The ecological, economic, and social damage of human-mediated dispersal of species into new regions, where they possess the ability to naturalize (become self-sustaining their new homeland), is one of the defining features of the Anthropocene Epoch. Globally, human activity has led to the naturalization of nearly 13,168 plant species (equal in size to the native European flora). The results from this research provide a baseline for monitoring global changes in biodiversity while highlighting the immediate action that has to be taken to comprehend and determine the spread of alien species on an international scale.
The ecological, economic, and social damage of human-mediated dispersal of species into new regions, where they possess the ability to naturalize (become self-sustaining their new homeland), is one of the defining features of the Anthropocene Epoch.
At least 3.9% of all currently known vascular plant species have become naturalized outside their natural ranges as a result of human activity. With the continued practice of international traffic and trade and globalization, the likelihood of more and more species being introduced and getting naturalized outside their native range is high.
To assess the accumulation of naturalized species in each continent as well as which continents have been the major donors of alien naturalized plant species globally, the researchers used a novel database, Global Naturalized Alien Flora (GloNAF), in addition to the data on the origin of naturalized species and estimates of the number of native species per continent. They found that when not taking into account the differences in total area, North America has accumulated the highest number of naturalized species (n=5,958). However, when considering the difference in total area, Australasia (a region comprising Australia, New Zealand, and neighboring islands) was found to have more extra-continental species than North America.
One possible explanation is that Australia’s long biogeographical isolation and drying climate have resulted in a native flora that is phylogenetically distinct, but not well-adapted to exploit the novel habitats created by European settlers [van Kleunen 2015: 101].
The major donors of alien species are Europe and temperate Asia, while North America is also a significant donor.
Van Kleunen, Mark, Wayne Dawson, Franz Essl, et al., 2015, Global exchange and accumulation of non-native plants, Nature 525, https://www.nature.com/articles/nature14910