Europe and many other parts of the world are currently grappling with extreme drought, and that could be bad news for efforts to curb climate change.
Grassland and shrubland remove a lot of carbon dioxide from the air. Researchers found that blocking precipitation from falling at 100 research sites around the world can reduce the growth of vegetation by more than 80%. The growth of plants in the grassy patches was much larger than previously thought. The study, presented last week at the annual meeting of the Ecological Society of America in Montreal, found that 20% of the sites continued to thrive even though there was no water.
Drew Peltier, who was not involved in the study, was surprised at how much the impacts varied. How much resilience is there in these systems?
In a warming world, three ecologists grew frustrated with their field, including Melinda Smith of Colorado State University, Osvaldo Sala of Arizona State University, and RichardPhillips from the University of Indiana, Bloomington. They and their colleagues put out a call for researchers to take part in theIDE, which is a standardized procedure for creating artificial dry spells.
Smith says that they expected to have about 20 sites. Iran and parts of South America are places where scientists haven't done much research on the issue. It is easier to build structures to block precipitation in shrub and grassland areas.
Each team agreed to recreate the worst conditions of the previous century in their area. Most of the precipitation was blocked by mounting plastic roofing slats over 1-meter squares of ground. The average amount of precipitation received by the roofed plots was less than 50%.
Each team took a look at the plants in the covered areas and the ones left open for comparison. All of the aboveground plant material in the roofed and open plots was weighed after a year of treatment.
Initial results were reported from 100 shrubby and grassy sites. Kate Wilkins is a grassland ecologist at the Denver Zoo who worked with Smith. There was a decline in plant productivity in the area. Wilkins thought it was dead.
Anke Jentsch-Beierkuhnlein from the University of Bayreuth says that the simulation did not have a noticeable effect on the grassland. The climate at the German site was not as bad as the one on the prairie. Plants in wet environments withstood the short-term dry spell better than those in arid environments. Shrubs have a lot of roots that can reach the soil's surface. The decline in the grassy plots is almost twice as much of a reduction as other studies have shown. She thinks the data is believable because the study used standard methods.
Many researchers have continued to monitor their plots, with some planning to collect data for four or more years in order to study the effects of long periods of dry weather Climate modelers can use the additional data to better estimate how much less carbon is absorbed by shrub- and grassland in a dry season. It is possible to forecast which ecosystems are most at risk when there is a dry spell. Less plant matter can mean less food for animals that are on the move. Plants play an important role in the health of many environments.
Land managers could also benefit. According to Jentsch-Beierkuhnlein, the current European dry spell has been hard on grassland with relatively few species. She says that planting more diverse assemblages could allow the grasslands to keep delivering services.
Andrew said that it was an important insight given the extreme heat and dry spell of recent years. Climate change is the main message of these extreme conditions. They show how relevant the tool is.
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