Format: ORAL

Margarita Arianoutsou1, Ioannis Bazos1, Anastasia Christopoulou1, Alexandros Galanidis2, Yannis Kokkoris1, Andreas Zikos1

1 Department of Ecology and Systematics, National and Kapodistrian University of Athens, Greece 2 Department of Environment, University of the Aegean, Mytilene, Greece

Biological invasions represent one of the most important threats to biodiversity, with invasive alien species (IAS) having severe negative consequences for the invaded environment. This contribution reports on the alien flora of Greece as well as on the worst invasive alien plant taxa in it. A compilation of the alien plants occurring in Greece has been performed resulting in 448 taxa (including 58 archaeophytes). For this task, various literature sources have been screened. Of those 448 taxa 270 are established, 171 are casual and 7 are of unknown establishment status. The richest families in number of taxa are Poaceae, Asteraceae, Fabaceae, Solanaceae and Amaranthaceae. Chorology of the established taxa indicates that 47,8% are of American origin followed by those of Asian (16,7%) and African origin (10,4%). Regarding their life form, therophytes prevail with 47% followed by hemicryptophytes and phanerophytes with 20% and 15% respectively. Artificial (man-made) habitats are the most invaded with 69% of the plant taxa found there followed by freshwater habitats and rocky habitats both with 12%. Taxa consisting the total alien flora of Greece as well as others that were added after a horizon scanning process were screened for their degree or potential of invasion. In total, 32 were considered as the most invasive ones and they were proposed to be included in the National Catalogue of Alien Invasive Species. The majority of these taxa have their native geographical distribution in the Americas. The most common introduction pathway is their use as ornamental and in horticulture. Risk assessments have been performed for all 32 plant species, to detect those presenting the highest risk to the local biodiversity and ecosystem services. Fifteen plants were found to have major impacts, with 80% of them being recorded in the wild, while 40% of them are already established in Greece.