The vegetation evolution on the modern territory of the Ulyanovsk City and its surroundings, beginning from the late glacial period, can be presented as follows. 11,000– 10,300 years ago: a “tundra-steppe” with wormwood-mazy, horsetail, fern, shrubbygreen-green communities. 10,300–9,500 years ago: wormwood-haze-cenotic cenoses, isolated islets of sparse pine forests. 9,500–8,500 years ago: sagebrush-cerebral, cereal steppes and pine forests. 8,500–8,000 years ago: turf-grass, grass-meadow-grass meadow steppes and pine forests. 8,000–6,000 years ago: forbred-cereal, less often turfgrass meadow steppes, birch, and birch-pine forests, the appearance of deciduous species. 6,000–4,500 years ago: pine-broad-leaved, broad-leaved forests, mixed-grassgrass meadow steppes, and the maximum afforestation. 4,500–3,200 years ago: broadleaved, pine-broadleaf forests, and the appearance of agrocenoses. 3200–2500 years ago: pine, pine-birch forests, reduction of broad-leaved species, the expansion of turfgrass steppes and agrocenoses. 2,500–700 years ago: the emergence of secondary forests and meadow steppes (fescue, wormwood-cereal), the expansion of agrocenoses. 700–350 years ago: pine, pine-birch, pine-broadleaf forests, reduction of agrocenoses. 350 years ago till the present time: a sharp decline in forests, the predomination of secondary pine, broad-leaved, small-leaved, mixed forests and secondary meadow steppes, the expansion of agrocenoses and residential areas. Thus, the vegetation of the territory of the Ulyanovsk City and its environs since the late glacial period varied from the steppe one (11,000–8,000 years ago) to the forest-steppe one (8,000–700 years ago) and again to the steppe one (700 years ago – modern time). The least afforestation of the territory was observed from 11,000 to 9,500 years ago (3–4%) and from 350 years ago to the present (6–7%). The greatest afforestation of the forest-steppe was from 6,000 to 3,200 years ago, when the forest-to-steppe ratio was equal.

In many systematic groups of mammalian species, the evolution of sociality leads to the formation of large social groups (group-size evolution). In rodents, however, the most social species live in family groups consisting, as a rule, of not numerous individuals. The family-group lifestyle of some ground-dwelling sciurids (Sciuridae) and voles (Microtus) results in fewer breeding adult females, a decreased litter size, and a longer time till first reproduction. Statistical analysis of published data has been conducted in the present study and has shown that transition to the family-group lifestyle leads to a decreased potential reproductive success in many muroid rodents: females produce fewer litters and, consequently, fewer pups during the reproduction season. However, the potential reproductive success in muroid rodents with a family-group lifestyle could be increased due to delayed offspring dispersal (who spend the severe winter period in family groups) and extensive cooperation in foraging, defending their territory and food stores, as well as in care-giving activities. One can suggest that females of these species produce fewer offspring, but of “better quality”. Ultimately, social rodent species may gain inclusive fitness benefits because of the higher fitness of their offspring as compared to solitary dwellers and gregarious species.

Features of the seasonal changes in the number of species, biomass, and the ratio of taxonomic groups of phytoplankton of flowing and flow-regulated sectors of the Ural River are described. In the unregulated sector of the river, the maximal number of species was recorded in July, and in the upper and lower reaches of the reservoir – in October. The maximal biomass of phytoplankton in the unregulated sector of the river and in the lower zone of the reservoir was observed in the summer, and in the upper zone – in the spring. The influence of combining a number of parameters of the water bodies and environmental factors (typology, morphometry, flow velocity, the flow of substances from the catchment and from the higher sections, and temperature) on the quantitative characteristics of communities is discussed. The leading role of water temperature for the phytoplankton development in the unregulated sections of the river and the lower zone of the reservoir is shown, which are characterized by environmental conditions that impede the abundant development of phytoplankton: high flow rates, the late onset of biological spring, and low nutrient availability. The biomass values in the unregulated sections of the river correspond to β-mesotrophic – β-eutrophic waters, in the upper part of the reservoir – to β-mesotrophicones , and at the dam section – to α-βmesotrophic ones. According to the saprobity index, the entire investigated water area is characterized by β-mesosaprobic conditions.

The teeth of an adult female of the Turkish hamster (Mesocricetus brandti) after hibernation in semi-natural conditions were examined to reveal a relationship between the hibernation pattern on the incisor surface and the data of a temperature logger. The female spent the winter in a burrow prepared by herself inside a wintering cage from October 2018 till May 2019. A temperature logger was implanted to the animal intraperitoneally to record body temperature at 20-min intervals. Regular bouts of hypothermia started in mid-October. The longevity of each hypothermia bout increased whereas the minimum body temperature decreased and reached its lowest value in March. Later, the process proceeded backwards until the end of the heterothermia period. In the apical region of the incisor, daily increments were wide and well-distinguished which indicates that they had formed before the onset of the heterothermal period. In the basal region, closer to the growth zone, the increments were narrow and distinct, and their number corresponded in general to the number of normothermia episodes bouts. At the very base of the incisor as well as at its apical part, typical daily increments were revealed again. However, no correlation between the longevity of normothermia bouts and the width of increments was found. These data varied greatly from two other hamsters. In the Ciscaucasian hamster (Mesocricetus raddei) the number and character of increments comply with the number and duration of normothermia bouts, in the Common hamster (Cricetus cricetus), the “hibernation zone” was not recorded on the incisor surface. The Turkish hamster demonstrate an intermediate pattern, which we explain by quite different hibernation conditions of these species.

Meteorological series and phenological data in the framework of our environmental monitoring in the South taiga Central Forest Reserve were analyzed. During 1984– 2017, the average annual air temperature was 4.63±0.41°C, and the average annual rainfall was 2.14±0.12 mm/day. For eight of the 43 (19%) climatic parameters, reliable linear trends of variability were found: an increase of air temperature in July, August, September, and December; an increase of soil temperature in December; an increase of precipitation in November and December; and a decrease of precipitation in September. Three causes of their directed long-term changes were revealed, namely: a shift of the winter timing, violation of the annual dynamics of climatic parameters and a change in the precipitation type during a longer autumn – snow to be replaced by rain. Of the 11 species of vascular plants, the statistical significance of the long-term displacement of phenological dates was proven for Anemone nemorosa: the longer the autumn and softer the beginning of the winter, the earlier the onset of its flowering. Two classification types of vascular plants in identifying interspecific synchrony in the phenological events variation were considered. Variability components of phenological phenomena occurrence was estimated: the share of long-term trends of the shift in phenological dates timing due to changes in reserve climatic system is from 20 to 68% of the total sign dispersion; interannual climatic fluctuations explain 5–34% of its variability; and the proportion of variability under unaccounted factors influence is high (21–64%). Species with a high proportion of their long-term variability components (Anemone nemorosa: more than 60%) are recommended to use as indicators of climate change under the conditions of the study area.

In a long-term model experiment, the abundance dynamics of soil microorganisms was studied as affected by pollution of southern chernozem soils with various concentrations and combinations of iron, nickel and copper ions. In the course of this study, soil microbiocenoses were seeded on solid nutrient media and the following values were estimated: the total numbers of heterotrophic microorganisms on meat–peptone agar, the numbers of iron-oxidizing microorganisms on a selective medium in 0, 30, 90 and 210 days after the introduction of heavy metal ions into the soil. A characteristic diverse impact of heavy metal ions on soil microorganisms was established, and the degree of stability of soil microbocenoses of southern chernozem was revealed. Iron and copper concentrations of 10 and 50 RGCB/MPC in 30 days after soil contamination by individual metal ions or their combinations stimulated the proliferation of heterotrophic microorganisms in the soil microbocenoses and 90 days later the number of this microbial group decreased to the control levels and below. After 210 days, the microbiocenoses returned to a stable state. Nickel ions, introduced into the soil at a concentration of 50 MPC separately and in a number of combinations with other heavy metal ions, did not stimulate the proliferation of heterotrophic microorganisms. Opposite trends were observed in the abundance dynamics of iron-oxidizing microorganisms. With the exception of some model variants such as 10 and 50 MPC of Cu (II), iron, nickel and their combinations in various concentrations inhibited the proliferation of ironoxidizing microorganisms in the first month after soil contamination. The inhibitory effect of a combination of heavy metal ions was stronger than that of individual metals. After 90 days, the numbers of iron-oxidizing microorganisms restored to the control level or even exceeded it. After 210 days, an inhibition of the proliferation of ironoxidizing microorganisms was observed in the microbocenoses, or their abundance corresponded to the value in the control soil sample.

Features, trends and the rates of formation of new forest biogeocenoses on anthropogenically disturbed lands, in particular, on an unused pond created on heavy loamy soils in the semi-desert of the Northern Caspian region are analyzed. At an early stage of spontaneous pond colonization by vegetation, the maximum influence on its development was exerted by the presence of a seed source 300 meters away – in the Arboretum of the Dzhanybek Research Station of the Institute of Forest Sciences (Russian Academy of Sciences) with 120 species of introduced tree and shrub plants. Initially 34 pioneer species colonized the lower parts of the unused pond, and 29 species survived by 2018. The formation of intrazonal willow-oleaster-poplar communities of a quasitugai type with a grass-wet-meadow association has been revealed. Their development was influenced by geographical isolation, self-regulation under rather unstable moisture conditions caused by occasional flooding by melt snow waters and bogging. A differentiation of the upper part of the soil-forming rock brought to the surface has occurred. The forest leaf litter has been formed from uncut moquette with a thickness of 1–2 cm, reaching currently quite substantial deposits of 0.953±0.196 kg/m2 , with the ash content reaching 13.85%. Ca prevails absolutely in the ash composition; while the amounts of Mg, Fe, and K are significantly lower. A humus horizon has been formed and the soil effervescence depth has changed. In the whole, for almost 40 years of vegetation colonization, the previously infertile substrate has acquired features of an immature soil, which is characterized by manifesttion of humus-accumulative process, gradual humification of organic matter and decarbonization of the material. In general, compact, diverse in structure, spontaneously arising self-developing forest biogeocenoses could significantly transform disturbed semi-desert territories. The peculiarities of their structure and the composition of emerging species make it possible to properly choose species preferred for landscaping.

Carabus communities of the industrial, habitual and recreational zones in a large industrial center (Nizhnekamsk City, Republic of Tatarstan) were examined. 31 species were revealed, and the highest abundance and diversity was in the recreational zone (23 species). Similar species (Carabus cancellatus Illiger, 1798, Pterostichus niger Schaller, 1783 and Pterostichus oblongopunctatus Fabricius, 1787) predominated in the industrial and recreational zones, while Pterostichus versicolor Sturm, 1824 prevailed in the habitual zone. The dynamic density of beetles was 12.1, 7.5 and 16.4 per 10 trapnights in the industrial, habitual and recreational zone, respectively. Discriminant analysis has shown significant differences of the carabids in the recreational zone from those in the other two zones ones by structure and dynamic density. In addition, multidimensional analysis has revealed differences of the carabid communities in conifer, deciduous and meadow biotopes. Urbanization also affects the morphometric structure of ground beetle populations. We chose two species – Pterostichus melanarius Ill., 1798 and P. niger as objects for morphometric analysis, because they had been included as model ones into the project on carabid morphometric variation on Research Gates. The body sizes of P. melanarius were smaller in the recreational zone than in the industrial one. By the morphometric structure, the populations of the species were similar in both zones explored. The beetles of P. niger increased in body size from the industrial zone to the recreational ones. The morphometric structure of populations of this species was similar in the habitual and recreational zones and differed significantly in the industrial one. Such traits as the pronotum width and the distance between eyes contributed much into discrimination.