Aim. This work aimed to qualitatively and quantitatively evaluate alterations in forest land cover and the transformation of woody vegetation at the upper limit of its growth within the western ridges of the Subpolar Urals.

   Methodology. Permanent sample plots were established on different slopes within the upper forest ecotone, encompassing a total of 750 trees across an area of 2,32 ha. Repeated landscape photography of woody vegetation was carried out from the same point. A comparative analysis of the spatial and altitudinal distribution of the forest vegetation was conducted using aerial photographs and satellite multispectral imagery acquired between 1963 and 2022. Corresponding treeline positions were determined using GIS. Based on the tree-ring data and allometric equations relating tree phytomass to diameter, we reconstructed annual phytomass accumulation and analyzed tree radial growth dynamics over the past century.

   Results. It has been established that a shift in the upper boundary of open forests into mountain tundra communities occurred on the western ridges of the Subpolar Urals over the past 50–70 years. The most intense cumulative change in total aboveground phytomass occurred during the last century, particularly after the 1950s. In recent decades (from the 1990^s to the present), there has been an increase in radial growth of trees of all ages. However, the expansion and transformation of woody vegetation during the last century occurred at a slower pace than in other previously studied parts of the Urals (the Southern, Northern, and Polar Urals). This can be explained by an increase in the amount of solid precipitation and later dates for the melting of snow cover.

   Research implications. Our results are indicative of the climate transformations in high-rise ecosystems of the Subpolar Urals.

   Aim. Quantitative analysis of long-term dynamics of bank erosion on small and medium-sized rivers of Udmurtia, which are important for modeling and forecasting the development of meanders necessary to prevent dangerous geoecological situations.

   Methodology. For the first time, the results of a study of channel displacement for 2003–2024 in 8 key areas located on small and medium-sized rivers of Udmurtia are presented. Geodetic survey was carried out on actively eroded areas of river bends using a laser tacheometer, which allows calculating not only linear erosion parameters, but also area and volume indicators. Since 2019, a satellite receiver has been used in instrumental surveys together with unmanned aerial vehicles.

   Results. It was found that for medium-sized rivers, the maximum erosion rates reach 6.15 m/year. The length of the eroded areas varied within the range of 115–533 m. The height of the studied coastal cliffs varies from 3.5 to 5.6 m. For small rivers, the greatest erosion values vary within the range of 2.3 to 8.14 m. The length of the eroded areas varies from 48–330 m. The average height of the eroded cliff on these rivers varies from 2.5 to 8.8 m. In the long-term dynamics of erosion on the Cheptsa (2 areas), Siva and Kyrykmas rivers, a positive trend is clearly visible with erosion maxima in 2011–2014, 2015–2016, 2019 and 2021. A close correlation has been established between the maximum width, area, and volume of erosion on the rivers Cheptsa (left tributary of the Vyatka), Siva (right tributary of the Kama), Kyrykmas (left tributary of the Izh) and their maximum annual discharges. The leading role of the bend curvature, the composition of the eroded rocks, and the order of the water flow, which we obtained earlier from benchmarker observations, is also confirmed. The location of intensively eroded areas within different types of bends is characterized by local features, but is more often confined to areas with the greatest steepness or shifted slightly downstream.

   Research implications. The results of the study are very relevant, since they can be used both for similar rivers of Udmurtia and for rivers of flat territories of the European part of the Russian Federation. The need for long-term field studies of erosion of river bank benches using modern instrumental methods is determined by the importance of identifying patterns of channel processes for making reliable forecasts of their development in specific landscape-geomorphological conditions in order to prevent dangerous geoecological situations.

   Aim. Investigation of dynamics of the herbaceous layer of the phytocoenosis of spruce forest after the death of the spruce stand in comparison with the plant community after clearcutting and living spruce forest.

   Methodology. In 2012, three permanent sample plots of 800 m² (20 × 40 m) were established in spruce forest after the death of spruce because of bark beetle outbreak. First plot was set in undamaged spruce stand (control plot), the second one – in spruce forest with dead spruce stand (snag stand), the third one – in a clear-cut sanitary felling of spruce deadwood (clear-cut). Each plot was divided into 8 sites of 10 × 10 m². The studies were conducted annually from 2014 to 2022 using the same methodology. Full species composition of plants and their belonging to coenotic groups was revealed on each site of each plot annually. Statistical processing of the collected data was carried out, mean values of the number of species at three sample plots and mean values of the number of species by coenotic groups were calculated and compared. The significance of differences between samples of the number of species in the sample plots was determined using the Mann-Whitney U test.

   Results. In the plant community with dead and unlogged spruce stands, there is a long-term significant increase in the number of weedy-forest species and a short-term significant increase in the number of meadow species. The coenotic spectrum remains close to the initial forest throughout the entire observation period. The development of the clear-cut phytocoenosis proceeds through the herbaceous and shrub stages, with a significant increase in biodiversity. The number of forest-meadow, grassland, meadow, weeds, weedy-forest, weedy-meadow species increases significantly, and bog species appear. The number of forest species is lower in the first year of the study and higher in the second year than in the control. Since the second year of the study the species diversity surged at the clearcut. In the 7^th year of development of clear-cut and spruce forest communities with preserved spruce deadwood, the coenotic spectrum of the sampled areas becomes close to the coenotic spectrum of the initial forest

   Research implication. To study the natural mechanism of the dynamics of spruce phytocenoses after bark beetle outbreak of spruce stands while preserving the dead stands. At present, there is vast area of spruce stands with dead spruce stands in the Moscow region, and understanding of the dynamics of such communities could allow more effective choice of forest management measures.

   Aim. This study investigates the biological characteristics of ammonia-oxidizing bacteria (AOB) isolated from wastewater sludge collected at several wood processing facilities in Vietnam.

   Methodology. To achieve the objectives of the study, composite sludge samples were collected from wastewater treatment units and processed within 6 hours to preserve microbial integrity. Ammonium-oxidizing bacteria were isolated using serial dilution and selective AMS medium, followed by screening for ammonium removal capability. Physiological characteristics of the isolates were evaluated under varying pH, temperature, and ammonium concentrations. Molecular identification was performed by PCR amplification and sequencing of the 16S rRNA gene. The combined use of microbiological and molecular techniques provided a comprehensive understanding of the diversity and functional traits of ammonium-oxidizing bacteria in sludge.

   Results. From six sludge samples collected at wood processing facilities in Yen Bai, Thanh Hoa, and Dong Nai provinces, a total of eleven bacterial strains with ammonium-oxidizing capabilities were isolated. Dong Nai samples yielded the highest number of isolates, suggesting favorable conditions for ammonia-oxidizing bacteria in this region. Among the isolates, three strains – Bacillus subtilis BT183.1.B1, Bacillus velezensis BT751.1.B2, and Bacillus amyloliquefaciens BT751.2.B1 – exhibited superior ammonium removal efficiency and were selected for detailed characterization. These strains showed optimal growth at neutral pH (7.0–7.5), temperatures between 35 °C and 37 °C, and ammonium concentrations up to 700 mg/L. Growth and activity decreased significantly at more extreme pH values, temperatures, and ammonium concentrations. The ability of these Bacillus strains to tolerate high ammonium levels and environmental variability highlights their potential for application in biological treatment of nitrogen-rich industrial wastewater, particularly in the wood processing sector.

   Research implications. Vietnam ranks fifth globally, second in Asia, and first in Southeast Asia in wood and forest product exports. The rapid growth of the wood industry has brought substantial economic benefits but has also caused environmental challenges, particularly pollution from wood processing wastewater containing high levels of ammonium – a pollutant difficult to treat biologically. These findings contribute to expanding the diversity of ammonium-oxidizing bacteria and highlight their potential application in treating ammonium-rich wastewater from wood processing industries.

   Aim. Assessment of the reliability, factors and features of the dynamics of information on atmospheric air pollution available on the Internet.

   Methodology. A comparison of nitrogen dioxide concentration indicators from official sources with freely available data from Internet sources on current concentrations of pollutants and meteorological characteristics, using the example of nitrogen dioxide, for cities in Northwestern Russia has been performed.: Kaliningrad, Pskov, Veliky Novgorod, Saint Petersburg, Kirishi, Pikalevo, Petrozavodsk. A quantitative assessment of the dependence of concentrations on wind speeds, atmospheric pressure, the presence or absence of precipitation, working or non-working days had been performed.

   Results. Nitrogen dioxide concentrations according to ground-based measurements and calculation results presented on the Ventusky website, using data from remote monitoring of emissions and weather conditions, are comparable and follow the same patterns of temporal variability. The correlations between nitrogen dioxide concentrations according to ground-
based measurements and the calculation results presented on the Ventusky website using the SILAM model, using data from remote monitoring of emissions and weather conditions, are weak but stable. In the winter and spring period, there was a clear tendency to decrease concentrations. This reflects a decrease in the use of fuel for heating. The downward trend is in cities with a predominance of industrial sources of emissions – Kirishi and Pikalevo, as well as Pskov, which can be explained by emissions from local boilers and individual furnaces. The decrease in concentrations on non-working days compared to working days ranges from 15.8 % to 50 %, and during precipitation from 4.4 % to 33.3 %. The data from the Ventusky website can be considered as an important addition to the results of ground-based observations, but not as an alternative.

   Research implications. It is an assessment of the possibilities of supplementing information on atmospheric air pollution from official sources with data available on the Internet. Trends in concentration dynamics have been identified and quantified.

   Aim. This study evaluates the application of Ordinary Kriging, a geostatistical interpolation method, for estimating basal area index in coppice oak forests of the northern Zagros region, Iran.

   Methodology. The research was conducted in a 6,103-hectare coppice oak forest in northern Zagros, Iran, dominated by Quercusbrantii alongside other oak species (Q. infectoria and Q. libani). A systematic-random sampling grid was employed to establish 136 sample plots (0.1 ha each), where diameter at breast height (DBH) was measured for all trees (DBH ≥ 5 cm) to calculate basal area. Exploratory data analysis was conducted to assess data normality and spatial trends, while variogram analysis was performed to determine the spatial correlation structure. Ordinary Kriging was then applied to predict basal area across the study area, with prediction accuracy evaluated through leave-one-out cross-validation using statistical metrics including mean absolute error (MAE), root mean square error (RMSE), and their relative values.

   Results. The forest exhibited relatively low basal area (14.53 m²/ha) despite high stem density (350 stems/ha), indicating the dominance of young trees and coppice regeneration. Variogram analysis revealed strong spatial dependence (spatial dependence degree = 99.8 %), with an exponential model providing the best fit to the data (r² = 0.676). Ordinary Kriging yielded accurate spatial predictions (MAE = 1.25 m²/ha, RMSE = 3.26 m²/ha), demonstrating its effectiveness for basal area estimation in coppice oak forests.

   Research implications. These findings demonstrate that geostatistical methods such as Ordinary Kriging provide a precise and cost-effective alternative to traditional forest inventories, enhancing sustainable forest management practices. The observed strong spatial dependence of basal area confirms its suitability as a regionalized variable, facilitating the development of optimized sampling strategies for future forest assessments. This geostatistical approach has significant potential to improve forest resource assessment, carbon stock estimation, and conservation planning in ecologically important ecosystems such as the Zagros oak forests.

   Aim. To identify the place and mission of small historical cities of Russia and the Republic of Belarus in the cultural landscape of the Union State

   Methodology. Based on the generalization of the experience of identifying historical settlements in the Russian Federation, rethink the criteria for classifying cities as "historical". It is noted that there are two main aspects of classifying the city as "historical". Firstly, it is a city in history, i.e. the role of the city as an actor of historical events. Secondly, there is history in the city, i. e. the saturation of the city with objects of historical and cultural heritage and monuments reminiscent of the past. For the first time, based on the content analysis of Russian and Belarusian textbooks of national history, the role of cities as participants in the historical process of their countries has been quantified. In the Republic of Belarus, unlike the Russian Federation, there is no official status of a "historical settlement", and the criteria for classifying cities as small are different.

   Results. It has been established that most of the small historical cities of the Union State arose before the 19^th century, many before the 14^th century. The development of small towns was largely determined by their geographical location. At the first stage, the situation is on the most important water communications, then on the main water and horse-drawn roads. In the 19^th century, railways became the main factor in development. Since the second half of the 20^th century, the main factor in the successful development of cities has been the location on the main transport corridors. The mention of small towns in school history textbooks largely depends on their administrative mission in the past, as well as their role in military history.

   Research implication. The previous lists of historical settlements are analyzed and reinterpreted, the author's list of small historical cities of the Union State is proposed, their high tourist attractiveness and their role in patriotic education are noted. For the first time, the "historicity" of official small historical cities, their hierarchy, and candidates for inclusion in the list have been quantified.

   Aim. To identify the presence and importance of the functions of small towns for agriculture, including for additional income for the population, due to low living standards in regions with low indicators of natural resource potential.

   Methodology. Based on systematic observations and statistical information verified during the 2023–2024 expeditionary studies in small towns of the subjects of the Federation bordering the Republic of Belarus, the current state of agricultural production in small towns has been studied. The available conditions of the state and development of agriculture in the urban environment are assessed.

   Results. The modern functions of a small town are revealed for small towns in the Non-Chernozem zone that are in a state of constant depopulation of the population, with high rates of the proportion of citizens of retirement age and low incomes of the majority of citizens. Based on the survey, the reasons for the use of personal utility plots in the city were identified: traditions, low incomes, the need to harvest products for the winter due to an insufficient assortment in stores, and assistance to children living in other regions. Based on the verification of agricultural data, the main directions of agriculture in groups of small towns are clarified; the relationship with agro-climatic conditions (physical and geographical location of the city), established traditions (for example, Demidov as an important center of cucumber production), and transport accessibility to large ("metropolitan") cities is shown. The efficiency of production in private subsidiary farms is calculated; the importance of a small town in the formation of efficiency is shown.

   Research implications. The factors characterizing the influence of a small town on the development of agriculture both within the city limits and within the surrounding territories are determined. It has been established that during the period of the depressive development of the territorial economy, the influence of the natural and climatic factor on the differentiation of specialization of urban agriculture by latitude is minimal. Possible trends in the development of the agricultural sector in small towns are shown.

   Aim. The purpose of the study is to clarify the specifics of the dynamics of tourism and spatial shifts in its development in the East of Russia in the post–Soviet period.

   Methodology. Comparative geographical, cartographic and statistical research methods wereused. The dynamics of tourism in 2003–2024 was revealed by an increase or decrease in the number of units in collective accommodation facilities and the number of people served there. Trend in tourism and tourism intensity in eastern Russia and the Russian Federation, the northern and southern parts of the Russia’s East, the East Siberian and Far Eastern economic regions have been compared. Spatial shifts in tourism development have been determined by an increase or decrease in percentage points in the share of eastern part of Russian Federation on a national scale in terms of the number of units and serviced persons in collective accommodation facilities, as well as the share of the Far East and Eastern Siberia, the north and the south on the scale of Russia’s East.

   Results. The trends in tourism dynamics in the Russian Federation, Russia’s East, the north and south of the macroregion, Eastern Siberia and the Far East were unidirectional: a decline in 1995–2000 and an increase in 2003–2024. But the growth rate of tourism in the Russia’s East in 2003–2024 was lower than in the Russian Federation. During the time under study, there was no "shift to the east" in the development of tourism in Russia. The share of Russia’s East nationwide in terms of the number of units and serviced persons in collective accommodation facilities decreased slightly. The pronounced asymmetry in the development of tourism in the Russia’s East along the north-south axis has intensified due to lower tourism growth in the north than in the south of the macroregion. On the contrary, the less pronounced contrasts in the development of tourism between Eastern Siberia and the Far East softened in 2003–2024. The regions of the south of Russia’s East, such as Krasnoyarsk (southern part) Krai and Primorsk Krai, Irkutsk Oblast with a more developed infrastructure and more favorable natural and socio-economic prerequisites for tourism, have retained leadership in its development. Chukotka is the only region where the number of tourists has decreased in 2003–2024 due to unfavorable natural and transport-geographical conditions, as well as restrictions related to the development of tourism industry in the border area.

   Research implications. The findings of this research hold significant practical value for the planning, programming, and forecasting of recreation and tourism development in the eastern regions of Russia. The author's methods for cross-scale comparison of the trends and intensity of dynamics, as well as ways to identify territorial shifts, make it possible to trace geographical variations in tourism development in different territories.

   Aim. Analysis of the possibilities of designing and developing tourism and recreational systems based on the use of the recreational potential of prehistoric objects of natural and cultural heritage of Russia, associated with navigation - orientation and movement.

   Methodology. The methodological basis of the study is the author's navigation concept of information modeling of the world, in which orientation and movement are considered as the main condition for the development of geographical space and territorial systems. The work used standard methods of collecting, processing and spatial analysis of geographical data on prehistoric objects of cultural heritage related to navigation.

   Results. The analysis of the placement of prehistoric heritage sites of natural, natural-anthropogenic and anthropogenic origin (weathering remnants, rock paintings, stone labyrinths, menhirs, revered stones, etc.) as elements of an ancient navigation network – visual landmarks and time-determining tools. In accordance with the objectives of developing domestic tourism in Russia, a research program "Natural and Cultural Heritage of Russia as a Resource for Tourism Development" was developed and areas of potential development of regional tourism and recreational systems were identified. An algorithm for developing the territory "point-line-area" was developed, in which the functions of growth points are performed by prehistoric heritage sites. Using the example of the model region of the White Sea, it is shown that navigation activities at prehistoric cultural heritage sites can become a driver of economic development of the territory. To maintain the sustainability of landscape complexes, it is recommended to combine navigational tourism with ecological tourism.

   Research implications. The aim of the work is to reveal the recreational and system-forming potential of prehistoric heritage sites that once had navigational significance. The navigational approach proposed in the article will allow more effective use of prehistoric heritage sites for the development of domestic tourism in the Russian Federation and economic development of the Arctic zone. In the future, the development of navigation tourism in the Arctic may become transboundary and circumpolar, which will contribute to the improvement of the economic and political situation.