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Aim: Forest-steppe complexes in the peri-Carpathian region harbour specific vegetation dominated by tall herbs. Our aim was to provide new phytosociological data on this vegetation type from the Ukraine and adjacent parts of Romania, compare it with previously published data, discuss its position in broad ecological and biogeographical context and suggest its syntaxonomic treatment respecting both its physiognomy and species composition. Study area: Western Ukraine and Romania. Methods: We assembled a dataset of 711 relevés of thermophilous herb-rich vegetation (Trifolio-Geranietea) from the study area and adjacent regions of Eastern Poland and Slovakia using own field research, literature survey and large databases. Using intersection of three different classification algorithms (beta-flexible, modified TWINSPAN and K-means clustering) we identified a consensus delimitation of the vegetation type. NMDS ordination, analysis of diagnostic, constant and dominant species, and Didukh indicator values were used to characterize its species composition and habitat conditions. Results: Altogether 58 relevés from Western Ukraine and Romania were classified to a tall herb-dominated vegetation type that we identified with the association Trollio-Clematidetum recti Täuber et Weber 1976 described from Romania. We assigned it to the alliance Geranion sanguinei. It differs from other communities of this alliance in its preference for shady slopes, greater stand height and considerable representation of mesophilous and montane species. It is confined to calcareous bedrock with high soil pH and high mineral richness. Conclusions: We suggest that the studied tall herb-dominated vegetation is a specific steppe type, confined to relatively moist and nutrient rich sites in the peri-Carpathian area. Analogous vegetation occurs in the Alps, Balkans, hemiboreal Europe, South Urals and Western Siberia. Its species composition and biogeographical relationships provide further support for the hypothesis that steppe meadows of Central Europe, including tall herb-dominated stands, are linked to the Pleistocene and early-Holocene forest-steppe of temperate Eurasia. [ABSTRACT FROM AUTHOR]

The extreme species richness of some temperate grasslands is a globally relevant yet understudied phenomenon. Until now, few records from thoroughly sampled, though not permanently fixed, vegetation plots were available. We therefore established a network of 40 permanent 4 × 4-m2 plots in species-rich grasslands of the White Carpathians (Czechia), Ukraine, Hungary and Romania. Thirty-one of them form the main dataset comprising plots from discrete forest-steppe grasslands (the Brachypodio-Molinietum association of the Cirsio-Brachypodion pinnati alliance), while nine of them forms the local dataset from a single locality in the White Carpathians, whose vegetation lacks most forest-steppe species and is transitional between the Bromion erecti and Arrhenatherion elatioris alliances (the Anthoxantho-Agrostietum and Anthyllido vulnerariae-Trifolietum montani associations). The permanent plots contain a nested subplot of 1 m2, except for five plots from Ukraine and Romania. Most plots harboured at least 80 vascular plant species per 16 m2, with the mean richness of 16-m2 plots was 95.3 species in the main dataset and 84 species in the local dataset. Mean richness of the 1-m2 subplots, presumably reflecting local environmental conditions and competitive relationships more than that of 16 m2 plots, did not vary between the two datasets, with a general mean of 57.6 species. Species counts of 16-m2 plots and 1-m2 subplots correlated, albeit only moderately, only in the main dataset. The presented datasets may be used for comparative analyses as well as for a future revisiting of the plots and may bring novel insights into the dynamics of extreme species richness. [ABSTRACT FROM AUTHOR]

Continentality is a globally significant gradient influencing broad-scale biogeographical patterns. An excellent example is the transition from the European temperate forest biome to the continental steppe and forest-steppe of Eurasia. One of the biogeographic crossroads where the two biomes meet is the Western Podillia in the western part of Ukraine. It is known for its rich biodiversity with a mixture of steppe, forest and montane species, despite a relatively humid climate suitable for closed-canopy forests. Biologists have postulated the refugial character of the local steppes, but a modern paleoecological reconstruction of the environmental history of the region has been lacking. We fill this gap here with a multi-proxy study (pollen, plant and mollusc macrofossils, microcharcoal, geochemistry) of two profiles sampled in calcareous fens adjacent to species-rich steppe grasslands. To link the reconstructed environmental history with the history of human settlement, we compiled available archaeological records from the studied region. Together, the analyzed profiles cover the entire Holocene and the end of the Last Glacial period, as shown by high-quality age-depth models. All studied proxies support the hypothesis that an open or semi-open landscape existed in Western Podillia during the Holocene. The complete absence of wood remains in Holocene sediments, and the persistence of fen specialists showed the exceptional long-term stability of open wetlands. The continuous presence of pollen of light-demanding plants, low abundance of closed-canopy trees compared to open-canopy trees, and stable concentrations of geochemical indicators of erosion suggest a semi-open landscape with a mosaic of forests, steppe grasslands, and other open habitats. Multivariate analysis revealed the similarity of pollen assemblages with sites in the forest-steppe zone at the interface between the Pannonian Basin and the Western Carpathians. The continuous presence of non-woody microcharcoal in high abundance suggests a role of fire in maintaining open habitats, and the archaeological record provides evidence of human activity throughout the Holocene near the study sites. Comparison with modern pollen spectra suggests that the landscape was probably somewhat more forested in the past than today, but rather by open-canopy trees. Our results indicate that Western Podillia has become a biogeographic crossroads not only because of its location on the border between Central and Eastern Europe, but also because of the unusual combination of relatively humid climate and continuity of open or semi-open landscapes since the Last Glacial. • Long-term continuity and mild climate shaped biodiversity of Western Podillia. • Prehistoric human and fires may have contributed to the maintenance of open landscape. • Open-canopy trees prevailed in the forests during the Holocene. • Several proxies show exceptional stability of open calcareous wetlands. [ABSTRACT FROM AUTHOR]