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Questions: Are negative invasion–diversity relationships due to biotic resistance of the invaded plant community or to post‐invasion displacement of less competitive species? Do invasion–diversity relationships change with habitat type or resident traits? Location/species: Lowlands and uplands of western and southern Germany, Heracleum mantegazzianum; mountain range in central Germany, Lupinus polyphyllus; and coastal dunes of northwest Germany, Rosa rugosa. Methods: We tested the significance and estimated regression slopes of invasion–diversity relationships using generalized linear (mixed effects) models relating invader cover and habitat type to species richness in different plant groups, stratified based on size, life cycle and community association. Results: We found negative, positive and neutral relationships between invader cover and species richness. There were negative linear correlations of invader cover with small plant species throughout, but no negative linear correlation with tall species. Invasion–diversity relationships tended to be more negative in early‐successional habitats, such as dunes or abandoned grasslands, than in late‐successional habitats. Conclusions: Invasion diversity–relationships are complex; they vary among habitat types and among different groups of resident species. Negative invasion–diversity relationships are due to asymmetric competitive displacement of inferior species and not due to biotic resistance. Small species are displaced in early‐successional habitats, while there is little effect on persistence of tall species.

Soil pH was measured at two different spatial scales in coastal dunes on Norderney, North Sea, and in Mecklenburg-Vorpommern, Baltic Sea, Germany. Relationships between the variability in soil pH, species richness and species diversity are presented. Species richness and diversity were highest in grey dunes, where soil pH was at intermediate levels; both variables were lower in yellow and brown dunes. The variability in pH increased with increasing species diversity and also with scale. Overall, soil pH variability decreased with increasing vegetation cover. The lowest pH heterogeneity was found in heath dominated by Empetrum nigrum L. and grey dunes dominated by Campylopus introflexus (Hedw.) Brid. Increasing abundance of dominant species and decreasing species diversity of vegetation apparently reduces soil heterogeneity. Decreasing species diversity of vegetation is likely to explain decreasing variability in soil pH.

QuestionsThe spread of alien plant species is one of the main threats to the biodiversity of different natural habitats, and coastal dune habitats are among the most affected. There is a considerable local and regional variation in the level of alien plant invasion on coastal dunes. We asked what are the patterns of invasion across European coastal dunes and how they depend on habitat types and coastal regions.LocationAtlantic, Baltic, Black Sea and Mediterranean coasts of Europe.MethodsWe used vegetation‐plot records from shifting dunes and stable dune grasslands extracted from the European Vegetation Archive (EVA). We quantified richness, frequency and distribution of alien plant (neophyte) species across dune habitats and coastal regions. We also explored the donor habitats and invasion trajectories of these species.ResultsIn the flora of European coastal dunes, 7% of species were neophytes, for two‐thirds originating from outside of Europe and mostly naturalised and ruderal. Shifting and stable dunes were similar in neophyte species composition, but there were more individual occurrences of neophytes in shifting dunes. The neophyte flora composition differed considerably between the Atlantic, Baltic, Black Sea and Mediterranean regions. The highest number of neophyte species was observed on the Atlantic dunes, while the highest number of neophyte occurrences was on the Black Sea dunes. Most of the neophytes originated from North America and the Mediterranean‐Turanian region. Erigeron canadensis, Xanthium orientale, Oenothera biennis and Oenothera oakesiana were the most common neophytes.ConclusionsWe provided a comprehensive assessment of alien plant invasions in the coastal dunes across Europe and highlighted that coastal dunes should be in the focus of European invasion management strategies.

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Aims: Although many phytosociological studies have provided detailed local and regional descriptions of coastal dune vegetation, a unified classification of this vegetation in Europe and the Mediterranean Basin has been missing. Our aim is to produce a formalized classification of this vegetation and to identify the main factors driving its plant species composition at a continental scale. Location: Atlantic and Baltic coasts of Europe, Mediterranean Basin and the Black Sea region. Methods:We compiled a database of 30,759 plots of coastal vegetation, which were resampled to reduce unbalanced sampling effort, obtaining a data set of 11,769 plots.We classified these plots with TWINSPAN, interpreted the resulting clusters and used them for developing formal definitions of phytosociological alliances of coastal dune vegetation, which were included in an expert system for automatic vegetation classification. We related the alliances to climatic factors and described their 534 |

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Aims Red Lists of threatened species are a well‐established conservation tool throughout the world. In contrast, Red Lists of ecosystems, habitats or plant community types have only recently found interest at the global level, although they have a longer tradition in Central Europe. We contribute to the debate by presenting and discussing a comprehensive conservation assessment methodology for plant communities that was developed within the framework of the project ‘The plant communities of Mecklenburg‐Vorpommern and their vulnerability’. Location Mecklenburg‐Vorpommern, Northeast Germany (23,174 km²). Approach Our approach adopts various concepts from modern red listing and prioritization at various organizational levels of biodiversity, and combines them into a methodological framework applicable for regional to continental Red Lists of plant communities. For each distinguished plant community, three steps are carried out, i.e. (1) assessment of endangerment (scientific part, using the three criteria ‘past trend’, ‘current status’ and ‘prognosis’), (2) assessment of conservation value (normative part, using the three criteria ‘degree of naturalness’, ‘relevance for species conservation’ and ‘global relevance’), and (3) a combination of (1) and (2) to derive a need for action (conservation prioritization). These steps are all based on the successive aggregation of quantitative criteria via decision matrices, which makes the assessment process transparent, avoids definition gaps and allows easy adjustment of the decision rules. Conclusions Plant community types derived from well‐documented classifications of extensive vegetation‐plot databases in combination with a transparent conservation assessment methodology have great potential in nature conservation and environmental monitoring. We suggest that the presented methodology is an improvement on traditional expert judgments as it separates the scientific and normative parts of the evaluation and uses clear, quantitative criteria and explicit rules to connect these into aggregated measures. It worked effectively and yielded meaningful results for a German federal state. By adjusting the scaling of the criteria, the approach can be adapted, as a whole or in part, to other regions or higher levels of ecosystem typology.