This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A substantial loss of plant diversity could mean that grasslands worldwide, including meadows and pastures, would absorb around 15% less CO₂ through photosynthesis by midcentury compared with a scenario in which diversity is maintained. In some of the most affected regions, CO₂ uptake through photosynthesis could decline by 50%, even in a scenario in which global warming remains below 2°C.
The findings were published in a new study from the Potsdam Institute for Climate Impact Research (PIK) and Kiel University (CAU) in PNAS. "Climate change could reduce the productivity of plants that at the moment dominate pastures and meadows. But if plant diversity is maintained, other plants that cope better with climate impacts have the chance to become more prominent and stem the decline," explained Stephen Wirth, PIK researcher and lead author of the study.
"It's not just about the lower rates of photosynthesis, but losing plant diversity also reduces forage supply for grazing animals, which in turn can threaten the livelihoods of people who depend on livestock grazing. Soils also store less carbon and contribute less to limiting global warming," Wirth added. Local experiments have previously shown that plant diversity supports grassland productivity.
This study built on that work, using a global vegetation model to investigate how the loss of diversity affects CO₂ uptake and soil carbon storage under climate change. The researchers compared how grasslands develop with maintained versus strongly reduced plant diversity. In the model, the researchers assumed an extreme loss of plant diversity to investigate its potential consequences.
They examined two climate scenarios with global warming of below 2°C and around 4°C. Under 2°C of warming, grasslands with strongly reduced diversity take up around 11 billion tonnes less CO₂ per year through photosynthesis in 2050 than grasslands where diversity is maintained. This reduction in uptake would be comparable to losing an area of grassland with average productivity roughly the size of the Arctic tundra.
The model also projects lower soil carbon stocks where diversity is reduced. Particularly large differences in CO₂ uptake in 2050 are evident in many tropical and subtropical regions. In these areas, grasslands with strongly reduced diversity take up as much as 50% less CO₂ than those where diversity is maintained.
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