PNAS Study - 4-Year Drought Has Likely Killed 58 Million California Trees; 120 Million More At Risk
California is littered with dead trees. Four years of drought have pushed countless lone pines and forests alike to the brink of collapse, turning entire swathes of mountains from verdant to withering rust.
The numbers began rolling in early last summer with a U.S. Forest Service survey that tallied the death toll at 12 million. By September the agency revised its count to 21 million trees statewide. Soon the California Department of Forestry and Fire Protection (CAL FIRE), weighed in with 29 million confirmed dead trees.
Even those grim numbers, gathered through conventional on-the-ground and aerial estimates, were upended by a high-tech assessment done by scientists with the Carnegie Institution for Science. Four dry summers and four winters with a dramatically reduced snowpack have taken a toll throughout the Golden State, and will likely kill 58 million trees due to severe water loss, said Greg Asner, a Carnegie Institution biologist who published his results online on December 28 in Proceedings of the Natural Academy of Sciences. As many as 120 million trees statewide are in jeopardy from loss of water in their canopies, he said.
The higher temperatures and reduced precipitation that contributed to the die-off are widely predicted to continue, leaving California's forests poised for radical transformation. "If drought conditions continue or reoccur, even with temporary reprieves such as El Niño, we predict substantial future forest change," Asner and his co-authors wrote.
EDIT
http://www.waterdeeply.org/articles/2016/02/9616/droughts-alarming-toll-california-forests/
= new reply since forum marked as read
