Scale-dependent plant diversity in Palaearctic grasslands: a comparative overview

Here we present an extensive overview of plant diversity values in Palaearctic grasslands for seven standard grain sizes from 0.0001 to 100 m². The data originate from 20 studies, including the Field Workshops of the Eurasian Dry Grassland Group (EDGG), ranging geographically from Spain in the west to Siberia in the east, from Sicily in the south to Estonia in the north and from the sea coast up to 3100 m a.s.l. The majority of data is from dry grasslands (Festuco-Brometea, Koelerio-Corynephoretea, Cleistogenetea squarrosae), but there are also some mesic, wet, saline, acidic, alpine and Mediterranean grasslands included. Among others, we compiled data from 1795 1-m², 1109 10-m² and 338 100-m² plots. In all cases we present mean, minimum and maximum richness for the seven grain sizes, plus, in cases where also terricolous bryophytes and lichens had been recorded, the same values for total “plant” species richness, non-vascular plant species richness and fraction of non-vascular plants. The maximum richness values were 82, 101 and 134 for all “plants”, and 79, 98 and 127 vascular plants at grain sizes of 1 m², 10 m² and 100 m², respectively (all in Transylvania, Romania). Our overview comprises new, hitherto unpublished world records of vascular plant species richness at the scales of 0.0001 m² (9) and 0.001 m² (19, both shoot presence), from meso-xeric, basiphilous grasslands in Navarre, Spain, which is much higher than the previously known maxima. The highest values of non-vascular plant richness at 1 m², 10 m² and 100 m², respectively, were 49, 64 and 64, respectively (all in Sedo-Scleranthenea communities of Öland, Sweden, and Saaremaa, Estonia). In general, the dry, alpine and Mediterranean grasslands were much richer than the studied mesic, wet or saline grasslands at any spatial scale. The presented set of mean, minimum and maximum values and their metadata is publically available and will be continuously updated. These data can serve as a reference of “normal” richness, both in fundamental and applied research. To facilitate the application, we provide an easy formula based on the power-law species-area relationship that allows the estimation of richness values at intermediate grain sizes not included in our dataset. In conclusion, our data emphasise the role of Palaearctic grasslands as global hotspot of small-scale vascular plant diversity, while at the same time highlighting that in some grassland types also the bryophyte and lichen diversity can be extraordinarily high

Vegetation classification and biogeography of European floodplain forests and alder carrs

Location: Europe. Methods: A database of more than 40 000 vegetation plots of floodplain forests and alder carrs across Europe was compiled. After geographic stratification, 16 392 plots were available for classification, which was performed using the supervised method Cocktail. We also searched for new associations using semi-supervised K-means classification. The main biogeographic patterns and climate-related gradients in species composition were determined using detrended correspondence analysis and cluster analysis. Results: Thirty associations of floodplain forests and alder carrs were distinguished, which belong to five alliances. The Alnion incanae includes riparian, seepage and hardwood floodplain forests in the nemoral and hemiboreal zones (dominated by Alnus glutinosa and Fraxinus excelsior) and in the boreal zone (dominated by A. incana). The Osmundo-Alnion represents oceanic vegetation dominated by Alnus glutinosa, Fraxinus angustifolia and F. excelsior distributed mostly on the Iberian Peninsula and composed of species with Atlantic distribution and Iberian endemics. The Populion albae comprises floodplain forests frequently dominated by Fraxinus angustifolia, Populus alba and P. nigra that are widespread in floodplains of large rivers under summer-dry climates in the Mediterranean region. The Platanion orientalis represents eastern Mediterranean floodplain forests dominated by Platanus orientalis. The Alnion glutinosae includes forest swamps dominated by Alnus glutinosa distributed mostly in the nemoral and hemiboreal zones. The main biogeographic patterns within European floodplain forests and alder carrs reflect the climatic contrasts between the Mediterranean, nemoral, boreal and mountain regions. Oceanic floodplain forests differ from those in the rest of Europe. The hydrological regime appears to be the most important factor influencing species composition within regions. Conclusions: This study is the first applying a formalized classification at the association level for a broad vegetation type at the continental scale. The proposed classification provides the scientific basis for the necessary improvement of the habitat classification systems used in European nature conservation

Alpha diversity of vascular plants in European forests

Aim The former continental‐scale studies modelled coarse‐grained plant species‐richness patterns (gamma diversity). Here we aim to refine this information for European forests by (a) modelling the number of vascular plant species that co‐occur in local communities (alpha diversity) within spatial units of 400 m2; and (b) assessing the factors likely determining the observed spatial patterns in alpha diversity. Location Europe roughly within 12°W–30°E and 35–60°N. Taxon Vascular plants. Methods The numbers of co‐occurring vascular plant species were counted in 73,134 georeferenced vegetation plots. Each plot was classified by an expert system into deciduous broadleaf, coniferous or sclerophyllous forest. Random Forest models were used to map and explain spatial patterns in alpha diversity for each forest type separately using 19 environmental, land‐use and historical variables. Results Our models explained from 51.0% to 70.9% of the variation in forest alpha diversity. The modelled alpha‐diversity pattern was dominated by a marked gradient from species‐poor north‐western to species‐rich south‐eastern Europe. The most prominent richness hotspots were identified in the Calcareous Alps and adjacent north‐western Dinarides, the Carpathian foothills in Romania and the Western Carpathians in Slovakia. Energy‐related factors, bedrock types and terrain ruggedness were identified as the main variables underlying the observed richness patterns. Alpha diversity increases especially with temperature seasonality in deciduous broadleaf forests, on limestone bedrock in coniferous forests and in areas with low annual actual evapotranspiration in sclerophyllous forests. Main conclusions We provide the first predictive maps and analyses of environmental factors driving the alpha diversity of vascular plants across European forests. Such information is important for the general understanding of European biodiversity. This study also demonstrates a high potential of vegetation‐plot databases as sources for robust estimation of the number of vascular plant species that co‐occur at fine spatial grains across large areas.M.V., J.D., I.K., M.Ř. and M.C. were supported by the Czech Science Foundation (Centre of Excellence Pladias; project no. 14–36079G). I.B. and J.A.C. were supported by the Basque Government (IT936‐16). B.J.‐A. was supported by the Marie Curie Clarín‐COFUND program of the Principate of Asturias and the European Union (ACB17‐26). J.‐C.S. considers this work a contribution to his VILLUM Investigator project “Biodiversity Dynamics in a Changing World” funded by VILLUM FONDEN (grant 16549) and his Danish Council for Independent Research | Natural Sciences TREECHANGE project (grant 6108‐00078B)

European Vegetation Archive: now EVA really starts!

European Vegetation Archive (EVA) was announced as a new initiative of the European Vegetation Survey at the EVS Meeting in Vienna in 2012. The aim of EVA is to create a centralized database of European vegetation plots by storing copies of national and regional databases on a single software platform using a unified taxonomic reference database. EVA does not affect the ongoing independent developments of source data­ bases and it guarantees that data property rights of the original contributors are re­ spected. EVA Data Property and Governance Rules were approved and the EVA website (www.euroveg.org/eva­database) was established in 2012. Since then several European vegetation­plot databases joined EVA. In the framework of the parallel Braun­Blanquet project, we obtained experience with handling multiple databases based on different taxonomies, and a prototype of Turboveg 3 was developed as a software tool for joint management of multiple databases. This prototype has recently been accepted as the platform for technical management of EVA according to the approved Rules. A spe­ cific challenge for EVA is joining multiple species lists with different taxonomies used in national and regional databases. To solve this issue, EVA took over the SynBioSys Taxon Database, developed earlier for the SynBioSys Europe project, which is a system of taxon names and concepts used in the individual databases and their matches to a unified list of European flora. This taxon database is currently being extended to ac­ count for new vegetation­plot databases and revised by taxonomic experts working in a newly established EVA Taxonomic Advisory Board. These technical developments made it possible that after two years since its formal establishment, first data sets could be uploaded to EVA, forming a basis for large­scale analyses of European vegeta­ tion diversity for both scientific purposes and applications