Sandy Steppe Research Articles

Mercury in the landscape components of the Don River Delta

The Don River Delta acts as a protective environmental barrier to the washout of pollutants from adjacent drainage areas. The priority pollutant is mercury, which comes as an industrial, agricultural and domestic wastewater`s part. The mercury concentrations levels in soils were determined by expeditionary and laboratory studies: the indicators ranged from 0,025 to 0,082 μg/g d.m. in the sandy-psammophyte meadow (section №1), in the sandy steppe (section №2) – from 0,012 to 0,022 μg/g d.m., in the true meadow (section №3) – from 0,027 to 0,4 μg/g d.m. and on the landscape with near-water vegetation (section №4) – from 0,035 to 0,565 μg/g d.m. The mercury accumulation in soils according to concentration coefficients is noted in the series «the Near-water landscape(13,5) > the True meadow landscape(5,9) > the Sandy-psammophyte meadow landscape(2,5) > the Sandy steppe landscape(1)». It was found that the soil moisture increased from the section №1 to the section №4 (on average from 18,06 to 35,4%), and the highest total biomass was recorded on the sandy-psammophyte landscape (46,55 t/ha) and the landscape with near-water vegetation (41,85 t/ha).

Exploring diversity within the genus Tulostoma (Basidiomycota, Agaricales) in the Pannonian sandy steppe: four fascinating novel species from Hungary

Steppe vegetation on sandy soil in Hungary has recently been revealed as one of the hot spots in Europe for the stalked puffballs (genus Tulostoma). In the framework of the taxonomic revision of gasteroid fungi in Hungary, four Tulostoma species are described here as new to science: T. dunense, T. hungaricum, T. sacchariolens and T. shaihuludii. The study is based on detailed macro- and micromorphological investigations (including light and scanning electron microscopy), as well as a three-locus phylogeny of nrDNA ITS, nrDNA LSU and tef1-α sequences. The ITS and LSU sequences generated from the type specimen of T. cretaceum are provided and this resolved partly the taxonomy of the difficult species complex of T. aff. cretaceum.

Small grassland fragments and connectivity support high arthropod functional diversity in highly modified landscapes

Abstract Grassland ecosystems undergo dramatic habitat loss and fragmentation worldwide due to agricultural expansion and intensification. Among different taxonomic groups, grassland arthropods are particularly sensitive to this process and, therefore, are exposed to considerable risk. Although many studies focus on land use impacts on arthropod diversity, these mostly consider taxonomic diversity and neglect trait‐mediated functional responses. However, studying functional diversity often provides more accurate insights into ecosystem processes. Here, we assessed the effect of fragment size and connectivity on the functional composition (community‐weighted mean trait values) and diversity (Rao's quadratic entropy) of two diverse and abundant arthropod groups: spiders and true bugs. We assigned functional traits for more than 300 species collected from 30 sandy steppe (forest‐steppes) and 30 loess steppe fragments (kurgans) in the southern part of the Hungarian Great Plain. Functional responses to fragmentation were observed for spiders in forest‐steppes and for true bugs in kurgans. We found higher functional diversity in better‐connected fragments for spiders and in small fragments for both groups. We collected small, humidity‐preferring and web‐building spiders in small fragments, and there were more ballooning spiders with moist habitat preferences in well‐connected fragments. Furthermore, increasing grassland connectivity resulted in a significantly higher proportion of polyphagous and humidity‐preferring individuals in the true bug communities. Our results highlight the importance of small grassland fragments in maintaining high arthropod functional diversity. Even small fragments in a well‐connected grassland network can promote ecosystem functioning and associated services within human‐dominated landscapes.

Effects of vegetation restoration on soil properties and vegetation attributes in the arid and semi-arid regions of China

Driven by the goal of reversing desertification and recovering degraded lands, a wide range of vegetation restoration practices (such as planting and fencing) have been implemented in China's drylands. It is essential to examine the effects of vegetation restoration and environmental factors on soil nutrients to optimize restoration approaches. However, quantitative evaluation on this topic is insufficient due to a lack of long-term field monitoring data. This study evaluated the effects of sandy steppe restoration and sand dune fixation in the semi-arid desert, and natural and artificial vegetation restoration in the arid desert. It considered soil and plant characteristics using long-term (2005–2015) data from the Naiman Research Station located in the semi-arid region and Shapotou Research Station in the arid region of China's drylands. Results showed the sandy steppe had higher soil nutrient contents, vegetation biomass and rate of accumulating soil organic matter (OM) than the fixed dunes and moving dunes. Soil nutrient contents and vegetation biomass of the natural vegetation of Artemisia ordosica were higher than those of the artificial restoration of Artemisia ordosica since 1956. Artificial restoration had a higher rate of accumulating soil OM, total nitrogen (TN) and grass litter biomass than natural restoration. Soil water indirectly affected soil OM by affecting vegetation. Grass diversity was the main influencing factor on soil OM variance in the semi-arid Naiman desert while shrub diversity was the main factor in the arid Shapotou desert. These findings indicate that sand fixation in the semi-arid desert and vegetation restoration in the arid desert bring benefits for soil nutrient accumulation and vegetation improvement, and that natural restoration is preferable to artificial restoration. Results can be used to formulate sustainable vegetation restoration strategies, such as encouraging natural restoration, considering local resource constraints, and giving priority to restoring shrubs in arid areas with limited water.

STATE OF COENOPOPULATIONS OF <i>THYMUS MONGOLICUS</i> (LAMIACEAE) DEPENDING ON ENVIRONMENTAL CONDITIONS

The application of the concept of population organization of ecosystems is an integral part in assessing the state of plant populations, as well as in modeling the response of vegetation to climate change. In this regard, it is especially important to focus on the plant species which are widespread in different habitat conditions, the study of their populations will reveal the range of adaptive capabilities of the species at different levels of organization (organismic, populational). One of such species is Thymus mongolicus (Ronn.) Ronn., an implicitly polycentric dwarf shrub, widely distributed in different environmental conditions of Tuva. The aim of the work is to study the features of the development and ontogenetic structure of T. mongolicus coenopopulations in different environmental conditions of Tuva.Three coenopopulations (CP) were studied: in a sandy steppe on a plain (51°34'55.6"N, 94°21'25.5"E), in a steppified meadow along the river bank (51°18'26.4"N, 95°50'45.7"E), in a petrophytic high-altitude steppe on a talus slope (50°31'55.6"N, 91°07'25.5"E). The polyvariance of individual development, the ontogenetic structure of CP, the type of the ontogenetic spectrum of CP, the type of CP, the ecological and average density of CP, demographic parameters (recovery index, aging index, efficiency and age indexes, the rate of population development) were analyzed (Uranov, 1975; Tsenopopulatsii…, 1976, 1988; Zhukova, 1995; Zhivotovsky, 2001). The variability of population traits in different years of the study (2012 and 2021) was analyzed in the CP in the sandy steppe. Spearman’s correlogram was used to study the interrelationships between the traits of coenopopulations and environmental conditions.In this research we revealed that a bimodal type of the ontogenetic spectrum with an absolute maximum on individuals of the young generative state (44.1%) is formed in the CP located in the sandy steppe. According to the peculiarities of the T. mongolicus development in the conditions of sandy steppes, the accumulation of individuals of a young generative state is associated with intensive vegetative reproduction. It was also revealed that their number increases with an increase in the amount of precipitation during the growing season, the height of the snow cover and the projective cover of the herbage. Due to increased competition for environmental resources, later on there is a rapid transition of young generative individuals to the old generative state, a second maximum is formed in the right part of the spectrum. The bimodal type of the ontogenetic spectrum is also formed in the CP located in the conditions of a petrophytic community on a steep slope (angle 40°) with a mobile rocky substrate. Virginal and young generative individuals accumulate in almost equal numbers (26.3% and 25.4%, respectively). Statistical analysis shows a relationship between the slope steepness and a high proportion of individuals of vegetative origin, and on the contrary, the number of individuals of seed origin is in inverse relation to the slope steepness. Ramets are characterized by low viability, they quickly pass into a subsenile state. In the CP in the conditions of a steppified meadow community, a left-sided type of the ontogenetic spectrum is formed. The maximum in the spectrum is accounted for young generative individuals. A strong positive relationship was revealed between the number of young individuals and such factors as the amount of precipitation during the growing season, leveled relief, static soil substrate, snow cover height, total projective cover of the herbage.It is established that fluctuations occurring in different years in the CP located in the sandy steppe are expressed in the alternation of the processes of aging (in 2012) and rejuvenation (in 2021). The rejuvenation of the CP in 2021 occurs due to intensive particulation in young and mature generative states and coincides with a more favorable humidification regime. In addition, there is a decrease in ecological and average density due to a decrease in the proportion of old individuals over the past 10 years.The revealed changes in the characteristics of coenopopulations due to the peculiarities of the development of individuals in specific habitat conditions should be considered as organismic and populational adaptation mechanisms that support the stable state of T. mongolicus coenopopulations in Tuva.

Растительные сообщества песчаного массива Сарыкум (Республика Дагестан)

Растительные сообщества песчаного массива Сарыкум (Республика Дагестан)

Taxonomical and chorological notes 18 (184–194)

Floristical records of one fungus and ten flowering plants are presented from Hungary. We report a new occurrence of Calvatia candida in a valuable Pannonian sandy steppe habitat. Some of our floristical data present new occurrences of species that are rare in Hungary, but in the case of Orobanche minor, Minuartia viscosa, due to the low number of recent floristical data, we also try to clarify the distribution pattern of the species with data from specimens documented in the BP herbarium. The first occurrences of the rare, red-listed species Papaver hybridum was detected from the Duna-sík region. We report the first data of Orobanche minor from the Hungarian Middle Mountain Ranges, Minuartia viscosa is new for the southern part of the Mezőföld. A new record of Dactylorhiza sambucina from the Vértes Mts, which is in decline in our low-middle mountain areas, is published, an important observation from a conservation point of view. The data of Potentilla patula reported here is a new observation for the area of Cserhát-vidék. Our other data are from ruderal habitats, where we report observations of taxa that are mainly expanding but with few records in Hungary. The second Hungarian record of Senecio × helwingii is from the district of Zugló in Budapest. Erigeron sumatrensis has been found in several regions of Hungary, Euphorbia glyptosperma, Gypsophila perfoliata new occurrences were found in the border of Kecskemét. The recently suggested spreading of Medicago orbicularis is confirmed by new occurrence data from the Tihany Peninsula.

Псаммофитная растительность долины реки Худан (Республика Бурятия)

Псаммофитная растительность долины реки Худан (Республика Бурятия)

Syntaxonomy of the Sandy Steppes’ Vegetation in Central Anatolia, Türkiye, and its Surroundings

Bu çalışmada Orta Anadolu ve çevresindeki, tamamı volkanik alanlarda bulunan kumlu bozkır vejetasyonunun sintaksonomik analizi yapılmıştır. Çalışma kapsamında 2018 ve 2019 yıllarında Karapınar (Konya) ve İscehisar (Afyonkarahisar) civarındaki kumlu bozkır vejetasyonundan kaydedilen 23 relevé ile Göreme (Nevşehir) çevresinde yapılmış çalışma birlikte değerlendirilmiştir. Sintaksonomik analizde Braun-Blanquet floristik metodu kullanılmıştır. Yapılan değerlendirme sonucu tamamı yeni iki alyans (Centaureo pulchellae-Artemision campestris, Poo bulbosae-Artemision campestris), iki birlik (Minuartio arachnoideae-Stipetum hohenackerianae, Poo bulbosae-Artemisetum campestris) ve bir alt birlik tanımlanmıştır. Tanımlanan bu sintaksonlar Avrupa orman-bozkır ve bozkır bölgelerinde gelişen tınlı kumlu bozkır topluluklarını temsil eden Festucetalia vaginatae ordosuna ve Koelerio glaucae-Corynephoretea canescentis sınıfına bağlanmıştır. Bu çalışma Festucetalia vaginatae ordosunun dağılışının Türkiye’ye (Orta Anadolu ve çevresi) kadar uzandığını ortaya koymuştur.

Ecological and biological characteristics and productivity of Kochia prostrata in the conditions of the Caspian semi-desert

Kochia prostrata (L.) Shrad. - a perennial plant with a height of 35-75 cm, according to its life form - a shrub, according to ecology - an euhaloxerophyte, according to an adaptive strategy - violent, an extremely drought-resistant and salt-tolerant, valuable forage plant in desert pastures. It grows on solonetz soils, stony soils, chalk outcrops, in saline and sandy steppes, plain desert sands, on gray soils. In the growing season, Kochia prostrata hay contains up to 16.5 % protein, 15.4 % ash substances, 2.7 % fat, 34.5 % nitrogen-free extractives and 29.6 % fiber. Fodder productivity reaches 2.2-2.5 t/ha of dry fodder mass, seed productivity - on average 100-150 kg/ha. High drought resistance and salt tolerance, good forage qualities make Kochia prostrata a promising forage plant for introduction into cultivation in arid regions of the Caspian semi-desert in order to restore the lost biodiversity and forage productivity of degraded pastures.

Phytoindication approach to assessing factors determining the habitat preferences of red deer (Cervus elaphus)

The study examined the possibility of using the phytoindication technique to describe habitat preferences of red deer in a relatively homogeneous area. Two alternative hypotheses were tested. Hypothesis 1 suggests that the relationship between red deer and vegetation is due to a trophic factor, so preferences for individual plant species cause vegetation to influence the distribution of animal numbers. Hypothesis 2 suggests that environmental factors influence vegetation, structuring and determining the productive level of the community as a whole. Therefore, environmental factors, rather than individual plant species, cause vegetation-animal interactions. The research was conducted on Biryuchiy Island Spit, where the Azov-Sivash National Nature Park is located. The geobotanical surveys were performed in three types of ecosystems: sandy steppe (vegetation class Festucetea vaginatae), saline meadows (vegetation class Festuco–Puccinellietea), and artificial forest plantation (vegetation class Robinietea). 250 releves were recorded according to the Brown-Blanquet approach. The number of fecal pellets and the number of groups of pellets of red deer was recorded together with geobotanical surveys in the same sample plots. The pellet groups counted in the field were converted to deer densities in specific vegetation classes taking into account the number of pellet groups on the site and the decay rate of the fecal pellets. The vegetation types were distinguished by the number of deer fecal pellets per unit area. The highest number of fecal pellets was found for the plant class Festucetea vaginatae, somewhat fewer fecal pellets were in the plant class Robinietea, and the lowest number was in the plant class Festuco-Puccinellietea. A geometric distribution model is adequate for explaining the experimental data on the number of fecal pellets. A total of 59 species of flowering plants were found. Based on the species composition and projective cover of species, the ecological regimes of ecotopes were identified by phytoindication. The correspondence analysis of the vegetation revealed two ordination axes. The ordination axis 1 (CA1) was able to explain 11.3% of community inertia, and the ordination axis 2 (CA2) was able to explain 5.2% of community inertia. The maximum excretory activity of animals was recorded for the central part of the ordination space, indicating the presence of an optimum zone in the gradient of environmental factors that structure plant communities. The forward selection procedure allowed the Nutrients Availability variable to be selected as the most important variable to explain variation in the plant community structure. The number of deer fecal pellets exhibited different patterns of response in the Nutrients Availability gradient. The response within the plant class Festucetea vaginatae could best be explained by Model III from the list of HOF-models. The response of the excretory activity of deer within the class Festuco-Puccinellietea could best be fitted by the model IV, which represents a symmetric Gaussian curve. The response of excretory activity in the Robinietea vegetation class was asymmetrical bimodal. The ecological properties of the red deer ecological niche in both the drier and less mineralized part of the range of ecological conditions and the wetter and more mineralized part should be assessed in the context of the prospects for future studies.

Habitat Mosaics of Sand Steppes and Forest-Steppes in the Ipoly Valley in Hungary

The present study focuses on the mosaic-like occurrences of patches of steppes and fore-steppes in the Pannonian forest-steppe zone. We present the current vegetation, which is maintained including by human landscape use, i.e., grazing and mowing. The area is complex and for this reason it shows the changes in the landscape and differences in the vegetation more diversely. We wanted to answer the questions: Do sand steppes and forest-steppes occur in the Ipoly Valley and what location? What kind of environmental effects influence the species composition on these areas? Besides classic habitat mapping, are the satellite data from Sentinel-2A useful for distinction of different areas? Comparison of vegetation patches was based on the Hungarian habitat classification system (ÁNÉR). Based on satellite images, quantile data of the Normalized Vegetation Index (NDVI) were used for comparison. Based on the result, water bodies and urban areas are clearly distinguishable from other natural habitats. In some natural vegetation types, we found visible differences, such as grasslands, i.e., sandy steppe meadows and shrubby, woody vegetation patches. Sandy vegetation mainly grows on calcareous soils, which appear to be mosaic-like in the landscape on raised alluvials on the patches of past islands and reefs. From open to continuous closed grasslands, these vegetation types mainly grow on lithosoils. New occurrences of Pannonian sandy vegetation were discovered. In the sandy areas along the Ipoly Valley, open sandy grasslands were found, which is where the northernmost known occurrences of this vegetation type are. Besides common sandy grassland species, the vegetation also contains herbs that are typical in loess-grasslands and it is maintained by grazing, similarly to the eastern Pannonian area. This type of grazing can be useful when maintaining the mosaic-like appearance and diversity of the vegetation.

ДИНАМІКА ЧИСЕЛЬНОСТІ СТЕПОВОЇ ГАДЮКИ VIPERA RENARDI НА ПІВДНІ ЛІВОБЕРЕЖНОЇ УКРАЇНИ

The steppe viper (Vipera renardi (= ursinii) Christoph, 1861) is a background species of snakes in the steppe zone of southern left-bank Ukraine. This species is a figurant in the Red Book of Ukraine and is protected in accordance with the Bern Convention. According to the IUCN Red List, Vipera renardi has a Vulnerable species (VU) status, which is assigned to species that are under threat of becoming endangered. Anthropogenic transformation, namely, plowing, afforestation, irrigated agriculture, fires, synanthropization, etc., lead to the fact that in the Black Sea steppe, in the Lower Dnieper arenas of steppe, the viper disappears. This species has been preserved in the protected areas of the region and in the less transformed areas of the coastal and sandy steppe. The study area includes the forest-steppe areas of the Black Sea Biosphere Reserve (BSBR) and the territory of the “Svyatoslav’s Biloberezhzhya” National Nature Park (NNP BS) on the Kinburn Peninsula, the Black Sea areas and the islands of Tendrivska and Yahorlytska Bays, which are part of the Black Sea Biosphere Reserve. The dynamics of the number of steppe vipers also depends on abiotic factors too. In wetter years and the next 1-2 years, the number of vipers in the region decreases. In dry years, the number of steppe vipers increases. In the last 20 years, according to the results of long-term monitoring, the dynamics of the steppe viper population has a negative trend both in the Black Sea steppe and in the arenas of the Lower Dnieper.The cyclic dynamics of the steppe viper in our region is 3-5 years, the highest amplitude is 1.4 units, the maximum values of the relative abundance over the past 20 years have decreased from 1.5 to 0.4 ind./km, the minimum - from 0.3 to 0,1 ind./km. To preserve the population of this species in the south of the left-bank Ukraine, it is necessary to increase the areas with limited use of natural resources, namely, with the prohibition of plowing, prevention of excessive grazing and exploitation of sand deposits. In addition, it is required to strengthen environmental education and propaganda among the local population about the need to preserve the steppe viper in natural conditions and change the hypertrophied thought about the danger of this snake. The extensive network of protected areas in the region: reserves, national nature parks, regional landscape parks, protected tracts, etc., contributes to the conservation of this species. Key words: steppe viper, Black Sea steppe, Lower Dnieper arenas, population dynamics, monitoring.

Характеристика ценопопуляций Serratula centauroides (Compositae) в Забайкалье

The coenopopulations of Serratula centauroides in various plant communities of Transbaikalia have been studied. In the study areas 10 geobotanical descriptions were made in plant communities with the participation of S. centauroides. In the investigated area S. centauroides is found on dry rocky slopes, in herb and sandy steppes. Depending on the growing conditions, the density of individuals in coenopopulations ranges from 0.18 to 1.80 individuals per 1 m2. The highest occurrence of S. centauroides is noted in communities dominated by Gramineous and Artemisia: Gramineous-Artemisia-herb, Filifolium-Artemisia-Gramineous, Gramineous-Artemisia, Oxytropis-Gramineous and Allium-Artemisia. Studied coenopopulations S. centauroides are confined to the following communities: Filifolium-herb, Gramineous- Artemisia-herb, Sophora-herb, Filifolium-Artemisia-Gramineous, Gramineous-Artemisia, Agropyron- Carex, Carex-herb, Oxytropis-Gramineous and Allium-Artemisia. The phytomass, biological and exploitation resources, the possible volumes of annual harvesting of raw material of S. centauroides were determined. The phytomass of S. centauroides herb ranges from 8.10±3.46 to 75.93±19.55 g/m2 (air-dry raw material). The average phytomass of 1 individual of S. centauroides herb varies from 13.67±3.59 to 67.14±14.30 g (air-dry raw materials). The total biological resources of S. centauroides herb is 777.9 t (fresh raw materials) and 266.8 tons (air-dry raw materials). The total exploitation resources of S. centauroides herb is 224.7 t (fresh raw materials) and 79.8 t (air-dry raw materials). The possible volume of annual harvesting of raw materials of S. centauroides in the studied coenopopulations on the territory of the Trans-Baikal Territory and the Republic of Buryatia amounts to 37.5 t (fresh raw materials) and 13.3 t (air-dry raw materials).

Ecological-Phytocenotic Organization of Psammophytic Communities of the Tsimlyanskiy Sandy Massif

Aim. Evaluation of species diversity and ecological and phytocenotic organization of psammophytic communities of the grass-shrub layer of the Tsimlyanskiy sandy massif, Rostovskaya Oblast and Volgogradskaya Oblast, Russian Federation Material and Methods. Generally accepted methods in environmental-geobotanical surveys were used. Species composition and yield of phytocenoses, dominant species and relative percentages of species in the phytomass were determined and vegetation groups were identified with respect to soil moisture and to nutrition. Results. 69 species from 17 families were identified. The largest number of species is from the Asteraceae (18), Poaceae (15) and Fabaceae (12) families. In terms of classification in relation to moisture, the largest numbers of species were xeromesophytes (30) and xerophytes (23). Species saturation was assessed as 3-6 species per 1 m 2 . The vegetation of the massif is azonal with a tendency in the direction of decreasing xerophyticity and the intrusion of meadow-bog and forest communities. As regards classification according to nutrition, of the total number of species, the largest number was of meso-trophs (41). In the communities of sandy steppe II terraces grains dominate (66.5%) with the proportion of grasses being 33%. Here 16 species were identified with a high proportion of the herbs Agropyron pectinatum (Bieb.) Beauv., Elytrigia elongata (Host) Nevski, Festuca valesiaca Gaudin, F. beckeri (Hack.) Trautv., Poa pratensis ssp. pratensis and Stipa capillata L., S. pennata L. Conclusions. The Tsimlyanskiy sand massif is characterised by regionally bo-tanico-geographic specific vegetation. In the flora, there are typical hemip-sammophilous and psammophilous species with a dominance of cereals -characteristic of the regional soil and climatic conditions. The species composition of communities varies depending on the landscape-ecological conditions.

Architecture of the Dwarf Shrub Thymus petraeus (Lamiaceae) in the Conditions of Southern Siberia

The structure of Thymus petraeus individuals has been studied architecturally. It has been established that in the south of Siberia the species occurs in similar habitats: in true, meadow, sandy steppes and their petrophytic variants on the slopes and low rocky peaks of hills. According to the classification proposed by I.G. Serebryakov (1964), T. petraeus is a vegetatively semimobile dwarf shrub with a system of the main root that is persistent throughout its life and with rooting runners. Three architectural units that differ in the spatial position of the compound skeletal axis (orthotropic–plagiotropic, plagiotropic, and orthotropic) have been identified in the structure of T. petraeus individuals. Each architectural unit consists of the main compound skeletal axis, compound skeletal axes of the 1st order, formation shoots, branching shoots, and enrichment shoots. It is shown that the structure of individuals can be formed by repeating only two architectural units. It is established that the structure of individuals growing in the true steppes and their petrophytic variants is built at the expense of the repetition of orthotropic–plagiotropic and plagiotropic architectural units. That in sandy steppes is built at the expense of repetition of plagiotropic and orthotropic architectural units. The features of T. petraeus development in specific ecological and coenotic conditions are shown. In this regard, we have characterized (1) morphological polyvariance, which is based on changes in the structure of shoots (shortened and elongated) and the composition of architectural units (no compound skeletal axes of the 1st order or enrichment shoots); (2) dimensional polyvariance, manifested in a change in the length and number of compound skeletal axes; and (3) dynamic polyvariance, associated with fluctuations in the duration of the monopodial growth of shoots formation (from 2 to 5 years) and the architectural unit as a whole (from 6 to 20 years). The revealed modifications of architecture do not lead to a change in the life form of the dwarf shrub, but reflect the mechanisms of its adaptation.

Estimating Grassland Carbon Stocks in Hulunber China, Using Landsat8 Oli Imagery and Regression Kriging.

Accurately estimating grassland carbon stocks is important in assessing grassland productivity and the global carbon balance. This study used the regression kriging (RK) method to estimate grassland carbon stocks in Northeast China based on Landsat8 operational land imager (OLI) images and five remote sensing variables. The normalized difference vegetation index (NDVI), the wide dynamic range vegetation index (WDRVI), the chlorophyll index (CI), Band6 and Band7 were used to build the RK models separately and to explore their capabilities for modeling spatial distributions of grassland carbon stocks. To explore the different model performances for typical grassland and meadow grassland, the models were validated separately using the typical steppe, meadow steppe or all-steppe ground measurements based on leave-one-out crossvalidation (LOOCV). When the results were validated against typical steppe samples, the Band6 model showed the best performance (coefficient of determination (R2) = 0.46, mean average error (MAE) = 8.47%, and root mean square error (RMSE) = 10.34 gC/m2) via the linear regression (LR) method, while for the RK method, the NDVI model showed the best performance (R2 = 0.63, MAE = 7.04 gC/m2, and RMSE = 8.51 gC/m2), which were much higher than the values of the best LR model. When the results were validated against the meadow steppe samples, the CI model achieved the best estimation accuracy, and the accuracy of the RK method (R2 = 0.72, MAE = 8.09 gC/m2, and RMSE = 9.89 gC/m2) was higher than that of the LR method (R2 = 0.70, MAE = 8.99 gC/m2, and RMSE = 10.69 gC/m2). Upon combining the results of the most accurate models of the typical steppe and meadow steppe, the RK method reaches the highest model accuracy of R2 = 0.69, MAE = 7.40 gC/m2, and RMSE = 9.01 gC/m2, while the LR method reaches the highest model accuracy of R2 = 0.53, MAE = 9.20 gC/m2, and RMSE = 11.10 gC/m2. The results showed an improved performance of the RK method compared to the LR method, and the improvement in the accuracy of the model is mainly attributed to the enhancement of the estimation accuracy of the typical steppe. In the study region, the carbon stocks showed an increasing trend from west to east, the total amount of grassland carbon stock was 79.77 × 104 Mg C, and the mean carbon stock density was 47.44 gC/m2. The density decreased in the order of temperate meadow steppe, lowland meadow steppe, temperate typical steppe, and sandy steppe. The methodology proposed in this study is particularly beneficial for carbon stock estimates at the regional scale, especially for countries such as China with many grassland types.

Contrasting responses of diazotrophic specialists, opportunists, and generalists to steppe types in Inner Mongolia

Assembly mechanisms and responses of diazotrophic habitat specialists, opportunists, and generalists may differ among various steppe ecosystems. In this study, we investigated the ecological processes that determine the assemblies of diazotrophic communities in meadows and typical steppes (MT), desert steppes (D), and sandy steppes (S) and the effects of habitat environments on diazotrophic specialists, opportunists, and generalists in Inner Mongolia, China. The results showed that taxonomic and phylogenetic communities of diazotrophs were clustered according to their habitat types, as community dissimilarities among habitat types were significantly higher than those within them. Variable selection and dispersal limitation were recognized as the dominant ecological processes that shape diazotrophic community assemblages. Furthermore, the diazotrophic populations were dichotomized into specialists, opportunists and generalists with various strategies to adapt to habitat types. The richness of specialists significantly correlated with vegetation variables, implying that specialists have greater responses to vegetation than generalists and opportunists. This study provides insights into the mechanisms of diazotrophic community differentiation when habitat environments change.

К синтаксономии псаммофитной растительности памятника природы «Дьяковский лес» (Саратовская область)

К синтаксономии псаммофитной растительности памятника природы «Дьяковский лес» (Саратовская область)

Community Sporobolus Cryptandrus (Torr.) A. Gray in the Northern Part of Volga-Akhtuba Floodplain

On the territory of the Volga-Akhtuba floodplain, plant communities including Sporobolus cryptandrus are found. This is an adventitious species from North America that came to Europe in the early 20th century. In Russia, Sporobolus cryptandrus was first discovered in 1998 on the territory of the Volgograd region. Currently, Sporobolus cryptandrus is actively distributed throughout the Volgograd regions. Probably, Sporobolus cryptandrus was introduced together with imported grain and mixed fodders. This species was originally built into the plant communities of sandy steppes. In this paper, we describe the S. cryptandrus communities that we found in the Volga-Akhtuba floodplain. The descriptions were carried out at two sites in the northern part of the floodplain. Geobotanical sites are located on the nearbed sand banks along the river bed. Akhtuba. Completed 19 geobotanical descriptions. All descriptions were accumulated in an electronic database based on the TURBOVEG program. Communities of Sporobolus cryptandrus are characterized by poor floristic composition, low overall projective cover. Habitats of communities are subject to short-term flooding in the spring-summer period, as well as cattle grazing. In communities dominated: Sporobolus cryptandrus, Secale sylvestre, Artemisia marschalliana. We assume that these phytocenoses can be classified as cl. Artemisietea tchernievianae Golub 1994. Sporobolus cryptandrus has shown itself as an agriophyte and a transformer species that can completely replace the dominant cereal species in sand steppe communities or be introduced to pioneer communities at an early stage of overgrowth. Settling of this adventive species can lead to the loss of the natural appearance of the vegetation of sandy substrates. Propagation processes need further observation and analysis.