Atmospheric carbon dioxide has been linked to problematic phenomena such as global warming, but new research suggests it could help trees use water more efficiently.
New research suggests European forests became 20 percent more efficient at using water during the 20th century because of an increase in carbon dioxide, Montana State University reported.
To make their findings, a team of researchers collected tree ring samples from Morocco to Norway and measured the carbon isotopes to determine changes of water efficiency over the years. They also used statistical techniques and model simulations to determine how trees responded to climate variations in carbon dioxide.
The researchers found water-use efficiency in temperate forests increased by 14 percent in broadleaf species and 22 percent in needleleaf species over the study period, but this change did not reduce the regional water balance. Any potential savings from increased water efficiency were countered by a longer growing season, also caused by rising carbon dioxide levels.
"It thus seems unlikely that plants will reduce the surface-to-atmosphere flux of water vapor -- a strong greenhouse gas," the researchers said. "It is also unlikely that plant responses to increased carbon dioxide will substantially increase soil moisture or river run-off."
The researchers also looked at stomata, which are tiny openings in the leaves, providing key insight into how trees respond to atmospheric carbon dioxide increases.
"We were able to compare the tree-ring-based estimates with various vegetation models and were pleased to see tight agreement. This sort of testing helps us understand where we can further improve models, or in this case gives us confidence in the model projections for these ecosystem metrics," said co-author Chris Huntingford, a climate modeler at the Center of Ecology and Hydrology in the United Kingdom.
The findings were published in a recent edition of the journal Nature Climate
