Yulia V. Shalaumova

Introduction. Shifts in the habitat ranges of tree species are among the continental-scale consequences of climate change. Mapping these shifts and their quantitative estimation are essential for evaluating the carbon balance. In this work, a method for mapping long-term changes in forest cover, thus permitting evaluation of treeline shifts, is demonstrated on the example of the mountain ecosystem of the Subpolar Urals. The stages of preliminary selection and processing of Landsat multispectral remote sensing data from the Google Earth Engine platform are described. The results of mapping long-term changes in forest cover and quantitative estimation of the total area of treeline transition are presented. Aim. Mapping of long-term changes in forest cover and their quantitative estimation using Landsat multispectral remote sensing data and expert assessments of ecological zone boundaries in the mountains of the Subpolar Urals (on the example of the Sablya Ridge). Materials and methods. Cloud-free multispectral images from Landsat satellites 4–9 of top-of-atmosphere reflectance, which underwent relative radiometric correction, as well as surface reflectance data, were used. Expert assessments of ecological zone boundaries were obtained, and regression analysis was used. Results. Based on the statistical time series analysis for the period from 1987 to 2024, the total area of treeline transition from 1960 to 2024 was established to be 4.82 km². An acceleration of treeline transition from 1970 to 1995 was recorded. Conclusion. The described method allows long-term spatial dynamics of treeline shifts to be mapped and quantitatively estimated. The obtained estimates agree well with those obtained by expert assessment. The recorded period of accelerated treeline transition coincides with that of global temperature changes.

Background: Logistic regression is the most commonly used method for establishing statistical relationships between quantitative predictors X and a dichotomous response Y (Y=0 or Y=1). Therefore, it is relevant to develop new approaches to the analysis of relationships between X and Y of this type. Aim: To demonstrate the specific characteristics of the application of stratification, moving average and cumulative probability function methods in the construction and analysis of logistic regression models in the context of health risk assessment. Materials and methods: The analysis of logistic regression models employs a range of statistical methods, including the stratification, moving average, cumulative probability function, goodness-of-fit tests, and proportion comparison tests. Results: It is shown that the standard stratification methods are not sufficient for exploring the nature of the relationships between dichotomous Y and quantitative X. Additional methods, including moving average and cumulative likelihood function, facilitate the identification of features characterizing these relationships. The utility of graphical representations of logistic regression results in elucidating the statistical relationships between variables X and Y is demonstrated. The efficacy of the stratification, moving average and cumulative probability function methods is illustrated by examples from the field of epidemiology. Conclusion: The combination of moving average and cumulative probability function methods with stratification enables the reliable identification of the nature of the relationship between dichotomous Y and quantitative X, as well as the potential for deviations from the conditions of applicability of logistic regression models.

On 29 September 1957, the so-called Kyshtym accident occurred at the USSR’s first nuclear weapons plutonium production facility. The East Ural State Reserve (EUSR) was established in the most contaminated part of the radioactive trace, where a substantial part of the forests died in the first years after the accident. The purpose of our study was to evaluate the natural restoration of forests and to verify and update the taxonomic parameters that characterize the current state of forest stands in the EUSR. Data on the forest inventory of 2003 and results of our research of 2020 performed by the same methods on 84 randomly selected sites served as the basis for this work. We developed models to approximate growth dynamics and then updated the 2003 taxation-related forest data for the entire EUSR. According to these models and ArcGIS construction of new data, forest-covered lands make up 55.8% of the whole EUSR territory. The proportion of birch forests in the forest-covered lands is 91.9%; 60.7% of wood resources are located in mature and overmature (81–120-year-old) birch forests. The total timber stock in the EUSR is > 1385 thousand tons. It was revealed that ~ 4.2 × 10¹⁴ Bq of ⁹⁰Sr is situated within the EUSR. The main stock of ⁹⁰Sr is found in soils. The ⁹⁰Sr stock in the stands is ~ 1.6–3.0% of the total content in the forests. Only a part of the EUSR forest stands can be used for practical applications.

Altitudinal forest limits are typically climatically dependent, such that increasing temperatures connected to global warming are causing upslope shifts in treeline ecotones worldwide. However, at the local and regional levels, the degree of such a response is dependent on differences in climate, topography and soil features. In recent decades, attempts have been undertaken to estimate tree stand dynamics with remote sensing methods, but their resolution is still too coarse for a precise assessment of stand structural changes, and requires ground-truthing, which is not possible without historical data collected on a single-tree level. We used aerial photos (1962) and satellite images (2021) in combination with historical inventory data to investigate changes in open forest positions at different spatial scales at the eastern macroslope of the Polar Urals over the past 60 years. Additionally, obtained remote sensing data were validated on a single-slope level using tree crown size estimations. Our investigations showed that since 1960 up to present day, the total crown coverage increased from 6.9 to 22.1% within the test polygon. A highly spatially variable upslope advance in an open forest boundary was identified from 1.7 up to 7.1 m in altitude per decade. We revealed that the rate of tree stand transformations was to a great extent depended on the stand density in the 1960s, soil substrate type, moisture regime, slope aspect and inclination. Our results highlighted the necessity to consider the abovementioned factors when trying to predict climate-induced tree distributional responses in subarctic mountain regions.

Snow cover is one of the most important factors affecting the regeneration and growth of shrubs in cold arctic and alpine ecosystems. In many of these cold regions, climate change in the last century is manifested not only in a rapid rise of temperature, but also in an increase in winter precipitation. For instance, in the Ural Mountains, winter turned warmer and more humid during the past century, leading to higher snow accumulation. We investigated how the change trends in the cold season (November to March) climate conditions affected the recruitment of the shrub Juniperus sibirica Burgsd., the most widespread shrub conifer in mountains of this region where it is dominant in treeless areas. Specifically, we considered seven sites located in the Southern and Northern Urals that are subjected to lower and higher continentality, respectively. We assessed how juniper recruitment changed along altitudinal gradients going from the open forest to the alpine tundra and passing by the transition zone. We found that juniper shrubs recruited at higher elevations during the 20th century in most sites, with a rapid shrub encroachment into alpine tundra (shrubification) after the 1990s. This process was especially intensive in the last decades at the uppermost parts of convex slopes where the snowpack is shallow. We found positive associations between juniper recruitment and cold-season precipitation or temperature in the Northern and Southern Urals, respectively. Shrubification is following upward treeline shifts in the Southern Urals. Our findings indicate that juniper shrubs will tend to colonize sites with low snowpack depth if winter conditions keep warm and wet enough and the snowpack allows the effective protection of shrubs.

The aim of this study was to determine the effect of smoking on BMI in male adolescents and explore the relationship between smoking status and diet. Methods: A cross-sectional epidemiological study into the health and diet of adolescents was carried out based on a representative sample of 375 vocational school male students aged 16–17 in the city of Chelyabinsk (Russian Federation). The students and their parents filled out verified questionnaires on their socioeconomic status, diet, and smoking status. Students’ height and body weight were measured. A comparative analysis of diets was performed between groups of smokers and non-smokers (149 and 226 individuals, respectively), and the relationship between smoking, body mass index, and actual diet was estimated. The methods used included descriptive statistics, Student’s t-test, Mann–Whitney U test, comparison of proportions, and moving average. Results: Non-smoking adolescent boys tended to have excess body mass compared with smokers (19.0% and 12.1%, respectively). Smokers (adolescent boys) consumed less meat, cereals, beans, and cheeses and more sweet beverages, added sugar, coffee, and alcohol. The bulk of the smokers’ diet was composed of carbohydrates (p = 0.026) and, to a lesser extent, proteins (p = 0.006). Conclusions: Significant differences were discovered in the diet between smokers and non-smokers (among adolescent boys), and smoking was associated with several indicators of unhealthy diet patterns. This is an important conclusion for developing a future program that could additionally protect at-risk groups of adolescents.

Climate warming impacts on alpine treeline dynamics. However, we still lack robust assessments of the long-term impacts of climate on tree recruitment at the treeline, particularly in remote areas such as the subarctic regions of Russia subjected to different climate influences. We expected that the treelines in two regions may have different features and dynamics patterns. We analyzed climate variables and assessed treeline dynamics by quantifying recruitment using the tree rings of ca. 7000 trees of four species (Betula pubescens Ehrh. ssp. tortuosa, Pinus sylvestris L., Picea abies Ledeb. ssp. obovata, Larix gmelinii Rupr.) along 14 altitudinal transects (series of study plots). We compared the Khibiny Massif (Kola Peninsula) and the western Putorana Plateau, subjected to oceanic and continental influences, respectively. In both regions, summers became warmer, and winters became snowier during the past century. At the low part of the treeline ecotone, tree recruitment has slowly increased since the mid-18th century at the Putorana Plateau and the mid-19th century at the Khibiny but accelerated in the early 20th century at both regions and reached a maximum peak in the second half of the past century. Treeline encroachment intensified in the 1930s at the Khibiny and the 1950s at the Putorana Plateau. Trees encroached in the tundra leading to upward treeline shifts in the late 20th century. The slope exposure affected the rates of treeline shift with higher upward advances on southern-oriented slopes. Tree recruitment and early-winter precipitation were positively correlated. The differences in species composition, treeline altitude and influences of slope orientation on treeline dynamics can be explained primarily by differences in the degree of continentality. The abundance of saplings in both regions allows the future encroachment of trees into tundra and further treeline upward shifts to be forecast.