The number of dead trees in California's drought-stricken forests has risen dramatically to more than 102 million, according to the results of a new aerial survey released Friday by the U.S. Department of Agriculture.
Officials said they were alarmed by the increase in dead trees, which they estimated to have risen by 36 million since the government's last survey in May.
"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 across California," Agriculture Secretary Tom Vilsack said in a statement.
Officials have said that a lethal combination of drought, heat and voracious bark beetles have killed trees across California, but the die-off is most notable in the south and central Sierra Nevada range.
U.S. Forest Service scientists believe that the remaining living trees need at least two years of normal or above-normal rain to fully regain their health. Water-starved trees are unable to produce their usual pitch or sap, the secretions that tend to protect them from fungi and insects. Bark beetles are notoriously fond of frail trees, burrowing destructive paths into limbs and trunks to mate and lay eggs.
Although the epicenter of the die-off is the southern Sierra Nevada, the march of death is rapidly moving north to places such as Lake Tahoe and Eldorado National Forest.
California was struck this summer by a series of deadly wildfires that destroyed hundreds of homes and forced thousands to flee across the state. Officials said some of those fires were fueled by dead trees.
The roughly 102 million dead trees died since 2010, just before the drought started. Officials say 62 million trees died just this year. The die-off is expected to continue through 2017.
