An atlas of alien-dominated vegetation in Italy

In this study, we reviewed the distribution of alien-dominated and co-dominated plant communities in Italy. We updated a former syntaxonomic scheme based on the Italian Vegetation Prodrome and also produced a syntaxonomic scheme based on FloraVeg.EU. For the first time, a cartographic synthesis has been produced. Mapping outputs were standardised using the European Environmental Agency 10 km × 10 km grid. The map visualisation is also available online at: https://comunellod.shinyapps.io/Atlas-of-alien-dominated-vegetation-Italy/. In total, 1,566 occurrences of alien-dominated or co-dominated plant communities were verified and recorded based on 170 bibliographical sources, 147 of which are georeferenced. The number of vegetation classes has increased from 27 to 30, while the number of lower-rank syntaxa has risen from 194 to 294, of which 274 are supported by georeferenced relevés/vegetation plots. The distribution of alien-dominated or co-dominated communities currently present in the database reveals numerous data-deficient areas, which appear to be more prevalent in central and southern Italy. This is most likely due to a lack of investigations rather than actual gaps in distribution. The results are presented according to different vegetation types and occurrence, and are discussed by syntaxonomic classes and their physiognomic and ecological attributes. A list of the alien species that constitute the alien-dominated or co-dominated communities identified here is also provided, with taxa distinguished according to their time of introduction and invasiveness.