatial distribution, abundance, and age–sex composition of snow sheep presented in the article were obtained during expeditions in 1992, 1993, 2009, 2018, and 2020–2024. The following were noted: uneven distribution on the mountain heaths of Tokinsko-Stanovoi (higher population density in the central part and lower density on the outskirts of the mountainous country), features of the seasonal distribution, and use of large natural mineral licks (significant concentrations on salt licks in the first half of summer). The observation results indicate the extreme living conditions of the group, determined by the harsh climate of the highlands. The proportion of yearlings (8.3–17.4%) and adult males (9.1–18.2%) is significantly lower than in other, even more northern populations of this species. Disturbances in the age and sex structure may also be associated with the consequences of intensive trophy hunting carried out in recent years before the establishment of the national park (2016–2019). The park has organized effective protection of bighorn sheep, but hunting for them is still permitted in the adjacent territory of Khabarovsk krai. To maintain the sustainability of the population in the region, additional measures are needed to protect and study this species: the creation of a buffer zone of the Tokinsko-Stanovoi National Park, the establishment of Bolshoe Toko Lake National Park in Yakutia, the creation of a wildlife refuge in the Ayano-Maiskii District of Khabarovsk krai on the northern macroslope of the Stanovoi Range, and a survey of Dzhugdyr ridge. It is advisable to study the age and sex structure of bighorn sheep in the first half of summer, when they are concentrated on mineral licks, and to count their numbers in the second half of summer, when they are relatively evenly distributed across the territory.