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With the potential extinction of threatened species, communities and species pools could become functionally and phylogenetically impoverished, especially if threatened species had distinct traits and evolutionary histories compared to least concern species. Alternatively, threatened species would have similar traits and evolutionary histories, and their extinction could imply the loss of functionally and phylogenetically ‘redundant’ species. We tested whether threatened plant species are functionally and phylogenetically rarer than least concern species. We considered two scales of plant assemblage (plots and species pools) from an intensively sampled temperate region (Czech Republic), using a sample of 23,072 vegetation plots classified into eight habitat groups. We analysed the traits and phylogeny of 1,730 species of angiosperms recorded in these plots. We found that the potential loss of threatened species could have minor functional and phylogenetic consequences for the communities in any habitat and at each assemblage scale. However, detailed analysis of individual traits revealed that some threatened species tend to have some unique trait value, such as being small and having lighter seeds. Phylogenetically unique species tended to be the most functionally rare, although this pattern was only weakly significant. This generally suggests similar conservation strategies for functionally rare and evolutionarily unique species. Policy implications. We show how novel tools related to functional rarity and phylogenetic uniqueness could be used to understand the role of threatened species in communities and different habitat types. This allows to understand which species and habitats could provide great functional and phylogenetic contributions to biodiversity to better guide management and conservation programmes. To fully achieve this potential, greater efforts in collecting functional trait information for threatened species remain urgent as well as considering both individual and combined trait information when estimating the functional originality of species., J.C.S. was supported by Capes (Post-doc grant process #88881.120150/2016-01). Z.L. and M.C. were supported by the Czech Science Foundation (grant 18-02773S). F.d.B. was supported by the Spanish Plan Nacional de I+D+i (project PGC2018-099027-B-I00).

Plant mycorrhizal status (a trait indicating the ability to form mycorrhizas) can be a useful plant trait for predicting changes in vegetation influenced by increased fertility. Mycorrhizal fungi enhance nutrient uptake and are expected to provide a competitive advantage for plants growing in nutrient-poor soils; while in nutrient-rich soils, mycorrhizal symbiosis may be disadvantageous. Some studies in natural systems have shown that mycorrhizal plants can be more frequent in P and N-poor soils (low nutrient availability) or Ca and Mg-high (high pH) soils, but empirical support is still not clear. Using vegetation and soil data from Scottish coastal habitats, and Latvian and Czech grasslands, we examined whether there is a link between plant mycorrhizal status and plant-available P, N, Ca and Mg. We performed the max test analysis (to examine the central tendency) and a combination of quantile regression and meta-analysis (to examine tendencies in different quantiles) on both community and plant species data combined with plant phylogenies. We consistently found no changes in mycorrhizal status at the community and species levels along the gradients of plant-available P, N, Ca and Mg in the central tendency and in almost all quantiles across all datasets. Thus, we found no support for the hypotheses that herbaceous species which are able to form mycorrhizas are more frequent in nutrient-poor and high pH environments. Obligatory, facultatively and non-mycorrhizal herbaceous species appear to assemble randomly along the gradients of nutrient availability in several European herbaceous habitats, suggesting that all these strategies perform similarly under non-extreme soil nutrient conditions.

[Aims] (a) To determine the contribution of current macro-environmental factors in explaining the phylogenetic structure of European forest vegetation, (b) to map and describe spatial patterns in their phylogenetic structure and (c) to examine which lineages are the most important contributors to phylogenetic clustering and whether their contribution varies across forest types and regions. [Location] Europe. [Taxon] Angiosperms. [Methods] We analysed the phylogenetic structure of 61,816 georeferenced forest vegetation plots across Europe considering alternative metrics either sensitive to basal (ancient evolutionary dynamics) or terminal (recent dynamics) branching in the phylogeny. We used boosted regression trees to model metrics of the phylogenetic structure as a function of current macro-environmental factors. We also identified clades encompassing significantly more taxa than under random expectation in phylogenetically clustered plots. [Results] Phylogenetic clustering was driven by climatic stress and instability and was strong in the areas glaciated during the Pleistocene, likely reflecting limited postglacial migration, and to a lower extent in areas of northern-central Europe and in summer-dry Mediterranean regions. Phylogenetic overdispersion was frequent in the hemiboreal zone in Russia, in some areas around the Mediterranean Basin, and along the Atlantic seaboard of the Iberian Peninsula. The families Ericaceae, Poaceae and Fagaceae were overrepresented in clustered plots in different regions of Europe. [Main conclusions] We provide the first maps and analyses on the phylogenetic structure of European forest vegetation at the plot level. Our results highlight the role of environmental filtering, postglacial dispersal limitation and spatial transitions between major biomes in determining the distribution of plant lineages in Europe., The study was supported by the Czech Science Foundation (19-28491X). IB and JAC were funded by the Basque Government (IT936-16). JCS considers this work a contribution to his VILLUM Investigator project “Biodiversity Dynamics in a Changing World” funded by VILLUM FONDEN (grant 16549).

The Pladias (Plant Diversity Analysis and Synthesis) Database of the Czech Flora and Vegetation was developed by the Pladias project team in 2014-2018 and has been continuously updated since then. The flora section of the database contains critically revised information on the Czech vascular flora, including 13.6 million plant occurrence records, which are dynamically displayed in maps, and data on 120 plant characteristics (traits, environmental associations and other information), divided into the sections: (1) Habitus and growth type, (2) Leaf, (3) Flower, (4) Fruit, seed and dispersal, (5) Belowground organs and clonality, (6) Trophic mode, (7) Karyology, (8) Taxon origin, (9) Ecological indicator values, (10) Habitat and sociology, (11) Distribution and frequency, and (12) Threats and protection. The vegetation section of the database contains information on Czech vegetation types extracted from the monograph Vegetation of the Czech Republic. The data are supplemented by national botanical bibliographies, electronic versions of the standard national flora and vegetation monographs, a database of more than 19,000 pictures of plant taxa and vegetation types, and digitalmaps (shapefiles) with botanical information. The data from the database are available online on a public portal www.pladias.cz, which also provides download options for various datasets and online identification keys to the species and vegetation types of the Czech Republic. In this paper, we describe the general scope, structure and content of the database, and details of the data on plant characteristics. To illustrate the data and describe the main geographic patterns in selected plant characteristics, we provide maps of mean values of numerical characteristics or proportions of categories for categorical characteristics on the map of the country in a grid of 5 longitudinal × 3 latitudinal minutes (approximately 6.0 km × 5.5 km). We also summarize the main variation patterns in the functional traits in the Czech flora using the principal component analysis.

1. Niche filtering predicts that abundant species in communities have similar traits that are suitable for the environment. However, niche filtering can operate on distinct axes of trait variation in response to different ecological conditions. Here, we use a trait-based approach to infer niche filtering processes and (a) test if abundant and rare species in grassland communities are differently positioned along distinct axes of trait variation, (b) determine if these trait variation axes, as well as phylogenetic and functional similarities, drive species relative abundance (above-ground cover) within communities, and (c) explore whether these relationships vary across grassland types and macro-climatic gradients. 2. We analysed species abundance in vegetation plots from temperate grasslands in Central Europe as a function of species position along three axes of trait variation: the ‘Plant Size Spectrum’ (PSS), the ‘Leaf Economics Spectrum’ (LES) and the ‘Life span/Clonality Spectrum’ (LCS). We also used phylogenetic and functional similarities in the multi-dimensional trait space as predictors of species abundance. We compared our results among alpine, wet, mesic and dry grasslands and tested whether the effect of the predictors on species abundance was significant across macro-climatic gradients. 3. Compared to abundant species, rare species in grassland communities were more commonly annual and non-clonal, had lower stature and smaller leaves and seeds, and relied on more acquisitive leaf economics. Our predictors significantly explained species abundance in approximately one-third of the plots. LES was the most important predictor across all plots, with the most prominent effect in alpine and dry grasslands and areas with more extreme temperatures. In contrast, in mesic and wet grasslands and grasslands located in warmer and less seasonal regions, species abundance was best predicted by phylogenetic similarities between species, with Poaceae species becoming more abundant. 4. Our study explored trait–abundance relationships for different community types across a large area and broad macro-climatic gradients. We conclude that niche filtering, and particularly resource-acquisition trade-offs, drives species abundance in temperate grassland communities of Central Europe. Our findings emphasize the interaction between local environmental conditions and plant function in determining community assembly.

Aim The first comprehensive checklist of European phytosociological alliances, orders and classes (EuroVegChecklist) was published by Mucina et al. (2016, Applied Vegetation Science, 19 (Suppl. 1), 3-264). However, this checklist did not contain detailed information on the distribution of individual vegetation types. Here we provide the first maps of all alliances in Europe. Location Europe, Greenland, Canary Islands, Madeira, Azores, Cyprus and the Caucasus countries. Methods We collected data on the occurrence of phytosociological alliances in European countries and regions from literature and vegetation-plot databases. We interpreted and complemented these data using the expert knowledge of an international team of vegetation scientists and matched all the previously reported alliance names and concepts with those of the EuroVegChecklist. We then mapped the occurrence of the EuroVegChecklist alliances in 82 territorial units corresponding to countries, large islands, archipelagos and peninsulas. We subdivided the mainland parts of large or biogeographically heterogeneous countries based on the European biogeographical regions. Specialized alliances of coastal habitats were mapped only for the coastal section of each territorial unit. Results Distribution maps were prepared for 1,105 alliances of vascular-plant dominated vegetation reported in the EuroVegChecklist. For each territorial unit, three levels of occurrence probability were plotted on the maps: (a) verified occurrence; (b) uncertain occurrence; and (c) absence. The maps of individual alliances were complemented by summary maps of the number of alliances and the alliance-area relationship. Distribution data are also provided in a spreadsheet. Conclusions The new map series represents the first attempt to characterize the distribution of all vegetation types at the alliance level across Europe. There are still many knowledge gaps, partly due to a lack of data for some regions and partly due to uncertainties in the definition of some alliances. The maps presented here provide a basis for future research aimed at filling these gaps. This project was funded by the Czech Science Foundation (grant no. 19-28491X). LM was supported by Iluka Chair of Vegetation Science & Biogeography, Murdoch University, Perth; IB, JAC and JL by the Basque Government (IT936-16); TMH by the European Social Fund (POCH and NORTE 2020) and National Funds (MCTES) through Fundacao para a Ciencia e a Tecnologia postdoctoral fellowship (SFRH/BPD/115057/2016) and project UIDB/04033/2020; AC and FK by the Slovenian Research Agency (P1-0236 to AC and program for Young Researchers to FK); SR by the University of Latvia (AAp2016/B041/Zd2016/AZ03); and KS by the Institute of Botany of the Czech Academy of Sciences (RVO 67985939).

1. It is increasingly recognized that the factors facilitating plant invasions depend on the stage along the introduction–naturalization–invasion continuum. Adaptative strategies, that is, combinations of functional traits that represent overall fitness in the face of one or more selection pressures, have shown promise in explaining plant invasions. However, whether adaptive strategy patterns change with stages of plant invasion is not yet known.2. Using the Pladias Database of the Czech Flora and Vegetation, we explored how Grime's adaptive strategies (competitors, stress-tolerators, ruderals; CSR) and introduction pathways (deliberate vs. accidental) relate to plant invasion along the introduction–naturalization–invasion continuum.3. Phylogenetically corrected ANOVAs showed that naturalized species (referring to non-invasive naturalized species in this study) were mostly R-selected, whereas invasive species tended to be C-selected. The results of phylogenetic regression analysis further confirmed that across the deliberately and accidentally introduced species, R- and C-selection were positively related to naturalization and invasion success respectively. We also found that deliberate introduction was negatively related to naturalization success and grid-cell occupancy of naturalized species, likely due to the different CSR strategies of deliberately and accidentally introduced aliens.4. Our study provides empirical evidence that different adaptive strategies are associated with species that have reached different invasion stages and confirms the usefulness of the CSR strategy framework for understanding plant invasion. This has implications for predicting and preventing potential high-impact invaders. For example, our results show that naturalized C-selected species have a higher probability of becoming invasive than naturalized R-selected species. Therefore, management actions are essential to prevent further introductions and spread of competitors. published

Aims: Arable habitats (i.e. fields, orchards, vineyards, and their fallows) were cre- ated by humans and have been essential elements in Central European landscapes for several millennia. In recent decades, these habitats have been drastically altered by changes in land use as well as agricultural practices and, more recently, by climate change. These changes have precipitated substantial changes in vegetation and their spatial and temporal trajectories have not yet been exhaustively studied. Here, we present the AgriWeedClim database —­ a new resource of vegetation plot (relevé) data of arable habitats in Central Europe. Location: Germany, Czech Republic, Slovakia, Switzerland, Liechtenstein, Austria, Hungary, Northern Italy, Slovenia, Croatia. Methods: Vegetation plot data were obtained from large repositories (e.g. European Vegetation Archive), specialized regional databases, colleagues and the literature. Data were then checked for completeness and standardized (e.g. taxonomy, nomenclature, crop types). Species were assigned native, archaeophyte (i.e. alien species introduced before c. 1492 CE) or neophyte (i.e. alien species introduced after c. 1492 CE) status. Results: The AgriWeedClim database version 1.0 contains georeferenced data from 32,889 vegetation plots sampled from 1916 to 2019. Conclusions: We provide an overview of this new resource and present example analyses to show its content and possible applications. We outline potential research questions including analysis of patterns and causes of vegetation changes in arable habitats from the early 20th century to the present.

Questions: Two scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot-based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis?. Location: Europe. Methods: We compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots). Results: Records from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing. Conclusion: This comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes., The work on this project was supported by Deutsche Forschungsgemeinschaft DFG (grant number BU 3097/1-1 for Jana Bürger), Czech Science Foundation (grant number 19-28491X for Milan Chytrý and Zdeňka Lososová), and by Slovenian Research Agency (research core funding No. P1-0236 for Urban Šilc and Young researcher programme for Filip Küzmič).

Plant mycorrhizal status (a trait indicating the ability to form mycorrhizas) can be a useful plant trait for predicting changes in vegetation influenced by increased fertility. Mycorrhizal fungi enhance nutrient uptake and are expected to provide a competitive advantage for plants growing in nutrient-poor soils; while in nutrient-rich soils, mycorrhizal symbiosis may be disadvantageous. Some studies in natural systems have shown that mycorrhizal plants can be more frequent in P and N-poor soils (low nutrient availability) or Ca and Mg-high (high pH) soils, but empirical support is still not clear. Using vegetation and soil data from Scottish coastal habitats, and Latvian and Czech grasslands, we examined whether there is a link between plant mycorrhizal status and plant-available P, N, Ca and Mg. We performed the max test analysis (to examine the central tendency) and a combination of quantile regression and meta-analysis (to examine tendencies in different quantiles) on both community and plant species data combined with plant phylogenies. We consistently found no changes in mycorrhizal status at the community and species levels along the gradients of plant-available P, N, Ca and Mg in the central tendency and in almost all quantiles across all datasets. Thus, we found no support for the hypotheses that herbaceous species which are able to form mycorrhizas are more frequent in nutrient-poor and high pH environments. Obligatory, facultatively and non-mycorrhizal herbaceous species appear to assemble randomly along the gradients of nutrient availability in several European herbaceous habitats, suggesting that all these strategies perform similarly under non-extreme soil nutrient conditions.

The species richness-productivity relationship is one of the most debated patterns in ecology. Species coexistence theory suggests that it could be tightly linked to the type of nutrient limitation (no limitation, single-nutrient limitation, colimitation by several nutrients). Yet, the effects of nutrient limitation on the species richness-productivity relationship have been rarely studied at the regional and continental scales. Combining the predictions of the humped-back model and the niche dimension hypothesis, we hypothesized that an increase in plant species richness with the number of different limiting nutrients is detectable only at higher productivity levels, at which competition for nutrients is more intense. Therefore, we expected the shape of the diversity-productivity relationship to differ between sites colimited by nitrogen (N) and phosphorus (P), sites limited by a single nutrient (either N or P), and sites not limited by any of these nutrients. To test this hypothesis, we used species richness data collected in 10 m x 10 m plots at 694 temperate dry grassland sites across eight regions in northern Eurasia. Productivity ranged from 10 to similar to 500 g/m(2) of above-ground standing biomass. The type of nutrient limitation was identified by critical nutrient ratios alone and their combination with critical nutrient concentrations measured in the plant tissue. Relationships were analysed using generalized linear and mixed-effect models. In line with our expectations, species richness of Eurasian temperate dry grasslands increased more steeply and peaked higher under higher productivity levels at N&P-colimited sites. When nutrient limitation was assessed by both ratios and concentrations, species richness at N&P-colimited sites continued to increase monotonically until the maximum productivity sampled in this study. In contrast, at sites with a single-nutrient limitation or no limitation, the peak in species richness was lower and occurred at a lower productivity of about 300-400 g/m(2). Synthesis. We provide the first evidence that the species richness-productivity relationship may depend on the type of nutrient limitation as predicted by the species coexistence theory. To generalize these findings, the role of nutrient limitation needs to be tested in other ecosystems, including more productive plant communities.

Aims: Biodiversity is traditionally studied mostly at the species level, but biogeographical and macroecological studies at higher taxonomic levels can provide valuable insights into the evolutionary processes at large spatial scales. Our aim was to assess the representation of vascular plant families within different vegetation formations across Europe. Location: Europe. Methods: We used a data set of 816,005 vegetation plots from the European Vegetation Archive (EVA). For each plot, we calculated the relative species richness of each plant family as the number of species belonging to that family divided by the total number of species. We mapped the relative species richness, averaged across all plots in 50 km × 50 km grid cells, for each family and broad habitat groups: forests, grasslands, scrub and wetlands. We also calculated the absolute species richness and the Shannon diversity index for each family. Results: We produced 522 maps of mean relative species richness for a total of 152 vascular plant families occurring in forests, grasslands, scrub and wetlands. We found distinct spatial patterns for many combinations of families and habitat groups. The resulting series of 522 maps is freely available, both as images and GIS layers. Conclusions: The distinct spatial patterns revealed in the maps suggest that the relative species richness of plant families at the community level reflects the evolutionary history of individual families. We believe that the maps and associated data can inspire further biogeographical and macroecological studies and strengthen the ongoing integration of phylogenetic, functional and taxonomic diversity concepts., MV, IA, JPC, ZL, IK, AJ and MC were funded by the Czech Science Foundation, programme EXPRO (project no. 19-28491X); JDi by the Czech Science Foundation (18-02773S); IB and JAC by the Basque Government (IT936-16); AČ by the Slovenian Research Agency (ARRS, P1-0236); AK by the National Research Foundation of Ukraine (project no. 2020.01/0140); JŠ by the Slovak Research and Development Agency (APVV 16-0431); KV by the National Science Fund (Contract DCOST 01/7/19.10.2018).

Cultivated exotic plants are often introduced for their aesthetic value and today comprise a substantial fraction of the flora of urban domestic gardens. Yet, their relative contribution to the functional diversity of domestic gardens and how it changes across different climate zones is insufficiently understood. Here, we investigated whether the effects of cultivated exotics on functional diversity of three plant traits related to plant aesthetics (that is, plant showiness, plant height, and leaf area) varied in suburban domestic gardens in three regions (Minnesota, USA; Alt Empordà, Spain; and central South Africa) that differ in aridity. For each garden, we calculated the mean and variance of each plant trait considering all co-occurring species and also splitting them into co-occurring cultivated exotics and natives. Our results revealed that mean plant showiness increased linearly with the proportion of cultivated exotics both across and within studied regions. Moreover, co-occurring cultivated exotics were, on average, showier than natives in all regions, but differences in their trait variances were context-dependent. The interaction between cultivated exotics and aridity explained variation in mean plant height and leaf area better than either predictor alone, with the effect of cultivated exotics being stronger in more arid regions. Accordingly, co-occurring cultivated exotics were taller and had larger leaves than natives in warmer and drier regions, while the opposite was true in cooler and wetter regions. Our study highlights the need to consider the combined effects of exotic species and climate in future studies of urban ecology.

Aims: The effect of biogeographical processes on the spatial turnover component of beta-diversity over large spatial extents remains scarcely understood. Here, we aim at disentangling the roles of environmental and historical factors on plant taxonomic and phylogenetic turnover, while controlling for the effects of species richness and rarity. Location: European beech (Fagus sylvatica) forests in Europe. Methods: We aggregated plant species occurrences from vegetation plots in spatial grid cells of 0.25º × 0.25º to calculate the spatial turnover component of taxonomic (TBD) and phylogenetic (PBD) beta-diversity for each cell. We also calculated the deviation of PBD given TBD (PBD), which measures the importance of phylogenetic turnover after factoring out taxonomic turnover. Beta-diversity was calculated for each grid cell as the mean pairwise dissimilarity between the focal cell and all other cells. We used structural equation modeling (SEM) to examine the relationships between environmental (climate, soil pH, and distance from the geographical distribution limit of beech) and historical (distance from beech glacial refugia) predictors and beta-diversity metrics. Results: We found a geographically consistent variation in taxonomic and phylogenetic turnover. Overall, TBD and PBD increased significantly toward more extreme climatic conditions, on more acidic soils, and toward the margins of beech distribution. The effects of environmental variables and the distance from glacial refugia on beta-diversity metrics were mediated by species richness and rarity. Phylogenetic turnover was low in relation to taxonomic turnover (i.e., high PBD) in areas closer to glacial refugia. Conclusions: Continental-scale patterns of beta-diversity in European beech forests are the result of complementary ecological and evolutionary processes. In general, beech forests are taxonomically and phylogenetically more distinct in climatically marginal areas of their European range. However, the spatial variation of beta-diversity in European beech forest flora is still strongly characterized by the distribution of groups of closely related species that evolved or survived in glacial refugia., The study was supported by the Czech Science Foundation (project no.19-28491X). I.B. and J.A.C. were funded by the Basque Government (IT936-16).

Whether cities are more or less diverse than surrounding environments, and the extent to which non-native species in cities impact regional species pools, remain two fundamental yet unanswered questions in urban ecology. Here we offer a unifying framework for understanding the mechanisms that generate biodiversity patterns across taxonomic groups and spatial scales in urban systems. One commonality between existing frameworks is the collective recognition that species co-occurrence locally is not simply a function of natural colonization and extinction processes. Instead, it is largely a consequence of human actions that are governed by a myriad of social processes occurring across groups, institutions, and stakeholders. Rather than challenging these frameworks, we expand upon them to explicitly consider how human and non-human mechanisms interact to control urban biodiversity and influence species composition over space and time. We present a comprehensive theory of the processes that drive biodiversity within cities, between cities and surrounding non-urbanized areas and across cities, using the general perspective of metacommunity ecology. Armed with this approach, we embrace the fact that humans substantially influence beta-diversity by creating a variety of different habitats in urban areas, and by influencing dispersal processes and rates, and suggest ways how these influences can be accommodated to existing metacommunity paradigms. Since patterns in urban biodiversity have been extensively described at the local or regional scale, we argue that the basic premises of the theory can be validated by studying the beta-diversity across spatial scales within and across urban areas. By explicitly integrating the myriad of processes that drive native and non-native urban species co-occurrence, the proposed theory not only helps reconcile contrasting views on whether urban ecosystems are biodiversity hotspots or biodiversity sinks, but also provides a mechanistic understanding to better predict when and why alternative biodiversity patterns might emerge. sDiv; Synthesis Centre of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig - German Research Foundation; NSF LTER grant [DEB-1027188] Published version This paper resulted from the sUrBioCity working group funded by sDiv, the Synthesis Centre of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation. CMS acknowledges support from NSF LTER grant no. DEB-1027188. The opinions and findings expressed in this paper are those of the authors and not of the National Science Foundation.

© 2021 The Authors., Aims: Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location: Palaearctic biogeographic realm. Methods: We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results: Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions: The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology., GrassPlot development has been supported by the Bavarian Research Alliance (BayIntAn_UBT_2017_58), the Eurasian Dry Grassland Group (EDGG) and the International Association for Vegetation Science (IAVS); IB, CorM, JAC, IGM, DGM, MHe, DL and MTo were supported by the Basque Government (IT936‐16); CorM, IAx, MCh, JDa, PD, MHá, ZL, ZPr, EŠ and LT were supported by the Czech Science Foundation (19‐28491X); TR was supported by the Estonian Research Council (PUT1173); RJP was funded by the Strategic Research Programme of the Scottish Government’s Rural and Environmental Science and Analytical Services Division”; SBa was supported by the GINOP‐2.3.2‐15‐2016‐00019 project; GFi was partially supported by the MIUR initiative “Department of excellence” (Law 232/2016)"; BJA was funded by the Spanish Research Agency (grant AEI/ 10.13039/501100011033); AK, VB, IM, DS, IV and DV were supported by the National Research Foundation of Ukraine (2020.01/0140); MP and AH were supported by the Estonian Research Council (PRG874, PRG609), and the European Regional Development Fund (Centre of Excellence EcolChange); Data collection of HCP was funded by FORMAS (Swedish Research Council for Environment, Agricultural Science and Spatial Planning) and The Swedish Institute; JR was supported by the Czech Science Foundation (grant No. 20‐09895S) and the long‐term developmental project of the Czech Academy of Sciences (RVO 67985939); ATRA was funded by the Grant of Excellence Departments, MIUR‐Italy (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016); JMA was supported by Carl Tryggers stiftelse för vetenskaplig forskning and Qatar Petroleum; AAli was supported by the Jiangsu Science and Technology Special Project (Grant No. BX2019084), and Metasequoia Faculty Research Startup Funding at Nanjing Forestry University (Grant No. 163010230), and he is currently supported by Hebei University through Faculty Research Startup Funding Program; ZB was supported by the NKFI K 124796 grant; The GLORIA‐ Aragón project of JLBA was funded by the Dirección General de Cambio Climático del Gobierno de Aragón (Spain); MCs and LDem were supported by DG Environment through the European Forum on Nature Conservation and Pastoralism and Barbara Knowles Fund, in collaboration with Pogány‐havas Association, Romania; JDa was partially supported by long‐term research development project no. RVO 67985939 of the Czech Academy of Sciences; BD and OV were supported by the NKFI KH 126476, NKFI KH 130338, NKFI FK 124404 and NKFI FK 135329 grants; BD, OV and AKe were supported by the Bolyai János Scholarship of the Hungarian Academy of Sciences; BE was funded by the Environmental Department of the Tyrolean Federal State Government, the MAB Programme of the Austrian Academy of Science, the Mountain Agriculture Research Unit and the Alpine Research Centre Obergurgl of Innsbruck University. The GLORIA projects of BE were funded by the EU project no. EVK2‐CT‐2000‐00056, the Earth System Sciences Program of the Austrian Academy of Sciences (project MEDIALPS), the Amt für Naturparke, Autonome Provinz Bozen‐Südtirol, the Südtiroler Wissenschaftsfonds and the Tiroler Wissenschaftsfonds; RGG was supported by the Spanish Ministry of Research to sample GLORIA sites in central Spain (CGL 2008‐00901/BOS) and present works by the Autonomous Region of Madrid (REMEDINAL TE‐CM, S2018/EMT‐4338); MJ was supporteLatviaed by Latvia Grant No. 194051; NP and SŠ were partly supported by the Slovenian Research Agency, core fundings P1‐0403 and J7‐1822.

Aim The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their unequivocal identification. Our goal was to develop a tool for assigning vegetation-plot records to the habitats of the EUNIS system, use it to classify a European vegetation-plot database, and compile statistically-derived characteristic species combinations and distribution maps for these habitats. Location Europe. Methods We developed the classification expert system EUNIS-ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set-theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species-to-habitat fidelity and constancy (occurrence frequency) in the classified data set. Finally, we mapped the plot locations for each habitat. Results Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man-made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination. Conclusions EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS-ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment. The previous versions of the expert system and related reports were produced within a contract from the European Environment Agency to Wageningen Environmental Research and Masaryk University. The opinions expressed are those of the contractor and do not represent the Agency's official position. EVA data management and preparation of this paper were supported by the Czech Science Foundation (project no. 19-28491X to MC, LT, IK, TP, CM, JDa, MH, PN, DZ, GB, AJ, AKu, ZL and DV). IB and JAC were supported by the Basque Government (project no. T936-16). TB, ET, and LK were supported by the Ministry of Science and Higher Education of the Russian Federation (TB and ET project no. AAAA-A18-118052590019-7; LK project no. AAAA-A19-119012490096-2).

Question Habitat‐specific species pools are shaped by ecological and evolutionary processes such as speciation, extinction, and migration. However, their role is poorly known because of the lack of robust data on species pools across a large number of plant community types and large areas. Here, we analyse a unique dataset of species pools of diagnostic species for all European vegetation types, asking: (a) what are the patterns of phylogenetic structure and phylogenetic beta‐diversity across European vegetation types and biomes; (b) what are the drivers of these patterns; and (c) is there a signal of niche conservatism at the level of biomes and broad categories of vegetation types? Location Europe, Canary Islands, Madeira, Azores, Cyprus, Caucasus, Iceland and Greenland. Methods We built a dataset comprising 10,804 vascular plant species (almost 85% of the European flora) assigned to 106 vegetation types representing all European vegetated habitats, grouped into 11 biomes. This dataset represented habitat‐specific species pools. We analysed the phylogenetic structure of the species pools and related it to distribution range sizes of individual vegetation types, their successional status, levels of disturbance and environmental stress. Results In European vegetation, phylogenetic overdispersion is associated with late‐successional habitats: several forest types, aquatic vegetation, and rock‐cliff vegetation serve as depositories of relict lineages. In contrast, phylogenetic clustering is typical of early successional and disturbed vegetation in anthropogenic, coastal and saline habitats, and in open‐canopy Mediterranean vegetation. The phylogenetic similarity of vegetation types is higher within than between broad categories of vegetation types and biomes. Conclusions The variable phylogenetic structure of European vegetation types is a heritage of evolutionary processes in the Tertiary and Quaternary. Habitat‐specific species pools of different vegetation types and biomes have been formed by different evolutionary processes as indicated by the observation that certain clades are significantly associated with certain vegetation types or biomes, hence indicating the phylogenetic niche conservatism.

1. Plant invasions can drastically change the structure of native communities, but it is not fully understood whether alien species occupy phylogenetic and functional space within the range occupied by natives, or provide a novel set of evolutionary origins and traits to the invaded communities. - 2. Here, we evaluated this open question with data on a large number of plant communities from different terrestrial habitats. We used 27,000 vegetation plots from 26 terrestrial habitats in the Czech Republic and compared phylogenetic and functional diversity (PD and FD, respectively) and community trait means in invaded and non-invaded plots. We tested for differences (1) between invaded vs. non-invaded plots, (2) among natives in invaded vs. non-invaded plots, and (3) in invaded plots only, with and without aliens. To minimize habitat filtering effects on PD and FD, we ran these tests within the habitat-specific species pools of the 26 vegetation types. - 3. In general, PD, FD and trait mean values changed with invasion, with changes being rather consistent across the habitats considered. Invaded plots were less phylogenetically, but more functionally diverse than non-invaded plots. The greater FD in invaded plots, compared to non-invaded ones, was due to greater dissimilarity between natives. In fact, native species in invaded plots showed higher PD and FD than native species in non-invaded plots, while alien species reduced PD and FD in invaded plots. Changes in the trait means with invasion were due to differences in native species in invaded and non-invaded plots, rather than to an effect of alien species. Within most habitats, the trait means and variance of all aliens were similar to those of all natives, while in some habitats, the variability in traits was greater between aliens that belonged to phylogenetically closer clades. - 4. Synthesis. Our results suggest that alien species more often occupy a phylogenetic and functional space within the range formed by the native species in a community. They do so either by filling empty gaps or by excluding natives from the existing phylogenetic and functional space, rather than occupying or creating a phylogenetic and trait space outside of it.

Aim: Urban floras are composed of species of different origin, both native and alien, and with various traits and niches. It is likely that these species will respond to the ongoing climate change in different ways, resulting in future species compositions with no analogues in current European cities. Our goal was to estimate potential shifts in plant species composition in European cities under different scenarios of climate change for the 21st century. - Location: Europe. - Methods: Potential changes in the distribution of 375 species currently growing in 60 large cities in Southern, Central and Western Europe were modelled using generalized linear models and four climate change projections for two future periods (2041-2060 and 2061-2080). These projections were based on two global climate models (CCSM4 and MIROC-ESM) and two Representative Concentration Pathways (2.6 and 8.5). - Results: Results were similar across all climate projections, suggesting that the composition of urban plant communities will change considerably due to future climate change. However, even under the most severe climate change scenario, native and alien species will respond to climate change similarly. Many currently established species will decline and others, especially annuals currently restricted to Southern Europe, will spread to northern cities. In contrast, perennial herbs, woody plants and most species with temperate continental and oceanic distribution ranges will make up a smaller proportion of future European urban plant communities in comparison with the present communities. - Main conclusions: The projected 21st century climate change will lead to considerable changes in the species composition of urban floras. These changes will affect the structure and functioning of urban plant communities.

Human made habitats are considered to be important hotspots of biodiversity of native as well as alien plant species. Due to high propagule pressure caused by human activities they serve as a source of introduction of alien plant species. We used the database of planted ornamental trees and shrubs for Brno, Czech Republic, to determine the significance of introduction effort given by intensity of planting as a factor in woody plant naturalization. Of all planted woody taxa, 15% were recognized as spontaneously growing in the urban area and there was a significant relationship between the number of planted individuals and the ability of a species to spontaneously occur in the urban area. The most often spontaneously escaping species originated in Europe (55%), followed by neophytes from North America (21%) and Central and Eastern Asia (14%). Although only a minor portion of planted woody species is able to escape from cultivation, this still could represent a potential risk for the native vegetation.

Summary Functional traits and phylogeny offer different, and often complementary, information about ecological differences between species, an essential step to uncover biodiversity assembly mechanisms and their feedbacks to ecosystem functions. However, traits and phylogeny are often related due to underlying trait evolution. Consequently, when combined, their shared information can be overemphasized, hindering their complementarity. It is therefore desirable to decouple their unique and overlapping contributions. We propose a conceptual and mathematical framework that produces a set of meaningful measures of ecological differences between species. We test the properties of these measures and the validity of the approach with extensive simulated data to show (i) the information provided by decoupling traits from phylogeny and vice versa, and (ii) that decoupling trait and phylogenetic information can uncover otherwise hidden signals underlying species coexistence and turnover. The application of the approach is further illustrated using a large dataset of Central European meadows as a case study. Decoupling traits and phylogeny particularly reveals the importance of differentiation between phylogenetically related species, which can be essential to understand species replacements along environmental gradients and the combined action of environmental filtering and limiting similarity within communities. Decoupling traits and phylogeny provides an avenue for connecting macro-evolutionary and local factors affecting coexistence and for understanding how complex species differences affect multiple ecosystem functions. We present an R function called ‘decouple’, which allows a simple and wide application of the framework.

Urbanized areas with high habitat heterogeneity and intense human impact form unique environment which is surprisingly rich in plant species. We explore the effect of the settlement size on plant species richness, composition and temperature requirements of plant communities. We studied three habitats with different disturbance regime in 45 Central European settlements of three different sizes. We sampled 1-ha plots in each habitat by recording all spontaneously occurring vascular plant species. We divided recorded species into groups according to their origin and residence time and according to their temperature requirements based on Ellenberg indicator values. We used ordination methods and ANOVA to detect that species communities in urban areas are generally more species rich in larger settlements than in small ones. These differences are mostly pronounced in residential areas. Increasing settlement size is significantly reflected by neophytes that are dependent on constant input of propagules caused by human activities and by native species that survive in remnants of semi-natural vegetation in urban environment. In contrast archaeophytes as a homogeneous group of species with similar traits are widespread equally through settlements of all sizes. We did not confirm the effect of urban heat island on species composition, indicating that species composition is significantly more affected by local habitat conditions than by urban size. Our results highlight the importance of urban size as important factor shaping biodiversity of native and alien plant communities in individual urban habitats and the important role of habitat mosaic for maintaining high species richness in city floras.

Aim: Climate is an important factor controlling plant distributions. However, it is not yet fully understood how climate interacts with human impacts or whether the effects of these factors differ between native and alien species. Facing ongoing climate change and urbanization, we explore the effects of climate on plant species richness and composition across European cities. - Location: Sixty cities in Western, Central and Southern Europe. - Taxon: Vascular plants. - Methods: Species presence was recorded in seven habitats in each city. Large scale climatic gradients were derived from 22 climatic variables using a partial principal component analysis that controlled for the effects of human population size and gross domestic product. The effects of climate and habitat type on the numbers of native and alien species were tested using linear mixed effect models. The native and alien compositional variation across cities and habitats was analysed using principal component analysis with variation partitioning. - Results: The Mediterranean to temperate climatic gradient had a significant effect on species numbers across all habitats. The numbers of both native and alien species increased from the Mediterranean to temperate Europe. Within each city, the proportion of alien species decreased from highly urbanized to less urbanized habitats. Climate had a stronger effect on the composition of alien plants than on the composition of native plants. The native species composition especially changed from the Mediterranean to temperate cities and alien species composition also from oceanic to continental cities. - Main conclusions: Urban native and alien species richness follow the pattern found for the whole European flora. Based on this observation, we suggest that the future shift of warm and dry conditions from the Mediterranean to the north that is expected under global change scenarios could affect richness and change the composition of European urban floras. However, this shift would not necessarily alter the proportions of aliens.

This is the final paper: “Segetal plant communities of traditional agroecosystems: a phytosociological survey in central Italy",published in PHYTOCOENOLOGIA, vol. 49, p. 165-183, ISSN: 0340-269X, doi: DOI: 10.1127/phyto/2019/0282, Abstract Aims: We present the results of a phytosociological investigation of segetal plant communities colonizing winter arable fields, olive groves, and vineyards in selected traditional agricultural areas of central Italy. Some of these communities have great environmental and cultural value and are threatened by changes in agriculture. Given the lack of knowledge, this paper aims to introduce the recent diversity of traditional agriculture weed vegetation in this part of Italy by means of the collection of original data. Study area: Latium and Abruzzo regions (central Italy). Methods: Hierarchical classification of 132 unpublished relevés, carried out with fixed area plots in 44 cultivated patches, and their characterization in phytosociological, chorological, structural, and ecological terms. Results: The numerical analyses detected the presence of 10 vegetation types, attributable to four phytosociological classes: Chenopodietea, Festuco-Ononidetea striatae, Molinio-Arrhenatheretea, and Papaveretea rhoeadis. Two Natura 2000 Habitats were recognized. Conclusions: The study allowed the detection and classification of well-preserved communities of traditional agricultural systems, some of which are disappearing in Europe.

The importance of macroclimate and dispersal limitation in the broad-scale variation of European urban land snail assemblages is likely to differ between native and non-native species because of the southern origin of many non-native snails, often spread by humans. We sampled land snails in each of 32 European cities and compiled from the literature a list of land snail species reported from the surroundings of each city. To quantify the predictive power of climate and local species pools, beta-sim dissimilarity matrices of both native and non-native species were explored using MDS and RDA ordination methods, Mantel tests with bootstrapping of each dataset, and multivariate homogeneity analysis of group variances. We observed no significant relation between the numbers of non-native species found in the cities and their surroundings (p > 0.133), while the percentage of native species in the cities derived from their local species pools decreased significantly with the increasing species richness of local faunas (rS = −0.75, p

Plants in cities must cope with various anthropogenic environments that differ from surrounding landscapes. Moreover, the differences in biotic and abiotic conditions among these habitats filter species with suitable traits and niche requirements. Here we aim to identify those attributes that promote species occurrence across and within urban habitat types of large cities. Species composition of spontaneously occurring vascular plant species was recorded in 1-ha plots in seven different urban habitat types in each of 32 European cities. Each species was characterized in terms of dispersal type, growth form, height, seed bank longevity, seed mass, selected leaf traits and ecological indicators including Ellenberg indicator values, Grime’s life strategies, and immigration pathways using information from available species-trait databases. For each species, total frequency of occurrence across all plots and habitat frequency of occurrence across plots of given habitat types were calculated and regression trees were used to relate them to traits and ecological indicators. The most frequently occurring species in the cities tended to be human-dispersed, nutrient-demanding plants that prefer drier to mesic soil conditions. These species do not possess the S-strategy and usually produce seeds of low mass forming short-term persistent seed banks. Habitat-specific responses were also revealed, indicating the effects of between- and within-habitat heterogeneity on trends in species performance in cities. Such patterns can be overlooked when differences in species occurrences in particular urban habitat types are not considered; thus, habitat-specific responses can resolve inconsistencies found when whole urban floras are analysed as a whole.

Question: It is often assumed, but poorly tested, that patterns of phylogenetic diversity reflect functional diversity in plant communities. Here we test whether phylogeny can be used as a proxy for functional diversity in general and specifically for diversity in plant niche preferences, dispersal strategies and competitiveness- related traits. Location: Central Europe, Belgiumand the Netherlands. Methods: We used a species composition data set from seven urban habitats, each sampled in 32 large cities of ten countries, and combined thiswith information about species phylogeny and functional traits, the latter divided into categories representing niche preferences, dispersal strategies and competitiveness. Results: We found positive significant, yet very weak, relationships between phylogenetic diversity and overall functional diversity, and between phylogenetic diversity and diversity in both species dispersal strategies and competitiveness. The relationship between phylogenetic diversity and diversity in species niche preferences was not significant. Conclusions: We suggest that the combination of multiple trait states that coexist in urban plant communities and even within the same lineages weakens the phylogeny–function relationship. Phylogenetic diversity is a weak proxy for functional diversity of urban plant communities. For some facets of functional diversity, the phylogeny–function relationshipmay not apply at all.

We ask whether changes in beta diversity of plant communities due to introduction of alien species result from changes in species turnover or from differences in species richness. Using dataset of European urban habitats we show that changes in beta diversity induced by the establishment of alien species reflect mainly species turnover, whereas the richness difference component has small effects.

Patterns of phylogenetic relatedness of species within community types (phylogenetic structure; PS) are often used to infer processes of community assembly, yet the causes of these patterns remain poorly understood. Here we ask whether PS of extant plant species pools is related to availability of correspoding habitats in the geological history.

Spread of alien species may result in biotic homogenization, i.e. increasing similarity between biotas of different areas. We examined whether the flora of Central European cities is becoming homogenized because of the spread of alien species, whether the contribution of aliens to homogenization depends on residence time, and whether habitats under more intense human pressure are more homogenized. Using floristic composition data from a standardized sample of 1-ha plots located in seven habitat types in 32 cities in Central Europe, Belgium and the Netherlands, we compared homogenization effects of archaeophytes (pre-AD 1500 aliens) and neophytes (post-AD 1500 aliens) using rarefaction curves, Jaccard dissimilarity index, Mantel tests and homogenization index. We found that archaeophytes contributed to homogenization and neophytes to differentiation of floras among cities, but generally the spread of alien species caused differentiation. Differentiation was low in the most disturbed urban habitats, such as city squares, boulevards or early successional sites, but was strongest in moderately disturbed habitats, such as city parks and residential areas with an open building pattern. We conclude that biotic homogenization depends on alien plants’ residence time. Aliens introduced within the past five centuries are often rare, not yet having achieved their potential range; they therefore increase floristic differentiation. Conversely, species introduced more than five centuries ago have had sufficient time to disperse into most suitable habitats, and consequently contribute to homogenization. Although invasions may therefore initially increase biodiversity, they could ultimately lead to homogenization. These processes are faster and stronger in more disturbed habitats.

Aim It is generally believed that communities of small organisms, or those with small propagules, are structured mainly by local niche-based processes, and less by dispersal limitation. Conversely, weaker environmental and stronger spatial structure, indicating dispersal limitation, are expected to occur more frequently in communities of large organisms. However, this hypothesis has rarely been tested by comparing spatial and environmental effects across groups of organisms of different size (or with different size of propagules) sampled at the same set of sites. Here, we test it in urban environments. Location Thirty-two cities in 10 countries of Central Europe and Benelux. Methods Wecompared effects of spatial location and climate on species composition of different groups of organisms sampled in corresponding types of urban habitats. The studied groups were: (1) subaerial cyanobacteria and algae, (2) vascular plants, (3) land snails; and subgroups of vascular plants with different life form and dispersal mode, namely: (4) herbs, (5) animal-dispersed trees and shrubs, and (6) wind-dispersed trees and shrubs. Data were analysed by variation partitioning based on redundancy analysis (RDA) with principal coordinates of neighbour matrices (PCNM). Eighteen PCNM eigenvectors (expressing spatial effects) and mean annual temperature, July–January temperature difference and annual precipitation sum (expressing environmental effects) were used as explanatory variables. Results Pure effects of climate on species composition, indicating niche-based processes, were not significant for any group or subgroup of the studied organisms. In contrast, pure effects of space, indicating dispersal limitation, were significant for all groups and subgroups except herbs. Surprisingly, the community of cyanobacteria/algae possessed much stronger spatial structure independent of climate than communities of larger organisms, although cyanobacteria/algae had the lowest beta diversity among the studied cities. Main conclusions We hypothesize that the community of subaerial cyanobacteria/ algae is structured by natural processes which involve dispersal limitation, whereas communities of urban plants and snails are influenced by human-assisted dispersal of their propagules between cities, which results in weaker dispersal limitation. Our study indicates that dispersal vectors can be more important for community structure than size of organisms or of their propagules.

A synthesis of the alliance Eragrostion cilianensi-minoris in the Czech Republic is presented on the basis of 82 releves including new unpublished data. A TWINSPAN classification and detrended correspondence analysis were used to identify the main vegetation types included in the alliance Eragrostion cilianensi-minoris. A syntaxonomic revision of the data set revealed five associations of the alliance: Digitario sanguinalis-Eragrostietum minoris, Portulacetum oleraceae, Eragrostio poaeoidis-Panicetum capillaris, Cynodontetum dactyli, and Hibisco trioni-Eragrostietum poaeoidis. The latter was recently found in several arable fields in Southern Moravia (Czech Republic) and was newly characterized.

Tillaea aquatica (Crassulaceae) is considered as annual wetland species threatened by changes in land use and progressing eutrophication in large part of its European distribution range. We summarised the historical and recent data on this species, and analysed its distribution and associated habitat changes in the Czech Republic. We used permanent plots as well as seed bank and seed dispersal studies to obtain better insight into the plant’s survival strategy. During the second half of the twentieth century T. aquatica disappeared from most historical localities situated mainly in large fishponds. After 1999, altogether 18 new populations were found in small fry ponds and other fish-farming ponds. The largest populations of Tillaea were found in ponds with long-term bottom exposure where the vegetation of perennial herbs was eliminated by herbicides or grazing. Propagules easily dispersible by water, on gumboots or tyres of vehicles, and long-term soil seed bank also might contribute to persistence of the species in the habitats, diminishing the chance of extinction. As the fishpond management has changed, and so have done the original habitats of Tillaea, the species could survive in habitats different from those in the past. In this article, we suggest management measures aimed at promoting survival of Tillaea under new circumstances.

Aim In contrast to non-forest vegetation, the species richness–productivity (SR-P)relationship in forests still remains insufficiently explored. Several studies have focused on the diversity of the tree layer, but the species richness of temperate deciduous forests is mainly determined by their species-rich herb layer. The factors controlling herb-layer productivity may differ from those affecting tree layers or open herbaceous vegetation, and thus the SR-P relationship and its underlying processes may differ. However, the few relevant studies have reported controversial results. Here we explore the SR-P relationship in the forest herb layer across different areas from oceanic to continental Europe, and put the effect of habitat productivity on species richness into context with other key factors, namely soil pH and light availability. Location North-western Germany, Czech Republic, Slovakia and southern Urals(Russia). Methods We measured herb-layer species richness and biomass, soil pH and tree-layer cover in 156 vegetation plots of 100 m2 in deciduous forests.We analysed the SR-P relationship and the relative importance of environmental variables using regression models for particular areas and separate forest types. Results We found a consistent monotonic increase in the herb-layer species richness with productivity across all study areas and all forest types. Soil pH and light availability also affected species richness, but their relative importance differed among areas. Main conclusions We suggest that the monotonically increasing SR-P relationship in the forest herb layer results from the fact that herb-layer productivity is limited by canopy shading; competition within the herb layer is therefore not strong enough to exclude many species. This differs fundamentally from open herbaceous vegetation, which is not subject to such productivity limits and consequently exhibits a unimodal SR-P relationship.We present a conceptual model that might explain the differences in the SR-P relationship between the forest herb layer and open herbaceous vegetation.

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.

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. Methods The 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 mid-successional 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.

Question: What are the differences in trait compositions which enable native plants to colonise comparable natural and man-made habitats? Are these traits independent of phylogenetic relationships between species? Location: Czech Republic Methods: The relative importance of biological, ecological and distributional traits of native species was studied, using a dataset of 75 species growing in rock and wall habitats in the Czech Republic. Species preferences for individual habitats due to climatic conditions and proportions of different vegetation types in their surrounding were partialled out using partial canonical correspondence analysis. The pattern of plant traits along a gradient from natural rock habitats to secondary wall habitats was analysed using regression trees and generalized linear models with and without phylogenetical correction. Results: The most common native species colonising rock habitats are phanerophytes, mostly woody juveniles, with a CSR life strategy and most of them are adapted to epizoochory. Summer green leaves, annual life span, CR life strategy, reproduction mostly by seeds and dispersal by ants are all traits positively associated with the ability of species to colonise wall habitats. These species are also characterized by their high demand for nutrients, temperature, base-rich substrates, and light. Biological and ecological traits are more important for colonizing new habitats than traits related to species dispersal ability or phylogenetical relationships between species. Biological and ecological traits alone explained 29.3% of variability in the species dataset, while dispersal characteristics and phylogeny alone explained 9.1% and 4.8% respectively. Conclusions: We outline how the process of environmental filtering determines the native species assemblages and identify a set of species traits that enable them to persist in particular habitats. We conclude that although urbanisation generally results in loss of natural habitats, there are new, man-made habitats potentially suitable for native species.

Aim The diversity changes that occurred in Central European forests during the early Holocene can be better understood using ecological knowledge of modern analogues of these forests, which occur in far Eastern Europe. Here we compare the diversity of vascular plants, bryophytes and snails among different forest types of the Southern Urals to provide insights into the palaeoecology of the vanished Central European forests. Location Southern Ural Mountains, Bashkortostan, Russia. Methods We recorded all species of vascular plants, ground-dwelling bryophytes and land snails, and measured biotic and abiotic variables, in 100-m2 plots located in four forest types dominated by different trees: Pinus sylvestris-Larix sibirica, Betula pendula-Populus tremula, Quercus robur and Acer platanoides-Tilia cordata-Ulmus glabra. These types correspond to the chronosequence of forest communities that occurred in Central Europe in the early Holocene. Results The species richness of herb-layer plants was most affected by the canopy-transmitted light. The former three forest types had open canopy and were rich in species, whereas the Acer-Tilia-Ulmus forests were darker and poor in species. The species richness of ground-dwelling bryophytes decreased from coniferous to broad-leaved deciduous forests. In contrast, the highest species richness of snails was in the Acer-Tilia-Ulmus forests owing to the higher calcium content in the litter of these trees. Main conclusions Based on the modern analogue of the Southern Ural forests, we propose the hypothesis that the late-glacial open-canopy pine and larch forests of Central European lowlands were rich in light-demanding species of vascular plants, many of which were also typical of tall-grass steppes or mesic grasslands. They also contained several species of ground-dwelling bryophytes. The spread of birch, aspen and oak in the early Holocene reduced the local species richness of ground-dwelling bryophytes but not of vascular plants. The subsequent spread of elm, lime, maple and ash caused canopy closure, a retreat of the light-demanding herbs and a decline in the local species richness of vascular plants. Besides the increased shading by these tree species, their litter enriched soils in calcium, and enhanced decomposition and nutrient cycling. This supported an increase in the species richness of land snails.

Walls are often considered secondary habitats for vegetation of natural rock surfaces. Compared with rocks, walls differ in many features, for example the presence of a binding material (mainly calcareous mortar), location in settlements and exposure to human impact. A data set of 1,205 phytosociological releves recorded on horizontal wall tops, wall verticals and rock verticals in the Czech Republic was used to compare their vegetation with regard to i) species composition (frequent species, species diversity, endangered and alien species) and ii) the ecological requirements of the respective species. Gamma diversity of vascular plant species was comparable in all habitat types (242 species on wall tops, 212 species on wall verticals and 197 species on rock verticals). Wall verticals had higher beta diversity, but lower alpha diversity than rocks. Remarkable differences were found comparing the diversity of alien species. Whereas alpha and gamma diversities of aliens were higher on both wall habitats, beta diversity of aliens was the highest on rocks. The high floristic heterogeneity of walls is mainly attributable to the large pool of species from the surrounding urbanized landscape (e.g., cultivated ornamental species and synanthropic weeds) that are favoured by high nutrient inputs. In contrast, species characteristic of rocks are mainly substrate specialists. Walls and rocks share the frequent occurrence of ferns, grasses and herbs typical of forest understorey and clearings. Compared with rocks, walls are generally colonized by species requiring higher nutrient content, soil reaction, temperature and moisture. Secondary wall habitats might be suitable for some rare and endangered species, but contrary to rocks their occurrences are only accidental and temporary. The representation of aliens was considerably higher on walls (approximately 35%) than on rocks (9%).

A malacological study at 41 forest sites in the Southern Urals (Bashkortostan, Russia) conducted in 2007 gave the first quantitative data about land snail assemblages from this region. We explore the hypothesis that forests of this area are modern analogues of the Early Holocene forests of Central Europe. Snail species significantly accumulated towards more fertile, calcium-rich, and lowland sites; the richest faunas were in alluvial alder forests and mesic lime-maple-elm forests. Several features such as low snail species richness, predominance of generalist species with wide distributions, and broader realized niches of particular species in the Southern Ural forests relative to their niches elsewhere, corresponded to those of fossil assemblages from the Early Holocene deposits of Central Europe. Our data also suggest that the very limited species pool, results in species poor assemblages which are structured mainly by environmental filtering.