New research shows that invasive plants will inch northward as climate change transforms growing zones across the country. That could mean more nuisance plants coming to Illinois and the Great Lakes region.
Invasive plant species like Japanese honeysuckle or buckthorn are already at home in yards, parks and forest preserves across Illinois. Yet they’re not supposed to be. These species, sometimes from halfway across the globe, can take over entire landscapes and siphon away resources from native species that have no way to compete.
Projecting into a future scenario where global temperatures are 2 degrees Celsius hotter than preindustrial levels, scientists found that the future climate conditions will support the spread of many invasive plant species.
“We modeled 144 invasive plants,” said Annette Evans, lead author of the study and a researcher at the University of Massachusetts Amherst. “These are plants that are not native to the United States but are already established somewhere in the Eastern United States.”
Evans and her colleagues pulled data from 14 invasive species databases and identified regions that, based on current climatic conditions, are most suitable to different species of invasive plants. Three hot spot regions emerged: the Great Lakes, the mid-Atlantic and the northeastern coast of Florida and Georgia.
And these hot spots are on the move. Future climatic conditions would cause those hot spots to shift toward the Northeast by over 100 miles. The introduction of nonnative species can result in new survival pressures with a significant impact on native species. Evans said that’s going to mean more work for resource managers.
“The climate for a lot of species is going to remain suitable,” Evans said. “But there’s going to be a whole boatload of new invasive species that we’re going to have to start managing as well.”
Not all invasive plants will become abundant. Scientists want to proactively determine which invasive plants pose the greatest ecological risk of invasion.
It’s not just invasive plant species contending with warming conditions — it’s all plant species. The U.S. Department of Agriculture released a new plant hardiness map last month. Gardeners rely on this federal map to know where flowers and vegetables can survive and grow.
About half the country has shifted into a new growing zone, according to Chris Daly, the director of the PRISM Climate Group at Oregon State University, which helped develop the map. He said the center of the country saw the greatest warming, including Illinois.
“Overall, changes to the map were greatest in the southern part of the state, up to 3 to 5 degrees Fahrenheit,” Daly said. “And the least was in the northwestern part of [Illinois], which warmed very little, maybe a half-degree to a degree.”
Evans said gardeners and resource managers are already seeing these changes and will continue to see them.
“There’s just not as much funding and support for invasive species management and monitoring compared to some other areas,” Evans said.
As climate shifts and plant distributions respond, she said that it’ll become increasingly important to understand which invasive species to prioritize before they spread too far.
Juanpablo Ramirez-Franco covers climate change and the environment for WBEZ and Grist. Follow him on X at @__juanpab.
