An inventory of all alien species known to inhabit Europe, represented the major activity in DAISIE and involved compiling and peer-reviewing national lists of fungi, bryophytes, vascular plants, invertebrates, fish, amphibians, reptiles, birds and mammals. Data were collated for all 27 European Union member states, and where these states had significant island regions, data were collated separately for these as well. In addition, data were collated for European states that are not in the European Union such as Andorra, Iceland, Liechtenstein, Moldova, Monaco, Norway, the European part of Russia, Switzerland, Ukraine as well as former Yugoslavian states in the Balkans (DAISIE 2008, Hulme et al. 2010). In total, the database contains documented introduction records of alien taxa for 71 terrestrial and nine marine regions. For each species, an attempt was made to gather information on native range, date of introduction, habitat, known impacts and population status. Considerable effort was required to ensure synonyms were accounted for accurately. About 11,000 alien species are included in the database, the majority of records are for vascular plants (5789 species) with invertebrates (2477 species) also a significant component. The data were used for detailed analyses within individual taxonomic groups (Lambdon et al. 2008, Pyšek et al. 2008 for plants) and for analyses of impacts of biological invasions at the European scale (Winter et al. 2009, Vila et al. 2010). Trends over time indicate that the rates of introduction of alien species to Europe are accelerating (Hulme 2009b). The results of the project provide solid backgroung information to formulating future strategy of maganement of alieb invasive species in Europe, with the European Alein Species Database being important instrument (Hulme et al. 2009a).

It is a “onestop-shop” for information on biological invasions in Europe. It provides accounts for 100 of the most invasive alien species in Europe and each includes information on biology, ecology, distribution and management, with references, links and images. These accounts deliver end users with relevant details for species identification and management but also help raise public awareness of the issue of invasions. The accounts cover three fungi, 18 terrestrial plants, 16 terrestrial invertebrates, 15 vertebrates, 16 inland and 32 marine aquatic species invading natural and semi-natural habitats. Selection was based on ensuring a broad spectrum of life forms and functional types, a range of invaded ecosystems and clear examples of different impacts on European biodiversity, economy and health. A key requirement for the effective management of invasive alien species is the ability to identify, map, and monitor invasions in order to assess their extent and dynamics. The Common European Chorological Grid Reference System with the size of the mapping grid ca. 50 × 50 km was used to produce distribution maps for the “100 worst” species.

The registry represents a fundamental step towards providing the critical mass of expertise in alien species research to meet European-scale requirements. The European Expertise Registry has enabled the current breadth and scope of European knowledge on alien species to be assessed for the first time. The registry contains information on the field of expertise (distribution, conservation, ecology, economy, genetics, legislation, management, pathways, physiology, risk assessment and taxonomy) and on the taxonomic and geographic structure of the expertise. As a result, the Registry facilitates both the clustering and information-sharing among different national programmes targeting the same alien species. By the end of 2008 the Registry contained already information on 1,700 experts from more than 90 countries for over 3,400 higher taxa and numbers steadily increase.

The DAISIE information has been distilled in a Handbook of Alien Species in Europe (DAISIE 2008), which contains: 1. Analytical chapters on alien fungi, bryophytes and lichens, vascular plants, terrestrial invertebrates, invertebrates and fish in inland waters, marine biota, birds, amphibians, reptiles, and mammals of Europe; 2. A list of all species alien in Europe and to Europe; 3. Species fact sheets of the 100 most invasive alien species in Europe; 4. A glossary of the main technical terms used in the handbook.