A rising ocean isn't the only thing creeping into the northeastern US as the climate changes. New invasive species are also moving into the area, according to a leading invasive species scientist.
Consider the hemlock woolly adelgid, a tiny sap-sucking parasite introduced to the eastern United States from Japan feeding on hemlock trees. At one time, people believed that cold winters in the Adirondack Mountains of northeastern New York would prevent the millimeter-long bug from moving into the area, he says Carrie Brown-Lima, director of the Capacitive Species Research Institute in New York. But as the climate has warmed, the insects have now settled into the Adirondacks, he says.
The spread of the woolly hemlock adelgid threatens the hemlock trees and the surrounding area forest ecosystem. Similarly, invasive species worldwide, ranging from plants to mongoose to cane toads, have threatened ecosystem stability, often out-competing or directly preying on non-invasive species. And many non-native species are now taking advantage of ecological opportunities — such as warmer temperatures created by climate change — often wreaking havoc on native plants and animals in the process, according to Brown-Lima, who spoke Oct. 22 webinar on the topic hosted by Cary Institute of Ecosystem Studies in Millbrook, NY.
The combination of climate change and species invasions, according to Brown-Lima, is the “perfect storm of global challenges.” Warmer weather presents the most obvious opportunities for invaders, allowing some plants and animals like the southern pine beetle, once found only in the southeastern U.S. and parts of Central America, to overwinter in places like Long Island that were previously too cold to survive. she says.
But warmer weather isn't the only potential driver of invasions fueled by climate change. Stronger storms and other disturbances could also play a role. For example, Brown-Lima says that by flattening forests, these storms could create opportunities for invasive plant species to outcompete natives.
With climate change or other disturbances in an ecosystem, the competitive advantage usually swings to the most flexible plants and animals, he explains Cascade Sorte, an ecologist at the University of California Irvine. That's because, Sorte says, invasive species are often “jack-of-all-trades” that can persist under any conditions. And that should give them a leg up as the climate changes.”
The northeastern US may be a hotspot for species invasions as the climate warms, Brown-Lima says. And indeed, some research has found that northeastern North America is likely to be a future global hotspot for some invasive species.
To that end, scientists are trying to predict which species are likely to invade and which are likely to do the most damage as climate change continues, Brown-Lima says. Halting or even simply slowing these invasions is nearly impossible once an exotic species has fully established itself in a new habitat, he says, but he adds that if conservationists are able to predict which species will emerge, they can focus on removing those species before they become widespread.
But even with these interventions, climate change will still provide new opportunities for invasive species to establish in the Northeast, Brown-Lima says.
“We're really going to have to pick our battles,” he says.
