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Ecologo-geographical differentiation and dynamics of spring migration of water and semiaquatic birds of the Putorana Plateau are analyzed. In 1988-2007 on an area of 250000 kmІ, 8 points were surveyed in the northern, southern, western and eastern parts of the region. The method of route accounting was used. The water and semiaquatic avifauna of the Putorana Plateau in the spring migration period includes 68 species. The most significant in its formation are tundra species (53 %) from among the Anseriformes and Charadriiformes, totaling 94 %. Birds fly in north, east and west directions. They make stops at the early areas of river deltas that are freed from snow and ice. There are species that are distributed in stopping places everywhere (38 %), locally (22 %), pointwise (40 %). Bird population density at stops 15-227, on average ( n = 8) 94 ind./1 km of coastline. The population of birds on lakes is always much poorer than on adjacent river sections. The vast majority of individuals of almost all migratory species are united in monospecific, rarely polyspecific flocks. The entire spring migration of water and semiaquatic birds on the Putorana Plateau takes place from May 19 to June 27 and lasts an average ( n = 10) 23 days. The main passage runs from May 25 to June 17 and lasts an average of ( n = 8) 7 days. Spring migration is most intense in the west of the Putorana, where at least 20000-30000 individuals of woter and semiaquatic birds fly through the surveyed points. The span is much weaker in the center and, especially, in the east of the region. There are 19 species among the dominants of water and semiaquatic habitats, incl. Eurasian Wigeon, Common Teal, Grey-taild Tattler, Northern Pintail, Little Stint.

Participating in the circulation of nutrients epilithic biofilms play an important role in water bodies. Denitrification actively proceeds in the epilithon of water bodies. However, the information on environmental factors that affect the process in biofilms is still limited. The object of study in this article involves the number of cultivated denitrifying bacteria in biofilms formed on the stony substrates in different parts of Lake Baikal littoral zone. It has been found out that the main factors explaining the differences in the number of cultivated bacteria who perform complete denitrification were the temperature and the concentration of total nitrogen in shallow water. The article shows that lower amount of denitrifiers is a typical for biofilms experiencing nitrogen deficiency as indicated by the low stoichiometric N: P ratio in biofilms. An uneven distribution of heavy metals in the biomass of epilithic biofilms has been determined. It also may potentially impact denitrification in the epilithon of Lake Baikal.

The hydrochemical and microelement composition of water and bot tom sediments was determined in the Kuchiger thermal spring (Baikal rift zone). The entry of chemicals with groundwater and high temperatures create favorable and specific conditions for the development of microorganisms. The taxonomic diversity of the microbial community of water and bottom sediments was studied using the analysis of 16S rRNA gene aplicons. 107619 nucleotide sequences assigned to 211 OTUs were analyzed. In the studied samples of water and bottom sediments, bacteria dominated, representatives of archaea accounted for 0.2-3.1 %. The phylum Proteobacteria dominated in microbial communities. The subdominants in the studied samples were the phyla Firmicutes, Chloroflexi, Nitrospirae, Acetothermia, and Actinobacteria, where their ratio varied depending on the biotope. A characteristic feature of the microbial community in the Kuchiger thermal spring is the dominance of chemolithotrophic bacteria.

In 2015-2019 catching of young bluethroats was carried out in order to determine the parameters of their migration stop in the taiga zone in the east of the Russian Plain. A total of 272 birds were analyzed, of which 186 were males and 86 were females. The average duration of the migration stop for young bluethroats was 1.45 days. Transient individuals have fat reserves that allow them to make migratory throws lasting an average of 4.39 ± 0.20 hours. Bluethroats with an average stopping time have a fat accumulation rate of 0.04 ± 0.36 g per day and by the time of departure are able to make non-stop flights lasting an average of 3.89 ± 0.58 hours. Individuals that make the decision to stop lose little of their fat reserves, reducing their ability to fly non-stop until the next stop. The significance of the river valleys in the east of the Russian Plain for a successful stopover remains open, and it has not been fully clarified whether these places have the necessary ecological conditions for the successful stopover of small birds.

The climate change is well pronounced in high latitudes. The quick westward expansion of the Sandhill Crane breeding range in Eurasia requires an analysis of the species impact on the Arctic ecosystems. We employ the data about 223 Sandhill Crane nests in the Chaun-Delta, West Chukotka. Weinvestigated date of clutch onset, clutch sizes, egg sizes, nesting density and nesting success. We tested above parameters vs climatic characteristics of the site in order the learn their effect on the reproductive potential of the species. The most important climatic characteristics that determine the increase in nesting density, clutch and egg sizes, earlier clutch onset and higher nesting success included the First frost free day, the integrated characteristic of May (cold or warm according to the sum of positive temperatures) and the sum of average daily temperatures in the second half of May. The maximum reproductive potential Sandhill crane is realized in conditions of warm and early spring.

Complex studies of soils, vegetation cover, and microbiota of coastal depressions of highly mineralized drainless chloride lakes in Southeastern Transbaikal Region (Dauria, Lake Babie) were performed for the first time. It was revealed that the lakeside ecosystems formed within the steppe zone under cyclic changes in the level of lakes and the resulting change in the lake water chemical composition. The eolian factor has a certain influence. The dynamic properties and material composition of soils of superaqueous-subaqueous, superaqueous, and eluvial-superaqueous positions have been studied. Current continental salinization of various chemistry and hydrogenous carbonization has been revealed there. The study of the spatial structure of phytocenoses and their species composition, depending on relief location in lakeside depressions, soil conditions and halogenesis revealed the confinement of pioneer hyperhalophytic and halophytic communities to quasigley solonchaks. Within the superaquatic part of the lakeside depression, plant communities grow with a predominance of halophytes and mesophytes with the participation of glyco-oligohalophytes and mesoxerophytes. The feather-grass-forb-leymus (Leymus chinensis, Artemisia frifida, Bupleurum bicaule, Stipa krylovi) steppe was formed on the light-humus soils, similar in composition to zonal steppes, with the presence of mesophytes and xerophytes. Various microbiomorphic complexes have been established to be in dynamically evolving lakeside soils, depending on abiotic factors. Highly mineralized chloride lake waters contribute to forming of similar microbial communities in the bottom sediments of the Lake Babie and highly saline horizons of the quasigley solonchak. At the same time, a large proportion of unclassified prokaryotes were found in all soil samples. This important unstudied microbial component is present at the level of the Bacteria domain in solonchaks (up to 22 %), saline humus-quasigley (up to 15 %), and light-humus saline (up to 16 %) soils. The microbiome structure in humus-quasigley soil is characterized by the presence of halobacteria and krenarcheotes. A significant proportion of taxa involved in carbon and nitrogen cycles, and play an important role in global biogeochemical cycles, have been established in light-humus saline soil. Also, halobacteria were no revealed in this type of soil due to insignificant content of easily soluble salts in the humus and transitional horizons.

The contribution of fungi and bacteria to the process of net ammonification in the soddy-podzolic soil of the sour-bilberry birch forest of the Yaroslavl region was determined using inhibitory analysis. Representatives of the genera Penicillium Link (70-99 %) and Trichoderma Pers. (6-20 %) dominated in the mycobiota of saprotrophic fungi. Seasonal changes in the total number of fungi and the content of C_org and N_org in the soil correlated only in the eluvial horizon, with r = -0.8 and -0.7. In horizons A₀ and A₂, total fungal abundance was negatively correlated with nitrogen accumulation, with _r = -0.85 - -0.89. It has been established that the litter is characterized by an equal participation of fungi and bacteria in this process. In the humus horizon, a slight excess of the participation of fungi over bacteria was noted. In the eluvial part of the profile, the contribution of bacteria is slightly higher than the contribution of fungi. The maximum air temperature is able to regulate the seasonal dynamics of the number of saprotrophic fungi in the soil.

Recent long-term dynamics of high mountain communities can be caused by climate warming as well as decrease in land use intencity. Every year, during the period of 1987-2019, we counted shoot numbers of vascular plants on permanent plots of an alpine Festuca varia grassland (Teberda national park, Karachai-Cherkessian, Russia). In the regression models of shoot number dynamics, the predictors were year (to reveal linear trends) and weather variables: mean temperatures and sum of precipitation in the previous growing season (July - August) and the beginning of the current season (May - June). Shoot numbers increased significantly in 6 species with lower mean value of altitudinal distribution in the national park area, and decreased in 5 high alpine species. However, these trends were not caused by increase in mean temperatures of July - August. Changes of weather variables influenced fluctuations in several species independent on the direction of their dynamics. The linear trend values in one of the sites were positively correlated with specific leaf area, leaf water content and ruderal strategy scores, and negatively correlated with stress-tolerant strategy scores. The dynamics of Festuca varia grasslands is mostly linked with long-term restoration succession after cessation of grazing, but not with growing season warming. The main community dominant Festuca varia Haenke is less subjected to fluctuations and climate change at the current amplitude, thus ensuring community stability.

Distribution and range of ecological factors of the rare species Hedysarum grandiflorum Pall. in the European part of Russia are discussed. Data on 387 species localities from 10 regions of the Russian Federation were used. Climate and soil indicators were calculated using raster data of 19 bioclimatic variables of BIOCLIM, the SoilGrids global digital soil mapping system and the SRTM 1arc_V3 digital elevation model. Indicators of the average annual temperature, temperature of the summer and winter months of H. grandiflorum habitats decrease in the northeast direction from the Rostov region to the Republic of Bashkortostan, and the annual precipitation is less in the southern regions of the steppe zone and more in the regions of the forest-steppe zone, while there is a higher amount of summer precipitation than winter. Boundary localities of the species range in most cases have extreme (maximum or minimum) values of climatic factors. In the northeast of the range of H. grandiflorum, the progress of the species is limited by low temperatures in the summer and winter months, from the south, the progress of the species is limited by high summer temperatures and low precipitation in the summer. Species protection is carried out in 19 reserves, wildlife areas, natural and national parks, as well as in more than 80 natural monuments, and is generally sufficient, but regional small localities of the species require special attention.

Tugai ecosystems of desert river valleys are one of the most affected and endangered landscape types. The largest areas of tugai vegetation in Uzbekistan are preserved in the lower basin of the Amudarya River. Here are the main massifs of poplar forests. To assess their current state the analysis of 284 relevés representing tugai plant communities in the lower basin of the Amudarya river was carried out. For each of them the position on ecological gradients was determined by species indicator values. It is shown that the greatest scatter of relevés is observed on moisture gradient - from 17 to 97 grades, it is noticeably smaller for pasture digression (2.5-6.5) and soil salinity (16.1-19.5). To reveal the relationships between the species composition and environmental factors, CCA ordination was done. Groups of relevés were identified, representing the native tugai vegetation and three ecological series which are connected with salinity, soil moisture, and anthropogenic pressure. Accordingly, 4 generalized plant communities were distinguished, differing in species composition, floristic diversity, and structure. Indicator plants were identified on the base of formalized assessment of species constancy and importance values. The changes in species composition and structure of communities (life form spectra) are shown. It has been established that the most active process followed the progressive desertification is the halophytization of vegetation. This process is reflected in the replasement of poplar forests to shrub communities dominated by Halostachys belangeriana and Tamarix hispida. As a result of intensive anthropogenic impact, the vegetation is transformed and the importance value of ruderal annual plants become higher.