- A team of three dozen researchers from around the world examined data from 46 grassland plant biodiversity experiments across Europe and North America to measure ecosystem productivity during a range of climatic events.
- The productivity of low–diversity ecosystems, those with one or two species, was reduced by about 50 percent on average during extreme climatic events.
- High-diversity communities, however, or those with 16 to 32 species, saw a reduction of only about 25 percent.
As global temperatures warm, climatic extremes are becoming more and more common. And as human activities are ushering in what many scientists believe to be a sixth mass extinction event, it’s increasingly crucial that we understand whether or not a healthy ecosystem capable of supporting a high number of species is more resilient to the unpredictable conditions brought about by climate change.
A new study published in the journal Nature last week finds that ecosystems that have a greater number of species are indeed more resistant to extreme climatic events, including prolonged wet and dry periods.
Forest Isbell, a researcher at the University of Minnesota, led a team that examined data from 46 grassland plant biodiversity experiments across Europe and North America to measure ecosystem productivity during a range of climatic events, from moderate to extreme, brief to prolonged and wet to dry conditions.
Using biomass production as a metric for overall health of each ecosystem because species are dependent on biomass for energy, the researchers found that the productivity of low–diversity ecosystems, those with one or two species, was reduced by about 50 percent on average during extreme climatic events. Meanwhile, high-diversity communities, or those with 16 to 32 species, saw a reduction of only about 25 percent.
In other words, the team, which included three dozen researchers from the U.S., Germany, the U.K., Ireland, France, Switzerland, the Netherlands, Czech Republic and Japan, found that increased plant diversity in those 46 grasslands decreased the extent to which extreme wet or dry conditions disrupted ecosystem productivity.
“We’ve long known that biodiversity has a stabilizing effect on productivity over time,” Isbell, the lead author of the Nature paper, said in a statement. “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 and team found that biodiversity did not have a discernible long-term impact on ecosystems, however, as both low- and high-biodiversity communities recovered from climatic extremes within a year.
This result came as something of a surprise to the research team. “Many of us were expecting that biodiversity would often promote both resistance during climate events and resilience after climate events,” Isbell said. Instead, resistance to change clearly superseded resilience as the main mechanism by which biodiversity helps to preserve ecosystem stability in the face of climatic extremes, he said.
Co-author Nico Eisenhauer of Leipzig University and the German Centre for Integrative Biodiversity Research, which funded the study, said this research “comprehensively shows that mankind is degrading the natural insurance of ecosystems.”
The team’s findings, Eisenhauer said, will help increase our understanding of the role biodiversity plays in helping nature weather the storms it faces as global temperatures continue to rise. “Researchers have been searching for decades for stabilizing ecosystem features,” he added. “The present results bring the significance of biodiversity home to scientists, land managers and politicians as stabilizing agents of ecosystem services in the face of global change.”
The study joins a growing body of research that has found global warming is having an impact on biodiversity right now. For instance, another study, recently published in the Journal of Animal Ecology, found that as temperatures have warmed, insect species that have adapted to warmer climates are becoming more prevalent, while insects that prefer cold climates are disappearing.
Now, according to the authors of the Nature paper, the challenge is to identify what factors, if not biodiversity, ultimately determine how rapidly and thoroughly ecosystems recover from extreme climate events.
Isbell added that “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.”
