Formalized phytosociological classification of Central Italy wetland vegetation by applying the Cocktail method: suitability, results and open questions.

During the last decade, a large set of published and unpublished data about Italian vegetation was stored in VegItaly, a web database hosted by AnArchive (http://www.anarchive.it). Supported by SISV (Società Italiana di Scienza della Vegetazione) and members of the IAVS Eco-informatics Working Group, VegItaly is a collaborative project involving several Italian Universities and coordinated by the University of Perugia; it aims at archiving, sharing and managing large data sets for statistical analyses at wide geographic scales. A data subset including phytosociological relevés from macrophytic, wetland and wet meadow vegetation from Central Italy was extracted from VegItaly and processed by using the Cocktail method. This method, designed to simulate the Braun-Blanquet approach using a formal method, is largely based on expert knowledge, reflecting the field experience of the author and the classifications published in the literature. All analyses were performed in the program Juice 7.0. Formal definitions were created using logical operators (AND, OR and AND NOT), combining species cover values and species groups. Sociological species groups and diagnostic species of the associations were determined using the phi coefficient of association. The plant communities recognized by this classification are representative of most of the diversity of wet ecosystems in central Italy. They included the following vegetation classes: Lemnetea, Potametea, Charetea, Bidentetea tripartitae, Phragmito-Magnocaricetea and Molino-Arrhenatheretea. The present work represents the first application of the Cocktail method to a large data set from a wide area in Southern Europe. For most of the associations distinguished here, the number and distribution of the relevés are sufficient to develop formal definitions that are valid for Italy.