Montane-subalpine tall-herb vegetation (Mulgedio-Aconitetea) in central Europe: large-scale synthesis and comparison with northern Europe

Many incompatible classifications have in the past been applied to the class of European montane-subalpine tall-herb communities (Mulgedio - Aconitetea). The aim of our paper is to develop a consistent classification of all vegetation types of this class from temperate and boreal Europe, derived from a database of individual releves. We compiled available releves from central, western and northern Europe. After excluding plots dominated by woody species, those outside the range of 9-50 m(2) size, and stands with prevailing diagnostic species of other classes, 993 releves remained for the classification, mainly from central Europe. We used cluster analysis (group linkage with flexible beta and Sorensen index) to analyse the structure of the dataset, and translated the results into a syntaxonomic system. The major division is between the temperate order Calamagrostietalia villosae and the newly described northern European order Epilobio lactiflori-Geranietalia sylvatici. The temperate order can be subdivided into five alliances: (i) subalpine tall-forb communities (Adenostylion alliariae), (ii) tall-forb communities of montane-subalpine eutrophic pastures (Rumicion alpini), (iii) subalpine tall-forb and tall-grass communities that are closely related to alpine meadows (Calamagrostion villosae), (iv) mainly montane tall-grass and fern communities of acidic soils (Calamagrostion arundinaceae), and (v) montane tall-forb communities (Arunco dioici-Petasition albi). The northern European order was not divided further at present because too few data were available. We characterise all syntaxa from the alliances upwards ecologically and floristically, provide a revision of their nomenclature, and list the included associations. We also discuss the methodological problems any supra-national classification has to face due to the high heterogeneity of such data and the lack of a continent-wide releve database of all vegetation types. The use of a priori lists of diagnostic species for the delimitation of the focal syntaxon and the restriction of the analysis to releves with similar plot sizes turned out to be crucial to derive consistent results. This study demonstrates that the analysis of a comprehensive supra-national database of individual releves can provide insights that go beyond what is achievable at a regional scale or by comparison of synoptic tables.