Priority invasive alien plants in the Tuscan Archipelago (Italy): comparing the EPPO prioritization scheme with the Australian WRA

For the first time, we tested the European and Mediterranean Plant Protection Organization (EPPO) prioritization process (EPP) on 212 alien plant species thriving in the Tuscan Archipelago, Central Italy. We compared the results of the EPPO procedure with those of the Australian Weed Risk Assessment (A-WRA) system. The two methods were also tested against the categorization performed at the national and local level by a panel of experts. Our results suggest that both methods accurately predict the invasiveness of species already present in the Tuscan Archipelago. However, the total numbers of species included in the highest risk categories by the two methods differed greatly, with the EPPO prioritization process including fewer species in the highest risk class. The two methods differed in the ability to correctly detect the invasive species, with the A-WRA method being more conservative, but at cost of more species in the highest risk class. Using Generalized Linear Models, we showed that both methods suffer from some degree of dependence from one or more of the tested explanatory variables (life span, year of first record). The results suggest that the choice of a risk assessment method should be driven by the main aim of the assessment, i.e., distinguishing between a more predictive tool (A-WRA) and a prioritization tool (EPP) for already introduced species.