As people search for ways to help Earth’s biosphere withstand the impacts of climate change, they might turn to a relatively little-appreciated phenomenon: how plant diversity stabilizes ecosystems in the face of stress.
This isn’t a brand-new idea. Various small-scale studies suggest that a greater variety of plants increases the likelihood that when rising temperatures or rainfall fluctuations harm some species, others may continue to thrive, thus keeping ecosystem productivity on an even keel.
Yet as researchers led by ecologist Guilherme Mazzochini of Brazil’s Federal University of Rio Grande do Norte note in the journal Global Ecology and Biogeography, the scale of those studies—sometimes involving experimental plots just a few meters across—means they’re not incorporated into system-wide models.
“There is no consensus about the relative importance of plant diversity on productivity at spatial scales at which earth system models are built,” write Mazzochini and colleagues, who analyzed relationships between plant diversity, ecosystem productivity, and weather patterns across 830,000 square kilometers of arid eastern Brazilian shrublands.
The dataset was as deep as it was broad, spanning the years between 2000 and 2010. And when the numbers were crunched, “plant phylogenetic diversity was the most important variable explaining vegetation productivity stability,” the researchers. Diversity was even more influential than rainfall and temperature.
“Our results expand by several orders of magnitude the spatial scale of evidence that high biodiversity strengthens the resistance of key ecosystem features to climatic fluctuation,” Mazzochini’s team writes.
To be clear, diversity was not a panacea. Droughts or extreme rainfall still meant vegetation didn’t grow at rates observed in favorable conditions—but diversity did offer protection against dramatic declines in productivity.
While the study focused on how models of climate change and carbon cycles would benefit from incorporating plant diversity into their estimates of ecosystem function, Mazzochini says the implications don’t end there.
Protecting areas with greater plant diversity could ensure more stable rates of carbon sequestration. It may also help prevent desertification or other ecological upheavals, and buffer animal populations from the privations of climate extremes.
That doesn’t mean plant diversity should be the only criteria for selecting protected areas, cautions Mazzochini. After all, he says, “there are very important ecosystems that do not necessarily have high phylogenetic diversity”—but it’s still worth taking into account. And when a highly diverse locale is threatened, there’s even more reasons to protect it.
Source: Mazzochini et al., “Plant phylogenetic diversity stabilizes large‐scale ecosystem productivity.” Global Ecology and Biogeography, 2019.
Image: A. Duarte
About the author: Brandon Keim is a freelance journalist specializing in animals, nature and science, and the author of The Eye of the Sandpiper: Stories From the Living World. Connect with him on Twitter, Instagram and Facebook.