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The possibility of using a combined method of control of an incompressible turbulent boundary layer on the NACA 0012 airfoil is studied experimentally and numerically. The method is based on air blowing and suction through finely perforated walls, which are parts of the airfoil. The study is performed for Reynolds numbers Re_c=0.7 · 10⁶ and angles of attack α =-6 - 60. It is demonstrated that the mechanism responsible for changes in the aerodynamic characteristics of the airfoil is the same for all variants of the control action in the form of air blowing and suction: an increase in pressure due to air blowing on one side of the airfoil and a decrease in pressure due to air suction on the opposite side lead to an increase in the lift force and, finally, to a gain in the lift-to-drag ratio of the airfoil, which reaches three units at α ≈ 0^o. Unfortunately, the efficiency of this method of boundary layer control decreases with increasing α.

A problem of a far field generated by internal gravity waves from an oscillating point source of perturbations that moves in a vertically infinite stratified medium with variable buoyancy. For a simulated quadratic distribution of buoyancy frequencies, analytical solutions of the main boundary-value problem are obtained, expressed through parabolic cylinder functions. Asymptotic solutions constructed in this paper make it possible to describe amplitude-phase characteristics of far fields generated by internal gravity waves in a stratified medium with a variable Brunt- Väiää frequency.

The filtration of a graphene suspension through a core sample has been studied experimentally. It has been found that at the oil-water interface in the porous medium of the core sample, a transient multilayer microheterophase structure consisting of planar graphene nanoparticles, hydrocarbon oil molecules and surfactants is formed. It has been found that with an increase in the concentration of graphene nanoparticles, the volume fraction of the displaced oil increases and the volume fraction of water in oil decreases.

Longitudinal waves in a saturated porous medium simulated by a double-phase medium are under study. Exact expressions for a wave propagation velocity and attenuation coefficient are obtained. High-frequency and low-frequency wave asymptotics is investigated, and partial cases of soft and dry soils are considered.

The results of eddy covariance measurements of carbon dioxide and water fluxes above spruce forest in the middle taiga subzone from April to August in 2013 and 2016 are presented. The ecosystem of spruce forest turned from source to sink of CO2 at average daily air temperatures below zero in late March and early April, in 2016 it was two weeks earlier than in 2013. The maximum net ecosystem exchange (NEE) of CO2 was recorded at the end of June and the beginning of July. In 2016 the average daily NEE of spruce forest decreased at high air temperature and a low amount of precipitation at the beginning of the growing season, and turning from the sink of CO2 to the source was observed in early August. Net exchange of CO2 between spruce and the atmosphere from April to August in 2013 reached -327 g C/m2, and in 2016 -174 g C/m2. Seasonal evapotranspiration of spruce forest in those years was 239-247 mm / m2, and the average value of the water use efficiency (WUE) for photosynthesis in the season was 2.3-3.3 g C/kg H2O. WUE was relatively constant during the growing season as a result of a close relationship between the exchange of CO2 and water, the main processes ensuring the production of organic matter in the spruce forest ecosystem.

Nematode communities were studied in the root-inhabited soil layer under trees introduced in the Polar-Alpine Botanical Garden of Kоla Scientific Centre, RAS in Murmansk region. Nematodes of 48 taxa were found under introduction; bacterial feeders and plant parasites showed the greatest diversity (56 and 21 % of the total number of taxa, respectively). Tendency of genera number decreasing was shown in series “deciduous tree - coniferous tree - natural biocoenosis”; and similar regularity was obtained for plant-parasites. There were found phytoparasitic taxa rare for North-West of Russia. An adaptive mechanism related to delay in egg laying by female and further intra-uterine development of juveniles was found in the populations of Rhabditis producta Schneider, 1866 (bacterial feeding nematodes). This mechanism is very important for offspring survival in unfavorable environmental conditions in the North. The study allows to establish reliable correlation between taxonomic diversity of nematodes and majority of investigated soil properties (pH, ash content, N, P): relative abundance of omnivorous and associated with plants nematodes correlates with content of organic matter, organic carbon, C : N ratio; and relative abundance of plant-parasitic nematodes shows a correlation with vegetation cover.

The features of the long-term fluctuational dynamics of the populations of tuberoid orchids ( Neottianthe cucullata and Dactylorhiza incarnаta ) growing in various phytocoenotic and climatic conditions are presented as the realization of the mechanism of population stability under conditions of a heterogeneous habitat. The work shows ability of populations to take advantage of microsites favorable for their existence, the conditions in which are determined by the temporal dynamics of climatic factors, the abiotic environment and interspecific interactions. It is established that the unidirectional dynamics of the populations of tuberoid orchids, determined by demutative-digressive successions in plant communities under the combined effect of abiotic, biotic and anthropogenic impacts, leads not only to a decrease in abundance and density, but also to the destruction of the spatial distribution and the population life stage structure. The relationship between species abundance and climatic factors is assessed using a correlation coefficient which is significant for adult reproductive plants of forest species ( N . cucullata ) and for juvenile plants of meadow species ( D . incarnаta ).

The authors estimated habitats’ ecological conditions and demographic parameters of Pulsatilla patens (L.) Mill s.l. in 10 coenopopulations in Kirov Region. The study states that within the investigated area the species is present in pine communities of green moss and herbaceous types with prevalence of anthropophobic species. Large proportion of anthropotolerant species is typical of communities significantly suppressed by human activity. P. patens s.l. is a hemistenobiotic species whose ecological space amplitude in Kirov Region does not exceed the limits of Tsyganov’s scale ecological range [1983], but soil humidity scale values are approaching the maximum limit and scales of humidity variability - near the minimum. Discomfort index calculated with phytoindication data allows determining the level of favour. We have determined that conditions of mixed herbs - gramineous meadow with bracken coincide with optimum ecological parameters for the species growth. The least favourable conditions for P. patens s.l. development are formed in cowberry-green moss pine forest and herbaceous pine forests where maximum discomfort indices are marked: 1.09 and 1.01, respectively. The coenopopulations studied are of low density and generativity, which demonstrate the decrease tendency on an ecological conditions gradient.

The Fagaria vesca L. seed reproduction in natural populations is characterized by a combination of xenogamy and autogamy. To determine the proportion of xenogamy, a field experiment was conducted. During flowering, inbred line N 08-2 was planted with native wild strawberry populations at two different biotopes. The inbred line is marked with a recessive allele c with a light yellow color of the berry. Plants from native population form berries with only red coloring - a dominant trait. Seeds from the plants of line No. 08-2 were collected after the flowering period. Genetic analysis of these seedlings was carried out on the genetic marker “berries coloring”. In case of autogamy realization, the seedlings had a light yellow color of the berries. If xenogamy was carried out, the plants had red berries. It occurred as a result of insects transfering of pollen with dominant allele C from native plants F. vesca . Significant differences in the ratio of systems of crossing - autogamy and xenogamy among a number of experimental plants after genetic analysis were shown. However, the integral value of xenogamy, realized in the seed progeny, in both natural populations of F. vesca was similar and amounted to 21 %, and the average share of autogamy was 79 %. This ratio of crossing systems for F. vesca population, is optimal for maintaining the heterogeneity of population and realizing life strategy in conditions of natural growth. With xenogamy, a certain proportion of heterozygous heterozygotes is maintained in the population capable of mastering new habitats, while the strategy of explerents is implemented. Autogamy contributes to an increase in the proportion of inbred genotypes - patients. Thus, under the conditions of the environmental heterogeneity of Western Siberia for F. vesca , due to xenogamy, there are conditions for implementing any of the three types of strategies: violents, patients and explerents, depending on the conditions of plant existence.

This work is aimed at assessing the dynamics of the composition of soil water in coniferous forests subjected to air pollution from copper-nickel smelters “Severonickel” in the Murmansk region. Objects of investigations were the most common in boreal zone spruce forests with dwarf shrubs + green mosses and pine forests with dwarf shrubs + lichens. The obtained results showed a significant intra- (below the crowns and between the crowns) and inter-biogeocoenotic (spruce and pine forests) variation in the composition of atmospheric deposition and soil waters in forests under pollution. Atmospheric deposition of pollutants and leaching their compounds from all soil genetic horizons were tens (sulfates) and hundreds (copper, nickel) times higher than in reference sites, and their fluxes below the crowns were usually more intense than between the crowns. Long-term dynamics (from 1993 to 2012) demonstrated reliable trends in reducing concentrations and leaching sulfates and heavy metals from the soil. The molar ratio of basic cations to aluminum (BC/Al) in soil waters from all soil horizons did not drop to the critical level, whereas for mineral nitrogen the lowest critical level (0.2 mg/l) was exceeded in waters from all horizons at all stages of digression. It has been shown that for early detection of exceedances of critical level for mineral nitrogen in soil waters an evaluation of their composition is necessary not only between the crowns but also below them.