Europe and many other parts of the world are now grappling with extreme drought, which could be bad news for efforts to curb climate change, says how shrubs and grasses respond to drought conditions. concludes a new global study of

Grasslands and shrubs cover over 40% of the earth’s land surface and remove large amounts of carbon dioxide from the air. However, by deliberately blocking rainfall at 100 research facilities around the world, one year of drought reduces vegetation growth by more than 80%, greatly reducing its ability to absorb carbon dioxide. was discovered by researchers. Overall, plant growth in artificially drought-hit grasslands decreased by 36%, much higher than previously estimated. But the study, presented last week at the Ecological Society of America’s annual meeting in Montreal, also found significant variability. Vegetation on 20% of the site continued to thrive despite water scarcity.

Drew Peltier, a physiological ecologist at Northern Arizona University, said, “I was surprised at how diverse the effects of drought were. He was not involved in this study.” It suggests some resilience, the question is how much and for how long.”

A decade ago, droughts were projected to become more frequent and severe in a warming world. Osvaldo Sala of Arizona State University Tempe. and Richard Phillips of Indiana University Bloomington complained that their field failed to produce consistent results on how dry weather affects plant productivity, especially in grasslands and scrublands. So they and their colleagues developed a standardized procedure for creating an artificial drought in the field and were willing to participate in what they termed the International Drought Experiment (IDE). recruited people.

“We expected to have about 20 sites,” recalls Smith, but what was called Drought-Net grew to 139. It is also found in places where scientists have done little research on drought, such as Iran and parts of South America. Most are found in shrubs and grasslands, where it is easier to build structures to block precipitation.

Each team agreed to recreate the worst drought conditions recorded in the region in the last century. In most cases, a one-meter-square-meter ground was fitted with plastic roof slats to block precipitation. The slats were spaced according to how much rain, sleet, or snow needed to be deflected. On average, the covered plots received less than half the normal rainfall.

Each team tallied the type and number of plants in the area covered and the number of similar plots opened for comparison. After one year of treatment, the researchers surveyed the plants again, harvesting, drying and weighing all above-ground plant material in covered and open plots.

Last week, researchers reported initial results for 100 shrubs and grasslands. There have been “catastrophic losses” in areas such as Colorado’s Shortgrass Prairie plot, reported Kate Wilkins, a grassland ecologist who now works at the Denver Zoo and has worked with Smith. Plant productivity in water-deficient areas fell by 88%, he said. “What surprised me was how dead it was,” said Wilkins.

In contrast, simulated droughts “did not have a significant impact” on the temperate grasslands of Germany, says Anke Jentsch-Bayerkuhnlein, a disturbance ecologist at the University of Bayreuth. In general, the German sites had a humid climate and droughts were less severe than in the prairies. Overall, plants in humid environments tolerated this short-term drought better than plants in dry climates, and shrub-dominated plots performed better than grass-dominated plots, Wilkins reported. Shrubs tend to have more extensive roots that allow moisture to reach deep into the soil. Elsa Cleland, an ecologist at the University of California, San Diego, says the average rate of decline seen in grassy plots (36%) is “almost double what other studies have shown.” However, she and others believe the data are reliable because the studies used standard methods at various sites.

Many researchers continue to monitor the plots, and some plan to collect data over four years or more to simulate long-term drought. Sarah Evans, an ecologist at Michigan State University’s WK Kellogg Biological Station, said this additional data could help climate modelers accurately estimate how much carbon is being absorbed by shrubs and grasslands during drought. said. IDE results can also help ecologists predict which ecosystems are most at risk during periods of drought, and may also have broader ecological ramifications. Less vegetation means less food for herbivores such as rodents and their predators. “The health of many ecosystems and their biodiversity depends on plant production,” she says.

Farmers, ranchers and land managers could also benefit. Jentsch-Beierkuhnlein says that during the current drought in Europe, relatively seedless and intensively managed grasslands such as hayfields have been hit hard. By planting more diverse communities, such grasslands may be able to “continue to provide ecosystem services even under severe drought.”

Andrew Hector, an ecologist at the University of Oxford, says this is an important insight given the extreme heat and drought in recent years. “The main message of these extremes is that climate change is … already happening,” he says.They “show how relevant [the IDE] teeth. “