Sunday, December 5, 2021

U.S. Forest Service Struggles To Complete Prescribed Burns

When a bushfire broke out in a federal research area in Klamath National Forest this summer, scientists were dismayed to see more than 20 years of work turned into smoke.

But when they returned to the charred exploration area near California’s northern border, they realized they were presented with a unique opportunity.

While scientists set out to understand how thinning and controlled burning of vegetation could help grow larger trees faster, they now had the opportunity to explore another pressing question: could these same treatments make forests more resistant to wildfires? Or, more specifically, could they soften the behavior of the fire so that the flames are less intense and the firefighters have a better chance of extinguishing the flames before they burst into the populated area?

The answer was convincing: yes.

“In areas where we did nothing, untreated controls, the predominant fire behavior was canopy fire, which destroyed every tree and destroyed the entire tree canopy,” said Eric Knapp, an environmental researcher with the US Forest Service.

However, he said, the sites that were thinned out and then treated with broadcast burning, on which a plot of land is set on fire, simulating a natural forest fire, remained relatively unscathed.

Once confirmed, the results will be some of the most compelling scientific evidence to support the effectiveness of these so-called fuel treatments, Knapp said. But they weren’t unexpected. In the past, researchers have found that the best result is achieved by a combination of thinning canopy or crown fuel and burning surface fuel or vegetation on the ground.

Despite this knowledge, however, the federal government, which manages roughly 57% of California’s forestland, has completed only half of the fuel it hoped to do in the state in a year – a statistic that deeply alarmed forest fire experts. …

As of mid-September, the Forest Service has completed or leased less than 37,000 acres of prescribed firefighting projects in California since October 1, 2020. This is mainly the burning of stacks of vegetation piled up after thinning, in which teams cut branches or cut down smaller trees, often using chainsaws or cranes.

A raw control unit in the Goosenest Adaptive Management Zone in Klamath National Forest is shown after a fire engulfed the area on 5 August 2021. said Eric Knapp, an environmental researcher at the US Forest Service.

(US Forest Service)

Another 6,063 acres of managed land included natural fires that were allowed to burn – a practice that the Forest Service suspended after it was heavily criticized in the summer.

An additional 5,000 acres were treated with broadcast burning, which, when combined with thinning, proved to be the most effective.

“It’s just depressing,” said Lenia Quinn-Davidson, a fire safety advisor at the University of California. “This is so small considering how much land in California the Forest Service manages. It’s just a drop in the bucket.

“I think this speaks to the need for such a radical change with regard to the prescribed fire.”

In total, as of September 17, the Forest Service met about 54% of its goal of cultivating 238,200 acres in the state during the fiscal year ending September 30. The target makes no distinction between prescribed incineration and other methods. removal of vegetation. These include grazing, thinning, chemical treatments such as herbicides, and the removal of thinned vegetation, including biomass removal, chopping, shredding and stockpiling.

The United States Bureau of Land Management and the National Park Service, which manage much less forested land in California, were no better. The NPS conducted a total of 616 acres of radio broadcasting in the state this calendar year; BLM plans to burn about 300 acres, but that hasn’t started yet.

Officials say the lag in timber processing is due to several factors, including a lack of funding and personnel, as well as fundamental changes in the fire season. They say drought, climate change and fuel overload have lengthened the season and narrowed the time frame in which prepared burns can be carried out.

“There are many structural problems that need to be overcome in order to incinerate at the scale required,” Knapp said.

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A block in the Goosenest adaptive control zone that has been processed by thinning pine supports and burning out radio broadcasts.

A block in the Goosenest adaptive control zone, which was processed by thinning pine supports as well as two rounds of broadcast burning, is shown after the Antelope fire on August 5, 2021. Initial observations indicate that sites that have been thinned out and burned in a prescriptive manner have been successful. the best.

(US Forest Service)

The Klamath study, dubbed the Guozenest Adaptive Management Zone, is an area of ​​old woodland that was heavily deforested before being handed over to the Forest Service in the mid-1950s. Before it was privately operated, fires burned every nine years or so, but by the time researchers began focusing on the area, it hadn’t been on fire for decades, Knapp said.

The site was filled with young trees that fought for light and resources, and they went from pine to fir, which is less resistant to fire and drought, he said.

Scientists have been trying to figure out if some of the vegetation can be removed in order to redistribute growth to fewer trees, speed up their growth and restore a forest that looks more like what it looked like a century ago.

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They implemented three treatments: thinning to help restore pine trees; pine tree thinning plus two burns in 2001 and 2010; and thinning with preference for the largest diameter trees without regard to species. Each was repeated on five 100-acre parcels. Five control plots were not treated.

The lightning-triggered Antelope fire engulfed all sites for four days starting on August 4.

“Since we have five copies of each of these treatments, all of which have been affected by fire in often similar conditions, we can identify the effects of the weather and the effects of fuel,” Knapp said. “This will be a very compelling example of how fuel handling and weather conditions interact to affect outcome.”

Initial observations show that thinned and burned areas performed better, control areas poorer, and areas that were only thinned out were highlighted somewhere in the middle. There was no discernible difference between the two types of decimation.

“This shows me that under the most extreme fire conditions, thinning alone is often not enough,” Knapp said. “You also have to deal with things on earth.”

“This is not to say that thinning alone has not changed fire behavior,” he said. Although many trees in the thinned areas still died, they died from the heat, their needles turned brown. In contrast, the trees in the control plots were completely burned by the fire, leaving behind only dead blackened sticks.

This suggests that there was a fire on a hot surface in the thinned plots. However, the control sites experienced an even hotter fire that reached the crown and burned the canopy, likely spitting out coals in front of the main fire, causing it to move faster, Knapp said. These differences in intensity and speed can mean the difference between firefighters being able to fight a fire or being forced to retreat.

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Traditionally, some parts of California will have rainstorms in late September or early October, and radio broadcasts may start burning a couple of weeks after the vegetation dries up, Knapp said.

But in the past few years, autumn rains have not come until late October or November. By then, he said, the sun was so low above the horizon and so cool that rain-soaked vegetation would never dry out enough to carry out these burns. Knapp added that even if conditions are right, considerations related to fire smoke and air quality limit the number of burns that can be performed in one go.

At the same time, the seasons of fires have become longer and more intense, so the crews who once switched from extinguishing fires to staging them are no longer available because they are still in firefighting mode.

The National Interagency Fire Center reached its highest alert level, 5, in July, the earliest in a decade. The designation indicates that 80% of the national wildlands firefighting personnel are involved in incidents.

US Forest Service Chief Randy Moore referred to these resource constraints in August when he announced that the agency would no longer consider conducting prescribed burns until readiness levels dropped to 2.

“We are in ‘triage mode’ where our main focus should be on fires that threaten communities and infrastructure,” he wrote in a memo explaining the decision.

The move highlighted the urgent need for full-time staff dedicated exclusively to prescribed incineration, with well-paid and attractive positions, Quinn-Davidson said.

“We need more jobs that focus on prescribed fire and fuel handling measures that are not used to put out a fire,” she said.

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Authorities warn that many forests in the western United States have suffered from imbalances for years due to aggressive firefighting practices and climate change that broadcast burning alone is not enough to restore them.

National forests like Eldorado are now so overgrown that the landscape often has to go through one or more rounds of thinning before the land can be safely ignited, said Jeff Marsolice, an Eldorado forest inspector who has not seen the prescribed burns this fiscal year.

“We’re trying to get to where we can broadcast burning, and natural fire burning the earth like it was 100 years ago is exactly what we’re aiming for,” he said. “But there is a tremendous amount of work to be done to restore forest resilience before we can reach that level.”

And even if federal authorities were able to carry out these treatments on the scale required, the increasingly extreme conditions in which fires still burn mean that they will not always be enough to protect forests and communities from damage.

One of the events that surprised the researchers in the Goosenest study, Knapp said, is that one of the diluted and prescribed fire-treated blocks that burned during the four-hour high wind appeared to have been quite badly damaged despite the low surface and top fuel load.

“In my opinion, this shows that there may be some limits to what can be done in harsh fire conditions,” he said. “Maybe when we are faced with the worst conditions, there is simply not much you can do to prevent it.”

However, he said, strong winds tend to be of limited duration and account for a fraction of the time a fire burns. In addition, treatment can slow the spread of the fire, so there will be fewer burns in such extreme conditions, he added.

The plot was also overdue to receive yet another batch of the prescribed fire, highlighting the importance of maintenance. And it still does better than control plots that burned under the same weather conditions, he said, estimating that 25% to 50% of trees would survive.

“So even in the worst conditions, he did something to make the forest more resilient,” he said. “Just maybe not as stable as we hoped.”

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