U of Minn. study: Invasive plants get a leg up in fertilized grasslands

A University of Minnesota study published Wednesday shows that invasive plant species have an advantage over native species when grasslands are fertilized.

The study involved multiple years of data on 64 grassland sites in 13 countries around the world, including the university's Cedar Creek Ecosystem Science Reserve near East Bethel, Minn.

Researchers added phosphorus and nitrogen to simulate the increased nutrients humans are putting in the air from burning fossil fuels.

Adding those nutrients give non-native species a leg up, and native species become less abundant.

Looking at how different plants respond to increased nutrients can help predict other changes to an ecosystem, study author Eric Seabloom said.

As native plants die off, so do other creatures that rely on them for food.

"Plants are the building blocks of all the other organisms that are in an ecosystem," Seabloom said. "They're the only organism that can make energy from the sun. Everything else — insects, mammals and birds — they basically are relying on the plants."

Worldwide, humans have dramatically increased nutrients including nitrogen and phosphorus in the environment, Seabloom said. It's happening inadvertently by burning fossil fuels and fertilizing agricultural crops.

Researchers say the study helps explain why invasive species like buckthorn and quackgrass have been able to take over in some places.

An exception to the equation is when animals that eat the plants are added. Grazing animals can boost native species by cutting back the plants that would otherwise shade out the native species.

The study was published in the journal Nature Communications and was funded by the National Science Foundation and the University of Minnesota Institute on the Environment.