Home – Home – Jornals – Russian Geology and Geophysics 2018 number 5

We have first generalized geochemical and mineralogical data indicating the important role of crystallization of Os-Ir-Ru phases and fractionation of refractory iridium subgroup of PGE (IPGE) at the early stages of the evolution of parental magmas and primitive cumulates from the Yoko-Dovyren layered massif (northern Baikal area, Russia). The object of study was two types of plagioclase peridotites from the lower part of the intrusion, differing in the porosity of primary olivine cumulates: less melanocratic (but more primitive) type I and more melanocratic type II. Inclusions of refractory IPGE (Os, Ir, and Ru) discovered during LA-ICP-MS studies of aluminochromite from type I rocks are the first evidence for the presence of Os-Ir-Ru phases. Subsequent electron microscopy examinations revealed more than 25 grains of laurite and Ir-containing osmium in aluminochromite from plagioperidotites of both types. Attention is focused on the importance of the Ru/Cr2O3 and Ir/Cr2O3 ratios in rocks for the separation of IPGE at early and late fractionation stages. The conclusion is drawn that the higher Ru/Cr2O3 and Ir/Cr2O3 ratios in type I plagioperidotites indicate higher enrichment of aluminochromite in inclusions of refractory IPGE minerals. This is consistent with the fact that these rocks are assigned to the most primitive high-temperature ultramafites genetically related to the parental magma, which was in equilibrium with olivine Fo₈₈ at ~1290 °C. We have established that the parental Dovyren magma was already depleted in IPGE and rhodium before its entrance into a chamber. No signs of early sulfide-silicate immiscibility have been detected.

We report data on the geology, mineralogy, petrography, and chemistry of 733 Ma gabbro-peridotite sills from the Late Riphean Dovyren plutonic complex. Thick sills were differentiated into plagiolherzolite to olivine gabbronorite compositions by fractional crystallization of the K-Na series high-Mg low-alkali low-Ti picritic parental magma. The magma already contained up to 5% of intratelluric olivine crystals when entering the reservoir. The sills emplaced before the whole complex, judging by the presence of their fragments as plagiolherzolite xenoliths in the gabbro zone of the Yoko-Dovyren layered pluton. The gabbro-peridotite sills are products of high-temperature within-plate magmatism. High heat flow during the generation of the magma, evident from its high-Mg composition, was, likely maintained by the activity of a mantle plume associated with the Neoproterozoic Franklin large igneous province.

Mosaic diamonds from the Zarnitsa kimberlite (Daldyn field, Yakutian diamondiferous province) are morphologicaly and structurally similar to dark gray mosaic diamonds of varieties V and VII found frequently in placers of the northeastern Siberian craton. However, although being similar in microstructure, the two groups of diamonds differ in formation mechanism: splitting of crystals in the case of placer diamonds (V and VII) and growth by geometric selection in the Zarnitsa kimberlite diamonds. Selective growth on originally polycrystalline substrates in the latter has produced radial microstructures with grains coarsening rimward from distinctly polycrystalline cores. Besides the formation mechanisms, diamonds of the two groups differ in origin of mineral inclusions, distribution of defects and nitrogen impurity, and carbon isotope composition. Unlike the placer diamonds of varieties V and VII, the analyzed crystals from the Zarnitsa kimberlite enclose peridotitic minerals (olivines and subcalcic Cr-bearing pyropes) and have total nitrogen contents common to natural kimberlitic diamonds (0 to 1761 ppm) and typical mantle carbon isotope compositions (-1.9 to -6.2‰ δ13C; -4.2‰ on average). The distribution of defect centers in the Zarnitsa diamond samples fits the annealing model implying that nitrogen aggregation decreases from core to rim.

In the Baiyun Sag, the oil relationship with possible source rocks is complicated, and little research on oil sources in the area has been performed. In this paper, geochemical studies of carbon isotopes, biomarkers, paleoenvironmental deposition, and crude oil maturity, carried out with the use of oil samples from the Baiyun Sag, demonstrate that the organic matter in crude oil has an oxidizing depositional environment and primarily lacustrine facies conditions, with a significantly higher plant input. The oil samples used are mature to highly mature. Crude oil in the northern area of the Baiyun Sag is more mature than samples in the eastern part of the sag. Despite limited source rock data, we were able to conclude that the crude oil samples were derived mainly from the Enping Formation; other potential source rocks of the Wenchang and Zhuhai Formations may also have contributed to the reservoirs in different parts of the sag. Furthermore, the source of crude oil in each structure in the Baiyun Sag was analyzed; for example, crude oil in the LH19-5 structure was generated from the organic matter of the Enping Formation, and crude oil in the LW3-1 structure was derived from the mixed organic matter of the Enping, Wenchang, and Zhuhai Formations.

The software was created that allows automatic retrieval of water vapor continuum absorption from experimental data. The program includes baseline correction (if necessary), automatic correction of the experimental spectrum by frequency, automatic “spectroscopic” correction of the measured pressure value, subtraction of the spectral line local contributions, automatic selection of microwindows of transparency with the most reliable results of continuum retrieval and smoothing of the values obtained. Currently the software is intended to be used for processing Fourier measurement data, but it can be adjusted for other experimental methods.

Spectral line contour found on the basis of the asymptotic line wing theory with parameters obtained from fitting to experiment in the 8-12 mm region and describing the spectral and temperature behavior of the water vapor absorption coefficient in this region is used to calculate absorption in the long-wave wing of the H₂O rotational band. The absorption coefficient calculated within the asymptotic line wing theory takes into account the absorption by any colliding molecular pairs except the absorption due to stable dimers. The application of this contour in calculation of the absorption coefficient in the range of 14-200 cm^-1 allows us to extract the absorption part due to stable dimers from the absorption measured with the special resonator spectrometer. The dimer absorption spectrum derived shows a consistency with the spectra from quantum-mechanical calculations and measured in other experiments.

Numerical experiment is used to study the distribution laws of intensity fluctuations of laser beams propagating in the atmosphere. The probability density functions of intensity of fundamental Gaussian beam and beam having an orbital angular momentum (vortex beam) are compared for different positions of the observation point in a cross plane. An analytical model is suggested for the probability density function of intensity fluctuations, which works well for the conditions of strong (when the variance of intensity fluctuations takes the highest values) and saturated intensity fluctuations.

The results of the statistical analysis of experimental data obtained during the polygon tests of a passive optical wind speed meter are presented. During the tests, a possibility of using the device for aiming correcting to compensate the wind shift of bullets was evaluated. During the experiments, the arrays of the coordinates of the impact points and the values of the component of the wind speed averaged over the line of sight were recorded; the one-to-one correspondence of the elements of the arrays was not established. A method for determining the coefficient of linear interrelation for such arrays is proposed. It is shown that taking into account the corrections formed on the basis of wind measurements by a passive optical meter decreases the spread of the impact points to values corresponding to shooting standards for the best snipers in the absence of wind.

The concept of non-stationary diffraction-beam optics of powerful femtosecond laser pulses is presented. According to the concept the power of a beam propagates along specific light structures--diffraction-beam tubes. These tubes do not intersect, do not exchange energy, but changes in their shape and cross sections during propagation reflect the effect of physical processes that occur with radiation in the medium. The non-stationary theory is supplemented with evolutionary equations for time averaged diffraction beams and effective squared radii of diffraction tubes.

The process of near-ground propagation of monochromatic acoustic radiation at frequencies of 300, 1000, 2000, and 3150 Hz along atmospheric paths up to 100 m long is investigated experimentally and theoretically depending on altitudes of acoustic source and receiver. Experiments were performed at the experimental site of the IMCES SB RAS using a specially developed setup. The dependence of the recorded sound pressure level on the propagation path length and the initial signal power is studied. The theoretical analysis is performed by the Monte Carlo method that allows contributions of multiple scattering of acoustic radiation, refraction, and reflection by the underlying surface to the acoustic signal recorded with the detector to be taken into account for realistic models of the atmosphere. The local estimation algorithm of the Monte Carlo method developed by the authors was used for calculations. The comparison of the experimental and theoretical results shows their satisfactory agreement, which testifies to the efficiency of the suggested Monte Carlo algorithm and its applicabilty to the prediction of near-ground acoustic radiation propagation.

A new hardware-software ultrasonic complex AMK-03-4 is created for measurements of the characteristics of turbulent weather fields. In contrast to similar measuring instruments, the complex consists of four identical ultrasonic anemometers. The design of the complex allows one to record not only turbulent, but also statistical characteristics of spatial derivatives of turbulent pulsations of temperature and orthogonal wind speed components along the Cartesian axes. This allows investigating the spatial-temporal structure of turbulent meteorological fields of a surface air layer for subsequent applications in the similarity theory. Besides, the standard algorithm for calculation of structural characteristics of fluctuations of temperature and wind speed used in the ultrasonic anemometers is improved, which provides for considerably lower errors of their measurements.

This research is a part of the series of works devoted to the study of different factors that influence the phase function of cloudless atmosphere’s brightness: the elongation of aerosol scattering phase function, solar zenith angle, optical thickness, and albedo of underlying surface. The near-infrared region is under the analysis. While calculating the brightness of the cloudless day sky in the solar almucantar, we use the radiation transfer equation. The form of the aerosol phase function is determined by including three types of particles into the atmospheric model: submicroscopic, submicron, and coarse, as well as their mixtures in different proportions. We have received the data for a wavelength of 1.02 μm. The data may be used in atmospheric optics as an additional assessment of asymmetry of the aerosol scattering phase function and in approximate calculations of the flow of scattered solar radiation incoming to Earth’s surface.

Results of measurements of a complex of aerosol microphysical, chemical, and optical characteristics in two cruises of the research vessel «Akademik Mstislav Keldysh» in 2016 are analyzed. The work was carried out in the Kara Sea from July 10 till August 20 and in the Barents Sea from August 25 till October 10, 2016. The mean values of the following aerosol characteristics are presented: AOD of the atmosphere, fine and coarse components of AOD, number concentration of particles in the near-water layer of the atmosphere, mass concentrations of the absorbing matter («soot»), water-soluble ions (Na⁺, Mg²⁺, Cl^-, K⁺, Ca²⁺, NH₄⁺, NO₃^-, SO₄^2-), and gaseous admixtures (SO₂, HCl, HNO₃, NH₃). The characteristic particle size distribution functions are presented for different regions of the Kara and Barents Seas. It is shown that the levels of both aerosol turbidity of the atmospheric column (AOD) and the concentrations of aerosol and soot in the near-water atmospheric layer were close to the long-term mean values in Arctic latitudes. The atmospheric turbidity during the period of measurements was noticeably affected by emissions of forest fire smokes from the continent. The contribution of smoke aerosol into the mean values of AOD at λ = 0.5 µm obtained from shipborne measurements is about 44%.

Atmospheric air quality is determined by the concentrations of some gaseous pollutants and mass concentrations of aerosol particles in different size ranges. A wide range of atmospheric pollutants in both gaseous and aerosol phases was studied in the vicinity of Gelendzhik simultaneously in several sites of the region and at altitudes of up to 2200 m in July 2009. No such complex experiment was conducted there before. The following characteristics of the atmospheric aerosol were studied in the partical size range 3 nm - 32 μm: elemental composition of particles (23 chemical elements) and concentrations of polyaromatic hydrocarbons (14 compounds), unsaturated hydrocarbons, total protein, biotoxins, and culturable microorganisms. The concentration fields of different air pollutants and the integrated air pollution index were constructed using mathematical models of pollutant propagation and data on the hydrometeorological conditions during the period of measurements. The sources of aerosols in the region were revealed by studying the chemical composition of the airborne particles. The data obtained allowed us to estimate air pollutants and to calculate air quality indexes for the Gelendzhik area. The daily average concentrations of all the pollutants were compared to the daily average maximum permissible concentrations. All these concentrations were less than appropriate values of daily average maximum permissible concentrations.The integrated air pollution index did not exceed 1. Consequently, the atmosphere in the vicinity of Gelendzhik did not contain any significant pollutants in that period.

Experimental data on variability of light absorption by yellow substance in the surface layer of Lake Teletskoye (Gorny Altai) received during field hydrophysical studies carried out in the summer of 2017 are presented. The indices of light absorption by yellow substance calculated in the spectral range 400-800 nm (at natural logarithmic base) are within 0.1-2.1 m^-1. The yellow substance concentration in Lake Teletskoye determined by the optical method from the measured light absorption by yellow substance varies from 2.9 to 5.1 g/m³. To assess the effect of light absorption by yellow substance on the total attenuation, the relative spectral contribution of major optically active components of the lake water (yellow substance, suspended matter, chlorophyll, and pure water) to the spectral attenuation index for the water area under study is calculated. It is found that just the yellow substance makes the maximum contribution at all sampling points (21) of the lake.

The cluster analysis is used in various fundamental and applied fields and is a current topic of research. Unlike conventional methods, the proposed algorithms are used for clustering objects represented by vectors in space with the non-observance of the axiom of symmetry. In this case, the feature of solving the clustering problem is the use of an asymmetric proximity measures. The first one among the proposed clustering algorithms sequentially forms clusters with a simultaneous generalization to clustered objects from previously created clusters to a current cluster if this reduces the quality criterion. This approach to the formation of clusters allows reducing the computational costs as compared with existing non-hierarchical cluster algorithms. The second algorithm is a modified version of the first algorithm. The second algorithm allows reassigning the main objects of clusters to further reduce the proposed quality criterion.

The paper deals with development of spectrum dichotomy methods for the matrices with a large norm. Such matrices appear as a result of discretization of differential operators. The results of some numerical experiments including the stability investigation for the Poiseuille plane-parallel stream are given.

The paper considers a model of double porosity for a fractured porous medium using a combination of classical and gradient mass transfer functions among cracks and porous blocks in the case of a flow of a weakly compressible single-phase fluid. As compared to well-known models, such a mass transfer function allows one to take into account the anisotropic properties of filtration in a more general form. The results of numerical tests for two-dimensional and three-dimensional model problems are presented. The computational algorithm is based on the use of finite element approximation with respect to space and completely implicit approximations with respect to time.

The optimal q-homotopy analysis method is employed in order to solve partial differential equations (PDEs) featuring a time-fractional derivative. Then, in order to illustrate the simplicity and ability of the suggested approach, some specific and clear examples are given. All numerical calculations in this manuscript have been carried out with Mathematica package.

The splitting method for the CABARET scheme approximating the non-uniform scalar conservation law with convex and monotonically increasing flux function has been proposed. It was shown that at the first step of this method, when the uniform conservation law is approximated, the CABARET scheme is monotonic and its numerical solutions do not have non-physical oscillations in the shock wavefronts. Test computations that illustrate these properties of the CABARET scheme are presented.

A nonlinear distributed second order equation is considered. An algorithm for tracking a prescribed solution based on constructions from the feedback control theory is designed. The algorithm is stable with respect to informational noise and computational errors. It is oriented to a large enough time interval, where the solution is considered.

The study of Painleve's equations has increased during the last years, due to the awareness that these equations and their solutions can accomplish good results both in the field of pure mathematics and theoretical physics. In this paper we introduced an optimal homotopy asymptotic method (OHAM) approach to propose analytic approximate solutions to the second Painlevè equation. The advantage of this method is that it provides a simple algebraic expression that can be used for further developments while maintaining good performance and fitting closely the numerical solution.

A mathematical model of the sea thermodynamics, developed at the Institute of Numerical Mathematics of the Russian Academy of Sciences is considered. The problem of variational assimilation of daily-averaged sea surface temperature (SST) data is formulated and investigated taking into account the observation error covariance matrices. On the basis of variational assimilation of satellite observation data, the inverse problem of restoring a heat flux on the sea surface is solved. The stability of the optimal solution of the problem of variational data assimilation is studied, and the results of numerical experiments for the model of the Baltic Sea dynamics are presented.

For the first time, there were offered consecutive stages of algorithm solution, such as phenolic antioxidants in the improvement of mechanical properties of polymers. The first step begins with studies of thermokinetic characteristics of thermolysis reactions of phenolic antioxidants accompanied by determination of their kinetic constants (activation energy, E and pre-exponents, Z). Modifiers of the main group of antioxidants can be distinguished according to the ratio of these constants. Polymer modification effect by them was determined at the second step. It appears in a temperature of the beginning of modifier decomposition under polymer thermal processing conditions. Furthermore, parameters of an increase in product service time under extreme operating conditions were defined. Examples are given of modification and stabilization of properties of polymer-derived composites

Rare metal ores of the Chuktukon deposit (Krasnoyarsk Territory) were explored. It was found that the ores were complex, mainly of iron-manganese composition (iron oxides content of 50% or above), with high contents of lanthanides, yttrium, niobium, vanadium, zinc, and phosphorus. The main mineral forms of rare earth metals are monazite and florencite, of niobium - barium-strontium pyrochlore. As demonstrated by granulometric composition study, above 50 % of ore mass is presented by a particle size of mainly 1-2 µm and ~12 µm. As a rule, elements are almost evenly distributed according to all size grades. According to microscopic study results, the ore is mainly formed by ultrafine micrometre-sized particles (the first micrometres) that, in turn, are nanoscale particle aggregates. The findings explain the complexity of excreting concentrates of rare earth metals and niobium from the ore using enrichment methods.

The causes and ways of reducing losses of zirconium and other rare elements with silica residues upon acid treatment of eudialite concentrate, i.e. a raw source of zirconium, hafnium, and rare earth elements of the middle and yttrium groups, were explored. Metals distribution was examined during acid treatment with 2 mass % solutions of nitric and sulphuric acids in the presence of sulphocationite. It was found that decomposition of the eudialite, the main Zr-containing mineral, proceeded entirely. Herewith, losses of zirconium and other rare elements with silica residues formed during nitric acid and sulphuric acid processing of eudialite concentrate are mainly related to their ingress to silica gels. Rare elements are present therein as bridges of hydrated silica-based polymers that are bridge-coupled by hydroxyl (olation) or oxygen (oxyolation). As demonstrated, zirconium and other elements may be additionally derived by acid treatment. Their losses with silica residues may be reduced during eudialite concentrate decomposition in the presence of sulphocationite with sol production in the initial stage.

An efficient mechanochemical method for producing composites based on LLDPE 6101RQ polyethylene and inorganic additives was investigated. Films with improved barrier and mechanical properties were produced therefrom. In obtaining films without master-batches, the content of additives (TiO₂, CaCO₃, SiO₂, or Na-montmorillonite) was 0.01-5 %. Herewith, gas permeability reduced to 30-50 %; modulus of elasticity (along) increased by 24-60 %, strength - by 15 %.

Natural and technogenic sources of mercury ingress to into ecosystems of Gorny Altai were characterised. The content of mobile Hg forms in polluted soils was determined and its inverse dependence on the gross content of mercury in the soil was revealed. The limited nature of migration of mobile forms of mercury from polluted soils was demonstrated. The main thermoforms of mercury in conditionally background and anthropogenically polluted soils were preliminarily found. Data on levels and forms of its occurrence in components of water ecosystems are presented. Features of their changes in different hydrological periods, and also during the water transfer are revealed. Quantitative characteristics of transfer of various forms of mercury coming from the industrial zone of the Aktash mining and metallurgical enterprise were assessed. A progressive decrease of their content in the waters that transmit pollution of rivers of the fifth-second orders (Yarlyamry, Chibitka, Chuya, and Katun) was shown.

The results of exploring cracking of high-sulphur bitumen (sulphur content of 3.7 %) from the Mordovo-Karmalskoye field with a mass content of fractions boiling out to 200 °C of 6.7 % are presented. The yields of gaseous, liquid, and solid products were determined at 450 °C and process time of 60-120 min. The hydrocarbon composition of liquid products from cracking was analysed. The effect of bitumen thermal treatment length on changes in molecular structures of high molecular mass heteroatomic compounds (resins and asphaltenes) was investigated. It was found that at cracking time of 100 min, molecules of asphaltenes of bitumen from the Mordovo-Karmalskoye field became larger due to an increase in the number of naphthenic rings. Whereas at 120 min, asphaltenes decomposed and got more aromatized.

Using gas chromatography-mass spectrometry (GC-MS), there was explored the composition of organic compounds in snow samples collected in the territory of Tomsk region in areas with diverse technogenic load: at the oilfield, in the forest-park area of the city of Tomsk (Academgorodok), and in wetlands remote from anthropogenic sources. In snow pack samples, there were determined the following components: alicyclic and aromatic hydrocarbons, normal aliphatic acids and their esters, acyclic and aromatic ketones, aldehydes, terpenes, phenols, orthophosphoric acid esters, furans, and thiophenes. According to the results of analysis of the composition of the organic compounds identified, sources of their entry to snow pack (biogenic and anthropogenic) were revealed.

Selection of the optimum synthetic path to the active ingredient for any drug is a complex task. The lack of computational methods for performance assessment of chemical transformations does not allow evaluating the proposed synthesis options and efficiently using computational methods in their development. The method of quantification of syntheses efficiency considering changes in structural complexity of organic compounds, reaction conditions and results is developed.

A thermogravimetric study of vitrinites of bituminous coals of different metamorphic stages was carried out in the oxidizing medium. It was demonstrated that with increasing the metamorphic grade of vitrinites, the temperature range of the oxidation process rose, while the maximum decomposition rates were shifted to higher temperature region. A strong correlation of the ignition temperature of vitrinites and organic (С^daf) and aromatic (С_ar) carbon content therein, and also of vitrinite reflectance values (R_o,r) and volatile matter yield (V^daf) was revealed.

Composition and structure changes of the macromolecules of asphaltenes from the Usinsk deposit were studied during sequential stepwise thermal decomposition at 120, 230, and 370 °C. Component composition data of thermolysis products were acquired and changes in structural-group characteristics of asphalthene molecules during thermal treatment were described. It was found that below 230 °С, asphaltene decomposition reactions prevailed over condensation ones, while above this temperature, compaction reactions were prevalent. It was demonstrated that the trend of heteroatoms towards accumulation in compaction products during stepwise thermolysis of oil asphaltenes from the Usinsk field increased in the series S → N → O.

Conceptual-methodological and economic bases of plantation forest growing are developed. The mathematical models of the dynamics of the productivity of stands of different tree species in the rich types of the forest-growing conditions of the Middle Volga region, their commodity structure, the stumpage cost and the market price of timber are presented. The algorithm of actions for managing forestry on cultivation of forest plantations is offered. It is noted that in the conditions of fresh dubrava (oak forest) and sudubrava (fresh oak and pine forest), pine and larch stands are the most productive. It is concluded that, taking into account the stumpage cost and the market price of timber, it is most profitable in this region of Russia, in oak forest types of forest conditions, to grow plantations of English oak Quercus robur L., in sudubrava conditions it’s more profitable to grow plantations of Scots pine Pinus sylvestris L., the Siberian larch Larix sibirica Ledeb., and tillet Tilia cordata Mill. In wet, near floodplain and short-flooded ecotopes, it is promising to grow European ash Fraxinus excelsior L. and high-grade poplar Populus crops. Less economic benefit in the current socio-economic conditions will be in the creation of plantations of common spruce Picea abies (L.) H. Karst, aspen Populus tremula L., and weeping birch Betula pendula Roth. The culmination of the average annual increment of the stand stumpage cost, which attests to the age of economic maturity, first occurs in aspen forests (at 45 years), and later - in spruce stands (at 70 years). In oak forests it occurs at the age of 65 years, in tillet stands and in larch crops - at 60 years, in birch forests - at 55 years, in pine crops - at 50 years. In the production of forest raw material plantations, the initial density is of great importance, the optimal values of which are determined by the tree species, the assortment and the economic efficiency of cultivation. Increasing the productivity of the stands and accelerating the process of forest growing is possible with the help of agrotechnical, meliorative and silvicultural measures, applying them considering forest growing conditions and the targeted purpose of plantations.

The DNA-diagnostic results of phytopathogens in 26 forest nurseries of Krasnoyarsk Krai and the Republic of Khakassia in the period from 2014 to 2016 were presented. The objects of research were the plants of conifer species Pinus sylvestris L., Pinus sibirica Du Tour and Picea obovata Ledeb. aged from 1 to 6 years. According to the data of molecular genetic analysis in the forest nurseries of the studied areas, the representatives of 13 genera of pathogenic and conditionally pathogenic fungi that cause diseases of conifers were revealed: Phoma Sacc., Didymella Sacc., Alternaria Nees, Cladosporium Link, Rhizoctonia DC., Lophodermium Chevall., Gremmenia Korf. ( Phacidium Fr.), Sclerophoma Höhn. (teleomorph - Sydowia Bres.), Typhula (Pers.) Fr., Botrytis P. Micheli ex Pers., Gremmeniella M. Morelet ( Scleroderris (Fr.) Bonord.), Septorioides Quaedvl., Verkley & Crous and Epicoccum Link. Seven genera of micromycetes are found in all three surveyed forest zones: taiga, forest-steppe and Southern-Siberian mountain. The most frequently occurred lesions were caused by the sac fungi. Some of the identified diseases practically had not been diagnosed before. In each of the nurseries, the pathogenic microflora was represented by 1-7 species of microscopic fungi, several pathogens were often presented simultaneously on the infected seedlings. In the process of working, the dominant pathogens, connection of pathogens with certain species and with the seedlings age composition have been identified. Such diseases as Phoma blight and Lophodermium needle cast predominated the frequency of occurrence, their relative abundance was 30 % and 28 % respectively of all identified fungal infections of plants. Also, given the climatic conditions of the region, attention should be paid to the phytopathogens - Gremmenia infestans (P. Karst.) Crous and Typhula sp .

When using biomass and net primary production (NPP) databases compiled by the authors for 6 forest-forming species in a number of 6694 and 2192 sample plots correspondingly, a system of regression models of their NPP is designed and some species-specific regularities of NPP distribution in two climatic gradients (natural zonality and climate continentality) are stated. It is found that according to a zonal gradient, aboveground and total NPP in 2-needled pine and spruce-fir forests are monotonically increasing in the direction from the northern to the southern tip of the continent, while larch and birch have the maximum in the southern moderate, and aspen and poplar - in the northern moderate zone, but oak forests do not show any significant pattern. Within a single zonal belt, the aboveground and total NPP of coniferous and deciduous are monotonically decreasing in direction from the Atlantic and Pacific coasts to the continentality pole in Yakutia. The understory NPP of all the species, except oak, monotonically increase towards the subequatorial zone. For oak forests, any clear regularity is not revealed. Within a single zonal belt, when approaching continentality pole, Pinus and Quercus NPP monotonically decreases and in other species, increases. Species-specific patterns in changing the relative indices of NPP (forest stand underground NPP to aboveground one and forest understory NPP to total forest stand one) in gradients of the natural zonality and climate continentality are established.

The principles for the formation of forest typological classification and outlines promising areas for development, allowing to solve problems of not only inventory and forest management, but also mapping forest types are discussed in the paper. The analysis is performed by interpreting the concept of «natural regularity» proposed by D. L. Armand (1975). It is shown when the left side of the pattern is a set of indicators of site condition, structure of forest typological constructions will take into account not only the static indicators of the stands, but also their location, the origin and direction of the succession. For relatively similar climatic conditions, the indicators of the lay of land mainly limit the environment of formation of vegetation cover. The method of mapping forest types provides for consideration of site condition and indicators of stands of forest types. Testing is conducted on a test axis West-Sayan forest district, located in the mountains of southern Siberia. Conjugation types of forests, indicators of the topography revealed through the analysis of literary sources and characteristics of forest types accompanying diagnostic table (Smagin et al., 1980). The work is done in a GIS environment using DEM SRTM and Landsat space images. For indexing locations, the inputs are accepted: altitude (gradation 100 m), flat location, slope up to 20° and 20° slopes with northern and southern exposure. Classification of pixels of satellite images is conducted by the method of unsupervised classification separately for each scene, the high-altitude zone and location, which allows increase of the quality of interpretation, because the types of forests are confined to the topography. However completely avoiding mistakes is not possible. The main reasons are an inaccuracy of the DEM and the hit in one class of spectral brightness of different objects of interpretation. The map legend includes characteristics of the terrain, description of the types of forests, including soil and groundwater conditions, and forest inventory parameters.

Despite a large number of publications covering various aspects of the influence of climatic factors on runoff, this direction in hydrological research acquires a new meaning in connection with the increase in anthropogenic pressure on river systems. In order to identify regional and local features of the hydrological regime of the rivers in Sayan mountain region, the spatial and temporal dynamics of runoff of the main rivers in the study area were analyzed; the analysis of river flow trends against the backdrop of climate change and forest management in the drain areas was performed. Studies have shown that the revealed trends in the annual runoff of the studied rivers differ in type and in magnitude. The hydrological regime of the rivers with the negative trend of annual runoff is determined by the general nature of the humidification of the territory, which overrides the influence of all other factors. Despite a general trend of decreasing precipitation, the positive trend of annual runoff is due to a decrease in evaporation in the drainage areas, which depends both on the temperature regime of the research area and on the anthropogenic transformation of forest vegetation under logging impact. In spite of the considerable variability of annual river flow, trends in runoff coefficients for study rivers vary slightly, indicating the relative stability in water availability. This is due to cumulative effect of anthropogenic transformation of forest vegetation in the drainage areas, i.e. new felling, regeneration on logging sites and creating forest crops. Obtained results show that at the regional level in conditions of anthropogenic pressure on the forests in the drainage areas of medium and small rivers, the trends of climatic parameters, in particular precipitation, are offset by the forest harvesting and subsequent reforestation dynamics at clear cuts.

The influence of experimental burning on ground cover in pine forests of different age stands with dominated herbs and mosses in the Krasnoyarsk forest-steppe was studied. Experimental burning decreased species diversity, percent cover, and biomass of shrubs and herbs. Mosses degraded after fires. The species diversity and biomass of shrubs and herbs increased in 2 years after fire. The greatest species diversity of ground cover was in 60 year old pine forest in 2 years after fire (moderate intensity) (28 species). The percent cover of shrubs and herbs was below pre burning values in 110-years aged stand in 2 years after fire. The seedlings of Scotch pine Pinus sylvestris L. were 35.2 thousand units/ha in 60-years aged pine forest in 2 years after experimental burning. The seedlings of pine were 61.1 thousand units/ha and self-sowing was 14.8 thousand units/ha in the next year after fire. The number of pine shoots was high (51.1 thousand units/ha) and self-sowing was by 3.2 times more than in last year (47.0 thousand units/ha). Experimental burning of low intensity stimulated emergence of pine shoots in 110-years aged stand where their amount were 31.1 thousand units/ha in 3 month after fire. The reforestation was presented by pine shoots (31.5) and self-sowing (2.0 thousand units/ha) in next year after experimental burning. The number of pine shoots was 17.4 thousand units/ha and self-sowing increased by 11.0 times or 21.9 thousand units/ha in two years after burning.

Boreal forests are one of the main carbon (С) pools on the planet. Decomposition of the litter is a main mechanism of C accumulation in soil. This process is often influenced by fires. Thus, we need to enhance our understanding about decomposition of the litter in post-fire forests to better understand the mechanism of C accumulation in boreal forests. Here, we studied initial stages of decomposition of litter in the post-fire forest (12 years after fires) and in the background larch forest located in the Tukuringra mountain range in the northern part of the Amur oblast. We present the results of a field experiment on the decomposition of the main typical fractions of larch forest. We used the litter bags method for studying rate of decomposition litter (leaves, grass, branches and needles). After 150 days mass loss of litter was 36.7 % of initial mass in the post-fire forest and 39.9 % in the background forest. Mass loss was most rapid in the first 75 days of the experiment in the both cases. In both plots the rate of decomposition of litter was decreased in order: grass - leaves - needles - branches. In both the post-fire and background forests, rate of litter decomposition is a function of moisture. Soil acidity was higher in post-fire forest than background forest (5.3 and 4.8, respectively, p < 0.01). However, this soil property does not influence early stages of litter decomposition in either case.