Assessement of the impact of ecological factors on the biotopes differentiation in the Krasna River Valley (Luhansk region)

The article offers results of the analysis of 12 major biotope types distribution in the valley of the Krasna river. The research territory is characterized by a great diversity of contrast biotopes and high heterogeneity of its combinations. We have highlighted the main types of habitats that characterize the vegetation differentiation of the studied areas. We also classified the biotopes by the Didukh classification scheme. The vegetation of the Krasna valley is represented by deciduous ravine forests, areas of herb bunchgrass steppe on upland and slopes, and motley-grass meadows at the foot of the slopes. The most xerophytic steep slopes are composed of chalk outputs occupied by tomiliars associations. The ecological analysis was conducted by using the method of synphytoindication. During the analysis, the differentiating indicators, limiting factors, and major patterns of vegetation distribution in the research territory were recognized. It has been found that mesophytic forests, meadows, and coastal communities have a fairly wide ecological amplitude and depend primarily on humidity and nitrogen content, which, in addition, is a leading factor in the meadow communities. Instead, xerophytic communities are stenotopic and are dependent on the acidity of the soil, the presence of carbonates, and continental climate. The development of forest and meadow habitat types is associated with endodynamic successions, passing all stages from pioneer to the climax ecosystem. However, endodynamic successions are not typical of tomiliars which are resistant to possible natural changes of ecological factors and most depend on the substrate on which they increase. Steppe communities could disappear due to climate changes that affect the processes of humification and podzolization of black soil because of increased rainfall. The obtained results have important implications for predicting changes in biotopes and developing measures for their conservation.