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How Wildfires Work

By Ryan Simonovich

Thursday, November 16, 2017 | Number of views (1326)

Wildfires have burned over 8.8 million acres of land in the United States this year, according to the National Interagency Fire Center.

 

Southwest Colorado has a legacy of wildfires. In 2002, the Missionary Ridge Fire burned over 70,000 acres north of Durango, and in 2013, the West Fork Complex Fire burned over 109,000 acres near Wolf Creek Pass, according to the National Wildfire Coordinating Group.

 

This past July, the Lightner Creek Fire burned 412 acres just miles west of downtown Durango. Numerous other fires burned throughout the region.

 

Fires start from three factors acting together - fuel, heat and oxygen, Julie Korb, a professor of biology at Fort Lewis College said. This is called the fire triangle, she said.

 

There is another fire triangle that describes the way fires behave, she said. The fire behavior triangle includes climate, fuel, and topography, she said.

 

"Fuel is that common leg between the fire triangle and the fire behavior triangle,” Korb said.  

 

Fuel

 

Historically, United States Forest Service fire suppression policy has led to a buildup of fuel, she said.

 

Since the early 1900s, the Forest Service has seen all fires as bad things that should be extinguished immediately, which led to the 10 a.m. rule, which said that all fires should be put out by 10 a.m. the next morning, Korb said.

 

This policy allows fuel to build up in forests. The ideal policy would be to let smaller fires burn naturally so that fuel does not build up and cause larger fires, Korb said.

 

Fire fighting policy is reflected in the Forest Service’s budget, Jimbo Buickerood, lands and forest protection program manager at San Juan Citizens Alliance said.


 

“More than 50 percent of the Forest Service’s national budget goes to firefighting,” Buickerood said.

 

One goal is to shift that budget more towards fire prevention up front, he said.  

 

Locally, the Forest Service focuses on both fire prevention and fire fighting, Lance Martin, assistant superintendent of the the San Juan Interagency Hotshot Crew said.

 

"It's a mixed bag,” Martin, said. “There obviously is a suppression budget, and we use it, but also there is a lot of money, too. Especially here on this forest, we've been doing a lot of hazardous fuels reduction projects.  We do a lot of prescribed burning on the forest.”

 

The Forest Service budget is determined by Congress, Martin said. Money is then allocated to each individual forest, he said.

 

It is beneficial to let forest fires burn if they do not threaten infrastructure and human life, Korb said. Letting a fire burn gets rid of vegetation that could be fuel for future fires, she said.   

 

“It just depends on where it's at,” Martin said. “If we have one up in the wilderness, maybe we're going to look at that one as a fire that we're going to kind of let it take its natural role on the landscape.”

 

Public safety is important, so if a fire is closer to infrastructure, then firefighters will be more aggressive in fighting it, he said.

 

"What we know is that fire is a natural part of all of these ecosystems,” Korb said.

 

Fuel has been building up for decades, so fuel is not a problem that is unique to 2017, Korb said. Rather, climate is the main factor as to why this year's fire season has been so large, she said.  

 

Climate

 

Climate, such as dry winters leading into hot summers, can lead to low fuel moisture content, which was a large factor in the Missionary Ridge Fire, Korb said.

 

“The fuel moisture content in the wood, the live trees in the forest, was lower than the fuel moisture content you would find in the wood at Home Depot,” she said.

 

Climate change explains why harsher fires can occur in the summer and fall, even if there was good snowpack during the previous winter, like this year in Durango, Korb said.

 

"One of the things with climate change is that we've been seeing that spring is coming earlier, and that the warming temperatures are happening for consecutive days,” she said.

 

Winter snowmelt runoff is occurring two to three weeks earlier than it did three decades ago, and in some areas the fire season is two months longer than it used to be, Buikerood said.

 

Durango saw a good winter and a dry spring, which led to perfect fire conditions in early July when the Lightner Creek Fire started, Korb said.  

 

Fire is not one event, but a series of events, Korb said. The third factor on the fire behavior triangle, and an important factor in the Lightner Creek fire, is topography.  

 

Topography

 

The topography near the Lightner Creek Fire was steep. The fire started climbing up a steep ridge, which allowed to fire to spread faster, Korb said. Once at the top of the ridge, the fire started traveling downhill, which slowed the fire down, she said.

 

Another factor of the Lighter Creek Fire topography was patchy vegetation, Korb said. Different types of vegetation and patches of bare ground slowed the fire down and allowed it to be put out, she said.

 

In order to put out a fire, one of the legs of the triangle has to be removed, Korb said. For example, topography can change, or if it rains, then the heat element is removed, she said.

 

Prevention

 

An important issue of wildfires is the wildland urban interface, Buikerood said. The wildland urban interface is the transition from the city to the forest, he said.

 

More and more people are choosing to live in the forest, and they are at a greater risk if a wildfire breaks out, he said.

 

People who live in the forest, or what experts call the wildland urban interface, can also contribute to wildfires starting. The Lightner Creek Fire began as a fire inside a house and then turned into a wildfire, Korb said.

 

There are multiple strategies to wildfire prevention in the wildland urban interface. Fuel mitigation, prescribed burns and building codes can improve the odds, Buikerood said.

 

Raking up leaves and trimming trees around houses can help insure that fire does not burn entire neighbourhoods down, Korb said. Organizations such as Firewise have been working to do this in communities around Durango.

 

“There's been much better collaboration between the Forest Service, Bureau of Land Management, Bureau of Indian Affairs and the state,” Buikerood said.

 

A good example of this cross landowners management is in Deer Valley Estates near Bayfield, he said. The homeowners association cleaned up all the fuel on their property, and then the Forest Service performed controlled burns on their bordering land, he said.  

 

As a part of this, the Forest Service completed a 6,000-acre burn along the U.S. Highway 160  corridor while working with different land managers, Martin said.

 

“We need to find that balance of where we allow fires to burn so that we have healthy ecosystems, but that we’re also then protecting people's lives and their homes and the communities which they live,” she said.

 

Fire is a natural part of ecosystems, and it is never going to go away, Korb said.

 

“Frankly the only way it’s going to come back into some kind of balance is if we start doing a lot more prescribed fires, and kind of fuels treatment, and then of course there’s the climate thing which were not doing basically anything about,” Buikerood said.

 

Follow general news editor Ryan Simonovich and The Independent on Twitter for news updates.

 
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