Aim  To determine relative effects of habitat type, climate and spatial pattern on species richness and composition of native and alien plant assemblages in central European cities. Location  Central Europe, Belgium and the Netherlands. Methods  The diversity of native and alien flora was analysed in 32 cities. In each city, plant species were recorded in seven 1‐ha plots that represented seven urban habitat types with specific disturbance regimes. Plants were classified into native species, archaeophytes (introduced before ad 1500) and neophytes (introduced later). Two sets of explanatory variables were obtained for each city: climatic data and all‐scale spatial variables generated by analysis of principal coordinates of neighbour matrices. For each group of species, the effect of habitat type, climate and spatial variables on variation in species composition was determined by variation partitioning. Responses of individual plant species to climatic variables were tested using a set of binomial regression models. Effects of climatic variables on the proportion of alien species were determined by linear regression. Results  In all cities, 562 native plant species, 188 archaeophytes and 386 neophytes were recorded. Proportions of alien species varied among urban habitats. The proportion of native species decreased with increasing range and mean annual temperature, and increased with increasing precipitation. In contrast, proportions of archaeophytes and neophytes increased with mean annual temperature. However, spatial pattern explained a larger proportion of variation in species composition of the urban flora than climate. Archaeophytes were more uniformly distributed across the studied cities than the native species and neophytes. Urban habitats rich in native species also tended to be rich in archaeophytes and neophytes. Main conclusions  Species richness and composition of central European urban floras are significantly affected by urban habitat types, climate and spatial pattern. Native species, archaeophytes and neophytes differ in their response to these factors.

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Aim Urbanization is associated with strong changes in biodiversity, but the diversity of plant and animal assemblages varies among urban habitats. We studied effects of urban habitats on the diversity of vascular plants and land snails in 32 large cities.Location Central Europe, Belgium and the Netherlands. MethodsThe species composition of all vascular plants that had not been planted by humans, and all land snails, was recorded in seven 1-ha plots within each city. Each plot contained one urban habitat type representing a different disturbance regime: historical city square, boulevard, residential area with compact building pattern, residential area with open building pattern, park, early successional and mid-successional site. For each plot, we obtained temperature and precipitation data. The effects of climate and habitat types on species composition were quantified using ordination methods with an adjusted variation partitioning algorithm. Differences in species composition among urban habitats were described using statistically determined diagnostic species, and differences in alpha, beta and gamma diversity were quantified.Results A total of 1196 plant and 87 snail species were recorded. Habitat type explained higher proportions of the total variation in both plant and snail species composition (11.2 and 8.2%, respectively) than did climate (4.6 and 6.3%). For both taxa, the main differences in species composition were observed between strongly urbanized sites in city centres and early successional and midsuccessional sites. For vascular plants, the number of species was lowest in city squares and boulevards, and highest at successional sites and in residential areas with compact building patterns. Beta diversity of vascular plants calculated for the same habitat types among cities was highest for squares and successional sites. The number of snail species was lowest in city squares and at early successional sites, and highest at mid-successional sites. The highest beta diversity of snail assemblages among cities was observed within the city square and early successional habitat types, and the lowest within residential area habitat types.Main conclusions Urban habitats differ notably in the diversity of their vascular plant flora and land snail fauna. Understanding the habitat-related biodiversity patterns in urbanized landscapes will allow projections of future impacts of urban land-use changes on the biota.

Questions: Although the role of landscape context, often interpreted as the available species pool, is generally assumed to be important for the restoration of disturbed sites, not many studies evaluating this role quantitatively in restored dry grasslands have been carried out. There is especially a lack of large-scale, multi-site studies. We asked how many unsown target species established spontaneously in restored dry grasslands and how spontaneous establishment depended on their occurrence in the surrounding landscape.Location: White Carpathian Mts., eastern Czech Republic (48°50 0 -49°05 0 N,Methods: We studied spontaneous colonization by unsown target species in dry grasslands on ex-arable land at 82 sites, sown with a regional seed mixture, commercial clover-grass seed mixtures or left to spontaneous succession. In total, 246 phytosociological relev es in 5-m 9 5-m plots were recorded. Restoration started 1-31 yr ago. Nearby semi-natural grasslands were included as reference sites (94 phytosociological relev es). A total of 108 target species were defined and their presence evaluated in the surroundings of the restored grasslands, i.e., in grid cells (3.1 km 9 2.8 km) in which the restored sites were situated. Data were processed using multivariate analyses (DCA, CCA) and GLM.Results: The number of target species at the restored sites significantly increased with time elapsed since restoration started and the number of target species occurring in the surroundings. The sites, although restored in different ways, converged in their species composition towards ancient grasslands. The maximum relative colonization of a restored grassland by target species from the surroundings was 23.4%, and the restored grasslands contained max. Fifty-seven percent of the average number of dry grassland target species present in the ancient grasslands.Conclusions: Sowing seed mixtures should be seen as not more than a first phase in the restoration of species-rich grasslands. In a next phase of restoration, we can reasonably rely on gradual spontaneous colonization by target species if they occur in the surroundings, even at sites sown with commercial seed mixtures or restoring spontaneously. However, full restoration probably takes decades or more.

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