Extreme weather eventsLike heat waves and droughts, they can modify the carbon sequestration capacity of terrestrial ecosystems. Thanks to a comprehensive experiment on a permanent mid-mountain meadow, researchers show for the first time that the enrichment of CO2 from the atmosphere improves recovery ofl meadow after these extreme events. In addition, it slows down the negative effects of water stress.
Between now and the end of the century, monitoring climate change would lead to an increase in the frequency and severity of extreme weather events combined with heat waves and droughts. These climatic extremes would have negative impacts on ecosystems, specifically on meadows, which are sensitive to drought and feed dairy and beef cattle. Finally, it could cause a degradation of the soil, reducing its content of organic matter rich in carbon.
Carbon dioxide increase
In any case, the increase in carbon dioxide in the atmosphere could limit these climate risks. Indeed, CO2 is the substrate for plant photosynthesis and usually favors the tolerance of plants to drought and the accumulation of organic matter in the soil.
Until today, it was not known whether these beneficial effects of CO2 they may or may not persist in the event of extreme weather. For the first time, an answer to this question is provided thanks to an experiment. The meadow samples were subjected to a climate like the one predicted from the year 2050, warmer and drier, as well as an increase in the atmospheric concentration of CO2 combined, or not, to a heatwave and extreme drought.
Drought and heatwave
During drought and heatwave, enrichment in Atmospheric CO2 slows down the negative effects of water stress and thermal, maintaining the physiological functions of the plants. It stimulates the growth of the roots, allowing access to more water and nutrients in the soil, which accelerates the growth of the meadow from the end of the extreme climate.
Throughout this experiment, the increase in atmospheric CO2 fully compensated the negative impacts of drought and the heatwave on the assimilation of carbon by the meadow. This study shows the importance of considering the set of interactions in the study of the impacts of climate change.
Indicates that the increase in atmospheric CO2 increases the resistance of soil organic matter, of the ecosystems of the meadows and of the cattle that are tributaries of an extreme climatic event of type heatwave and drought, but it does not allow to conclude on the cumulative effects of such climatic extremes. These cumulative effects must be evaluated by another battery of experiments.