Aim Alpine habitats support unique biodiversity confined to high‐elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups. Location European mountains below 50° N. Time period Between 1928 and 2019. Major taxa studied Vascular plants. Methods We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non‐alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed‐effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions. Results Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non‐alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non‐alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions. Main conclusions Besides area effects, edaphic, topographic and spatio‐temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post‐glacial environmental filtering, while non‐alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.

A taxonomic revision of the populations belonging to the Dianthus sylvestris Wulfen group (Caryophyllaceae) occurring in central and southern Italy, Sardinia and Sicily has been made. This group is represented in the surveyed territories by 17 morphologically and ecologically well differentiated species: Dianthus arrosti C. Presl, D. siculus C. Presl, D. graminifolius C. Presl, D. cyathophorus Moris, D. gasparrinii Guss., D. longicaulis Ten., D. virgatus Pasquale, D. tarentinus Lacaita, D. morisianus Vals., D. japygicus Bianco & Brullo, D. sardous Bacch., Brullo, Casti & Giusso, D. busambrae Soldano & F. Conti, D. brachycalyx Huet sp. nov., D. oliastrae sp. nov., D. insularis sp. nov., D. genargenteus sp. nov. and D. ichnusae sp. nov. Besides, two new subspecies are recognized within D. ichnusae (subsp. ichnusae and subsp. toddei). This taxonomical treatment is supported by a multivariate analysis based on 25 morphological characters and 1 phenological character. Each of the taxa is described and illustrated. In addition, notes on nomenclature, ecology, chorology, taxonomical relationships and conservation status are given. Lectotypes are designated for those taxa that are based on material from the investigated territories.

Orophilous plant communities of the Pino‐Juniperetea class, occurring in the Central and Eastern Mediterranean area, are examined. This vegetation is characterized by the dominance of trees and shrubs, mostly represented by conifers belonging to the genera Juniperus, Abies and Pinus. These communities are nowadays relegated to the supra‐ and oromediterranean belt, and show a fragmentary distribution, which is an evident proof of their relict connotation. The comparison among these communities, based on original and literature data, has highlighted a remarkable floristic and structural homogeneity, together with a series of geographical vicariances. From the phytosociological point of view, this justifies the arrangement of the aforesaid communities in the class Pino‐Juniperetea RIVAS‐MARTÍNEZ 1964, whose range is therefore extended to the whole Mediterranean basin. In the Central and Eastern Mediterranean area, the class is represented by the order Juniperetalia hemisphaericae, which comprises two new alliances: Berberidion aetnensis, restricted to the Central Mediterranean area, and Berberido creticae‐Juniperion foetidissimae, distributed in the Eastern Mediterranean area. Both of them have been on its turn split up in some suballiances, to emphasize the floristic autonomy of some well‐defined phytogeographical districts. The identified associations, many of them new to science, are examined from the nomenclatural, floristical, ecological, structural and chorological point of view. New groups described pp. 265 ff.

The vegetation of mining dumps of SW-Sardinia includes\ud several endemic or rare species, that have\ud been confined to such artificial habitats by a millennial\ud mining activity. The extreme edaphic specialization\ud of these species reflects with unusual fidelity the\ud heterogeneity of substrata, therefore creating a system\ud of plant communities that largely contributes to\ud the environmental diversity of this part of the island.\ud The phytosociological study presented in this paper\ud recognized eight associations, distinguished by the\ud cluster analysis in two main groups, the first including\ud hemicrypto-chamaephytic vegetation, the second\ud including nanophanerophytic garigues.\ud Six associations are belonging to the first group,\ud five of which newly described: Helichryso tyrrhenici-\ud Dianthetum sardoi ass. nova occurring on\ud gross-grained, hard-sloping dumps deriving from the\ud geologic unit of Gonnesa; Coincyo recurvatae-\ud Helichrysetum tyrrhenici ass. nova colonizing\ud dumps made of metamorphitic flakes and finer particles;\ud Resedo luteolae-Limonietum merxmuelleri\ud ass. nova colonizing small-grained mining dumps\ud with high concentrations in sulphides and heavy\ud metals; Ptilostemono casabonae-Iberidetum integerrimae\ud ass. nova replacing the previous one on\ud older and more consolidated dumps, where the concentration\ud of phytotoxic elements was reduced by\ud the meteoric agents; Epipactidetum tremolsii ass.\ud nova colonizing muddy deposits originating from\ud ferrous clay; Euphorbio cupanii-Santolinetum insularis\ud ANGIOLINI & BACCHETTA 2003, occurring on\ud very old, stabilized dumps. All these associations\ud can be ascribed to the class Scrophulario-Helichrysetea\ud BRULLO, SCELSI & SPAMPINATO 1998. Within\ud this class, a new Sardo-Corsican alliance, Ptilostemono\ud casabonae-Euphorbion cupanii all. nov. is\ud here proposed, differentiated by a pool of rare or\ud endemic species. In addition to the above-mentioned associations, it is proposed, as well, to include into\ud the new alliance the Polygono scoparii-Helichrysetum\ud tyrrhenici BIONDI, VAGGE, FOGU & MOSSA 1996\ud corr., that was described for the gravelly riverbeds of\ud Central-Southern Sardinia.\ud As concerns the second group, two new association\ud have been recognized: Dorycnio suffruticosi-\ud Genistetum corsicae ass. nova, found on abandoned,\ud well consolidated mining dumps, with an upper\ud layer altered by pedogenetic processes; Polygalo\ud sardoae-Linetum muelleri ass. nova, occurring in\ud the vicinities of the mines on steep rocky slopes\ud made of Paleozoic metalliferous limestones. Both of\ud them can be ascribed to the alliance Teucrion mari\ud GAMISANS & MURACCIOLE 1985, grouping the\ud Sardo-Corsican aspects of Cisto-Lavanduletea BR.-\ud BL. in BR.-BL., MOLINIER & WAGNER 1940.\ud Two taxa are new for science: Dianthus sardous\ud BACCHETTA, BRULLO, CASTI & GIUSSO, sp. nova and\ud Helichrysum microphyllum (WILLD.) CAMB. subsp.\ud tyrrhenicum BACCHETTA, BRULLO & GIUSSO, subsp.\ud nova

Motivation Indicator values are numerical values used to characterize the ecological niches of species and to estimate their occurrence along gradients. Indicator values on climatic and edaphic niches of plant species have received considerable attention in ecological research, whereas data on the optimal positioning of species along disturbance gradients are less developed. Here, we present a new data set of disturbance indicator values identifying optima along gradients of natural and anthropogenic disturbance for 6382 vascular plant species based on the analysis of 736,366 European vegetation plots and using expert‐based characterization of disturbance regimes in 236 habitat types. The indicator values presented here are crucial for integrating disturbance niche optima into large‐scale vegetation analyses and macroecological studies. Main types of variables contained We set up five main continuous indicator values for European vascular plants: disturbance severity, disturbance frequency, mowing frequency, grazing pressure and soil disturbance. The first two indicators are provided separately for the whole community and for the herb layer. We calculated the values as the average of expert‐based estimates of disturbance values in all habitat types where a species occurs, weighted by the number of plots in which the species occurs within a given habitat type. Spatial location and grain Europe. Vegetation plots ranging in size from 1 to 1000 m2. Time period and grain Vegetation plots mostly sampled between 1956 and 2013 (= 5th and 95th quantiles of the sampling year, respectively). Major taxa and level of measurement Species‐level indicator values for vascular plants. Software format csv file.