The Braun-Blanquet project: evaluating and characterizing European vegetation alliances

European tradition on vegetation classification provides an extraordinary legacy for understanding biodiversity. However, this classification lacks explicit data on vegetation attributes, especially if we extend national or regional concepts to a continental perspective. An additional effort for evaluating and characterizing European vegetation types is therefore needed, and the data contained in vegetation databases are probably the main tool for these purposes. The Braun-Blanquet project is an initiative of the European Vegetation Survey for characterizing vegetation alliances across Europe. By analyzing more than 500, 000 vegetation plots from 22 European countries, we developed a framework consisting of: (1) evaluating the consistency and robustness of alliances using the information provided by vegetation plot databases, (2) calibrating assignment rules for classifying, at least partially, the plots not assigned to alliances and (3) characterizing vegetation types by providing lists of diagnostic species and major distributional patterns. The Braun-Blanquet project represents the first attempt for extrapolating European vegetation information into a comprehensive definition of vegetation types. Furthermore, the outputs of the project are expected to improve biodiversity assessment and the conservation management of natural habitats. As a study case, we illustrate how our framework can be used to characterize different forest types across Europe.