It sounded ridiculous when Gina McCarthy claimed nature was fixing itself after they created a toxic waste disaster in Colorado but that future methane needed the EPA to halt it right now, yet science has again shown that nature is more resilient than political bodies think.

Biodiversity can often help protect ecosystems from extreme conditions, according to a study of 46 grasslands in North America and Europe. The results showed that increasing plant diversity decreased the extent to which extremely wet or dry conditions disrupt grassland productivity. 

The researchers began by classifying each year of each experiment on a five-point scale from extremely dry to extremely wet. They then measured corresponding productivity -- basically, how much above-ground plant material each level of plant biodiversity produced each year.

Combining results across the 46 study sites, the researchers found that the higher the plant biodiversity, the lower the variability in productivity during wet or dry climate events. Overall, productivity of communities with only one or two species changed an average of 50 percent during events, while those with 16 to 32 species changed only half that much. Biodiversity did not, however, seem to strongly influence how quickly a site returned to normal productivity after wet or dry events.

"We've long known that biodiversity has a stabilizing effect on productivity over time," said lead author Forest Isbell, principle investigator on the project and associate director for the University of Minnesota's Cedar Creek Ecosystem Science Reserve, one of the study sites. "But we haven't been quite sure whether that's during extreme events, after them, or both. This research showed that diverse communities are more stable because they exhibit resistance during extreme climate events."

Isbell, who is also an adjunct faculty member in the College of Biological Sciences, says the research team found the results somewhat unexpected. "Many of us were expecting that biodiversity would often promote both resistance during climate events and resilience after climate events," he says. Instead, resistance to change clearly trumped resilience as the main mechanism through which biodiversity helps to preserve ecosystem stability in times of change. "We also need to understand how biodiversity increases resistance during extreme climate events so we can determine what types of biodiversity are needed to help nature thrive under adverse circumstances."