Fire Does Not Equal Destruction

The Cameron Peak Fire has burned more than 205,000 acres of northern Colorado, making it the largest wildfire in Colorado’s recorded history. It’s alarming, it’s scary, and a lot of people are very upset. On social media, lots of people are mourning how the fire has “destroyed” so much forest and wildlife habitat. This concerns me as much as the fire itself.

Our forest is definitely at great risk, but the impacts of fire are complicated. What I want people to understand is that fire does not inherently equal destruction.

Don’t get me wrong; fire certainly can destroy forests, but it doesn’t always destroy them. The fire may have burned 205,005 acres, but that doesn’t mean that it’s destroyed 205,005 acres. The fire may have been less damaging than many people are assuming. In fact, many types of forests rely on fire to reseed themselves or stay healthy. This is because not all fire is the same, and not all forests are the same.

Fire is actually one of our most important tools for saving our forests, but we will only succeed in doing so if the public has a nuanced understanding of fire. If you care about Colorado’s forests, please read on.

Smoke from the Cameron Peak Fire floats out of Roosevelt National Forest and towards Loveland, Colorado.

Not All Forests Are the Same

If you hike in Colorado and pay attention to the plants around you, you’ll know that the forest at the mouth of the Big Thompson Canyon is completely different from the forest just below Long’s Peak. Down low you have open Ponderosa Pine forest mixed with shrubs and grasses. Higher up you have mixed conifer forests where Douglas-Fir, spruces, and firs start to grow. Then there’s Lodgepole Pine forests, where virtually only one species grows densely. And just below the alpine you find spruce-fir forests.

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  Ponderosa Pine forest in Roosevelt National Forest.

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  Mixed conifer forest in Rocky Mountain National Park.

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  Aspen forest in Roosevelt National Forest.

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  Spruce-fir forest in Roosevelt National Forest.

These forests respond very differently to fire. While spruce-fir forests evolved with fire typically occurring once every 300 years, Ponderosa Pine forest “evolved with a natural cycle of frequent, low-intensity fire,” according to the Colorado State Forest Service.

Fire is also essential to the health and existence of some forests. Lodgepole Pine forests are the most obvious example. This species reseeds prolifically after intense fires that kill virtually all the trees in its path. Over millennia, severe fires have become a natural part of its ecology. Much of the forest in the Cameron Peak Fire is Lodgepole Pine forest. These areas may look the way they used to within a few decades.

Our beloved Aspen trees also do well after fires that kill a majority of conifers. Shortly after the fire, they resprout in dense numbers. According to the U.S. Forest Service, “Fire appears to be necessary for the continued well-being of aspen on most sites.”

Aspen grow prolifically on a hillside that had a high-severity fire recently in Roosevelt National Forest. From the Cameron Peak Fire map, it appears that the fire burned right up to the edge of these aspen and stopped, probably because the last fire reduced the fuel load.

Ponderosa Pines also depend on fire to burn away competing shrubs and trees. After existing with frequent fire for thousands of years, this species has evolved adaptations that help it survive low-intensity fire.

So when you look at a map of the Cameron Peak Fire, don’t assume it’s one homogenous forest. There are many kinds of forest within the burn perimeter, and all of them benefit from the right kind of fire.

Not All Fire Is the Same

So what do I mean by “the right kind of fire”? This brings me to the next main point: not all fire is the same. Fires vary in intensity and severity. Depending on the conditions like slope, wind, and humidity, the amount of heat that a fire creates varies widely–even with the same amount of available fuel. This is called fire intensity.

Depending on a forest’s resilience to fire, its structure, and the fire’s intensity, the amount of vegetation that a fire kills also varies widely. This is called fire severity.

Because there are so many factors affecting whether or not an individual tree survives a fire, the impact of a fire can be extremely varied across the land that it burns. You may have some areas where 100 percent of the trees are killed right next to an area where no trees die.

The patchy burn will likely add diversity and resilience to this mixed conifer forest in Rogue River-Siskiyou National Forest. It’s possible that the Cameron Peak Fire has left areas like this too.

The media usually shows us images of the areas where wildfires were most severe because they’re the most eye-catching. This can give the impression that all wildfires leave areas entirely devoid of all life, a blackened Mordor landscape. In reality, there is often much left unburned or partially unburned. And, as I explained above, much of our forest can benefit from this fire.

Finally, fires can also have one other major benefit: they can help prevent severe fires in the future. Fires need fuel to burn. The more fuel there is and the more continuous it is, the larger and more intense fires tend to be. For about 20 years after a low-severity fire, there tends to be much less fuel for future fires to burn because it’s been burnt up. (The exception is when high-severity fires leave a lot of dead logs, which become fuel). When a fire leaves a landscape with a patchwork of burned, partially burned, and unburned areas, it greatly reduces the likelihood of future megafires.

In the case of the Cameron Peak Fire, it strongly appears that the 2012 High Park Fire stopped the Cameron Peak Fire from heading straight towards Fort Collins. Now, the High Park Fire was larger and more severe than I and probably anyone else wanted it to be, but I mention this to illustrate the potential for fire to limit the size and spread of future fires.

A map of the burn perimeters of the High Park and Cameron Peak fires strongly suggests that the High Park Fire partially shielded Fort Collins from the Cameron Peak Fire. Image: National Interagency Fire Center, found on Yale Climate Connections

It’s Too Early to Know How the Forest Will Respond

My point in all this is that we don’t know yet how the Cameron Peak Fire has left the area it’s burned. Yes, some areas probably have burned with high severity and the forests there may never return. Yes, that might even be the case for most of the burned area, but it’s too early to say.

I understand that this fire is taking a very real emotional toll on people. Some of the places I love have been affected by it. But we shouldn’t assume that our forest has been destroyed before we’ve seen how it reacts over the next couple years. Grief is normal in a time like this, but demonizing fire will only make it harder for us to use fires to prevent more megafires.

We Need Fire to Save Our Forests

Regardless of how the Cameron Peak Fire turns out, we do know two very troubling things about forests in Colorado. One is that they are more vulnerable to fire than ever due to a century of fire suppression. Since it became U.S. policy to suppress all forest fires in 1911, western forests have changed drastically. The low-severity fires that used to frequently reduce fuels were largely stopped and our forests became unnaturally dense.

As a result, they became less healthy. When you have more trees competing for the same amount of sunlight, water, and nutrients, they all become weaker. Unhealthy trees are less likely to recover from fire, insect outbreaks, and disease. And, it’s easier for fire, insects, and disease to sweep through forests when they’re dense and homogenous.

An unnaturally dense forest choked with unhealthy Douglas-Firs, ready to burn in the Rogue River-Siskiyou National Forest.

The second thing is climate change. Northern Colorado is a very difficult place to be a tree. The soil is terrible, there’s very little water, and it gets really hot in the summer. It’s almost a miracle that forests did establish themselves here thousands of years ago.

But with our climate becoming hotter and drier, the forests may not be able to do it again after severe fire. We may have crossed the limit of what native tree seedlings can withstand. We’re finding evidence of this in the area burned by the High Park Fire in 2012. Even after eight years we’re seeing almost no trees growing back in this area.

Eight years after the High Park Fire, virtually no trees have returned.

To save our forests, we need to address both of these issues. Climate change is definitely creating hotter and longer fire seasons and preventing forests from regenerating, but it is just part of the problem. A century of fire suppression slowly but drastically changed our forests, making them prone to larger and more severe fires.

Stopping climate change is definitely a must, but it probably won’t save our forests alone or in time. We need to take immediate action on the ground to restore the conditions that historically made western forests resilient to fire. Currently, the vast majority of scientific research indicates that forest thinning followed by prescribed fire is our best hope for doing that.