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In this paper, we provide an overview of the distribution and invasive status of non-native species in the Italian flora across its administrative regions, biogeographic regions and main land use types, and a synthesis of current knowledge on the threats they pose within the country. The information on non-native plant species collected during the project “A survey of the non-native Italian flora” was used to compile comprehensive regional and national databases. The number of non-native species within a given administrative region increases in proportion to its size, resident population density and latitude, reaching the highest values in the intensively cultivated, heavily industrialized and urbanized Po Plain in northern Italy. The number of casual species is positively correlated with the number of yearly visitors in each region and negatively correlated with the proportion of mountainous terrain within the region. If compared with the Continental and Mediterranean biogeographic regions, the Alpine region yields the lowest number of non-native species and lowest proportion of casual species. The number and density of introduced species is highest in artificial land use types, particularly in urban areas. A negative impact is reported to be exerted by 203 species, most of which are agricultural weeds. [ABSTRACT FROM AUTHOR]

In this paper we present a comprehensive inventory of the non-native vascular flora of Italy, which was produced within the project “A survey of the Italian non-native flora”, funded by the Italian Ministry for the Environment. Previously published floristic accounts were the main source of information. Historical records were critically revised and integrated with recent literature, data from herbaria and some unpublished information, so as to obtain a complete, up-to-date catalogue of the non-native vascular plant species that occur spontaneously in Italy. The inventory lists 1023 non-native species and subspecies, which account for 13.4% of all the Italian flora. The Italian non-native flora was divided, according to its residence time, into 103 archaeophytes and 920 neophytes. According to its current invasion status, it was classified into 437 casual (42.7% of all non-native) and 524 established taxa, the latter being divided into 361 naturalized non-invasive (35.3%) and 163 invasive taxa (15.9%). The inventory includes a group of 62 species (6.1%) that lack recent records (i.e. since 1950). By combining local expertise into a unified, nationwide scheme using a standardized method and terminology, the inventory provides the essential scientific basis for the development of plant invasion research and management in the country. [ABSTRACT FROM AUTHOR]