A common assertion, oft repeated by the timber industry, the Forest Service, and even far too many conservation groups (like The Nature Conservancy) is that a hundred years of fire suppression has contributed to the large wildfires we are seeing around the West.

The logic goes like this. Due to effective fire suppression, fuels have accumulated in most forest types and hence we are experiencing large fires. The solution, therefore, is to reduce the fuels—usually proponents of the fire suppression paradigm want to accomplish this by logging.

The only problem with this logic is that most plant communities in the West are not characterized by frequent fires under natural conditions, thus fire suppression, even if it were effective, have not altered the natural fire regime.

This includes forests of lodgepole pine, spruce, various fir species, and even shrub communities dominated by sagebrush and chaparral. The natural fire rotation of these plant community is often on the scale of hundreds of years.


Fires are not like clocks. I’ve heard some suggest that if the natural fire rotation was 200 years for some forest type, than half should have burned in the last hundred years. Fires are more like floods on rivers. When you have the right conditions for a major 100 year flood, you get the high water. But you don’t get a percentage of that high water in years leading up to the 100 year event. Fires are similar.

Large fires only occur when there are weather/climate conditions that facilitate fire ignition and spread. These special conditions include drought, high temperatures, low humidity and high winds. Assuming you have the other conditions, high winds are the major driver of large fires. These conditions do not occur very often in most ecosystems.


Even the assertion that fire suppression was effective for 100 years can be questioned. Fire-fighting ability has radically changed during the past century. Early fire-fighting ability was extremely limited. To suggest that widely scattered Forest Service rangers riding mules across miles of wilderness and working with nothing more than shovels and axes were “effective” at significantly reducing fires begs credibility.

In these early years, livestock grazing, by eliminating the fine fuels (grasses) in the understory of some plant communities, likely had a greater influence on fires than fire-fighting and suppression by humans.

It was not until after WW11 when air support became common in the 1950s and 1960s with the advent of smoke jumpers, air tankers and helicopters that fire fighters could easily reach ignitions. Add to that air access, the greatly expanding road access due to a logging boom on public lands that occurred throughout the 1960s, 1970s, 1980s, and 1990s, and one could perhaps suggest that fire suppression may have been effective in some locations.

However, at the same time that massive fire-fighting capabilities were implemented, the climate was less conducive for fire ignition and spread. Between the 1940s to the end of the 1980s, most of the West was cooler and moister than in earlier decades and since that time. The climatic conditions may have contributed to the notion that fire suppression was actually effective.


I remember attending a conference where a Forest Supervisor remarked that his agency was “darn good at putting out fires when it rained, but not so good when it was hot and dry”. What he was admitting is that fire suppression is largely effective when the weather conditions make it easy to put out a fire.

Another interpretation is that most fires would self-extinguish whether they were attacked by fire-fighters or not. Indeed, there is evidence to suggest that even in the absence of fire suppression, the majority of fires would simply burn out without affecting much of the landscape.

For instance, an experiment in Yellowstone appears to bear this out. Between 1972 and 1987, some 235 fires were permitted to burn without any fire suppression. Most of them went out after burning less than 100 acres. And all of these fires self-extinguished.


The vast majority of all wildfires burn very little acreage. We may be effective at squelching the small fires—the fires that are most likely to self-extinguish anyway. But thus far, fortunately we are not very successful at affecting the larger fires. And these fires account for the vast majority of all acreage burned.

Between 1980-2003 there were 56,350 fires on federal lands in the Rockies which burned 3.6 ha (9 million plus acres).

Some 55,228 blazes out of 56,350 fires burned only 4% of the entire area.

Even more telling 0.1% (50) of the fires were responsible for half of the acres burned.

It is the occasional large fires that pose the threat to homes and communities but they are rare and unpredictable.


Another factor that is part of this debate is the question of how accurate are fire scar studies which are the primary means of establishing fire history. Researchers find trees that have been burned, but not killed, by fires. Trees that survive fires often have scars that can be read like tree rings, establishing the frequency of fires on that particular tree.

One of the problems with this method is sampling bias. Most fire scars are found by walking through the forest looking for scarred trees. However, this method is not random. And one can’t assume that the trees with scars represent the fire history of the surrounding landscape, any more than a survey of people in a bar represents an accurate reflection of the overall alcohol use in a community.

A second common problem is the use of “composite” fire scars, whereby all the trees with any fire scar in a particular year are counted as a fire year. The problem with this method, according to critics, is that composite fire histories consider all fires as equal. However, we know that most fires are not large, and tend to self-extinguish without burning more than a few acres, so counting every fire scar a fire “year” may bias the sample to shorter fire intervals.

More recent fire scar history studies have attempted to get around this problem by only including fire years where more than a certain number or percentage of trees were burned in that year. This helps to reduce the bias, but does not necessarily overcome the problem completely.


Even if fire scars accurately portrayed the historic fire regime for a particular site, it’s important to consider the ecological influence of fires. One large blaze will burn far more acreage than hundreds of small blazes.

Consider a 1,000 acre study plot where over a 100 years, 100 fires were recorded. This would lead one to conclude that the fire frequency was one fire per year. But if each fire burned an acre or less, even a 100 blazes would only char a 100 acres or a tenth of the 1000 acre study area. At this rate, it would take a 1000 years to burn an equal amount of the entire study area.

Since large blazes are, by their definition, infrequent, counting only the larger fires that have burned across a significant proportion of the landscape may be more accurate characterization of the fire history. Often in fire history studies there are certain decades with many fires (often small) with many decades without any fires in between.

For instance, you could have 10 fires in a 100 years or a fire every 10 years on average. But those fires may be temporally irregular. We know that fires tend to occur in “fire decades” so you could have 5 fires in the first decade, and five fires in the last decade but a fire free period of 80 years in between.  Thus even forests characterized by “frequent fire, low intensity” may still have long periods without any fires at all.  As a result even these forest types may not have been that influenced by fire suppression—even assuming that it is effective.


Some argue that fire suppression must have reduced blazes in low elevation ponderosa pine forests since this particular forest type is commonly assumed to have been influenced by frequent, low intensity fires. In all likelihood it is possible that fire suppression has had an effect upon these forests, especially at the lowest driest locations. However, even this assertion has some nuance to it.

For example, a number of recent studies have documented that high severity fires historically occurred even in the ponderosa pine zone. For instance, some studies in Colorado’s Front Range suggest that 80% of the pine were burned in stand replacement high severity fires. Another study of ponderosa pine along the Payette River in Idaho found evidence for periodic large stand replacement fires there as well. A third study of dry forests in British Columbia found similar results. So the idea that even ponderosa pine forests are somehow outside of their “historic” condition because we see an occasional mixed to high severity fire in these ecosystems may be inaccurate.


The hand wringing over the occurrence of large blazes around the West ignores the fact that historically we always had large fires. There are many plants and animals that have evolutionary adaptations and requirements for periodic large blazes. These evolutionary adaptations would not have occurred if large fires were historically absence.

Some ecologists are suggesting that we have a fire deficit due to the decades of moist, cool weather. The acreage burned annually in recent years while seemingly large compared to the 1940-1980s period, is still quite a bit less than what burned earlier in the last century, as well as much less than has been established for earlier dry, drought conditions such as occurred during the Medieval Warm Period between 800-1300 AD. This was the same time period when Greenland was mild enough for colonization by Vikings, and Anasazi Indians cliff dwellers successfully colonized the Four Corners region.

Given that wildfire is a major contributor to snags and wood in the ecosystem, we really need to have more large fires, not less. Even if fire suppression were really having an influence, it would be problematic to control such fires. We need large fires for a healthy forest ecosystem.



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  1. snaildarter Avatar

    I remember taking my son to Yellowstone the summer after the big fire of 1988. There were a lot fewer visitors than usual but we saw the most spectacualr wildflowers I’ve ever seen. Truely amazing.

    1. rork Avatar

      I was there in 1990, while going for a backpacking trip in the Beartooths. We knew enough not to even think of it as a bad thing. And yeah, flowers.
      Places we burn on purpose in MI can be pretty cool too. We think the natives burned quite a bit in the old days, but we aren’t sure just how much – but looking at the burns, we are sure about why they may have wanted to. I’ve not seen the aftermath in every forest type, but in oaks, it makes hunting (and acorn-collecting) paradise. In some conifer forests, berry nirvana follows.

      1. rork Avatar

        Perhaps I should make clear that the larger oaks mostly survive the fires, and fire makes more of the saplings be oaks too (by killing others more).

  2. Gary Humbard Avatar
    Gary Humbard

    I worked on approximately 35 “project fires”; fires that the feds and states send Incident Command teams to during my career and I can count on one hand when fire suppression had some effect. Those fires consisted within sagebrush steepe fuel types (not forest types) and basically consisted of setting backfires to consume the fuels ahead of the fire front. Although most don’t consider setting backfires as “fire suppression” IMO it is the only true effective method of fire suppression if done under the right conditions by the right people. I saw countless times, fire run through forest types that had repeated retardant drops and hose lays. Fuels reduction can be effective, but that is a different subject.

    Sadly, fire suppression is a culture and business in the federal and state agencies today. If you are between 20 and ~50 years old, there is a lot of pressure to be dispatched to fires. It saves the home district you work at money, since firefighting funds are paid by a separate fund. It’s a business as agencies enter into contracts with companies ranging from helicopter services to caterers. Then the firefighters are portrayed as heroes by the local community, but in actuality, if they truly answered, probably 90% of them are there not to protect homes and property but for one simple reason, money. I made at least twice as much working on a fire than my normal occupation. Working hard 14 hours a day in hot dry weather, getting black from the soot and dust, eating crappy food, sleeping maybe 4 hours/day and away from family can only go so far. Of those 35 fires, (of which I attended most fire team briefings) I only heard one time the question, “how much has this fire cost to date”?

    If the agencies truly wanted to restore ecosystems, they would tell Congress to drastically reduce fire suppression funding and increase funding for ecosystem based thinnings and other activities such as road decommissioning and maintenance, noxious weed control, and stream and wildlife enhancement.

  3. Ida Lupines Avatar
    Ida Lupines

    I remember seeing the aftermath in Yellowstone too. Amazing, I might even have a photo or two.

    There’s a lot to read here. I know that some of our trees require fire for seed germination, pine cones (not news to many of you, I know, but fascinating to me). The more we interfere with natural processes and keep pushing further and further into these areas, the more damage we are doing to the environment and the wildlife who depend on it to live. We wouldn’t need to put our firefighters in such jeopardy and grief as much either.


George Wuerthner is an ecologist and writer who has published 38 books on various topics related to environmental and natural history. He has visited over 400 designated wilderness areas and over 200 national park units.

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George Wuerthner