An international research team led by the University of Vienna has produced, for the first time, high-resolution global maps of invasion risk for thousands of alien plant species under current conditions and future climate and land use scenarios. Their results show that global hotspots of plant invasion risk will shift geographically, with temperate regions facing increasing risks, while risks may decline in some subtropical areas. The study was published in Nature Ecology & Evolution.
The introduction of alien species into new regions by humans has become a defining signature of the Anthropocene, with an increasing number becoming widespread and exerting severe negative impacts on native species and human livelihoods. Many alien plants reduce agricultural yields, while others, such as allergenic ragweed, affect human health. Against this background, the researchers asked how global hotspots of plant invasion risk may change under future environmental conditions.
About the study
The researchers combined global data on alien plant distributions with environmental variables to model the invasion risk of 9,701 species. Using high-resolution data and robust modelling approaches, they assessed current patterns and projected future changes under different climate and land use scenarios until the end of the 21st century.
Hotspots of plant invasion are centered in subtropical regions
"Overall, we found that one third of the global land surface is currently suitable for at least 10 % of these alien species, making these areas invasion hotspots, where many alien plants are expected to occur", biodiversity researcher Ali Omer from the Department of Botany and Biodiversity Research at the University of Vienna and lead author of the study explains. He adds: "Most of these current hotspots are located in subtropical and warm temperate regions, including already large parts of Europe."
Current hotspots of plant invasion will shift poleward
"The results indicate that while the overall extent of hotspots may increase only moderately, their distribution will change substantially", explains biodiversity expert and senior author of the study Franz Essl, University of Vienna. This finding indicates that Europe belongs to the regions facing some of the highest invasion risks worldwide.
Hotspots are expected to shift poleward into colder regions such as Central Europe and contract in increasingly hot and dry subtropical semi-arid regions. In Europe, species such as ragweed with its highly allergenic pollen and black locust, which invades forests and grasslands, are expected to become more widespread under a warming climate. Remote areas in boreal and polar regions are also projected to become more susceptible to plant invasions, causing rising negative impacts on these currently often untouched ecosystems.
New set of alien plants replaces current alien plants
"Not only the location of the invasion hotspots but also the identity of invading species is expected to change", Ali Omer highlights an important finding of the study. Under severe climate change, there may be little overlap between current and future assemblages of non-native plant species in some regions, indicating substantial species turnover. "We expect a new set of alien plant species adapted to warmer conditions to invade many regions", Essl adds.
Rising impacts by alien plants are expected in many densely populated areas
The study highlights the dynamic nature of plant invasions under global change. The shift of invasion hotspots towards densely populated temperate regions is likely to increase impacts on native biota and human well-being. This first high-resolution global assessment of invasion risk for thousands of alien plant species provides an important basis for developing proactive and region-specific management strategies to reduce the impacts of biological invasions under changing environmental conditions.
Summary
- Global modelling of 9,701 alien plant species under current and future conditions
- Current invasion hotspots are concentrated in subtropical and warm temperate regions
- Hotspots are projected to shift towards temperate regions under climate and land use change
- Species composition is expected to change substantially in many regions
- Increasing risks in densely populated areas highlight the need for region-specific management strategies
About the University of Vienna:
At the University of Vienna, curiosity has been the core principle of academic life for more than 650 years. For over 650 years the University of Vienna has stood for education, research and innovation. Today, it is ranked among the top 100 and thus the top four per cent of all universities worldwide and is globally connected. With degree programmes covering over 180 disciplines, and more than 10,000 employees we are one of the largest academic institutions in Europe. Here, people from a broad spectrum of disciplines come together to carry out research at the highest level and develop solutions for current and future challenges. Its students and graduates develop reflected and sustainable solutions to complex challenges using innovative spirit and curiosity.