Newsletter Feature

TREE SCIENCE IN THE NEWS by Robin Romero

     New Information About Drought In The West. California’s ongoing drought has had a devastating impact on 888 million trees putting them at increased risk of death or catching fire. Gov. Jerry Brown declared a state of emergency over what he referred to as the “worst epidemic of tree mortality in its modern history.”

     For years the state has relied on data from field testing and plot sampling to figure out how forests are doing. Now researchers from The Carnegie Institution for Science have used an imaging technology that allows them to measure a tree’s water content from above using airplanes. The computer in the planes collected data for 12 days that measured water content currently housed in the trees. Then researchers developed a model that allowed them to estimate the trees’ past water content using satellite data from the past few years.

     Comparing the two figures, the study showed that between 2011 and 2015 nearly 40,000 square miles of forest experienced progressive water loss of at least 10 per cent. Some forests experienced water losses of more than 30 percent. Trees on slopes were most likely to loose water. Researchers said that not all affected trees are at an immediate risk of death, but the study does help state officials identify areas that are most likely to be fire hazards. The combination of the two techniques, using present and long-term data, gives new insight on how climate change is affecting California's environment.