Invasive alien plants of European Union concern in Italy: distribution and threats

Invasive alien species are among the main global drivers of biodiversity loss, posing major challenges to nature conservation in Italy and in its network of protected areas. Furthermore, they causes significant economic loss to agriculture and forestry. In the European Union a dedicated regulation “on the prevention and management of the introduction and spread of invasive alien species” - Regulation (EU) no. 1143/2014 - was adopted and came in force in 2015. The Regulation identifies a list of invasive alien species of “Union concern” whose introduction or spread threaten or negatively impact biodiversity and ecosystem services and such adverse impacts require concerted actions at the European Union level. The iden- tification of these invasive alien plants follows a strict administrative and technical procedure that, besides documenting with a standard and peer reviewed risk assessment document the species pressure on natural ecosystems, verifies their capability of establishing viable pop- ulations and spreading under current environmental conditions and in foreseeable climate change scenarios. Among the 41 invasive alien plant species of Union concern that are actually regulated, around 50% of them are already present in Italy with different degrees of naturalization and invasiveness. Importantly, some of them are quite widespread, requiring long-term persistent controls that are likely to only mitigate further spread of prevent re-invasion in areas were local eradications took place. However, given the limited available resource for invasive alien species management all efforts should be preferentially addressed to tackle invasive alien plants in the Italian Mediterranean and Continental bioregions and on small Italian is- lands. Furthermore, considering that climate change scenarios predict an increment of two factors that at present limit invasive alien plants altitudinal spread (e.g., temperatures and precipitations), an expansion in the Alpine region could be also expected and should be pre- vented. Local authorities and the managers of protected areas should pay particular attention to the presence of communication infrastructures as well as to the local landscape and land use changes which may have crucial roles in promoting or preventing plant invasions. The staff of protected areas should conduct periodical field surveys in particular on areas with high/medium invasion risk to record the presence of alien species and their invasion stage.