The stable water isotopes in snow (primarily ¹⁸O and ²H) are widely used for tracing hydrological and ecological processes. However, isotopic signatures of snow can be significantly modified by topography and land cover. This study assesses spatial and temporal variability of the bulk snowpack isotopic composition (δ¹⁸O, δ²H, d-excess) between forested (pine and birch) and open areas in the West Siberian forest steppes. Isotopic samples were collected over the peak snow accumulation in 2017–2019. The snow isotopic composition within forested areas differed from open steppes, mainly in reducing d-excess (1.6‰ on average). We did not find a significant effect of canopy interception on snow enrichment in heavier isotopes. Snowpack in the pine forests was even lighter by 3.6‰ for δ²H compared to open areas, probably, due to low energy inputs and interception capacity. Additionally, snow depth significantly influenced the isotopic composition spatial variability. As snow depth increased, δ¹⁸O and δ²H values decreased due to conservation within the snowpack and less influence of sublimation and moisture exchange with the soil. However, this pattern was only evident in winters with below-average snow depth. Therefore, taking into account snow depth spatial and seasonal variability is advisable when applying the isotopic methods.

The overarching goal of this survey was to identify the challenges of ecosystem services assessment and mapping in Russian and Bulgarian mountain protected areas in the context of post-socialist transformations, new conservation paradigms and climate change. The Altai Mountains in Russia and the Rhodope Mountains in Bulgaria were selected as key mountain territories for comparison due to their similar characteristics: agriculture, forest exploitation, tourism activities, etc. Both in Bulgaria and in Russia, perceptions of the protected areas functioning have been changing, facilitated by global shifts. Thus, the concept of ecosystem services has now been actively introduced in nature and biodiversity conservation policies. Based on WDPA data the emergence of different types of protected areas in Russia and Bulgaria was determined. Key problems of assessment and mapping of ecosystem services in Russian and Bulgarian mountain protected areas were recognised, mainly related to the shortage and quality of baseline data. At the same time, there were also some specifics for the two countries due to their size and national legislation. Like many other mountainous regions in the world, the Rhodopes in Bulgaria and the Altai Mountains in Russia are flagships in the improvement of nature conservation strategies. These regions often participate in a variety of international conservation programmes and are constantly expanding the range of protected areas. It is generally accepted that the Altai Mountains and the Rhodopes are not only centres of biodiversity richness in their countries, but also hotspots of a variety of ecosystem services.

The analysis of landscape differentiation of the low-mountain Maima basin was performed due to the field studies for different periods as well as the remote sensing data. The formation of modern landscapes of the basin depends on regional features related to geographical location of landscapes on the periphery of the mountain region (mainly in its low-mountain part) and local factors as well. Structural-lithological and geomorphological heterogeneity, high-altitude along with climatic background parameters determine the development of the landscape structure of the territory. The basin map represents the peculiarities of current landscapes arrangement at the local level (groups of stows, their spatial modifications) and atregional one (subtypes of landscapes). In the forest-steppe area, slopes (4-10 and 10-20) of the southern, western and eastern aspects with grass-forb real and steppe meadows dominate. Sub-taiga landscapes are represented by terraced slopes (10-20) of northern and northeastern aspects with birch-pine and pine-birch forests. Among the chern-taiga landscapes, the slopes (10-20) of the eastern and western aspects with birch-aspen-fir forests prevail. Modified and transformed landscapes occupy about 30 % of the basin area due to the largest agglomeration (Gorno- Altaisk, Maima and Kyzyl-Ozek) in the Russian Altai. Secondary grasslands occupy 20 % of the basin area that is mainly related with anthropogenic modifications (deforestation, grasslands). The share of perennial plantations and arable land accounts for 2 %; built – up areas-about 4 %.

This article provides a database of the local snow-measuring observations for three river basins in the south of Western Siberia, reviews the methodological peculiarities of the conduct of measurements, and compares the acquired data with the observations at weather stations and available satellite data (CGLS SWE). Observations were carried out in several stages over the period of ten years (2011-2021) in small river basins of Kuchuk, Kasmala, and Mayma Rivers, and reflect the transition from the West Siberian Plain to the Altai lowlands. Total of 25,000 measurements of the parameters of snow deposits (snow mass and snow storage) were made over the years. The database of snow measuring observations is accessible to public. The comparison with station and satellite data indicated significant variances, but also fairly good coherence in some reservoir basins. According to satellite data, the common to basins mean squared error of snow storages was 42.9 mm, which is slightly higher than the claimed by the product engineers (37.4 mm). The time-limited observation data on the permanent routes of weather stations demonstrated the mean squared error of snow storages of 43.5 mm. In winter period, the mean squared error of satellite data gradually increased to the period of maximum accumulation of snow in reservoir basins. Moreover, the errors of satellite data did not depend on the snowiness of the winter period; and most likely, are associated with the parameters of microstructure of the snow mass in separate seasons.

ОСОБЕННОСТИ ПРОСТРАНСТВЕННОЙ ДИФФЕРЕНЦИАЦИИ СНЕЖНОГО ПОКРОВА В НИЗКОГОРНЫХ ЛАНДШАФТАХ РУССКОГО АЛТАЯ (НА ПРИМЕРЕ БАССЕЙНА Р. МАЙМА)

Сравниваются материалы наблюдений за снежным покровом на метеостанциях и снегомерные наблюдения в водосборных бассейнах, где расположены эти станции. Исследования вели в трёх бассейнах на юге Западной Сибири: в лесостепном бассейне р. Касмала (2011-2020 гг.), низкогорном бассейне р. Майма (2015-2020 гг.) и степном бассейне р. Кучук (2019-2020 гг.). Сравнение проводилось на трёх пространственно-временных уровнях изменчивости: межгодовом (влияние межгодовой изменчивости осадков); внутрибассейновом (влияние рельефа и растительности); внутригодовом (влияние метеорологических условий конкретного зимнего периода).