Scientists exposed plants to a yearlong drought. The result is worrying for climate change
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Grasslands and shrublands cover more than 40% of Earth’s terra firma, and they remove hefty amounts of carbon dioxide from the air. But by deliberately blocking precipitation from falling at 100 research sites around the world, researchers found that a single year of drought can reduce the growth of vegetation by more than 80%, greatly diminishing its ability to absorb carbon dioxide. Overall, plant growth in the artificially drought-stricken grassy patches fell by 36%, far more than earlier estimates. But the study, presented last week at the annual meeting of the Ecological Society of America in Montreal, also found great variability: Vegetation at 20% of the sites continued to thrive despite the lack of water.
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Many researchers have continued to monitor their plots, with some planning to collect data for four or more years, in part to simulate prolonged droughts. The additional data could help climate modelers sharpen estimates of how much less carbon is absorbed by shrub- and grasslands in a drought, says Sarah Evans, an ecologist at Michigan State University’s W.K. Kellogg Biological Station. IDE results could also help ecologists forecast which ecosystems are most at risk during dry spells, as well as broader ecological ripple effects. Less plant matter can mean less food for grazing animals such as rodents and for their predators, Evans notes. “The health of many ecosystems and their biodiversity relies on plant production,” she says.
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