The Mythology of Fire Suppression

The recent piece published in the December 22 Guardian titled: Heat, wind, and a cruel twist of Nature: inside Oregon’s nightmarish wildfire season was, on the whole, a…

The recent piece published in the December 22 Guardian titled: Heat, wind, and a cruel twist of Nature: inside Oregon’s nightmarish wildfire season was, on the whole, a very good overview of events. The article’s general thrust was how climate/weather conspired to create the perfect conditions for large-scale wildfire in Oregon’s Cascade Range.

Despite making an excellent case for the influence of climate and weather on fire spread, the reporter several times referenced the myth that fire suppression was partially responsible for these large blazes.

Ecologically speaking, fire suppression and the consequence fuel build-up have almost nothing to do with the large blazes occurring around the West. Most forest types in Oregon and the rest of the West have long fire-free intervals of centuries between major fires, during which they do not burn for a host of reasons related to climate and weather.

For instance, the old-growth Douglas fir that burned on the west slope of the Cascades mentioned in the article has natural fire intervals of 300-600 years. In other words, the usual situation is for these forests to be fire-free for centuries. During these periods, the forest is growing and dying and building up biomass (or foresters call fuel, and I call wildlife habitat).

Fire suppression does not influence plant communities with naturally long fire-free intervals. Even if fire suppression were effective, which is questionable in many instances since most fires are suppressed or controlled when the weather conditions change. The vast majority of fires are small and have little consequence on fuel accumulation.

Ruins of home charred by the Holiday Farm Fire along the McKenzie River where the fire interval is 300-600 years in the Douglas fir forests of the Western Cascades, Oregon. Photo George Wuerthner.

These forests burn because the climate/weather conspires to create the right conditions for a burn, not because there is fuel.

We have evidence of this from several on the ground experiments. For example, in the years between 1972 and 1987, Yellowstone NP allowed all backcountry fires to burn without suppression. The lodgepole pine forests that dominate Yellowstone tend to burn on 300-400 year intervals.  There are 235 fires during those years, and 222 burned five acres or less. Not because they were “suppressed’ but because the climate/weather conditions were not conducive for fire spread.

Only one of the 235 blazes was larger than a thousand acres. All went out without suppression. Then in 1988, you had 800,000 acres burn in the park (36%). Was there suddenly more fuel in 1988? Why didn’t’ tens of thousands of acres burn in 1987 or 1986 or whatever date you want to pick?  There was obviously plenty of fuel.

Snags from the 1988 Yellowstone blazes. The natural fire interval over much of Yellowstone NP is 200-400 years between blazes. Photo George Wuerthner.

The reason there were no large blazes in those years was due to the climate/weather which was not conducive to fire spread. But 1988 was the driest year on record since records were started in 1872. And you had some days with 50 mph winds. And with a number of ignitions instead of fire quietly extinguishing as occurred in the previous years, you got the massive Yellowstone blazes.

It’s the same thing for most of the forest types around the West. They don’t burn because of fire suppression, but Nature suppresses fires through the climate and weather. And when they burn, it is because Nature has changed the weather conditions to make it easier to burn and spread, as occurred this past September in Oregon. As noted in the article, the forests were parched, and this, combined with powerful dry winds, blew embers miles ahead of the fire front, starting new blazes.

When you have the right conditions of low humidity, high temperatures, drought, and most importantly, high winds, fires can overwhelm all “fuel reductions.”

Not mentioned in the article was the fact that many acres charred were commercial timberlands regularly logged, thus reducing “fuel.” These lands burned at higher severity (greater mortality of trees) than non-managed landscapes.

Clearcuts in the western Cascades. The recent fires burned more severely in previously thinned or logged lands. Photo George Wuerthner.

 The only exception to the above generalization is the ponderosa pine forests and a few other similar “dry” woods in the West like Jeffrey pine in CA.  But those forests are a small part of the West’s total forested area and even the total acreage charred annually by wildfire.

For instance, most of the acreage burned in California in 2020 was chaparral scrub, grassland, and other non-forested plant communities.

However, the article was correct in noting that climate change is creating the conditions that foster massive burns. The way to alter these fires is to get serious about climate change. In the meantime, we would be better served by fireproofing communities than by trying to fireproof the forest through logging or prescribed burning.


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