Prescribed Burning: Using little fires to reduce the threat of big fires

Wild Fire! Just the words spark terror in the hearts of folks in the Sierra Nevada and other dry regions of the Western United States. When we think of a forest fire, what comes to mind is thick plumes of smoke, devastated forests, and in some cases the loss of homes and lives. But it turns out that one of the most important tools to reduce the amount and impact of those monster fires is getting into the forest ahead of time under the right conditions to set small fires. 

“This portion of the Sierra Nevada is a fire adapted ecosystem. There is a long history of low intensity fires, every 7-15 years on average. Fires are nature’s clean up crews,” said Joe Flannery, Tahoe National Forest public affairs officer. The problem is that “100 years ago we started suppressing them all and now we have this giant fuel problem. We have a lot more trees growing to maturity, a lot more dead and downed trees. Now when we have fires they are high intensity fires. We need to break that cycle, to get back to routine low intensity fires. How do we get there?”

Fire management experts say we do it through a combination of forest thinning, pile burning and low intensity understory burning during periods of low fire danger. It will take time, concerted effort, and lots of money from federal, state, and local governments, as well as private companies and non-profit organizations to bring about the healthy forest that we all need. It will also take a focus shift from just fighting forest fires to forest management to reduce the need for fighting fires. And perhaps most importantly, it will take an understanding among the general public of what a healthy forest should look like, and that reducing the fuel load in our forests is key, even if it sometimes means our skies are filled with smoke. 

Since fires have been curtailed for so long, much of the public doesn’t realize that stands of fir and pines so thick that you can hardly see through them is not the way the forest looked like until the last 100 years. When forests are thinned followed by understory burns they often look naked and sparse to our eyes. But that is what the forest used to look like, and once you begin to understand that, you will truly appreciate the power and majesty of the ancient behemoths of the forest standing alone.  

An example of an overgrown forest in the Sierra Nevada – photo: Tim Hauserman

In early July, I took a tour of Burton Creek State Park with Rich Adams, prescribed fire manager for the Sierra District of the California State Parks. Adams showed me what the ground now looks like in places where he has conducted prescribed burns over the past 25 years. We passed by sections of untreated forest that were a thick hodgepodge of crowded live and dead trees, as well as sections of forest that had been treated and now have good spacing between the trees and healthy undergrowth. Where prescribed fires had been conducted there was a significantly reduced danger of future catastrophic fires. These areas were also a more open and inviting place for wildlife.

This part of the forest has been cleared of undergrowth using a prescribed burn and manual removal – photo: Tim Hauserman

Before we headed out on our tour, Adams showed me an ancient stump recovered in the Sierra from a petrified tree that had died in 1776, well before Americans had a chance to start altering western forests. The tree rings show evidence that it survived over a dozen fires during its two hundred plus year life span. These fires never got big enough to kill the tree because they were occurring often enough to clear out the weed-like growth of smaller trees and brush.

A cross section of a tree that died in 1776 – photo: Tim Hauserman

The Process of Prescribed Burning

Given the thick forests we now have to treat, in most cases the process of prescribed burning begins without a fire, but with a saw. The forests are too dense and dangerous to burn until they are thinned first. Trees are removed for lumber and bio mass, and often piles created for burning and smaller trees are left to sit and dry out in the thinned areas. Then once the piles are dried enough, they are burned.

The next step, sometimes a few years later, is a low intensity understory burn which cleans up the remaining brush and debris between the larger trees, thus eliminating what can become ladders into the canopies of the larger trees. Low intensity burning also adds needed nutrients to the soil. 

Sounds pretty simple? Sure, the concept is. Actually getting it done, not so much. “Each fire has a burn plan with specific conditions, a prescription,” said Flannery. It needs to be “not too hot, but not too wet, because then we won’t get enough area burned. Fuel moisture conditions have to be within a set of parameters. We can’t have it too windy, because that will move the flames, but we also need the smoke to disperse, so we can’t have an inversion.” 

And then sometimes they can have the perfect conditions to light the fire, “but do we have the people available to implement this? Fall used to be a great time to do fires, but now fire season is extended into the fall. Sometimes in the fall we don’t have the human resources,” said Flannery. The people who light small fires, are also the folks who fight big fires. 

Both Flannery and Adams emphasized the importance of prescribed burning, but spoke about the need for the public to understand and embrace the process. “There will be impact. There will be some smoke, equipment operating and personnel in your neighborhood. The landscape won’t look the same,” said Flannery. He suggested, however, that the public consider the alternative, “a wildfire event, with a more massive aesthetic impact and massive amounts of unhealthy smoke.” 

Adams’ job for the California State Parks includes conducting burns in small chunks of state owned land that is surrounded by nearby communities and residential development. This work is important because it can protect the homes and businesses close to the parks,  but it is also challenging because people in those communities don’t like to see smoke and fear a fire close to them will get out of control. 

Adams says an example of the challenge was a 19 acre burn in Burton Creek State Park in 2019. It went well during the day, but at night an inversion set in and the smoke didn’t disperse and settled down into Tahoe City. Businesses lit up the State Park phone lines and complained to the County Supervisor about the impact of the smoke. A fire planned for another 20 acres the next day had to be cancelled … and it is still waiting for the next window of opportunity to be lit up again.  And those windows are few and far between. 

For her book, “Wild Fire,” Heather Hansen spent a year with Fire Station 8 in the Wildland-Urban interface outside Boulder, Colorado. She says in the book:  

“Setting up an rx (prescribed) burn isn’t as simple as choosing an area where fire used to be and then lighting it up. Initially an area is assessed for ecological goals. Is it a place that will benefit from reintroducing fire? Will there be strategic benefits, like creating a fuel break between these resources and nearby homes? Will curtailing the fire be possible considering the area’s fuels and topography? is it possible to burn without smoking out nearby communities? Each potential patch is looked at individually to assess what constitutes a healthy state in that particular area.

“This process can take a year and a half. Sometimes burns are delayed weeks or even entire seasons. They build a plan considering every possible contingency, which can take 400 or 500 hours of work, and can be shut down by an unexpected event in town or an unanticipated cold front.”

Fire management in the Western United States is loaded with contradictions and challenges. We need to thin the forest and bring low intensity fires back to the ecosystem, but with the fuel build up over the last 100 years that has become very expensive and challenging to do. Reducing the fuel load would reduce the fire danger, but so much money is being spent on fighting fires it is hard to find the funding needed to reduce the fire danger. 

In addition, with more and more people living in the Wildland-Urban Interface there is resistance to any burning near homes and businesses. Hansen sums up the public reaction to prescribed burning, “Wait’ you’re going to light fire on purpose? That’s weird.’ ‘We don’t want you to do that.’ Or, ‘We want you to do it but we don’t want to be impacted.’ As soon as the smell of smoke gets in their windows it’s, “What are you guys doing? I can’t believe this. You are terrible. My curtains smell like smoke. Who is going to pay for my dry cleaning?”

Unfortunately, nature will get the last word. The forest and grasslands will burn, the only question is in small doses or catastrophic ones. Rich Adams is still optimistic about the long view.

“Once an area has been piled and burned, it will be much easier to burn again 10-20 years later, to keep the understory under control. The vision is that someday if we keep plugging away it will get easier, maybe the next forester will be able to accomplish more.”

Top photo caption and credit: A prescribed fire at Burton Creek State Park near Lake Tahoe – photo: California Department of Parks and Recreation

Tim Hauserman is a nearly life-long resident of North Lake Tahoe. He wrote the official guide to the Tahoe Rim Trail, the 4th edition of which was published last July. He also wrote Monsters in the Woods: Backpacking with Children and writes frequently on a variety of topics. In the winter, he runs the Strider Glider after school program at Tahoe Cross Country Ski Area. Support his work in the Ally.


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