Drivers of the relative richness of naturalized and invasive plant species on Earth

Why do some places have more invasive species than others? Essl and colleagues look at human action.

Biological invasions are a defining feature of the Anthropocene (the human epoch). Approximately 4% of all extant vascular plant species have now established wild populations beyond their native range (naturalised). The number of these species that have become invasive, i.e. spread widely and to the detriment of other species, is substantial and is rapidly increasing. Thus, the human-mediated introduction of species outside their native range is considered to be one of the greatest threats to biodiversity, yet a comprehensive analysis of the drivers of global invasions is currently lacking.

Black locust (Robinia pseudocacacia) is a tree native to North America that has become widely established in temperate and Mediterranean regions on other continents. While it has attractive flowers, it is causing considerable damage when in invading natural habitats such as grasslands and forests. Image credit: F. Essl.

In a recent Editor’s Choice article published in AoBP, Essl et al. analyse the effects of biogeographical, physical environment and socio-economic factors on the numbers of naturalized and invasive plant species relative to native species in 838 terrestrial regions. They demonstrate that the numbers of naturalized and invasive plant species relative to native species richness is highest on (sub)tropical islands, and that socio-economic factors foster invasive spread after naturalization. To meet international biodiversity targets and to halt the detrimental consequences of plant invasions, it is essential to disrupt the connection between socio-economic development and rising levels of plant invasions by improving pathway management, early detection and rapid response, with a specific focus on islands.

Researcher highlight

Image credit: Upper Austrian Museum.

Franz Essl lives in Austria. He conducted his PhD at the University of Vienna, and currently is Assistant-Professor there. Franz is an ecologist with a focus on global change biology, macroecology and conservation biology. He is particularly interested in invasion ecology. He published c. 160 publications, and he is included in the list of “Highly Cited Scientists”. Recent work deals with documenting and understanding large-scale biogeographical patterns of alien species, forecasting how these patterns may change under global change, and aims to improve our understanding the impacts caused by alien species.

Further reading

Essl, F., Dawson, W., Kreft, H., Pergl, J., Pyšek, P., Van Kleunen, M., … Winter, M. (2019). Drivers of the relative richness of naturalized and invasive plant species on Earth. AoB PLANTS, 11(5). https://doi.org/10.1093/aobpla/plz051