The U.S. Forest Service calculates the drought in California has killed about 102 million trees since 2010, and the tree die-off is happening at an increasing pace. Some 66 million trees died between 2010 and June of this year, and more than half that number — 36 million — died between June and November.
Mass tree deaths make drought conditions even more dangerous than they already would be. "These dead and dying trees continue to elevate the risk of wildfire, complicate our efforts to respond safely and effectively to fires when they do occur and pose a host of threats to life and property," explains Agriculture Secretary Tom Vilsack.
Drought is stressful for trees for reasons beyond simple water deprivation. For instance, dehydrated pine trees make less resin, which leaves them vulnerable to insect infestations. Dry ground can also lead to trees drawing air bubbles into their "veins," or xylem, which can eventually prove deadly.