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Aim: The steppe grasslands of eastern Central Europe are exceptionally species rich and valuable from a nature conservation point of view. However, their historical biogeography is still poorly understood. Here we use the regional diversity of habitat specialists and chloroplast DNA data to investigate potential long-term refugia of steppe species in this region. Location: Pannonian Basin and adjacent regions; SW Russia. Taxon: Vascular plants. Methods: After identifying habitat specialists of the three main steppe types (meadow steppes, grass steppes and rocky steppes), we compiled their regional presence--absence in grid cells of 75 km x 75 km. We analysed the dependency of habitat specialist diversity to climate, topographic heterogeneity and geographical distance to potential refugia. For genetic analysis, we sampled three or four habitat specialists of each steppe type and used cpDNA markers to investigate intraspecific diversity and geographical distribution of haplotypes. We also tested for correspondence between the number of habitat specialists and haplotype diversity. Results: Climate and topography explained between 40% and 63% of the variance in habitat specialist diversity. Adding geographical distance to potential refugia increased the explained variance in the models for all steppe types. Chloroplast haplotypes featured a complex pattern across the study area. Several species showed a strong geographical differentiation, suggesting migration waves from multiple refugia with only limited subsequent genetic intermixture. Maximum haplotype diversity in a region showed a better correlation with the number of habitat specialists per steppe type than mean haplotype diversity. Main conclusions: We can clearly reject the scenario of a late-Holocene immigration of steppe species from areas outside the Pannonian Basin. Most species must have been present in the region since at least the early Holocene, highlighting the importance of the lower mountain ranges surrounding the Pannonian Basin as long-term refugia for European steppe species. Dispersal limitation and resulting migration lags seem to have a strong influence on the distribution of steppe species in Central Europe. [ABSTRACT FROM AUTHOR]

The drivers of plant richness at fine spatial scales in steppe ecosystems are still not sufficiently understood. Our main research questions were: (i) How rich in plant species are the natural steppes of Southern Siberia compared to natural and semi-natural grasslands in other regions of the Palaearctic? (ii) What are the main environmental drivers of the diversity patterns in these steppes? (iii) What are the diversity-environment relationships and do they vary between spatial scales and among different taxonomic groups? We sampled the steppe vegetation (vascular plants, bryophytes and lichens) in Khakassia (Russia) with 39 nested-plot series (0.0001-100-m plot size) and 54 additional 10-m quadrats across the regional range of steppe types and measured various environmental variables. We measured β-diversity using z-values of power-law species-area relationships. GLM analyses were performed to assess the importance of environmental variables as predictors of species richness and z-value. Khakassian steppes showed both high α- and β-diversity. We found significant scale dependence for the z-values, which had their highest values at small spatial scales and then decreased exponentially. Total species richness was controlled predominantly by heat load index, mean annual precipitation, humus content and soil skeleton content. The positive role of soil pH was evident only for vascular plant species richness. Similar to other studies, we found that the importance of environmental factors strongly differed among taxonomic groups and across spatial scales, thus highlighting the need to study more than one taxon and more than one plot size to get a reliable picture. [ABSTRACT FROM AUTHOR]

The paper presents new approaches for assessing the conservation value of plant communities based on the use of quantitative criteria contained in databases and eco-floristic classification of steppe vegetation in the Don basin (Rostov region). The Black Sea and Kazakhstan steppes have significant potential for environmental protection. Analysis of biodiversity levels has been facilitated by descriptions of plant communities and quantitative indicators of major faunal groups of soil invertebrates (macrofauna) in the Tobol-Turgai basin (Kostanay region, Kazakhstan). As the structure of soil invertebrate communities is closely associated with vegetation, its assessment can provide insight into the degree of preservation or the depth of disturbance of ecosystems such as those found in the Black Sea and Kazakhstan steppes. [ABSTRACT FROM AUTHOR]