Californians trembled two years ago as 200-foot flames from the Rim fire sent up pyrocumulus clouds visible 100 miles away from the central Sierra Nevada.
Burning from August to October, it left a charred footprint nearly the size of Los Angeles — a reminder that the state had just passed through two dry winters. The lack of moisture alone killed nearly 2 million trees.
Things are much worse now. The combined totals from the last two winters make them the driest back-to-back years on record. Last winter, the snowpack was 5% of average in the Sierra, one of America’s snowiest mountain ranges.
In April, federal authorities estimated 12 million trees dead just in the southern Sierra Nevada and Southern California. The state Department of Forestry and Fire Protection, known as Cal Fire, has seen nearly 1,000 more fires than usual.
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We’re in an unparalleled situation. This is an emergency.
Matt Dias, assistant executive officer of the California Board of Forestry and Fire Protection
California waits in dread of the next big wildfire. Ground zero is east of Fresno in the southern Sierra, home to Yosemite and Sequoia and Kings Canyon national parks as wells as the last native giant sequoia groves on the planet.
“We’re in an unparalleled situation,” says Matt Dias, assistant executive officer of the California Board of Forestry and Fire Protection. “This is an emergency.”
There is big concern for mountain communities. The forestry and fire protection board adopted an emergency rule bypassing usual procedures so private landowners can quickly remove dead and dying trees. It is expected to take effect July 11.
In Yosemite National Park communities, such as Yosemite West and Wawona, people are very aware of the situation.
“Residents are keeping the areas around their homes defensible,” says Gary Wuchner, Yosemite fire information and education specialist. “They’re removing tree needles and trimming back limbs. They’re prepared. They’re a little afraid.”
From green to red
Bark beetles and drought are companions in forests. Droughts weaken trees. Bark becomes an easier target for beetles — like the western pine beetle, which is feasting right now in 2 million acres of Sierra and Sequoia national forests.
The U.S. Forest Service in April estimated 5 million trees have died in the lower elevations of the two forests east and southeast of Fresno. Last year, only 300,000 trees died in the same areas, the Forest Service reported.
How can you determine if a green and seemingly healthy tree is being attacked? Experts say look on the bark for tubes of pitch, a tar-like substance that a healthy tree uses to push out a beetle trying to bore into it.
When a tree is stressed by drought, you don’t see pitch tubes, says Tom Smith, Sacramento-based forest pest management specialist with Cal Fire. The beetles take over the bark, and green trees slowly change over to red as they wither and die.
Aerial photographs this year show vast stretches of red.
“The epidemic seems to be hitting hard for the ponderosa pine,” Smith says. “It will get worse as the summer continues.”
5 milliontrees have died in Sierra and Sequoia national forests, east of Fresno
Scientists say the Sierra’s forests have long been stressed by overcrowding, due to the practice of dousing every fire spotted over many decades in the last century. Before fire suppression, small, frequent fires started by lightning strikes would naturally control such overgrowth.
The practice was stopped many years ago, but dense stands of trees and undergrowth remain. The Rim fire, which burned more than 400 square miles in 2013, hit overdrive when it passed through thick-forested areas that had not burned in a century.
At times, such a fire can send smoke into the San Joaquin Valley, one of the most compromised air basins in the country. The smoke carries dangerous, microscopic debris. Breezes also bring ozone-making gases, called oxides of nitrogen, from the flames.
In addition, a large fire can send climate-warming gases into the atmosphere in the form of carbon being released as trees burn.
“If we have a catastrophic fire, there will be a huge release of carbon into the atmosphere,” says Smith. “Forests are supposed to be a carbon sink or reservoir, not a big contributor of carbon.”
Completely defensive now
Since the late 1960s, the adjoining Sequoia and Kings Canyon National Parks in the southern Sierra have been setting small fires to clear dense brush and small trees that would create a destructive fire.
It’s called prescribed burning, but now is not the time for this important ecological tool. In most places, it’s just too dangerous to intentionally set even a small fire.
Around Sequoia and Kings Canyon, foothill areas have lost up to 50% of their graceful and stout oak trees. Higher in elevation, there are large pockets of pines turning red.
“We will aggressively suppress fires in the front country where there are people and buildings,” says Dave Allen, fire management officer for the parks. ‘There are developed areas like Wilsonia, Silver City and Mineral King.”
2,500years of living gives giant sequoias a lot of exposure to drought and wildfires
The parks will defend their giant sequoia groves, as well. Seven of the world’s largest trees live in the parks, including the General Sherman Tree, the largest tree by volume in the world.
The fire-scarred mature trees can live more than 2,500 years, so they have seen many droughts and many wildland blazes. Their fire-resistant bark, along with the National Park Service’s years of prescribed burning, will help protect them.
The prescribed burning helps in other ways, too, says parks fire ecologist Tony Caprio.
“Plots in prescribed burns tend to have less tree mortality in drought,” he says. “The vegetation has been thinned, so there’s less competition for water.”
More than 60% of Sequoia and Kings Canyon parks is above 9,000 feet in elevation, Allen says. Four of every five fires in these parks are started by lightning, he adds.
At the same time, he urges visitors to avoid becoming a part of the fire problem. Follow the fire restrictions in the park.
No wood or charcoal fires are allowed at Buckeye Flat, Potwisha and South Fork campgrounds, as well as Ash Mountain and Hospital Rock picnic areas. The restriction extends to all wilderness areas below 6,000 feet.
“This season is different because it is so dry,” Allen says. “We’re staffing up for fire suppression, and hoping for the best.”