As three major fires blaze in California, we consider some of their causes, both human and meteorological. Science correspondent Miles O’Brien has been filming a NOVA documentary on megafires and witnessed the Camp Fire not long after it began. He joins William Brangham to describe that stunning experience, along with the broader scientific context around these destructive phenomena.
By Guy Kovner
Sudden oak death has killed up to 50 million trees and 100 million more may be infeceted, according to new research.
A dry winter curtailed the presence of a deadly forest pathogen this year in Sonoma County and 13 other Northern and Central California counties, but experts still expect the oak-killing disease to spread and warned landowners to be vigilant.
Since the mid-1990s, sudden oak death has killed up to 50 million trees from Big Sur to southwest Oregon and is entrenched in the woodlands, spreading rapidly after wet winters and slower during dry years.
“It’s constant, it’s emerging,” said Richard Cobb, an assistant professor of forest health at Cal Poly San Luis Obispo. “It’s probably going to get a lot worse.”
Cobb said Monday he’s about to publish his estimate of tree mortality, 90 percent of which are tanoaks and most of the rest coast live oaks. Another 100 million trees may be infected by the insidious pathogen that typically takes one or two years to produce symptoms in the infected trees, he said.
The pathogen can be spread by human footprints and nursery plants, but in nature it rides on water droplets blown from the leaves of bay laurel trees, a host species that abounds among the oak and tanoak trees susceptible to the disease.
“We know there’s a lot of disease out there,” said Matteo Garbelotto, director of the forest pathology and mycology laboratory at UC Berkeley, which has organized annual sudden oak death surveys, known as the SOD Blitz, since 2008.
This year’s survey found the estimated rate of infection — based on lab analysis of leaves collected from bay laurels and tanoaks — at 3.5 percent throughout the 14-county region, a marked decline from 12.8 percent last year.
Sonoma County, divided into three areas, also showed sharp declines, which Garbelotto said were anticipated because the 2017 survey, conducted in the wake of two straight wet winters, found the highest infection rate ever recorded in 11 years.
But the survey conducted in May found another consequence — the presence of oaks showing symptoms of infection had increased to 12.2 percent throughout the region, up from 9.4 percent last year.
Next year’s rate should be higher, Garbelotto said, coming two years after the 2017 rains and matching the time it takes for symptoms, such as bleeding cankers in oak tree bark, to appear.
By Thomas Fuller
After a three-year restoration project, the Mariposa Grove of giant sequoias in Yosemite National Park has reopened, with less asphalt and more concern for the health of the trees.
YOSEMITE NATIONAL PARK, Calif. — John Muir, the naturalist who was most at home sleeping outdoors on a bed of pine needles in the Sierra Nevada, called giant sequoias the “noblest of God’s trees.”
For three years, some of the most striking examples of these towering marvels were off limits to visitors in Yosemite National Park. After a $40 million renovation — the largest restoration project in the park’s history — the Mariposa Grove, a collection of around 500 mature giant sequoias, reopened last week.
What Muir called a “forest masterpiece” is now back on display.
The renovation addressed a problem that the park has struggled with for years. On the busiest summer days, more than 7,000 cars may converge on the park, which is about a four-hour drive from San Francisco. The gridlock they create amid the stunning chutes of water running down the steep granite slopes of Yosemite’s glacier-carved valley results in a kind of drive-by naturalism that frustrates many.
By Christine Souza
Despite the wet winter and far-above-average Sierra Nevada snowpack, California forests remain at risk from tree mortality, bark beetle infestations and overgrown landscapes, according to presentations at the 2017 California Farm Bureau Federation Leaders Conference.
During the event, foresters and forest landowners discussed all those issues and communicated concerns directly to Randy Moore, U.S. Forest Service Pacific Southwest regional forester, who participated as a guest speaker.
Shaun Crook, a timber operator and president of the Tuolumne County Farm Bureau, emphasized to Moore the need for effective forest management and that it be included in the agency’s updated forest plans, to reverse the damage happening in the national forests. The Forest Service is currently working on forest plans to serve as the land management framework for the Inyo, Sequoia and Sierra national forests, which are expected to serve as blueprints for other forests in the Sierra and across the country.
“As we go forward with the forest plan revisions and the (tree) mortality, we need to be more proactive with the green and timber sale program to start getting the forest back into that state that it was 100 years ago, before we can just let fire do its thing, or we’re going to continue to have the catastrophic fires like the King Fire and the Rim Fire,” said Crook, a contract logger and grazing permittee in the Stanislaus National Forest. “We need a guaranteed harvest level coming off of the national forest because without that, we won’t get this private infrastructure back.”
Scientists say more low-intensity wildfires are needed to clear out overgrown forests to help prevent bigger fires. Deciding where and when to let fires burn is tricky.
Dangerous wildfires made a lot of news across this country last year. But there are scientists who say we need more fires, low-intensity ones that clear out overgrown forests and help prevent the bigger fires. Deciding where and when to let fires burn is tricky, and so the U.S. Forest Service is working on a new approach.
Fires aren’t all bad. Some fires help forests become healthier, but scientists say they’re sorely lacking in California.
Sierra Nevada forests are adapted to low-intensity fires that clear the underbrush and prevent trees from getting too dense. After a century of fire suppression, many forests are overgrown, which can make catastrophic fires worse.
So forest managers are piloting a new policy designed to shift a century-old mentality about fire in the West.
The idea is to let naturally-caused fires burn when they aren’t a threat to homes or people. But actually making those decisions on the ground isn’t easy in a crowded state like California.
There are killing machines on the loose in California and the entire Western region.
They’re found in packs and look for the weak but they’re not the scary predator you’d imagine. In fact, they’re about the size of a rice grain.
They’re called bark beetles.
A June 2016 Cal Fire report stated the ongoing drought in combination with the tiny insects are responsible for killing about 66 million trees in California since 2010. That’s up from 29 million trees in 2015 and 3.3 million in 2014, according to the report.
Pine trees in California forests will die out and give way to brush and chaparral, forestry experts warn, unless agencies undertake what one analyst called a “massive effort” to reduce fuels and replant trees. Otherwise, the conversion to chaparral could further increase risk of wildfires and affect the state’s water supply.
A U.S. Forest Service survey, released in June, revealed that 66 million trees—mostly pine species—have died in the southern Sierra alone, due to bark beetle infestations, drought, wildfire and climate change. One question now, experts say, is what will replace those dead trees.
“We know in the Sierra and Sequoia national forests east of Fresno, the beetles have killed at least 85 percent of the entire pine vegetative type and at least 20 percent of the mixed conifer type, which is pine and fir,” said Steve Brink, California Forestry Association vice president of public resources. “By the end of this summer, essentially 100 percent of the pine type will be dead in the Sierra and Sequoia national forests, and you are going to have a massive conversion to chaparral.”
California has suffered more than 5,000 wildfires this year, and we’ve only reached the beginning of the season. Just last week, more than 10,000 firefighters were battling blazes throughout the state – fires largely fueled by already-dead, dry trees.
But many of those trees aren’t dying of old age. They were killed by one tiny culprit: the bark beetle.
The California legislature has passed legislation that aims, in part, to support existing biomass plants within the state. The bill, SB 859, features an expenditure plan for unallocated cap-and-trade proceeds.