Combining GBIF-mediated occurrences with data from a novel database, the Global Naturalized Alien Flora (GloNAF), this study seeks to identify and quantify the spread and distribution of naturalized plant species worldwide. The researchers present an analysis of 13,168 naturalized vascular plants in 843 non-overlapping regions covering 83 per cent of the Earth’s land surface. They determine number of native species per continent, and find that at least 3.9 per cent of all known vascular plants have been naturalized outside their native ranges. The biggest recipients of naturalized species from other continents by area are Australasia and Pacific Islands, and the major donors are the temperate regions of Europe and Asia. The study suggests that plant invasions overall have been a Northern-to-Southern hemisphere phenomenon rather than one from the Old World to the New.
van Kleunen, M., Dawson, W., Essl, F., Pergl, J., Winter, M., Weber, E., … Pyšek, P. (2015). Global exchange and accumulation of non-native plants. Nature, 525(7567), 100–103. doi:10.1038/nature14910