(CN) – When the University of California, Davis, released its annual State of the Lake Report this month it broached an unusual topic. The report that delves into the health of Lake Tahoe typically focuses on water quality issues that affect the famed and peerless clarity of the largest alpine lake in North America. But this year, scientists and researchers cast an eye toward the forests that surround Lake Tahoe, noting an increasing presence of brown, desiccated and dying trees.
Large swaths of the stately pines of the Lake Tahoe Basin have turned brown. Dying and dead trees intermingle with the otherwise healthy coniferous forest, the signs of enduring years of a sustained and deep drought.
“Tree mortality in Tahoe has become evident in the last two or three years, but this year it was through the roof,” said Geoffrey Schladow, director of the Tahoe Environmental Research Center.
Schladow said the problem isn’t mere cosmetics, but will cause ecological issues as well.
“Sugar pines have been hit disproportionately by the drought,” Schladow said. “There are species in the system that rely on certain trees or live at certain altitudes, so it has ramifications for the entire system.”
Residents and visitors to the Tahoe Basin may have just begun to notice the strain on the forest created by a 5-year drought, extreme in both intensity and duration.
Compounding the problem is an ill-timed explosion in the population of bark beetles, which move into a drought-stressed tree to finish the job.
But while Tahoe’s problem is just manifesting, the southern stretches of the Sierra Nevada have been devastated.
“Tahoe’s witnessed tree mortality recently, but it is not nearly as bad as Southern California,” said Malcolm North, a forest ecologist with UC Davis. “In some areas of the Southern Sierra there are entire watersheds where 80 or even 90 percent of the trees are dying.”
The U.S. Forest Service estimates that more than 102 million trees have died in California forests since 2010. More than half the deaths occurred in the last year alone.
Most agree on the two primary factors in tree mortality – drought and insects. But scientists, policymakers and forest managers debate whether decades of fire suppression in the Sierra, in the interest of protecting private property, has rendered the forests of California’s most prominent mountain range overcrowded, unhealthy and prone to catastrophe.
Let it burn
Increasingly, experts wonder whether the policy of fire suppression in California forests, as carried out by both federal and state forest management agencies, is too expensive, dangerous for firefighters and residents and bad for ecological health.
Malcolm North has published several scientific studies that discuss the unnatural density of the forests, which makes them more prone to catastrophic wildland fires and more susceptible to water scarcity and drought.
“The lack of fire in forest systems is the real cause of tree instability and a lack of forest health,” North said.
The ecologist said there is increasing recognition among government institutions and forest management agencies that the fire suppression techniques they have been relying on for the better part of a century should be reconsidered.
Dave Fournier, natural resources staff officer for the Tahoe National Forest said fire suppression has caused an unnatural condition for the forest.