THREE RIVERS, California: Firefighters wrapped the base of the world’s largest tree in a fire-resistant blanket as they tried to save a famous grove of gigantic old-growth sequoias from wildfires burning in California’s rugged Sierra Nevada.
The colossal General Sherman Tree in Sequoia National Park’s Giant Forest, some other sequoias, the Giant Forest Museum and other buildings were wrapped for protection against the possibility of intense flames, fire spokeswoman Rebecca Paterson said.
The aluminum wrapping can withstand intensive heat for short periods. Federal officials say they have been using the material for several years throughout the US West to protect sensitive structures from flames. Near Lake Tahoe, some homes that were wrapped in protective material survived a recent wildfire while others nearby were destroyed.
* Giant sequoias are adapted to fire, which can help them thrive by releasing seeds from their cones and creating clearings that allow young sequoias to grow. But the extraordinary intensity of fires — fuelled by climate change — can overwhelm the trees.
The Colony Fire, one of two burning in Sequoia National Park, was expected to reach the Giant Forest, a grove of 2,000 sequoias, at some point within days, fire officials said.
However, the fire didn’t grow significantly on Thursday as a layer of smoke reduced its spread in the morning, fire spokeswoman Katy Hooper said.
It comes after a wildfire killed thousands of sequoias, some as tall as high-rises and thousands of years old, in the region last year.
Sequoia and Kings Canyon national parks Superintendent Clay Jordan stressed the importance of protecting the massive trees from high-intensity fire during a briefing for firefighters.
A 50-year history of using prescribed burns — fires set on purpose to remove other types of trees and vegetation that would otherwise feed wildfires — in the parks’ sequoia groves was expected to help the giant trees survive by lessening the impact if flames reach them.
A “robust fire history of prescribed fire in that area is reason for optimism,’’ Paterson said. “Hopefully, the Giant Forest will emerge from this unscathed.’’
That happened last year when the Castle Fire killed what studies estimate were 7,500 to 10,600 large sequoias, according to the National Park Service.
A historic drought and heat waves tied to climate change have made wildfires harder to fight in the American West. Scientists say climate change has made the region much warmer and drier in the past 30 years and will continue to make weather more extreme and wildfires more frequent and destructive.
A national interagency fire management team took command of efforts to fight the 11.5-square-mile (30-square-kilometre) Paradise Fire and the 3-square-mile (8-square-kilometre) Colony Fire, which was closest to the grove. Operations to burn away vegetation and other fuel that could feed the flames were done in that area.
The fires forced the evacuation of the park this week, and parts of the town of Three Rivers outside the main entrance remained evacuated.
To the south, a fire on the Tule River Indian Reservation and in Giant Sequoia National Monument grew significantly overnight to more than 6 square miles (15 square kilometers), and crews had no containment of it, a Sequoia National Forest statement said.
The Windy Fire, also started by lightning, has burned into part of the Peyrone Sequoia Grove in the national monument, and other groves were threatened.
“Due to inaccessible terrain, a preliminary assessment of the fire’s effects on giant sequoia trees within the grove will be difficult and may take days to complete,’’ the statement said.
The fire led the Tulare County Sheriff’s Office to warn the communities of Ponderosa, Quaking Aspen, Johnsondale and Camp Whitsett, a Boy Scouts camp, to be ready to evacuate if necessary.
The wildfires are among the latest in a long summer of blazes that have scorched nearly 3,550 square miles (9,195 square kilometers) in California, destroying hundreds of homes.
Crews had limited ground access to the Colony Fire and the extreme steepness of the terrain around the Paradise Fire prevented it completely, requiring extensive aerial water and flame-retardant drops on both fires. The two fires were being managed collectively as the KNP Complex.
Using firing operations to burn out flammable vegetation and other matter before the wildfire arrives in the Giant Forest is one of several ways firefighters can use their nemesis as a tool to stop, slow or redirect fires.
The tactic comes with considerable risks if conditions change. But it is routinely used to protect communities, homes or valuable resources now under threat from fires, including the grove of about 2,000 massive sequoias, including the General Sherman Tree, the world’s largest by volume.
Here’s how it works:
IT’S ALL ABOUT THE FUEL: Three things influence how hot and fast a fire burns: the landscape, with fire burning faster up steep slopes” weather, with winds and dry conditions fanning flames” and fuel, the amount of material that can burn.
The first two can’t be controlled, but there are ways to reduce fuels long before any fire breaks out _ or even as one is approaching.
“Of all the things that affect fire behaviour, the fuels is really where we can take action,’’ said Maureen Kennedy, a professor of wildfire ecology at the University of Washington.
Historically, low- to moderate-severity fires every five to 30 years burned out excess brush and timber before deadly fires in the early 20th century led to aggressive firefighting and a US Forest Service policy to suppress all fires by 10a.m. the day after they were reported.
That led to dense forests of dead trees, fallen logs and overgrown brush that accumulated over the past century, fueling more massive fires.
SLOWING FIRE BY CREATING FIRE: For centuries, Native Americans have used fire to thin out forests.
Prescribed burns set under favourable weather conditions can help mimic the lower-intensity fires of the past and burn off excess fuels when they are not at risk of getting out of control. If fire eventually burns the area, it will likely do so at lower intensity and with less damage.
The idea is the same during a wildfire. Fire chiefs try to take advantage of shifting winds or changing landscapes to burn out an area before the fire gets there, depriving it of the fuel it needs to keep going.
“They’re trying to achieve the same effect,’’ Kennedy said. “They’re trying to moderate the fire behavior. They’re trying to remove the fuels that make the fire burn so intensely. Of course, their goal there is to better contain and control the fire and protect the more valuable resources.’’
SAFELY SETTING MILD FIRES: All wildland firefighters learn about burnout operations in basic training, but it takes a higher level of training to plan and carry out firing operations.
“You need to know how to fight fire before you light fire,’’ said Paul Broyles, a former chief of fire operations for the National Park Service.
Burning an area between the fire front and a projected point — such as a firebreak or the Giant Forest in Sequoia — requires the right conditions and enough time to complete the burnout before the fire can reach a fire line constructed by firefighters.
Often such operations are conducted at night when fires tend to die down or slow their advance as temperatures cool and humidity rises.
The convection of a fire pulls in winds from all direction, which can help. As fires climb steep terrain, burnouts are sometimes set on the other side of a ridge so any embers will land in an area where dry grasses and brush have already burned.
The firing operations require a crew making sure the fire does not spread in the wrong direction. It may also include bulldozers cutting fire lines or air tankers dropping retardant to further slow the flames.
All of it has to work in sync, Broyles said.
“Air tankers by themselves do not put fires out unless you follow up with personnel,’’ he said. “It’s like the military. You don’t just bomb the hell out of your enemy without ground troops.’’
While burnouts are commonly used, they can backfire if winds shift or they aren’t lit early enough.
“When you put more fire on the ground, there is a risk,’’ said Rebecca Paterson, a spokeswoman for Sequoia National Park. “It carries the potential to create more problems than it solves.’’
Broyles said there were times he didn’t get a burnout started in time and firefighters had to be evacuated.
“Fortunately, in my case, we didn’t have any losses,’’ he said.
SMALL FLAMES TO PROTECT GIANT SEQUOIAS: Firefighters on Thursday were conducting burnout operations in the Giant Forest at almost a micro level, moving from tree to tree, Paterson said. Ground cover and organic debris known as duff close to the trees was being set on fire, allowing the flames to creep away from the tree to create a buffer.
The General Sherman and other massive conifers were wrapped in aluminum blankets to protect them from the extreme heat.
The park was the first in the West to use prescribed fire more than 50 years ago and regularly burns some of its groves to remove fuels. Paterson said that was a reason for optimism.
"Hopefully, the Giant Forest will emerge from this unscathed,’’ she said.
Around 500 personnel were engaged in battling the Paradise Fire and the Colony Fire, which together have already consumed 9,365 acres of woodland since they erupted from lightning strikes on September 10.
The enormous trees of the Giant Forest are a huge tourist draw, with visitors travelling from all over the world to marvel at their imposing height and extraordinary girth.
While not the tallest trees - California redwoods can grow to more than 300 feet - the giant sequoias are the largest by volume.
Smaller fires generally do not harm the sequoias, which are protected by a thick bark, and actually help them to reproduce; the heat they generate opens cones to release seeds.
But the larger, hotter blazes that are laying waste to the western United States are dangerous to them because they climb higher up the trunks and into the canopy. -- AP