Tree mortality in Lake Tahoe’s forests has increased drastically

Monday, July 31, 2017

Lake Tahoe’s famously clear waters continue to warm, and the surrounding forests face dire threats due to drought, disease and insects, according to the annual Tahoe State of the Lake report by researchers at UC Davis.

The second deepest lake in the United States after Crater Lake, Lake Tahoe has warmed by half a degree Fahrenheit each year for the past four years — 14 times faster than the historic rate, the report said.

Overall, summer weather has been persisting for longer, with earlier spring snowmelts. Last year’s snowmelt began on March 29, 2016 — 19 days earlier than in 1961, the report found. A warming climate may bring changes to Lake Tahoe’s ecosystems and the plants and animals they support.

Tree mortality in Tahoe’s forests has increased drastically, with the number of dead trees more than doubling from 35,000 in 2015 to 72,000 last year due to the stress of the drought combined with attacks from insects and disease, according to the report. The problem was worst on Tahoe’s north shore, but forests on the east shore were also affected.

Beth Moxley, an arborist and owner of Rockwood Tree Service, has witnessed the damage from the blister rust fungus and pine beetle infestation. She’s worked in the Tahoe area since 1986.

“We’re basically in a crisis,” she said about the large number of dead and dying trees in the Tahoe Basin. “It all started with the drought. The trees become weakened and then they’re susceptible to attack by disease or insect infestation.”

Pines in the area have been severely affected by the blister rust, which has no cure. “I took down a 600-year-old sugar pine the other day,” Moxley said. The massive tree die-offs also raise the risk of forest fires.

“We’re sitting ducks,” Moxley said. “It’s not a matter of if. It’s when and where.”

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