Due to the global increase in CO₂ in the atmosphere, studies focusing on the carbon balance in forest ecosystems are currently particularly relevant. Abandoned agricultural lands could provide an important contribution to carbon sequestration in many parts of the world. In the broad-leaved forest zone of the Cis-Ural (Southern Ural region, Russia), the carbon sequestration dynamics in the biomass of woody and herbaceous plants, as well as in the litter and soil on abandoned arable lands repopulated with silver birch (Betula pendula), was studied. The data were collected on 35 round (with diameter of 30 m) sample plots located within communities representing the different stages of reforestation with tree stands aged 3 to 30 years. It was found that the carbon content of the stem wood and herbaceous understory did not depend on the succession stages, which largely corresponds to the literature data. The carbon content in root biomass and soil organic matter increased along with the growth of tree stands. While the forest stand grew, the carbon content in the grey forest soil increased from 2.5 to 4.4%, and in the more fertile dark grey forest soil it changed only slightly. The carbon deposition by the forest stands on the sample plots located on the dark grey forest soils was higher than on grey forest soils. The average rate of carbon sequestration in the tree stand was 2.7 t/ha/year. Most mature, 25–30-years-old silver birch tree stands provided the highest average annual increase in tree biomass and the rate of carbon sequestration evaluated was 9 t/ha/year. Also, the carbon pool in the 30 cm soil layer was 2.7 times greater than in the tree stand. It was concluded that abandoned agricultural lands overgrowing by forest in the Cis-Ural are promising for carbon sequestration.

Currently, studies investigating the carbon balance in forest ecosystems are particularly relevant due to the global increase in CO₂ content in the atmosphere. Due to natural reforestation over the past 25–30 years, birch (Betula pendula Roth.) forests were extensively grown and established on abandoned agricultural lands in Bashkir Cis-Ural (Republic of Bashkortostan, Russia). The significant positive aspect of reforestation on fallow lands is the carbon sequestration that takes place in the tree phytomass, especially at the growth stage of stand formation. The aim of this article is to test the approach of using a UAV-mounted LiDAR camera to estimate the phytomass and carbon stocks in different-aged birch forests growing on abandoned arable lands in Bashkir Cis-Ural. The methodology was developed using 28 sample plots, where the LiDAR survey was performed using a DJI Matrice 300 RTK UAV. Simultaneously, the stand characteristics and phytomass of stem wood were also estimated, using traditional methods in the field of forest science. The regression equations of phytomass dependence on stand characteristics at different stages of reforestation were constructed using data obtained from LiDAR imagery. It was shown that the above-ground tree biomass could be precisely estimated using the index obtained by multiplying the number of trees and their average height. A comparison of the data obtained using traditional and LiDAR survey methods found that the accuracy of the latter increased in conjunction with stand density. The accuracy of estimation ranged from 0.2 to 6.8% in birch forests aged 20 years and over. To calculate carbon stocks of the above-ground tree stands, the use of regional conversion coefficients is suggested, which could also be applied for the estimation of carbon content in trunk wood and leaves. An equation for the calculation of above-ground biomass carbon stocks of birch forests on abandoned arable lands is proposed.

An analysis of the current potential range of the Pleistocene relict plant species Schoenus ferrugineus and modeling of changes in its future range under moderate (RCP4.5) and strong (RCP8.5) climate change in the middle and second half of the 21st century were carried out. The MaxEnt program was used for modeling. Climate variables from CHELSA Bioclim, the global digital soil mapping system SoilGrids, and a digital elevation model were used as predictors. Modeling has shown that climate change will lead to a significant reduction in the suitability of S. ferrugineus habitat conditions by the mid-21st century. The predicted changes in the distribution of habitats of S. ferrugineus, a diagnostic species of calcareous mires and an indicator of their ecological state, indicate a possible strong transformation of wetland complexes in the Southern Urals region even under moderate climate change. A reduction in the distribution of S. ferrugineus at the eastern limit of its range will also be facilitated by more frequent extreme droughts. To maintain the distribution of S. ferrugineus on the eastern border of its range, a number of measures are proposed to mitigate the negative consequences of climate change, contributing to the preservation of the hydrological regime of calcareous mires.

   Aim. Data collection and analysis of the composition and productivity of vegetation and assessment of carbon sequestration by vegetation and soil in meadow steppe at a fallow site in the Bashkir Cis‐Urals, Russia.   Material and Methods. The work is based on a survey of vegetation and soils of meadow steppe located in fallow areas, where post‐agrogenic restoration succession has been going on for more than 20 years.   Results. The plant cover of the area studied is close to natural rich‐forb meadow steppes but differs in lower indicators of species richness and saturation, as well as the presence of weedy segetal species. The total plant biomass on the plot studied was estimated at 11.35 t/ha (including live aboveground biomass 2.98 t/ha, mortmass 3.11 t/ha, root weight 5.25 t/ha). The average stock of carbon in the plant biomass is 427.6 g/m², and the total carbon stock in plant matter within the site is 36.88 tons. The soil cover of the area studied is Chernozem Calcic. The average levels of carbon stocks in short‐thickness soil at the 0–90 cm layer is 308 t/ha, while in medium‐thick soil it is 378 t/ha.   Conclusions. A feature of the communities surveyed is a poor floristic composition, low productivity and low proportion of roots (47 % of the total plant biomass), which is caused by incomplete recovering of steppe vegetation and low thickness of the humus horizon. The soils of the site are close to virgin steppe lands in terms of carbon content and reserves.

Silver birch (Betula pendula Roth) is one of the fast-growing tree species that often colonize abandoned agricultural lands in Europe and the European part of Russia. The purpose of this article is to analyze the spatiotemporal dynamics of Betula pendula crown cover on abandoned arable lands in a zone of broad-leaved forests of the Bashkir Cis-Ural (Russia, Republic of Bashkortostan). The assessment of current and retrospective values of crown cover was carried out using a regression model of the dependence of crown cover on the values of red channel brightness in early-spring images from Landsat 5–8 and Sentinel-2 satellites from 2012–2022. To estimate the number and height of trees, a survey was carried out using a LiDAR camera mounted on a UAV. After calculating the crown cover in grid squares and their distance from the seed source in QGIS, variance analysis was carried out to assess the influence of the factor of distance from the seed source on the crown cover. The influence of the factor of distance from the seed source on the crown cover was higher at earlier stages of overgrowth of abandoned agricultural lands. An exception to this dependence was only one sample plot where the prevailing wind direction was opposite to the direction of seed dispersal. The leading factors affecting the distribution of birch on abandoned agricultural lands were wind direction, height of seed trees, and grazing. In the parts of the sample plots that were furthest away from seed sources, the trees were 1–3 years younger or the same age, and stand density was lower than in sites located closer to the seed trees. In general, the results of the present study indicate two opposite relationships between seedling survival and distance to seed trees: (1) seed fall and seedling density decrease with increasing distance from the seed tree, and (2) the probability of seed/seedling survival increases due to decreased competition.