Invasive species widespread, but not more than at home range

Terra Daily: Invasive plant species have long had a reputation as being bad for a new ecosystem when they are introduced. Stan Harpole, assistant professor of ecology, evolution and organismal biology at Iowa State University, is founding organizer of a team of more than 70 researchers working at 65 sites worldwide that tested that assumption. They wanted to know if it is true that problematic invasive species often spread widely in their new habitats because they don't encounter predators or diseases that help keep them in check in their home ranges.

"There is this assumption that when plants invade a new area that they become much more abundant in the new area than they were in the native areas," said Harpole. "It turns out that, on average, they aren't any more abundant away from home than they are at home."

Harpole says there is a "rule of 10s" that can apply to invasive species. "Of, say, 100 plants that arrive in a new area, only about 10 percent of those will survive without being in a greenhouse or some other controlled area," said Harpole. "Of those 10 that can survive, only about 10 percent of those really cause problems.

"When you think about all the species we've brought over from other areas, relatively few have become serious pest species. The problem is we've brought over so many that quite a few have become major problems and they get a lot of attention."…

A kudzu-covered field in Port Gibson, Mississippi, shot by Galen Parks Smith (Gsmith), under the Creative Commons Attribution-Share Alike 3.0 Unported licenseWikimedia Commons