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Study of Early Cambrian sedimentary-volcanogenic complexes hosting the Kyzyl–Tashtyg pyrite deposit in Eastern Tuva has revealed cyanobacteria and algae that existed in zones of ore-forming hydrothermal systems similar in characteristics to present-day “black smokers” at ocean bottoms. Along with archaeocyaths and Cyanophyta from the host sedimentary rocks and microfossils from basalt amygdules, various cyanobacteria, monocyatheans, and sponge spicules have been found in ferrosiliceous deposits and metasedimentary rocks. Scanning electron microscopic, mineralogical, and thermobarogeochemical studies helped to reconstruct their hydrothermal environment.

Paleomagnetic studies of thick lava series are one of the most reliable sources of data on the ancient geomagnetic field. However, most of such data are younger than 5 Ma, with much fewer results on the rest of the Cenozoic and the Mesozoic. Two wholesome results are available for the Precambrian but none for the Paleozoic. Late Permian basalts and rhyolites from northeastern Kazakhstan were studied to obtain first estimates of the geomagnetic-field characteristics during that period. We present preliminary results on part of the collection (66 flows (sites)) from a section ~1600 m thick. The characteristic component of reversed polarity was isolated by stepwise demagnetization at all the sites with a slight error. This component is of prefolding age and, most likely, primary. No abnormal magnetization direction is observed in the data, and the average directions of the characteristic component at the sites are tightly clustered ( D = 243.3º; I = –57.0º, k = 79.1; α ₉₅ = 2.0º; 65 sites). As compared with the published data on Cenozoic and Mesozoic thick lava series, secular variation was much weaker in the Late Permian than in the Mesozoic or Cenozoic, and the geomagnetic field was less disturbed. Secular-variation models based on the Late Cenozoic data show even more dramatic differences.

A group of point transformations permitted by the three-dimensional Kadomtsev-Petviashvili equation is calculated. An example of an invariant solution is given. Exact solutions for the equation under study in the form of double waves are found. The resulting solutions are expressed in terms of elementary functions and describe the interaction of a pair of solitons. Smooth bounded rational solutions are also constructed.

During the study, the structural adaptations of the desiccation-resistant homosporous fern Ceterach officinarum Willd were revealed at the organ and cellular-tissue levels. Among them, the main role is played by features that contribute to the maintenance of cell hydration. Xero-heliomorphic signs at the organ level: nanism, area reduction and leatheriness of fronds; dense cover of trichomes and scales. At the cellular-tissue level, water is retained due to the relatively thick blade of fronds, their small cells, a large number of cells per unit area and pycnomorphy, high values of the specific surface area of the fronds (UPW), dorsiventrality of the mesophyll, a relatively dense network of veins per unit area of the frond. Biochemical and functional - by increasing the concentration of osmotically active substances, lowering osmotic pressure, accumulation of water-retaining chemical compounds (catechins and tannins); on the phytocenotic - due to facultative bryophily. Sciomorphic features: at the cellular-tissue level - hypostomaticity, a relatively small number of stomata per unit area of frond, tortuous seams of epidermal cells, minimal values of the ratio of cell surface to volume. Mesomorphic features: differentiation of the mesophyll into columnar and spongy tissue, a thin cuticle layer on the surface of the epidermis, the presence of stomata in the lower epidermis. Another adaptation mechanism that determines the rhythm of fern development is the ability to inactivate life processes and fall into cryptobiosis under conditions of water stress and high temperatures. Unlike poikilohydric ectohydric bryophytes, the sporophytes of this fern, resistant to dehydration, can withstand drying out (and are, to this extent, poikilohydric), but are endohydric. In a word, the poikilohydricity of fern sporophytes is realized on a different structural basis, which is more evolutionarily advanced in comparison with thalloid plants. However, the frequent state of cryptobiosis, especially under conditions of alternating wet and long dry seasons, leads to an imbalance in carbon metabolism. Apparently, poikilohydricity is not the most perfect and productive way to combat drought.

The paper presents an overview of ontogeny of 11 life forms on the example of 16 species of boreal willows belonging to two ecological groups - alluvial and non-alluvial. At the intraspecific level, among the studied species, the greatest variety of life forms was found in alluvial species, and the smallest in non-alluvial species. In the species studied, polyvariety of evolution was revealed: structural and dynamic. As part of the structural polyvariety, morphological (as a result of which two or more (up to 4) life forms are formed in the adult state), dimensional (expressed in changing the size and life state of an individual within one ontogenetic state) are distinguished. Dynamic polyvariety is associated with different duration of pre-generative and generative periods of ontogeny. In all alluvial and most non-alluvial species, the predominance of the generative period of ontogeny over the generative one is observed. In individuals of two life forms of non-alluvial species, the pre-generative period prevails during ontogeny. Alluvial species have mastered a narrower range of environmental conditions compared to non-alluvial ones. At the intraspecific level, among the studied species, the greatest variety of life forms was found in alluvial species (2-4 life forms in each species), and the smallest in non-alluvial species (1-3 life forms in each species). Alluvial species are characterized by the presence of a small number of long shoots, a large number of shoots of medium length and a smaller number of short ones, which determines their high height compared to non-alluvial ones.

The ecological and geographical regularities of the spatial differentiation of the fauna of birds and mammals of the seas of northeastern Russia were studied at the end of the winter period of 1987-1988. The aerial surveys covered the Bering, Chukchi, East Siberian Seas, and the eastern part of the Laptev Sea. Mammals are ecologically associated with open sea areas, sea ice, continental and island coasts, and mainland tundra. Wintering flocks of birds form species of inland mountain streams, species common circumpolarly in the Holarctic tundra, marine species of the continental and island coasts of the North Pacific and the Arctic Ocean, including high-latitude endemics. 7 species of mammals and 23 species of birds have been registered. There are 22 bird species recorded exclusively in the Bering Sea (24 % of the marine avifauna of the Russian Far East). In terms of the number of species represented ( n = 9), auks prevail, which are very characteristic of the avifauna of the subpolar marine areas of the Palaearctic. Mammals have been regularly recorded in both the Arctic Ocean and the Pacific research sector. The winter fauna of mammals in the seas of northeastern Russia, in which the number of species is dominated by pinnipeds and cetaceans, makes up 23 % of the total mammalian fauna of this region. In the Bering Sea, 3 areas of concentration of wintering birds have been identified: in the southeast of Chukotka, southeast of Cape Navarin, south of about. St. Lawrence. The maximum density of the bird population (21.8 ind./km²) is in young ice and ice of primary education - where there are many forage polynyas. The population of birds of all types of ice is numerically dominated by fulmar, thin-billed and thick-billed guillemots. Most of the marine mammals were observed on the openings in the contact zones of different types of ice or in the ice openings of autumn formation. Polar bears form clusters near the island. Wrangel, beluga whales - to the east and northeast of Cape Navarin, walruses - to the south of it. The stability of winter spatial groups of walrus and polar bears in the Arctic Ocean, which annually demonstrated similar levels of abundance, has been established. Winter aerial surveys showed that beluga whales and humpback whales are not found north of the Bering Strait, and polar bears are almost never found outside the Arctic Basin.

Data on the seasonal development of 78 species of perennial plants in the Western Siberia forest-steppe due to changes in the regional climate are summarized over a 20-year period 1996-2015. It is shown that the meteorological indicators of the warm season in Novosibirsk have undergone noticeable changes: the average daily air temperature has increased by 0.16 °C, the growing season has extended by 12 days, and the period of active vegetation of plants at temperatures above 10 °C - by 8 days. Correlations of the dates of regrowth and flowering in perennials with the date of snowfall, the dates when the average daily air temperatures exceed 5 °C and 10 °C, and the sums of these temperatures were revealed. Using linear phenological trends, a delay within 2-6 days of the spring regrowth and an advance in the flowering by 2-10 days, except for early summer species, were established. A reduction of the prefloral period duration from 5 to 24 days indicated an acceleration in the rate of seasonal development in perennials against the background of the identified meteorological trends. The change in the duration of vegetation period was significant in spring-summer-fall green species and spring-summer-winter green species - 10 and 12 days, respectively. Low values of the coefficient of determination for most of the trends R ² < 0.06 showed changes in the phenology were mainly due to interannual variability.

The results of the study of biological and ecological features of the invasive species Elaeagnus angustifolia L. in the territory of the South Urals are given. The species is actively naturalized mainly in river floodplains and around other reservoirs. It is included in the Black Book of flora of Central Russia, Siberia, “black lists” of the Middle Volga region, Voronezh, Orenburg and other regions. The total number in the investigated coenopulations is estimated at 18-20 thousand individuals. The species is naturalized in various types of phytocoenoses - from steeped meadows to halophytic communities. Most of the investigated coenopulations are located in an arid climate, with little precipitation. The northernmost coenopopulations are in more favorable natural and climatic conditions. DCA-ordination of communities revealed leading environmental factors: continental climate, humidification, soil acidity, rich soils with nitrogen, moisture variability. Individuals of E. angustifolia vary in height from 2 to 8 m. Tall plants are noted mainly on unsalted habitats with sufficient humidification. Lower plants are found in saline or dry habitats. The study of reproductive biology revealed that the greatest indicators for the parameters of fruits are observed in the coenopulations Aslykul, Izobilnoye, Sol-Iletsk, the minimum - in the coenopulation Tatar Kargala. Regression analysis of the dependence of the bone fraction on the fetal mass shows that with an increase in fetal mass, a decrease in the bone fraction is observed. The naturalization of E. angustifolia in river floodplains negatively affects the growth, development and resumption of native forest-forming species, which leads to irreversible consequences of the degeneration of floodplain forests.

The investigation of belowground plant production and its determining factors is critical for better understanding carbon turnover in the biosphere. The measurement of fine root production is a methodical and difficult task. To reveal factors determining fine root production in mountain ecosystems, we introduced a new modification of ingrowth method with the use of filter balls (tea strainers). We studied root production in 16 communities from upper forest to subnival belts in the range of 2184-3069 m a. s. l. in the Teberda Reserve, Northwestern Caucasus, Russia. The filter balls were filled with sifted soil (without roots or stones) and buried in the soil 7-8 cm deep. The mass of root ingrowth was measured after two months of incubation under natural conditions. Mixed-effect models were applied to test the relationships between root mass, elevation, soil moisture, organic matter content, and pH. The highest root production was observed in an alpine snowbed (247 mg per filter ball in 60 days), the lowest was in forest and subnival communities (3-20 mg per filter ball in 60 days). The communities with woody dominants had lower production than herb communities. It increased with soil moisture, which was the most important factor. In herb communities the production of roots tended to decrease with the elevation. Soil organic matter as a separate factor had a positive relationship with root production in herb communities. There were no links between root ingrowth and soil pH. The method introduced presently both allows for the comparison of plant communities by their root production and reveals factors determining it.