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.

Climatic changes have a significant impact on the composition and distribution of forests, especially on ecotone ones. In the Southern Ural, pine-broadleaf ecotone forests were widespread during the early Holocene time, but now have persisted as relic plant communities. This study aimed to analyze the current potential range and to model changes in habitat suitability of relic pine-broadleaf ecotone forests of the suballiance Tilio-Pinenion under scenarios of moderate (RCP4.5) and strong (RCP8.5) climate change. For modelling, we used MaxEnt software with the predictors being climate variables from CHELSA Bioclim, the global digital soil mapping system SoilGrids and the digital elevation model. In the Southern and Middle Urals, climate change is expected to increase the areas with suitable habitat conditions of these forests by the middle of the 21st century and decrease them in the second half of the century. By the middle of the 21st century, the eastern range boundary of these forests will shift eastward due to the penetration of broad-leaved tree species into coniferous forests of the Southern Ural. In the second half of the century, on the contrary, it is expected that climate aridization will again shift the potential range border of these forests to the west due to their gradual replacement by hemiboreal coniferous forests. The relationship between the floristic composition of pine-broadleaf forests and habitat suitability was identified. In low and medium habitat suitability, pine-broadleaf forests contain more nemoral species characteristic of deciduous forests of the temperate zone, and can be replaced by broadleaf forests after thinning and removal of pine. In the Volga Upland, suitable habitats are occupied by pine-broadleaf forests of the vicariant suballiance Querco robori-Tilienion cordatae. Projected climatic changes will have a significant impact on these ecotone forests, which remained completely unaltered for a long time.

   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.

Floristic composition and syntaxonomy of the boreal oligotrophic pine forests covering vast areas in the boreal, hemiboreal, and temperate zones of continental Eurasia still remain poorly studied in the Southern Ural region. Using the Braun–Blanquet approach and TURBOVEG and JUICE software, the phytocoenotic diversity of boreal oligotrophic pine forests of the Southern Ural region was studied, and their position in the system of ecological and floristic classification of Eurasian vegetation was determined. Geobotanical data on boreal oligotrophic pine forests of Europe, including the European part of Russia; the Southern Urals; and Siberia were compared. A new alliance of oligotrophic boreal pine forests Brachypodio pinnati-Pinion sylvestris all. nov. hoc loco is described. The communities of this new alliance (i.e., five associations from the Southern Ural region) are characterized by a special floristic composition, occupying an intermediate position between the typical European oligotrophic pine forests of the alliance Dicrano-Pinion (Libbert 1933) Matuszkiewicz 1962 and oligotrophic (mainly psammophilous) South Siberian pine forests of the alliance Hieracio-Pinion Anenkhonov et Chytrý 1998. The communities of the alliance Brachypodio pinnati-Pinion sylvestris prefer to grow on poor soils with different moisture conditions. Due to intensive forestry activities, the distribution area of these forests has decreased, and these communities have been replaced by secondary birch forests. We have proposed a set of conservation measures to preserve these communities. A new association of oligotrophic pine forests Psephello sumensis-Pinetum sylvestris ass. nov. hoc loco is also described. These communities from the Kurgan region of Western Siberia were ordered into the alliance Dicrano-Pinion. It confirms the idea that the distribution area of this alliance may reach Siberia. Unlike the Southern Ural pine forests of the alliance Brachypodio pinnati-Pinion sylvestris, the recovery of these West Siberian pine forests after felling is quite high, and these communities do not require special measures for their protection.