Long-term dynamics of aquatic vegetation and the state of ecosystems of soda lakes in southeastern Transbaikalia

The cyclical nature of long-term changes in the annual amounts of atmospheric precipitation in Transbaikalia controls most of the processes in ecosystems. The paper briefly describes the long-term vegetation dynamics of soda lakes in the southeast of Transbaikal territory. These dynamics are driven by changes in abiotic parameters of the lakes, mainly water salinity and pH values. When the values of these indicators increase, the perennial succession series of vegetation of higher plants is as following: Helophytes + Neustophytes + Hydatophytes → Helophytes + Hydatophytes → Helophytes. The succession series of macrophytic algae is as following: Stigeoclonium sp. or Spirogyra sp. → Cladophora fracta + Charophyta → Enteromorpha intestinalis.

Patterns of formation and functioning of geosystems of Stebnyk tailings dam

The specifics of the landscape structure within the first section of the Stebnyk tailings dam are considered. Two landscape terrains (of natural and anthropogenic genesis), 3 separate landscape belts, 8 types of landscape tracts, and 30 types of landscape sub-tracts have been identified. Geosystems are dominated by flat sloping surfaces of the tailings dam, the external embanked of which forms closed drainless areas requiring systematic regulation of the level of the final reservoir. Features of filling the tailings surfaces played an important relief-forming role. At the same time, there were raised areas (0.5‒2.5 m) confined to the southern and south-western parts of it. Actually, conditions for the formation of tree-bush and meadow-marsh vegetation of different stages of succession were created in these areas. Spatial-temporal regularities of the occurrence and development of plant communities within the first section of the Stebnyk tailings dam were determined based on the decryption of space images for 2006‒2018. Primary meadow-marsh, bush-meadow, and tree-bush communities on surfaces with different levels of salinization were distinguished. In fact, these communities form the primary succession series in the formation of vegetation cover of post-mining geosystems. To decipher the boundaries of plant communities, 16 space images were obtained from the publicly available Google Earth Pro program. The tendencies of changes in the number and area of the plots occupied by different plant groups have been determined. Currently, the area of tree-bush communities is 5.59 hectares (7.87 % of the total area). Bush-meadow and meadow-marsh communities recorded an intensive increase in areas by 2014, followed by a rapid decrease caused by salinization of areas due to significant elevations of the reservoir’s level. In 2014, maximum areas of plant communities (37.55 ha) were identified, covering more than half of the study area (52.84 %), and in 2018 they occupied 21.71 ha (30.55 %). The gradual differentiation of phytocoenoses by moisture gradients and soil salinization continues. To maintain the rate of overgrowth of the first section of the Stebnyk tailings dam, it is necessary to reduce the level of brines regularly.

Ecological and biological characteristics of restoration with tree plants in the conditions of the Steppe Pridniprovia

The change of forest cover in Dnipropetrovsk Oblast within the framework of the concept of agroforestry reclamation development in Ukraine was investigated. It was established that the forested area in Dnipropetrovsk Oblast is currently about 5%, which does not correspond to the optimal level of forest cover for this area, which is determined at 8%. The increase of forested areas within the surveyed territory was observed because of the two such processes, as reforestation and afforestation. In recent years, these processes have shown a steady downward trend in the number of forested areas. Succession series can be fundamentally different in the reproduction of forest plantations due to reforestation and afforestation. During reforestation, the succession series will be much slower, but it will be able to reach climax stage can due to the fact that the plantations will include indigenous plant species. When fast-growing species will be selected during afforestation, plantations will develop more rapidly, but will be much less stable and need constant care. Thus, the processes of forest plantations development in the Dnipropetrovsk region need significant processing and intensification. Until recently, there was no doubt about the beneficial effects of forest vegetation on air quality. A large number of wood species can not only emit volatiles, but also absorb in their biomass a significant amount of toxic elements, such as heavy metals, radionuclides and others. However, recently, due to the large anthropogenic and man-made load on the atmosphere (industrial emissions, transport, pesticides, herbicides, etc.), the process of so-called secondary air pollution has been observed. This is manifested as follows – woody vegetation absorbs toxic substances, processes them into even more toxic and releases them into the air. Significant impact of forests is also observed on the stability of systems. It is known that the higher the species diversity – the lower the dominance index, and the more stable the system. The introduction of new species of woody plants, and behind them new species of fauna increases the diversity of the ecosystem, which is undoubtedly favorable. But on the other hand, this leads to the extinction of typical steppe species, for example, in forest biogeocenoses live a large number of small predators, and most species of steppe birds nesting on the ground can be easily destroyed by them. Forest vegetation significantly changes the landscape. Any woody plants in the steppe create an ecotone, ie the zone of contact of different habitats, which increases the species diversity and, in general, alpha diversity of the territory and, consequently, increases its resistance to anthropogenic and man-made loads. On the other hand, it contributes to the even more intensive disappearance of zonal steppe landscapes, of which there are very few left in the Dnipropetrovsk region due to high population density and a high degree of agricultural development. Forest plantations in the region can be created in two fundamentally different forms – forest belts and forests. It is clear that the creation of forest belts will be timed to the massifs of agricultural land as their main function is to create an optimal microclimate. The creation of forests, first of all, should be aimed at increasing and maintaining species diversity, secondly, it will undoubtedly expand the recreational potential of the region, which is currently clearly insufficient. Currently, when creating any of these types of plantations, there are serious environmental miscalculations. First of all, it is the creation of plantations from allochthonous, that is, from the very beginning species not peculiar to this territory. As a rule, it is a pine or an acacia white. These unpretentious breeds grow quite quickly, well acclimatized, which, of course, makes their use more cost-effective and attractive. But on the other hand, the plantations created from them are much less long-lived than, for example, oak groves typical for this region and, unlike them, require constant care, because they are practically unable to reach menopause.

ОСОБЕННОСТИ ЕСТЕСТВЕННОГО ВОССТАНОВЛЕНИЯ ЛЕСНЫХ ЭКОСИСТЕМ НА БЫВШИХ СЕЛЬСКОХОЗЯЙСТВЕННЫХ ЗЕМЛЯХ (НА ПРИМЕРЕ ЮЖНОГО АГРОКЛИМАТИЧЕСКОГО РАЙОНА КАРЕЛИИ)

Karelian Research Centre, Russian Academy of Sciences, Petrozavodsk, Russia The chronological succession series of forest communities regenerating in abandoned farmland is described. A period of 110 years since abandonment was studied based on reference stands aged 20-65-110 years. The typical process in the settings studied is the regeneration of coniferous stands with a gradual reduction in the share of deciduous stands as they are approaching their limit. These changes are accompanied by shifts in soil characteristics. Changes in microbial biocenoses are more apparent in the upper soil levels (0-20 cm). Transition from arable to fallow soil conditions results in organic matter accumulation at the level from 0 to 10 cm, which is associated with increasing respiratory activity and microbial carbon content. At the level of 10 to 20 cm, microbial carbon content is highest in the arable soil. The soil contents of microorganisms generally increases in the series from 110-years to 65-years old spruce forests and further on to 20-years old birch forest, grassland and arable land. A century after a land has been abandoned plant communities developed there are hardly discernible from native ones. Only indirect signs are indicative of the former. One of the signs is that the tree stands developing in abandoned farmland are far more productive than the stands that grow prior to cultivation. The results of the present study may be useful for diagnostics of soils at different stages of restoration after anthropogenic transformation and for environmental monitoring.

Primary and secondary succession on wooded peat-bogs

Study of primary and secondary succession on wooded peat- bogs are presented. Research has been done on a complex of mountain peat-bogs in the Bohemian Moravian Highland (Czechoslovakia). Natural succession series began with reed sedge and reed stands and terminated with <i>Viccinio uliginosi-Pinetum</i>, <i>Calamagrostio villosae-Piceatum</i> and <i>Alnion glutinosae</i> uder oligotrophic, oligo-mesotrophic and meso-eutrophic conditions, respectively. In marginal parts of peat-bogs (lagg) sedge fens are followed by birch cart. Open pine stands (<i>Pino rotundatae-Sphagnetum</i>) is submitted to cyclic succesion. The secondary succession may begin with the <i>Sphagnum cuspidatum</i>, <i>Eriophorum angustifolium</i> or <i>Carex rostrata</i>, and <i>Carex rostrata</i> stages, depending on trophic conditions of water. The final stage is usually <i>Vaccinio uliginosi</i>-<i>Pinetum</i> or <i>Pino rotundatae</i>-<i>Spagnetum</i>. Secondary succession pattern is influenced both by eutrophication and peat-land drainage.