Study finds that as biodiversity declines, overall plant growth is stunted

By Jeremy Hance / Mongabay

For decades scientists have been warning that if global society continues with “business-as-usual” practices the result will be a mass extinction of the world’s species, an extinction event some researchers say is already underway. However, the direct impacts of global biodiversity loss has been more difficult to compile. Now a new study in Nature finds that loss of plant biodiversity could cripple overall plant growth.

“Some people have assumed that biodiversity effects are relatively minor compared to other environmental stressors,” lead author David Hooper with Western Washington University said in a press release. “Our new results show that future loss of species has the potential to reduce plant production just as much as global warming and pollution.”

Looking at nearly 200 studies, the researchers compiled data on how primary production, i.e. plant growth, and decomposition are impacted by biodiversity loss in a wide-variety of ecosystems. According to the study, it depends on the magnitude of biodiversity loss. If up to 20 percent of the world’s plant species are lost, the impact on growth will be “negligible” says the study. However if 21-40 percent of the world’s plants vanish, primary production would be hit to the tune of 5-10 percent, and if half the world’s plant species vanish, primary production will fall by 13 percent. Some biologists have warned that species could be halved by the end of this century.

“Our analyses suggest that biodiversity loss in the 21st century could rank among the major drivers of ecosystem change,” the authors write, noting that a 13 percent loss in primary production compares to the impact of anthropogenic climate change on primary production.

While scientists found that the overall loss in decomposition was generally less than primary production, it was still worrisome. Moreover, the lopsided nature in which biodiversity loss impacts production over decomposition could hamper ecosystems’ ability to sequester carbon.

“Species loss ranks among the major drivers of primary production and decomposition—key processes involved in the carbon cycle and the provisioning of many ecosystem services,” the authors write.

The paper is buoyed by a number of recent studies which have shown that the more biodiverse an ecosystem, the more productive it is.

Complicating the situation is the fact that the world is not just facing mass extinction, but a wide variety of global environmental issues including climate change, nutrient pollution, and ozone loss.

“The biggest challenge looking forward is to predict the combined impacts of these environmental challenges to natural ecosystems and to society,” says co-author J. Emmett Duffy of the Virginia Institute of Marine Science.

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