Plant species diversity in Eurasian wetlands and grasslands depends not only on productivity but also on the relative availability of nutrients, particularly of nitrogen and phosphorus. Here we show that the impacts of nitrogen:phosphorus stoichiometry on plant species richness can be explained by selected plant life-history traits, notably by plant investments in growth versus reproduction. In 599 Eurasian sites with herbaceous vegetation we examined the relationship between the local nutrient conditions and community-mean life-history traits. We found that compared with plants in nitrogen-limited communities, plants in phosphorus-limited communities invest little in sexual reproduction (for example, less investment in seed, shorter flowering period, longer lifespan) and have conservative leaf economy traits (that is, a low specific leaf area and a high leaf dry-matter content). Endangered species were more frequent in phosphorus-limited ecosystems and they too invested little in sexual reproduction. The results provide new insight into how plant adaptations to nutrient conditions can drive the distribution of plant species in natural ecosystems and can account for the vulnerability of endangered species.

Aims Phytosociological classification of fen vegetation (Scheuchzerio palustris‐Caricetea fuscae class) differs among European countries. Here we propose a unified vegetation classification of European fens at the alliance level, provide unequivocal assignment rules for individual vegetation plots, identify diagnostic species of fen alliances, and map their distribution. Location Europe, western Siberia and SE Greenland. Methods 29 049 vegetation‐plot records of fens were selected from databases using a list of specialist fen species. Formal definitions of alliances were created using the presence, absence and abundance of Cocktail‐based species groups and indicator species. DCA visualized the similarities among the alliances in an ordination space. The ISOPAM classification algorithm was applied to regional subsets with homogeneous plot size to check whether the classification based on formal definitions matches the results of unsupervised classifications. Results The following alliances were defined: Caricion viridulo‐trinervis (sub‐halophytic Atlantic dune‐slack fens), Caricion davallianae (temperate calcareous fens), Caricion atrofusco‐saxatilis (arcto‐alpine calcareous fens), Stygio‐Caricion limosae (boreal topogenic brown‐moss fens), Sphagno warnstorfii‐Tomentypnion nitentis (Sphagnum‐brown‐moss rich fens), Saxifrago‐Tomentypnion (continental to boreo‐continental nitrogen‐limited brown‐moss rich fens), Narthecion scardici (alpine fens with Balkan endemics), Caricion stantis (arctic brown‐moss rich fens), Anagallido tenellae‐Juncion bulbosi (Ibero‐Atlantic moderately rich fens), Drepanocladion exannulati (arcto‐boreal‐alpine non‐calcareous fens), Caricion fuscae (temperate moderately rich fens), Sphagno‐Caricion canescentis (poor fens) and Scheuchzerion palustris (dystrophic hollows). The main variation in the species composition of European fens reflected site chemistry (pH, mineral richness) and sorted the plots from calcareous and extremely rich fens, through rich and moderately rich fens, to poor fens and dystrophic hollows. ISOPAM classified regional subsets according to this gradient, supporting the ecological meaningfulness of this classification concept on both the regional and continental scale. Geographic/macroclimatic variation was reflected in the second most important gradient. Conclusions The pan‐European classification of fen vegetation was proposed and supported by the data for the first time. Formal definitions developed here allow consistent and unequivocal assignment of individual vegetation plots to fen alliances at the continental scale.

Although conservation of percolation mires is very important for the European biodiversity, our understanding of their functioning is still insufficient, as most of the studied sites are to some extent degraded. We present a study on the relationship between vegetation patterns, hydrochemical gradients and water level fluctuations carried out in the Rospuda valley (NE Poland), which was recently discovered for science as a uniquely preserved fully functioning percolation mire. Vegetation composition, mire water chemistry and water level dynamics were studied along five transects perpendicular to the valley. Eight major vegetation types were identified: brown moss-small and slender sedge fens, Sphagnum-small sedge fens, brown moss-tall sedge fens, tall sedge-reed fens, pinebirch fen woodlands and shrublands, spruce fen woodlands, inundated alder woodlands, alder spring fen woodlands. The seasonal dynamics of water table was revealed as the major factor explaining vegetation patterns. The studied chemical parameters were relatively homogeneous in the whole mire-there is a rather uniform type of mineral-rich nutrient-poor subsurface water all across the fen.

International audienceQuestions: What is the distribution of base-rich fen vegetation and the specia- list species along European biogeographic regions? How do the gradients in spe- cies composition correlate to geography and climate at continental scale? What are the implications of such patterns for the classification of these habitats?Location: Fifteen countries of Central, Western and Northern Europe.Methods: We compiled a vegetation plot database of base-rich fens and related communities including vascular plants and bryophytes. The initial data set with 6943 plots was filtered according to the presence of specialists using discriminant analysis. We used DCA to analyse the correlation of species composition with geography and climate, and kriging interpolation for mapping gradients in the study area. Modified TWINSPAN was used to detect major vegetation groups. The results of the whole data set (plot size 1–100 m2) were compared with those obtained from two subsets with plots of 1–5 m2 and 6–30 m2.Results: Most of the specialists were distributed among all the biogeographic regions, but many were more represented in the Alpine than in the Atlantic, Boreal and Continental regions. Variation in species composition was mainly correlated to temperature, precipitation and latitude in the three data sets, showing a major gradient from (1) alpine belt fens characterized by spring species to (2) small sedge fens mainly distributed in mountain regions and (3) boreo-temperate fens reflecting waterlogged conditions.Conclusions: Base-rich fen communities are widely distributed across Europe- an biogeographic regions, but the Alpine region can be considered as the compositional centre of this vegetation type. Large-scale gradients of species composition are mainly explained by climate, while the influence of latitude is probably correlated to increasing water table in the boreo-temperate regions. These gradients can be better understood by differentiating three major vegeta- tion types, which should be considered when establishing classification systems of base-rich fens in Europe

Rising temperatures may endanger fragile ecosystems because their character and key species show different habitat affinities under different climates. This assumption has only been tested in limited geographical scales. In fens, one of the most endangered ecosystems in Europe, broader pH niches have been reported from cold areas and are expected for colder past periods. We used the largest European-scale vegetation database from fens to test the hypothesis that pH interacts with macroclimate temperature in forming realized niches of fen moss and vascular plant species. We calibrated the data set (29,885 plots after heterogeneity-constrained resampling) with temperature, using two macroclimate variables, and with the adjusted pH, a variable combining pH and calcium richness. We modelled temperature, pH and water level niches for one hundred species best characterizing European fens using generalized additive models and tested the interaction between pH and temperature. Fifty-five fen species showed a statistically significant interaction between pH and temperature (adj p ˂ .01). Forty-six of them (84%) showed a positive interaction manifested