Alien flora of Europe: Species diversity, temporal trends, geographical patterns and research needs

Abstract

The poster presents the first estimate of the composition and structure of alien plants occurring in the wild in the European continent (Lambdon et al. 2008), based on the results of the DAISIE project (2004–2008), funded by the 6th Framework Programme of the European Union. The area of interest covered 48 European countries/regions and Israel. In total, the database contains records of 5789 alien
\nplant species in Europe (including those native to a part of Europe but alien to another part), of which 2843 are alien to Europe (of extra-European origin). The research focus was on naturalized species; there are in total 3749 naturalized aliens in Europe, of which 1780 are alien to Europe. The highest diversity of alien species is concentrated in industrialized countries with a tradition of good botanical recording or intensive recent research. The United Kingdom (857), Germany (450), Belgium (447) and Italy (440) are countries with the most naturalized neophytes. The number of naturalized neophytes in European countries increases with increasing precipitation but
\nonly in climatically warm and moderately warm regions. Of the neophytes alien to Europe, 50%
\narrived after 1899, 25% after 1962 and 10% after 1989. At present, approximately 6.2 new species are arriving each year. Most alien species have relatively restricted European distributions; half of all naturalized species occur in four or fewer countries/regions, whereas 70% of non-naturalized species occur in only one region. Intentional introductions to Europe (62.8% of the total number of naturalized
\naliens) prevail over unintentional (37.2%). Most aliens in Europe have a native range in the same continent; considering aliens to Europe separately, 45.8% of species have their native distribution in North and South America, 45.9% in Asia, 20.7% in Africa and 5.3% in Australasia.
\nThe data currently available are of varying quality and need to be further assessed with respect to the invasion status and residence time of the species included. Collating an integrated database on the alien flora of Europe can form a principal contribution to developing a European-wide management strategy of alien species.