“Burning Down the House” or How have Forest Fires Gotten so Bad?

I’m certainly more aware of forest fires this year than I have been in the past, but it’s not my imagination that the fires have been getting worse over time.  Forest fires were not as bad when I was younger, and it was not only because of the extremely effective campaign with Smokey the Bear telling us, “Only you can prevent forest fires.”

In the late 1800’s and early 1900’s, a number of major fires devastated the West including the “Big Burn,” in 1910 which scorched a large swath of Montana and Idaho in the Yellowstone region.  The Forest Service was in its infancy at that point, and those large fires substantially shaped the resulting mission of the agency.  The two significant take-home messages of the Big Burn were, “Fire is Bad,” and “Humanity can control its environment.”  Thus began a program of ruthless suppression (putting out) of all wildfire ignitions.

There’s only one problem with this philosophy.  Fire is a natural part of the forest environment, particularly in the dry West where fallen vegetation does not decompose as rapidly as in the wetter East.  Fire sweeps through an area every 10-30 years and burns off all the small fuels low down toward the forest floor.  With regular burning, the fuels don’t build up, which means that the fires burn with low intensity on the surface.  Larger older trees can withstand these low intensity surface fires and survive with ease.  Indeed, Lodgepole pines have cones that only open to release seeds under the high temperatures of fire.

Decades of suppression took their toll on the forest.  Fuels built up in the absence of fire, and trees became much more densely packed.  In the Rocky Mountains, we look at lush forests of evergreens with admiration, but those wonderful expanses of green actually represent an unhealthy forest.  Where there should be 10 trees per acre, there are instead 100.  When forests with high fuel loads burn, the fires are much hotter and the damage is more intense.  Trees that have fallen but have not dropped all the way to the ground act as ladders to convey fire from the surface to the canopy creating crown fires.  Even the most resilient trees can’t survive these high intensity crown fires, and everything burns in what is known as a “stand replacement fire.”  The entire forest must come back from seed.  That’s if it comes back at all.  As climate is changing, the edges of forest ecosystems may no longer be ideally adapted to the new climate zone, so without intervention, some forests come back with a different mix of species, and some may be permanently converted to grassland.

I had the opportunity to ask a researcher in the Forest Service why we hear so much more about forest fires in the West than in the East.  I asked if part of it is that there simply are not the acres to burn in the East, and she said that’s part of it, but in the East, there somehow evolved a culture of understanding the need for forests to burn with some regularity.  So we can still get fires in the East, but they don’t have the expanse or the intensity of fires in the West.  Much more of the land in the East is also owned privately and is cut periodically when a landowner needs to send a child to college or to retire.  The West, with its wealth of National Forests and wilderness areas, includes preservation as one of its missions which makes management much more complex.


Oddly enough, improving the forest fuel issue through prescribed burns in the West is accomplished at the temporary expense of other environmental factors.  Forest fires create smoke, which is a source of Particulate Matter (PM), one of the metrics for air quality.  Smoke isn’t fun to breathe for anyone, so prescribed fires are unpopular because of the respiratory problems they may cause.  I can think of two prescribed fires in the past 10 years or so that escaped and burned far more than was intended.  That’s only two out of a large number of prescribed fires that went off without a hitch, but those incidents make people resist all prescribed burning.

The big Yellowstone fire of 1987 marked a turning point in the history of fires in the US.  Everyone thought that it was a once in a lifetime incident, but it turned out to be an indicator of a new era in forest fires.  Since then, fires have been getting bigger, more intense, and more expensive to fight.  In the rugged terrain of the West, especially in Colorado, fires are still contained through “boots on the ground.”  Air tankers carrying fire suppressant and helicopters carrying water in “bambi buckets,” are vital support elements and are critical for cooling off hot spots and protecting structures, but sometimes weather conditions and even smoke from the fires prevent the air support from flying.  Containment is achieved through cutting fire breaks, removing fuel, and sometimes through creating back-fires, which deprive the fires of anything to burn.  If the high fuel loads and steep terrain haven’t been enough challenge for firefighters, several other additional challenges have emerged in the past decade to make fires even more difficult to fight.

Bark Beetle kill in Rocky Mountain National Park

Bark Beetle kill in Rocky Mountain National Park

Outbreaks of various bark beetles have added to the fire risk.  Lodgepole pines and Mountain Pine Beetles have co-evolved to have mutual defenses.  The pines have chemical defenses to throw off small attacks, but the beetles respond with massive attacks on a tree to overwhelm the defenses.  In the first years after a beetle attack, the trees remain standing, and the dry brown needles that have yet to fall serve as very effective tinder to fuel a fire.  Eventually the needles and the trees fall, which reduces the fuel load and the fire risk, but in areas of recent beetle kill where there may be up to 80% tree mortality, humans don’t stand much of a chance against fire.

Fire in the WUI

Fire in the WUI

In the past ten years, the development of the Wildland-Urban Interface (WUI, pronounced woo-ey), has made fighting forest fires additionally challenging.  I certainly understand the draw of a cabin in the woods, but when building codes allow wooden roofs and wooden decks, and when trees and brush come right up to the structure, the house doesn’t stand much of a chance from flying embers.  When fighting fires, the priorities are protecting people, structures, and infrastructure (roads, dams, bridges, etc.).  If a fire is burning entirely in a forest, then the goal is to contain it and then let it burn itself out.  If, however, a fire is burning near a neighborhood, then far greater effort is expended to try to protect the houses.  My guess is that the 100,000 acre West Fork fire in the Rio Grande and San Juan National Forests in Colorado will ultimately have a lower damage assessment than the 15,000 acre Black Forest fire in the Colorado Springs suburbs.  No structures were lost in the West Fork fire, whereas over 500 houses burned in the Black Forest fire.

Where the major damage occurs

Where the major damage occurs

On top of all these factors, climate change is also contributing to the problem.  Does climate change cause any particular fire?  No, of course not.  It does however contribute to a longer fire season, up to a month longer on either end.  Higher temperatures mean that the last snow falls early in the spring and later in the fall, so the trees have even longer to try out and fires have longer to burn.  The ongoing drought in the West is also not necessarily directly caused by climate change, but those weather conditions also contribute to much hire fire risks.

The prevention and treatment of forest fires has been a frequent topic on Capitol Hill lately, but unfortunately there are no easy answers.  The combination of so many different factors, each of which is feeding larger and hotter fires that are more challenging to fight in the WUI mean that we will be seeing active and extensive fire seasons for the foreseeable future.

2012 Waldo Canyon Fire burn scar

2012 Waldo Canyon Fire burn scar



1 Comment

Filed under Brain Food, Work

One response to ““Burning Down the House” or How have Forest Fires Gotten so Bad?

  1. Heather Pence

    I was impressed when I visited Yosemite that the Ahwahnee hotel in the middle of the park, while it looks like it’s built of wood – is mostly stone and concrete colored to look like wood – due to risk of forest fires. At least we’ve learned our lessons from the “fire is bad” and are trying to make it right now…

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