Trees Using Water more efficiently Due to Carbon Dioxide Increase

Trees are using water more efficiently now than they did two decades back, according to a new study from Harvard University and the U.S. Forest Service.

Researchers said that increased levels of carbon dioxide along and lower levels of water in many parts of the world have increased the efficiency of water usage in trees.

Plants use carbon dioxide from the atmosphere via a process called photosynthesis, where they lose water through leaves. The ratio of water loss to fixed carbon is important to the water and carbon cycles of an ecosystem.

Rise of carbon dioxide in the atmosphere has already led to the greening of many deserts. Industry experts claim that rise in greenhouse gases will help woody trees more than the grasses.

"What's surprising is we didn't expect the effect to be this big. A large proportion of the ecosystems in the world are limited by water. They don't have enough water during the year to reach their maximum growth. If they become more efficient at using water, they should be able to take more carbon out of the atmosphere due to higher growth rates," said Dr. Trevor F. Keenan Research Fellow, Macquarie University in Sydney, according to a news release.

However, Andrew Richardson, assistant professor of organismic and evolutionary biology from Harvard University said that the rise in carbon dioxide levels will help trees only for a short time.

"There is little doubt that as carbon dioxide continues to rise - and last month we just passed a critical milestone, 400 ppm, for the first time in human history - rising global temperatures and changes in rainfall patterns will, in coming decades, have very negative consequences for plant growth in many ecosystems around the world," Richardson cautioned.

For the study, researchers obtained 20 years of data from the Harvard Forest research towers. Sophisticated instruments mounted on these towers provide information about the levels of carbon dioxide and water use of the ecosystem.

They found that forest towers around the world are showing that these jungles have begun using water more efficiently since the past two decades.

The study team has planned to obtain more records from forests towers around the globe, including tropics to see if there is a link between rise of carbon dioxide and water efficiency.

The study, "Increase in forest water-use efficiency as atmospheric carbon dioxide concentrations rise," was published in the journal Nature.