Ancient North Coast Forests Losing Their Protection; Redwoods Face Warmer Drier Weather, Failing Fog
EDIT
But rather than an anomalous freak of weather creating once-in-a-decade wildfires, experts say the recent blazes provide a vision of a future with much more fire endangering the North Coast’s pine and oak forests. “We’re starting to see fires and devastating type of activities in the redwoods, which doesn’t happen. In our lifetimes, this has not happened,” Cal Fire Chief Thom Porter recently told CNN.
The ancient conifers and oaks of the North Coast are historically so resilient to fire that they are known as “asbestos forests.” Fire has long been part of the coastal landscape, yet the typical low-intensity burns don’t permanently harm redwoods because they are armored in two-foot-thick bark. But uncontrolled fire among giant trees is a more urgent matter that poses a new danger to the forests.
“There’s a long-held belief that redwood forests just don’t burn or are resistant to fire. Not true,” said Angela Bernheisel, a Cal Fire Division Chief in the San Mateo/Santa Cruz Unit, where multiple fires are burning in coastal zones. Even the recent high-severity fires are not likely to kill entire forests. Older, larger trees can withstand scorching. Park officials at Big Basin Redwoods said that flames burned the understory but the tallest trees are expected to recover. But Bernheisel said the ferocity of this year’s fires in the big trees should sound an alarm about the changes underway in California’s forests.
EDIT
Even the fog that reliably blankets the North Coast is dissipating. Research from University of California, Berkeley found that fog frequency has declined by a third compared with a century ago. Because the oceans have warmed, their cold, deep water can’t mix with warmer surface water, which weakens the upwellings that create the coast’s fog. “Coast redwood and other ecosystems along the United States west coast may be increasingly drought stressed under a summer climate of reduced fog frequency and greater evaporative demand,” the study found. Fog is critical to tree health because coastal forests receive as much of a third of their water from fog banks, absorbing moisture through their leaves or needles. A decline in the marine layer that tempers the sun’s radiation also results in dry soils and stressed, fire-ready vegetation.
EDIT
https://calmatters.org/environment/2020/09/california-asbestos-forests-no-longer-immune/