The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and regional vegetationplot databases on a single software platform. Data storage in EVA does not affect on-going independent development of the contributing databases, which remain the property of the data contributors. EVA uses a prototype of the database management software TURBOVEG 3 developed for joint management of multiple databases that use different species lists. This is facilitated by the SynBioSys Taxon Database, a system of taxon names and concepts used in the individual European databases and their corresponding names on a unified list of European flora. TURBOVEG 3 also includes procedures for handling data requests, selections and provisions according to the approved EVA Data Property and Governance Rules. By 30 June 2015, 61 databases from all European regions have joined EVA, contributing in total 1 027 376 vegetation plots, 82% of them with geographic coordinates, from 57 countries. EVA provides a unique data source for largescale analyses of European vegetation diversity both for fundamental research and nature conservation applications. Updated information on EVA is available online at http://euroveg.org/evadatabase.

Question: Collaborative research efforts and synthetic vegetation analyses are often limited by difficulties in sharing or combining datasets. Can we facilitate these activities by means of an exchange standard for plot-based vegetation data?Methods: In 2003, the Ecoinformatics Working Group and the Council of the International Association for Vegetation Science endorsed the development of a standard exchange schema for vegetation-plot data. In 2007, a first workshop was held to formulate a common set of goals, concepts, and terminology for plot-based vegetation data. At a second workshop in 2008, this ontology was developed into an XML (extensible markup language) schema representation designed to be maximally compatible with existing standards and databases.Results: The exchange standard for plot-based vegetation data (Veg-X) allows for observations of vegetation at both individual plant and aggregated observation levels. It ensures that observations are fixed to physical sample plots at specific points in space and time, and makes a distinction between the entity of interest (e.g. an individual tree) and the observational act (i.e. a measurement). The standard supports repeated measurements of both individual organisms and plots, allows observations of entities to be grouped following predefined or user-defined criteria, and ensures that the connection between the entity observed and taxonomic concept associated with that observation are maintained.Conclusions: Establishment of exchange standards followed by development of ecoinformatics tools built around those standards should allow scientists to efficiently combine plot data over extensive spatial and temporal gradients in order to perform analyses and make predictions of vegetation change and dynamics at local and global scales.

VegetWeb (GIVD ID EU-DE-013) is an online archive for vegetation-plot data from Germany and can be accessed at the FloraWeb website of the Federal Agency for Nature Conservation (http://www.floraweb.de). The data model of VegetWeb allows upload, storage and interactive search of plot data with different original formats and taxonomic reference. Due to financial constraints only a small proportion of Germany's legacy of plot data has been captured so far. VegetWeb co-operates with the journal Tuexenia, for which it provides an interactive online archive of relevé tables by capturing and distributing all newly published data.