Beneath the canopy of snow that recently blanketed California’s mountainsides are vast swaths of forest struggling to survive the drought.
A study released Monday by the Carnegie Institution for Science counts as many as 58 million trees statewide experiencing severe water loss, whose ruin would not only turn massive stands of pristine green to ugly brown but upset vital watersheds and wildlife.
The research, published in the Proceedings of the National Academy of Sciences, follows a U.S. Forest Service report last spring that identified 12 million trees killed by drought but left questions about how many more might wither.
“Our maps reveal much wider, much larger-scale impacts on our forest than the dead trees would tell in themselves,” said Greg Asner, an ecologist at Stanford University who led the new study. “What we found are large sections of forest at high risk of mortality if drought persists after the El Niño.”
Asner and his team evaluated the health of California’s woodlands by using laser-guided imaging, deployed from an airplane and unique to the Carnegie Airborne Observatory, to measure water content in trees. Their flight observations across the state were compared to older satellite data.
The results show that 7 to 10 percent of trees are severely stressed by the drought. In an average non-drought year, only about 1 percent of California’s forests typically die.