Global warming kills forests by restricting tree transpiration

UN International Day of Forests on 21 March is the perfect opportunity to showcase some of the important forest research being done at EPFL. For instance, one recent study found that the changes in relative humidity caused by higher temperatures are having a significant impact on trees. "The data clearly show that tree mortality is increasing at an exponential rate," says Prof. Charlotte Grossiord, the head of EPFL's Plant Ecology Research Laboratory (PERL)*. No stranger to forest health, she's studying the mechanisms behind forest ecosystems and how they're responding to climate change. This year, 21 March will mark not only the first day of spring but also the 11th annual UN International Day of Forests - an occasion to shine the spotlight on Grossiord's research. A study she published recently in Journal of Applied Ecology shows that the lower relative humidity resulting from higher temperatures is disrupting trees' natural transpiration process, putting many species at risk. Forests cover some four billion hectares of land, or nearly 31% of the Earth's surface.