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 m2 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.

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Riparian ecosystems have been described as highly prone to alien plant invasions; thus, disentangling the contributing factors of the invasion process is of utmost importance to conserving and managing these valuable ecosystems. In this study we examined the drivers of riparian plant invasion in 16 Cantabrian river basins (northern Spain) ranging from 100 to ca. 1050 km2. A complete flora was determined for five randomly selected sites within those basins. One hundred and thirty alien plant species were found across the 80 sampling sites, representing 21% of the recorded total flora. At site scale, the level of plant invasion, measured as alien richness (AR) and relative alien richness (RAR), was assessed in relation to a set of explanatory variables by means of Generalised Linear Mixed Models. This level of invasion was influenced by environmental variables such as the thermicity index, the average riverbed width and the number of plant communities and by human‐related variables such as the distance to the nearest town and the proportion of surrounding urban land. At basin scale, industrialised river basins were more heavily invaded than non‐industrialised basins, and they both differed in their alien plant composition. Given that some of the alien species occurring in Cantabrian streams are specially abundant (Crocosmia x crocosmiiflora) and/or form very dense stands (Fallopia japonica, Paspalum distichum), future research should focus on the drivers that influence the presence and distribution of these species of special concern. Copyright © 2016 John Wiley & Sons, Ltd.

Questions: Phylogenetic analyses provide important insights in the study of biological invasions. Previous studies have shown contrasting effects of alien species on the phylogenetic structure of recipient communities. In this study, we focus on two riparian plant communities with contrasting natural disturbance regimes: riparian forests and river bar communities. We ask whether these communities differ in alpha diversity and degree of plant invasion. Further, are the phylogenetic diversity (PD) and structure of these habitats related to the level of plant invasion? Location: Northern Spain. Methods: We determined level of plant invasion in forest and river bar vegetation plots, and calculated PD using mean pairwise distance (MPD) and mean nearest taxon distance (MNTD). We applied null models to analyse the phylogenetic structure of plots, and we tested whether inclusion of alien plant species was associated with differences in observed phylogenetic structure. Results: River bar plots experienced more invasion than forest plots, but the level of invasion was only related to the PD of native species in forests. Most plots had random phylogenetic structure, with a minority of plots tending to phylogenetic overdispersion in forests and to phylogenetic clustering in river bars. MPD increased with the inclusion of alien plant species in forest plots, suggesting phylogenetic overdispersion, while no such pattern was detected with MNTD. MPD increased slightly with increasing invasion in river bar plots, suggesting reduced clustering, while MNTD values decreased with increasing invasion, suggesting the opposite trend. Conclusions: Invasion by alien plants is differentially associated with phylogenetic structure in riparian habitats with different disturbance levels. Our results contrast with those of previous studies of plant invasion of riparian communities, which suggests geographic and ecological variation in the relationship between invasion and phylogenetic community structure in riparian systems. Research is needed to identify the causal factors underlying this variation.

Allergies to grass pollen affects about 20% of the population worldwide. In the last few decades, the South American grass Cortaderia selloana (CS, Pampas grass) has expanded worldwide in a variety of countries including the USA, Australia and Western Europe. In many of these locations, CS has strikingly spread and has now been classified an invasive species. Many pernicious consequences of CS have been reported for local biodiversity, landscape and structures. However, the effect on human health has not been studied. To investigate this issue, we have chosen a European region on the northern cost of Spain where CS spread is overwhelming, Cantabria. We obtained CS pollen extract and analysed the allergenic reaction of 98 patients that were allergic to pollen of local grasses. We determined the skin reaction and the presence of specific IgE antibodies (sIgE) to CS or to a typical autochthonous grass, Phleum pratense. We also compared the seasonal symptoms with reported grass pollen counts in the area. The results strongly suggest that CS can cause respiratory allergies at a similar extent to the local grasses. Given that CS pollinises later than the local grasses, this would extend the period of grass allergies in the region for about three months every year, as stated by most of the patients. This is the first study reported on the effects of the striking expansion of CS on human health. Considering the strong impact that respiratory allergies have on the population, our results suggest that CS can currently constitute a relevant environmental health issue.

A revision of the alien Erigeron L. species formerly included in Conyza Less. found in the central-northern Iberian Peninsula is presented. A close examination of numerous specimens collected by the authors as well as voucher specimens preserved at several herbaria has helped clarify several aspects regarding this group. Four species have been recognised in the study area: Erigeron canadensis (=Conyza canadensis), E. bonariensis (=C. bonariensis), E. sumatrensis (=C. sumatrensis) and E. floribundus (=C. floribunda, including C. bilbaoana). They occupy anthropogenic habitats, such as road edges, abandoned fields, crops and waste ground, as well as natural and semi-natural communities, such as nitrophilous river bar communities and ruderal communities on coastal dunes subjected to substantial levels of anthropogenic disturbance. Erigeron sumatrensis and E. floribundus emerge as the two most frequent taxa. Erigeron canadensis, regarded in the past as the most widespread species of the group, is almost absent from the study area, especially from the Atlantic watershed. Furthermore, an important number of specimens previously identified as E. bonariensis do actually correspond to E. sumatrensis. No hybrids have been found. A detailed identification key highlighting the main features that help to separate the four Erigeron species is presented. Finally, as E. floribundus is the most controversial species in the group and the last to arrive, a study of its expansion across western Europe in the last century is included, where it has become a frequent alien especially along the Atlantic regions.

Abstract. AsaresultofafloristicsurveycarriedoutinriparianhabitatsofnorthernSpain,newchorologicaldataare providedfor9alienand6nativeplantspecies.Somespeciesarereportedforthefirsttimeatregionalscale,suchas Carex strigosa,Helianthus x laetiflorus andPersicaria pensylvanica inCantabria.Alsonoteworthyisthefindingof naturalisedpopulationsoftheNorthAmericangrassMuhlenbergia schreberi attheUrumeariverbasin,whichrepresentsthesecondreferencefortheIberianPeninsula.

The original Article has been corrected.