The Global Naturalized Alien Flora (GloNAF) database

Humans have intentionally and unintentionally introduced many species from their native regions into regions where they did not previously occur. Some of them have become naturalized, and some of those have become invasive. However, we still know little about patterns and drivers of distributions of naturalized and invasive alien plant species at a global scale. Together with an international consortium, we have compiled a first version of a global database for naturalized alien plants (GloNAF), which includes 12,615 species and 827 non-overlapping regions. Here we propose to further develop this unique database by adding e.g. invasiveness status of species and attributes of the species and regions. Then we will analyse the database to provide a first global overview of patterns of naturalized and invasive alien plant species distribution, and for testing major questions in invasion biology.

Humans have intentionally and unintentionally introduced many species from their native regions into regions where they did not previously occur. Although most of these introduced alien species fail to establish wild populations, a considerable number has become naturalized (i.e. has established self-sustaining populations). Some of these naturalized alien species have spread widely across landscapes or have become abundant in certain ecosystems, and are considered invasive, i.e. are causing negative environmental impacts. Although it is widely acknowledged that the spread of alien species constitutes a threat to regional and global biodiversity, we still know little about patterns and drivers of distributions of naturalized and invasive alien plant species at a global scale. Additionally, current research on the causes and consequences of naturalization and invasive success is both geographically and taxonomically biased which makes it impossible to draw robust general conclusions at a global scale. Therefore, we urgently need a database that compiles information on the distribution of naturalized alien plants at continental and global scales. The main objective of the GloNAF (Global Naturalized Alien Flora)-project was the establishment of such a globally comprehensive dataset of naturalized alien floras that addresses the current shortcomings in terms of taxonomic and spatial coverage as best as possible. Subsequently, the overarching project aim was to assess the status quo of the spatial distribution of alien plants worldwide and identify hotspots of biological invasion. Furthermore, drivers of alien species distributions and accumulation were identified. The Austrian subproject mainly focused on these driver analyses with an additional special focus on island systems, on the importance of evolutionary history on naturalization success and on the temporal dynamics of alien species accumulation. In essence, the results suggest that globally islands are among the regions that harbor most alien species. With the relative richness of naturalized and invasive species being six and 3- fold respectively compared to mainland regions. Socio-economic drivers show highest relative importance in explain relative naturalized and invasive species richness. Finally, there was no difference detected between the regions in the New vs. Old World as previously suggested. Additionally, in tropical and subtropical island systems the invasibility of an island increases with its distance to the mainland and analyses suggest that this pattern is not only driven by socio-economic drivers but also by universal ecological process. From an evolutionary perspective, we found that naturalization success of plant families is partly influenced by their evolutionary history. High diversification rates affect naturalization success in a complex way either promoting it through promoting high adaptability and relevant invasion traits or hindering it through the development of high environmental specialization. Finally, our analysis of the temporal dynamics of alien species accumulation shows that we are nowhere near a saturation of alien species accumulation and that still many species are further newly added to the alien species pool. Of these new introductions many species have never been recorded as alien anywhere else before. This has strong implications for biodiversity conservation and alien species management as current alien species distributions and driver analysis can only so far provide information about future dynamics and spread of new alien species.