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New sedimentological, lithochemical, and biostratigraphic data were applied to describe the main part of the Inikan Formation, which is comprised in the Kuonamka Complex of the lower and middle Cambrian of the Siberian Platform. A classification of carbonaceous rocks in the Inikan and Chaya formations was proposed, based on a comprehensive approach, including textural analysis, study of geochemistry of rock-forming oxides and organic carbon, lithochemical calculations, optical petrographic, and X-ray structural data. This made it possible to clarify the structure of the overall section and the conditions under which Cambrian deposits formed. The widespread influence of volcanic activity during sedimentation in the Kuonamka Complex in the southeastern Siberian Platform was identified for the first time. The distribution of paleoseismic breccia in the section was also described, with horizons that represent good regional stratigraphic markers. Limitations in the use of the Strakhov modulus and the Nesbit-Young chemical index of alteration for characterizing sedimentation conditions of Domanikoids were revealed.

This article presents results of a multidisciplinary study of late Pleistocene deposits exposed at the newly discovered Nozhii locality in eastern Transbaikalia. New data on small mammals have filled a gap in the fossil record of the late Pleistocene faunas in the studied region. The faunal remnants originate from loessial deposits, which are rarely distributed in the region, where spore-pollen samples were collected. A rich, diverse faunal assemblage has been identified, and information on the paleoflora of one of the late Pleistocene ages has been obtained. The fauna is predominantly composed of species characteristic of open steppe landscapes: Ochotona dauurica , Marmota sibirica , Lasiopodomys brandti , Cricetulus barabensis , and Allactaga. The species composition, the quantitative ratio of taxa, and evidence on paleovegetation indicate that, during the existence of the vertebrate community at the Nozhii site, forest-steppes with open steppe landscapes were widespread along with patches of desertified areas and forb meadows as well as sparse forests with a herbaceous cover.

The taxonomic composition of acritarchs from Albian-Cenomanian deposits recovered by boreholes in the southwest of Western Siberia has been studied. Two new genera and species of acritarchs have been described monographically: Pyramidinium annulatum gen. et sp. nov. and Trilobatina angusta gen. et sp. nov. The species P. annulatum is found both in the Albian, Khanty-Mansiysk Formation, and in the Cenomanian, lower part of the Uvat Formation. The species T. angusta is found only in the Cenomanian, Uvat Formation.

Based on the results of studies in 2022-2023, an assessment was made of carbon reserves in the pools of phytomass of the stand, forest litter, and soil organic matter in birch stands in different areas of the southern forest-steppe of Omsk Oblast - on the territory of the carbon polygon site of the Omsk State Agrarian University and in the vicinity of the village of Kordon (Isilkulsky District of Omsk Oblast). Birch forests in the studied areas differ in forest survey indicators - average height, density of growth and the sum of cross-sectional areas. The stem wood stock (155.3-159.6 m³/ha) and the carbon stock in phytomass (57.05-61.07 t/ha) in birch stands on meadow-black soil of the carbon testing site are significantly lower than the corresponding indicators (233.1-259.3 m³/ha; 87.35-94.81 t/ha) on gray forest soil in the vicinity of the village of Kordon. On the contrary, the total reserves of soil carbon in the 0-50 cm layer on the meadow-black soil of the carbon polygon are higher (170.35 t/ha) than on the dark gray forest soil in the vicinity of the village of Kordon (115.72 t/ha).The total carbon stocks in the forest litter in the study areas differ insignificantly - 3.65 t/ha in the vicinity of the village of Kordon and 4.23 t/ha in the carbon testing site. The total carbon stock in birch stands according to 2023 data differs slightly in different areas, amounting to 292.7 t/ha in the carbon polygon and 301.53 t/ha in the vicinity of the village of Kordon. It has been established that the productivity and carbon deposition function of birch tree stands in the southern forest-steppe of Omsk Oblast depends on the density of their growth and the type of soil cover.

The article presents the results of the study of the age structure of high-productive pine stands in Pribaykalie. The structure of forest stands by area, timber stocks, age, species composition and other characteristics is analyzed. An attempt is made to identify patterns in the distribution of the age structure of forest stands in sections with different forest inventory formulas. The establishment of these patterns and common features can be used in economic activities, as well as for solving forest restoration issues. Determining the relationship between tree species and their age structure in specific areas allows us to distinguish simple stands with one storey in height and complex stands with two or more storeys. The age character of a forest stand establishes a certain set of trees that form homogeneity in the age and biological development of the stand, which predetermines its economic importance in organizing forestry. The studies have shown that the intra-population structure of the stands has two predominant species, belonging to the pine (Scots pine ( Pinus sylvestris L.)) and aspen (common aspen ( Populus tremula L.)) economic parts. In relation to these economic parts, an analysis of the age character of the forest stand of the predominant pine economic part is given, which grows in the lingonberry, forb, green moss, alder and nettle groups of forest types. Pine stands of the first quality class are defined as even-aged and uneven-aged. Simple even-aged stands are characterized as pure and absolutely even-aged, as well as even-aged with the inclusion of accompanying species, having in the composition less than one in the reserve of the allotment. Among complex multi-storey stands, relatively even-aged stands located within the same age class, absolutely uneven-aged, relatively uneven-aged with an age spread of up to sixty years stand out. Intermediate types of age structures are characterized by stepped-uneven-aged forest generations.

The results of long-term trials of species of the genus Prunus L. (the currently included genus Padus Hill.) in the arboretum of the dry steppe zone of Khakassia are presented. The objects of research were five species of the genus with different origins: bird cherry ( Prunus padus L. - syn. Padus avium Mill.), Manchurian cherry ( P. maackii Rupr. - syn. P. maackii (Rupr.) Kom.), Hokkaido bird cherry ( P. ssiori F. Schmidt - syn. P. ssiori (F. Schmidt) C. K. Schneid.), Gray’s bird cherry ( P. grayana Maxim. - syn. P. grayana (Maxim.) C. K. Schneid.), Virginia bird cherry ( P. virginiana L. - syn. P. virginiana (L.) Mill.). The aim of the study is to trace the rhythm of growth, development and condition of new species of the genus Padus at introduction in changing climatic conditions of the dry steppe zone of Khakassia for introduction into landscaping. Using the methodology of phenological observations and statistical processing of the obtained data, the rhythm of growth and development of the studied species was established. The timing and duration of flowering, vegetation, fruit ripening and leaf fall periods were determined. A high degree of correlation between the passage of phenological phases and the influence of air temperature and the amount of precipitation was revealed. It was observed that plant height of 80 % of species in the nursery is lower than in natural conditions. Flowering of Padus species occurs in the second third decade of May with periods of 9 to 16 days. The longest flowering period is characterized by Manchurian cherry and the shortest by bird cherry. In the conditions of the arboretum 80 % of Padus species form root shoots, in 40 % - self-seeding was found. Seeds of the studied species have low ground germination - from 2.2 to 17.7 %, which makes seed multiplication of the considered plants difficult. Among the characterized species, two are long vegetative with a growing season of 178 and 186 days (Hokkaido bird cherry and Gray’s bird cherry, respectively). A scale with plant evaluation adapted to steppe conditions was used to determine the most promising Padus species for introduction. Four of the five species were quite promising. The highest number of points is characterized by bird cherry (105 points), 102 points each were scored by Virginia bird cherry and Gray’s bird cherry, 92 by Manchurian cherry. These species can be used in the landscaping of settlements to create alleys, in group and single plantings of parks, squares and adjacent territories.

Two types of salinization are compared: mineralized Cenomanian waters and crude oil bottom waters in different pollution zones (epicenter, impact zone, boundary). The systematic position of soils was determined according to the Classification and Diagnostics of Soils of Russia (Shishov et al., 2004) and the World Reference Base for Soil Resources (IUSS…, 2022). Contaminated soils are classified as technogenically saline podzolic soils ( Chloridictechnic Salictechnic Gleyic Podzol ) and technogenically saline alluvial soils ( Salictechnic Chloridictechnic Technic Gleyic Fluvisol ). To identify the features of salt accumulation during salinization by mineralized Cenomanian waters and crude oil bottom waters, two soil profiles (P-1, P-2, respectively) were laid in the most transformed zone - the epicenter. Samples were taken along the entire depth of the soil profile. In the epicenter, impact zone, pollution boundary, a number of soil pits are also laid (P-1.1, P-1.2, P-1.3; P-2.1, P-2.2, P-2.3). The sampling depth was 0-10 cm and 10-30 cm. In most cases, oil-contaminated soils are characterized by the sulfate type of salinization with anionic composition and the sodium type of salinization with cationic composition. Toxic salts are represented by NaCl, Na₂SO₄, MgCl₂. For technogenically saline soils, sulfate-chloride and sodium types of salinization are characteristic. Toxic salts are represented by NaHCO₃, Na₂SO₄, MgCl₂. The degree of salinization in both types of pollution varies widely: from weak to strong. In oil-contaminated soils, it was found that an increase in the content of oil products is closely related to an increase in the degree of soil salinization at a reliably significant level ( p < 0.05). A method for restoring technogenically saline soils is proposed, based on measures used in melioration practice (arrangement of a system of drainage trenches, ditches; gypsum application; fertilization). It is advisable to supplement the set of measures with a biological stage of reclamation using salt-tolerant vegetation. In oil production, organochlorine compounds are used as a chemical reagent to increase the recovery of the oil reservoir. Chloride ion (the main component of these reagents) is also an available and good solvent capable of removing paraffin deposits in wells. In this regard, this ion was chosen as the main indicator characterizing the efficiency of the applied reclamation solutions. In subsequent years, monitoring of the dynamics of changes in the content of chloride ions in various areas (background, experimental and control) was carried out. The identified features of changes in the ecological state of soils (development of the process of technogenic halogenesis and processes of technogenic alkalization) should be taken into account when conducting new large-scale pilot industrial tests of new environmental protection measures in the middle taiga subzone of Western Siberia.

Methods of the objective periodization of the age dynamics of forest stands are considered on the example of southern taiga birch forests in the process of demutational changing birch ( Betula L.) to spruce ( Picea A. Dietr.). The analysis of the age range of birch forests has allowed to determine four distinct stages of age development which differ one another by the qualitative state of birch population. There are Stage of regeneration (before forest canopy has closed), Stage of youthfulness (before “quantitative maturity”, when the curve of mean annual increment of trunk volume of trees at peak), Stage of maturing (from “quantitative maturity” to “natural maturity”, when the curve of trunk volume of trees at peak) and Stage of ripeness (from “natural maturity” to full treefall of first layer of forest). Then, according to the determined stages of age development of main breed, the phases of age dynamics of birch forests have been defined: Phase of young birch forest formation, Phase of active growth of birch and appearance of spruce under birch canopy, Phase of two layers tree stand - first tree layer of birch, second tree layer of spruce, Phase of changing of chief breed in forest as result of death and treefall of birch trees.

Paperbark maple ( Acer griseum (Franch.) Pax, Sapindaceae), a plant of central China, is known in the documents of the Peter the Great Botanical Garden of the Botanical Institute of the Russian Academy of Sciences, in St. Petersburg, since 1949, in the modern collection of the Arboretum there are individuals that have been growing since 1999. At the age of 26, the tree reaches 4.85 m in height, with a trunk diameter of 8 cm, forming a crown of 2.9 × 3.8 m. The first flowering was noted in 2015. The first fruiting was noted in 2019, when the plants were already 21 years old. In the conditions of the modern climate of the North-West of Russia, the species is quite winter-hardy. An original ornamental tree, attracts attention primarily with its bright color of the bark throughout the year, as well as the autumn color of the leaves. This species is resistant to diseases and pests. In nature, the species is rare and has an important conservation value. And it is important to preserve it both in situ and ex situ . It is suitable for city parks, squares and small gardens, as well as for rockeries and rock gardens. In terms of decoration, it stands out throughout the calendar year due to its bright special bark, which no other maple has, and is also noticeably attractive in the bright orange-yellow autumn color of the leaves. However, until now, breeding has been limited by the lack of a local seed base and the unstudied quality of the seeds. Thanks to the X-ray analysis of seeds of different years of ripening, it was shown that all the first seeds (harvest 2020) were empty. The seeds of the 2024 harvest are already almost 50 % complete, there is a high hope of getting the first offspring of its own reproduction.

The article analyzes the impact of forest management (primarily industrial logging) on the habitat structure and territorial distribution of the moose ( Alces alces (Linnaeus)) in the taiga landscapes of Eastern Fennoscandia (Eastern Finland and the Republic of Karelia). Materials of population counts (Winter Track Account) and forest inventory data were used. Higher population values are noted in the landscapes of the western part of the studied region that are intensively used by the forestry industry. A positive relationship is noted between the Winter Track Account index and the representation of deciduous and mixed young stands ( R = 0.30-0.45) and a consistently negative relationship with the proportion of bog area ( R = -0.78; p < 0.01). There are significant differences in the patterns of moose distribution in different parts of the studied region. The results of modeling the territorial distribution of moose depending on the habitat structure are considered: step-by-step multiple regression analysis of the influence of natural and anthropogenic factors. The calculations used 17 independent variables characterizing the structure of forest vegetation, and the index of Winter Track Account of moose as a dependent variable. In statistical models of multiple regression, the effective regressors are the proportion of mature forests, the representation of open bogs, the proportion of agricultural lands, the proportion of secondary middle-aged forests and the proportion of clear-cuts. Anthropogenic transformation of forest landscapes generally has a positive effect on the number and distribution of the moose population, especially in the early stages of forest industry development of taiga forest. At the same time, not only forest management, but also other forms of anthropogenic impact have a significant impact (ambiguous in the border regions of the two countries).