Arid Ecosystems最新文献

The effect of climate changes on productivity of the aboveground phytomass of steppe plants on Vodnyi Island of Manych-Gudilo Lake in the Rostovskii Reserve was analyzed. In the period 1991–2022, the mean annual temperature in the study area increased, on average, by 0.07°C/year, and the annual precipitation decreased by 1.93 mm/year. The de Martonne aridity index decreased significantly (by 1.16 per year, on average), which indicated arid warming. Temperatures increased in all seasons, while precipitation shifted from summer and autumn to winter and spring against the background of a general decrease. The structure of the vegetation cover was dominated by grasses, the share of which averaged 62%. The effect of precipitation on the total productivity of the phytomass was the leading one and amounted to 51.3%. The overall decrease in precipitation favored a decrease in the phytomass of the studied plant groups, except for cereals, the productivity of which became greater with an increase in precipitation in winter and spring. These changes resulted in a further increase in the proportion of grasses in the plant cover of steppes on Vodnyi Island and to a decrease in the participation of other families. The revealed climatic trends will contribute to a drop in the productivity of the aboveground phytomass of steppes on Vodnyi Island, of grasses, in particular.

An analysis of the coenoflora of unique botanical and geographical objects, like chalk uplands within the steppe and desert zones of the Russian Federation and the Republic of Kazakhstan, where specific plant communities develop, consisting mainly of calciphytes, is presented. The study area covered five districts of Orenburg oblast of Russia, as well as five districts of the Aktobe and Atyrau regions of the Republic of Kazakhstan. The total flora of the chalk uplands contains 218 species of vascular plants from 35 families and 121 genera. The floristic diversity of chalk uplands reflects their distribution both on the latitudinal gradient and in successional series of plant communities at different stages of overgrowth of chalk rocks. It was revealed that the highest concentration of rare and endemic plant species is characteristic of the massifs of the Sub-Ural Plateau—34 rare plant species from 18 families. Of these, 22 species are included in the Red Data Books at the state level. It is noted that, on the territory of Kazakhstan, where chalk massifs occupy the largest areas, chalks remain largely without a special protection system.

In the province of Naâma numerous projects have been initiated over the years to rehabilitate areas and combat desertification. This study focuses on the northern region between the municipalities of El Biodh and Mécheria, which is divided into three sites: Site A, Site B, and Site C. The Transformed Soil Adjusted Vegetation Index (TSAVI) was employed to monitor the evolution of vegetation cover and degradation resulting from these projects, and a concept of fuzzy logic was used to build a map for desertification and drought severity using TSAVI, SVI (sandy veil index) and LST (land surface temperature) over five years 1984, 1994, 2000, 2013 and 2023. The results revealed varying degrees of success among these projects, with some achieving their objectives and others experiencing degradation. The contributing factors can be summarized as follows: climate change emerged as a major influencer, with high temperature values and low precipitation rates causing interconnected damages. Overgrazing impacted the pastoral plantation project, which achieved some success despite being degraded. Urban sprawl has affected the green belt project, which has been deteriorated due to trees felling for urbanization. The choice of plant species, namely Pinus halepensis and Eucalyptus camaldulensis, in rehabilitation projects led to no regeneration and subsequent degradation due to their incompatibility with the harsh climatic conditions of the region. This was observed in projects, such as green belt project and mass tree afforestation. In contrast, the sand dune fixation project exhibited significant development over the years, attributed to the use of Tamarix articulata and Retama raetam species, known for their tolerance to the climatic conditions of the study area, and were very useful to stabilize the sand and protect the area.

The interannual structure of four coenopopulations (CPs) of Dracocephalum peregrinum L. located in the steppe communities of Siberia is considered. A range of ontogenetic spectra has been established: left-sided, centered, and bimodal. During the period studied, the ontogenetic spectra of all CPs show an accumulation of individuals of the pregenerative period; the proportion of the generative fraction in the CPs of Tuva increases (CP2, CP3), and those of Gornyi Altai (CP1) and Khakassia (CP4) decrease. Changes in the structure of the spectra occur for various reasons: a decrease in anthropogenic load (CP1–CP4), an increase in the amount of precipitation (CP2, CP3), the growth of shrubs in the cenosis (CP3), and microconditions of the local area (CP4). Demographic and development rate indicators confirmed the rejuvenation and stability of the studied CPs.

Hyperhalophytes dwarf semishrubs communities in the desert zone of the North-Western Caspian lowland are confined only to solonchaks along the shores of saline lakes, which stretch from north to south and southeast from 47° N to 45° N. Cenoses are poor in species composition and include from 1 to 10 species. The exception is the formation formed by Artemisia santonica, which has 42 species. The communities of the Caroxylon dendroides, Kalidium foliatum, and Anabasis salsa formations are located at the northwestern limit of their range, most of which are located in the vast Iranian–Turanian desert. The cenoses of Halocnemum strobilaceum have a wider range – the Mediterranean (from North Africa to Middle and Central Asia). Communities of Halimione verrucifera, Artemisia santonica, Frankenia hirsuta, and Limonium suffruticosum are distributed from the Black Sea region to the Caspian lowland (Lavrenko, 1980). The communities of the hyperhalophytes under consideration are confined to a certain type of salinity and the range of the position of the groundwater level. In the northern part of the region, the sodium sulfate type of salinity predominates mainly in the first meter of soils, and communities formed by Artemisia santonica, Caroxylon dendroides, and Anabasis salsa are associated with these conditions. In the southern part, chlorine ions dominate in the salt composition of soils, and the cenoses of other formations are associated with these conditions (Goryaev, 2019; Goryaev, Korablev, 2020). The novelty of the work is related to the fact that, based on research data conducted in the period 2017–2024 in the North-Western Caspian lowland, located in the desert zone, the ecological and phytocenotic classification of hyperhalophytic dwarf semishrubs communities was performed for the first time, ordination and cluster analysis was carried out with respect to salinization and soil moisture factors.

A new method for compilation of a map of soil organic matter content based on multitemporal spectral characteristics of the open soil surface has been implemented in the South Russian province of the steppe zone of the East European Plain. The map is based on the revealed functional relationship between the content of soil organic matter and the multitemporal characteristics of the open soil surface with the coefficient of determination of 0.81. The spatial resolution of map is 30 m, which exceeds the accuracy of the existing agrochemical survey of plowed land in Russia. The implementation of the new approach has required modification of the terrain agrochemical survey based on a map of the C coefficient of the multitemporal soil line. The detailed map of the soil organic matter content develops methods of mapping the soil cover structure in the direction of identifying the intra-field heterogeneity of the soil cover for precision farming systems.

The genesis and the transformation of the concept of “steppe” are discussed. It has been shown that initially the etymology of this term can be linked to a terrain feature and forestlessness and in general corresponds to the “steppe forefatherland” of Indo-European peoples and languages. We have found that this term has a dualistic nature, the latter having played a role in how it was interpreted in the ancient literature and scientific sources. We have traced the diversity of the meanings of “steppe” as an orographic term, its correlation with the concept of “field,” and how it happened that “steppe” became a landscape concept. For the first time, an attempt was made to explain the spread of this term based on the results obtained by the interdisciplinary collaboration of geneticists, linguists, and archaeologists and their estimates of the time of formation and settlement of Indo-European peoples.

Study of regional indicators of the tree canopy of forest shelterbelts, one of which is reduction numbers, is of considerable scientific and practical interest. Such data are not available for the conditions of the Northwestern Caucasus. The goal of this work is to investigate the pattern of change and to calculate the values of reduction numbers of tree heights in the shelterbelts of the region. For this purpose, problems related to measuring tree heights in the inner and outer rows of shelterbelts were solved. The values of reduction numbers were determined using various methods, and models of their change depending on the rank of trees were created. Ten trial plots with 106–141 individuals in each were laid out for the five main species. Reduction numbers were determined using the classical Schiffel method, average values for rank groups, and newly created models. The value of reduction numbers did not depend on the type of tree species (F = 0.011, P = 0.999) or the row of growth in the belt (F = 0.0002, P = 0.995) and changed in parallel in the inner and outer rows (T = 0.058, P = 0.9528). A similar trend was observed when using the method of averaged values for rank groups. The reduction numbers of heights in forest shelterbelts, when compared with the classic ones for massive forest plantations, demonstrated a difference of over 5% in the extreme ranks; with Schiffel’s data, rank 10 at 5.98, rank 100 at 10.4; with Davidov’s data, rank 100 at 10.4%. This indicates the need to clarify the values of reduction numbers for the objects under study. An adequate model (R ² = 1) was developed, and new values of reduction numbers of heights for trees growing in forest shelterbelts of the Northwestern Caucasus were calculated on its basis.

The morphological variability and plasticity of traits, age structure, abundance, and density of Trifolium repens L. were studied in arid conditions of the Surkhandarya region of the Republic of Uzbekistan. These studies were conducted on different phytocenoses under anthropogenic load. The species is characterized by low–medium plasticity and medium variability of the morphological traits. In undisturbed cenopopulations, high vitality (IVC = 0.87) and a large proportion of pregenerative individuals are observed. Increased anthropogenic impact leads to a decrease in vitality (IVC = 0.62). An ontogenetic structure with the left-sided (CP 1) and centered type (CP 2, 3, 4) is observed. The characteristic ontogenetic spectrum of Trifolium repens is left-sided, with an absolute maximum in one of the pregenerative groups. Cenopopulation 1 coincides with the characteristic type of the species studied; it has no anthropogenic load and a high projective cover (90%), and the density of individuals is 5.3 ind./m². Cenopopulations 2–4 do not coincide with the characteristic one. Their young fractions die off, and middle-aged individuals accumulate. The reasons for the reduction in the number of individuals are the negative impact of the anthropogenic factor and climate change.

This article considers the features of the mean iteration method when studying populations the quantitative indicators of which have different statistical distributions. The studies were conducted in the central part of the Northwest Caucasus. The published and field data used by the authors came from eight sample plots laid out in the lower mountain, forest–steppe, and steppe zones of the central part of the region, where various indicators were studied for seven plant species. The sample size in the sample plots was 122–485 individuals. Statistical data processing was carried out using the Stadia8.0 and Microsoft Excel for Windows programs. The values of inter-iteration means and gradations were established using known and original methods. It was revealed that, with a normal statistical distribution, the inter-iteration means have close values (difference of 0–4.23%) with the values of the means increased by 0.5–2 standard deviations. To correct extreme inter-iteration values, where the sample is insignificant (1–4 observations), it is recommended to use forecast models, which should be calculated separately for each option. The allocation of gradations of quantitative traits in populations by the iteration of means method ensures an adequate distribution of indicators in three or five gradations compared to methods focused on the average increased by the value of the standard deviation or dividing the indicators into equal values.