Loss of biodiversity appears to impact ecosystems as much as climate change, pollution and other major forms of environmental stress, according to a research study published this week in the journal Nature.
The study, funded by the National Science Foundation and the National Center for Ecological Analysis and Synthesis, is the first comprehensive effort to directly compare the impacts of biological diversity loss to the anticipated effects of a host of other human-caused environmental changes.
“It has been clear for some time that species loss affects ecosystems, but the impacts we found were very surprising,” said Bruce Hungate, co-author and professor of biological sciences at Northern Arizona University. “Our findings indicate that losing half of the plant species in an area is like dousing it in acid rain.”
Studies over the last two decades have demonstrated that more biologically diverse ecosystems are more productive. As a result, there has been growing concern that the very high rates of modern extinctions—due to habitat loss, overharvesting and other human-caused environmental changes—could reduce nature’s ability to provide goods and services like food, clean water and a stable climate.
But until now, it’s been unclear how biodiversity losses stack up against other human-caused environmental changes that affect ecosystem health and productivity.
“Some people have assumed that biodiversity effects are relatively minor compared to other environmental stressors,” said David Hooper, the study’s lead author and biologist at Western Washington University. “Our new results show that future loss of species has the potential to reduce plant production just as much as global warming and pollution.”
The researchers used data from 192 peer-reviewed publications to compare how various global environmental stressors affect two processes important in all ecosystems: plant growth and the decomposition of dead plants by bacteria and fungi. The data was derived from experiments that manipulated species richness and examined the impact on ecosystem processes.
The team found that in areas where local plant species loss falls between 1 to 20 percent this century, negligible impacts on ecosystem plant growth will result, and changes in species richness will rank low relative to the impacts projected for other environmental changes.
In ecosystems where losses fall within intermediate projections of 21 to 40 percent of species, however, species loss is expected to reduce plant growth by 5 to 10 percent. This effect is comparable in magnitude to the expected impacts of climate warming and increased ultraviolet radiation due to stratospheric ozone loss.
At higher levels of extinction of 41 to 60 percent, the impacts of species loss ranked with those of many other major drivers of environmental change such as ozone pollution, acid deposition on forests and nutrient pollution.
The strength of the observed biodiversity effects suggests that policymakers searching for solutions to other pressing environmental problems should be aware of potential adverse effects on biodiversity, Hungate said.
“Species loss and other environmental changes depend on the choices people make about land conversion, habitat destruction, climate change, and much more. As a species, we have tremendous leverage over the global environment, which is both troubling and empowering.”