Analysis of the genus thymus of the southeastern part of the northern caucasus

The paper presents the analysis of the genus Thymus of the flora of the South-East of the North Caucasus. Revealed the total species, compiled an aspect of the genus Thymus, and conducted the analysis's bioecological, geographical composition. In the investigated territory, we have registered eight thymus species, distributed mainly in xerophilic types of vegetation: steppe, friganoid, alpine, meadow-steppe, and meadow societies.

Community Differentiation and Ecological Influencing Factors along Environmental Gradients: Evidence from 1200 km Belt Transect across Inner Mongolia Grassland, China

In this work, we conducted a 1200 km belt transect for field survey in typical and meadow steppes across Inner Mongolia Plateau in 2018. The field investigation, laboratory soil analysis, and quantitative ecology methods were utilized to explore the differentiation characteristics of the plant community, and their relationships with ecological factors. The results showed that a total of 140 vascular plants within 108 quadrats mainly comprised of Asteraceae, Poaceae, Rosaceae, and Fabaceae. Two-way Indicator Species Analysis (TWINSPAN) revealed eight vegetation typologies: I: Stipa sareptana var. krylovii + Dysphania aristata, II: Stipa grandis + Leymus chinensis, III: Stipa sareptana var. krylovii + Leymus chinensis, IV: Stipa grandis + Cleistogenes squarrosa, V: Stipa grandis + Carex duriuscula, VI: Stipa baicalensis + Leymus chinensis, VII: Carex pediformis + Stipa baicalensis, VIII: Leymus chinensis + Elymus dahuricus. Detrend Correspondence Analysis (DCA) confirmed the above eight vegetation typologies and indicated a relatively small variation. Redundancy analysis (RDA) revealed that the spatial differentiation characteristics in the typical steppe were chiefly driven by precipitation, while the influencing factor in the meadow steppe was soil nutrients, followed by temperature and precipitation. The contrast between typical and meadow steppes revealed that the spatial distribution of typical steppe was influenced by precipitation, while the contribution of heat and water in the meadow steppe was equal. The conclusion revealed that the temperature and precipitation conditions coupled with soil nutrients shaped the spatial differentiation characteristics of temperate steppe vegetation in the Inner Mongolia grassland. Therefore, this study advanced our knowledge of the spatial patterns of temperate steppe along longitude and latitude gradients, providing scientific and theoretical guidance for the biodiversity conservation and sustainable ecosystem management of the Inner Mongolia grassland.

Пространственное распределение птиц Алданского нагорья.

The results of bird route censuses, conducted on the territory of the Aldan Highland in the first half of summer and generally covering the period from 2000 to 2019, were analyzed. The total length of the routes was about 2815 km. A total of 116 initial variants of the bird population were used. Based on the results of multivariate factor analysis for 160 species registered in these censuses, a hierarchical classification of their preference for habitats was drawn up. The classification showed that 45 % of birds prefer forests, woodlands and burned areas, 26.2 % - water bodies and their banks, 13.8 % - bogs and meadows, 9.4 % - villages and cities, 5.6 % - mountain tundra. A comparative analysis with a similar classification for the Altai Highland has been performed. The main differences in the territorial distribution of bird species in the Aldan Highland and Altai lie in a smaller number of identified types of preferences in our region. Due to the homogeneity of forest biotopes and the absence of the steppe, forest-steppe, subnival, and nival zones in the Aldan Highland, the corresponding landscapes are not represented here, which determines the absence of the steppe, forest-meadow-steppe, meadow-bog, and subnival types. Similarly to Altai, the forest, tundra and synanthropic types of preference are distinguished in the Aldan Highland.

Effects of Livestock Grazing on Interannual Variation of Soil Methane Uptake in an Inner Mongolian Meadow Steppe

Background and aims. This study aimed at identifying the effects of livestock grazing on interannual variation in soil CH4 uptake and underlying mechanisms in a meadow steppe ecosystem. Methods. A multi-year grazing experiment subject to six stocking rates was conducted to quantify CH4 fluxes as well as the changes in driving factors: vegetation traits, soil physicochemical properties and climatic parameters. The closed static chamber technique and a gas chromatograph were used to measure methane fluxes. Multivariate regression analysis was performed to explore empirical relationships. Results. With increasing stocking rate, the multi-year mean CH4 uptake rate decreased in a sigmoid curve-shaped manner, with the threshold point appearing in the light grazing treatment. The interannual changes in soil CH4 uptake were highly dependent on stocking rate, with increasing, leveling and decreasing trends detected with increasing grazing intensity. Major factors affecting CH4 fluxes included vegetation traits, soil moisture, and soil nitrogen content, with the soil NH4+-N content assuming the most important role. However, predominant factors regulating interannual changes in CH4 uptake were rainfall, belowground biomass, and soil nitrogen regime. Conclusions. The steppe ecosystem acted as a CH4 sink, irrespective of stocking rate and year. However, light grazing can be the threshold grazing intensity in terms of both the CH4 uptake potential and primary production in this steppe ecosystem. Our findings have important implications for further understanding magnitudes and regulations of CH4 uptake in grassland soils worldwide.

Study of acid-alkaline conditions of different-age arable soils of landscape catens of Central Forest-Steppe

Fertility of soils is largely determined by their physical and chemical properties. Response of soil environment is a mobile indicator of soil fertility. Direction and intensity of almost all soil processes that provide nitrogen, phosphorus and potassi- um regimes of soils, as well as availability of macro- and microelements for plants, depend on it. The paper presents the result of a field study of acid-alkaline conditions of profiles of black soil of typical and leached different terms of agricultural use of soil cat- ens of the meadow-steppe section of the Belgorod region in 2019. The research object was different-age arable areas with an age of agricultural development of 140 and 240 years, respectively. The steepness of surface in areas corresponding to the meadow-steppe zonal landscape of the forest-steppe did not exceed 4-6 °. As a result of field studies, 32 incisions were studied in the mead- ow-steppe section (6 incisions on background catens and 12 incisions on open catens). Each incision was provided with layered values of morphometric indicators of soil horizons. For background steppe soils, shade slopes are characterized by more alkaline conditions, in comparison with southern slopes. For 140-year-old arable land, the situation is opposite: shadow slopes have a more acidic reaction of the medium, in comparison with insoluble ones; for 240-year-old arable land, alkaline-acid conditions on the slopes of opposite expositions did not differ significantly. In the first 140 years of plowing, acidification of the soil profile occurs; the difference in the pH value between the background and arable land values of 140 years of age on the slope of the northern ex- position reaches 1.6 on the surface, gradually decreasing to 0.2 at depth. Further plowing leads to alkalization of the soil profile by 0.6-0.9 pH units. The research results can be used in development of agricultural systems in crop industries.