Surprise! 20 Year Study On Elevated CO2 Shows Divergence Between Grasses, Trees In CO2 Uptake
Two major groups of plants have shown a surprising reversal of fortunes in the face of rising levels of carbon dioxide in the atmosphere.
During a 20-year field experiment in Minnesota, a widespread group of plants that initially grew faster when fed more CO2 stopped doing so after 12 years, researchers report in the April 20 Science. Meanwhile, the extra CO2 began to stimulate the growth of a less common group of plants that includes many grasses. This switcheroo, if it holds true elsewhere, suggests that in the future the majority of Earth’s plants might not soak up as much of the greenhouse gas as previously expected, while some grasslands might take up more.
“We need to be less sure about what land ecosystems will do and what we expect in the future,” says ecosystem ecologist Peter Reich of the University of Minnesota in St. Paul, who led the study. Today, land plants scrub about a third of the CO2 that humans emit into the air. “We need to be more worried,” he says, about whether that trend continues.
The two kinds of plants in the study respond differently to CO2 because they use different types of photosynthesis. About 97 percent of plant species, including all trees, use a method called C3, which gets its name from the three-carbon molecules it produces. Most plants using the other method, called C4, are grasses.
EDIT
https://www.sciencenews.org/article/rising-co2-levels-might-not-be-good-plants-we-thought
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