McCulley added that some species in the study, like Kentucky bluegrass, aren’t necessarily considered invasive by everyone, but were chosen because they were considered invasive by enough people to make a country’s invasive species list.

“In Kentucky, we don’t consider some of the species on the list to be invasive. They are widespread throughout the state and have proven beneficial to our forage systems,” said McCulley, a grassland agroecologist. “However, they aren’t native to the United States, and some states do consider them to be invasive and problematic.”

One species found in Kentucky, Canada thistle, is widely considered an invasive, noxious weed that threatens ecosystems throughout North America. Results from this study indicate this species tends to be less abundant in its invasive range than in its home site worldwide.

“The results suggest that it’s relatively unusual for invasive plants to have a population explosion at introduced sites,” McCulley said. “Instead, abundance at native sites, in most cases, can predict abundance at introduced sites.”

In addition, the scientists’ findings held up across diverse climate zones. McCulley said sites in Kentucky, New Zealand and Switzerland had as many as six shared species, all with similar plant abundances.

These findings might help scientists speculate how new invasive species will behave once introduced into a foreign site.

The group, known as the Nutrient Network, was funded by a research coordination network grant from the National Science Foundation’s Division of Environmental Biology. The UK College of Agriculture also helped fund McCulley’s research.