© U.S. Drought MonitorThis color-coded map shows drought conditions across the U.S., on April 30, 2015. Much of San Diego County, shown in red, is in an "extreme" drought. At this level, major crop and pasture losses are common, fire risk is extreme, and widespread water shortages can be expected, requiring restrictions.
An estimated 12 million trees across California's forestlands have died over the past year because of extreme drought conditions, according to an aerial survey conducted April 8-17 by the U.S. Forest Service.
In San Diego County, 82,528 trees, mostly Jeffrey pines across Mt. Laguna,
have succumbed to a lack of rainfall, with many more struggling to survive, said Jeffrey Moore, interim aerial survey program manager for the U.S. Forest Service.
There is "very heavy mortality, a lot of discoloration in the pine trees that probably will expire sometime during this growing season, as well as oak trees that are suffering," Moore said.
Moore was part of a team that surveyed the trees visually, using a digital mapping system while flying in a fixed-wing aircraft 1,000 feet above ground.
A tree's survival often depends on its proximity to other trees, he said.
"A lot of trees are competing for whatever available moisture there is in a drought situation," Moore said. "When you have too many trees in an area, it makes it hard on all of the trees."
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