Richard Miller, professor of range ecology at Oregon State University, replies:
Well, a prescribed burn is a fire thats actually purposely set for certain objectives, but within a certain "window" of environmental conditions. Its not just set at any time. A prescribed burn is basically an organized, purposely set fire that you might, depending on the types of fuel youre burning [i.e., types of trees, bushes, grass, etc.], set within a windowwith winds that will not exceed, say, 12 - 15 miles per hour, and relative humidity that would not drop below, say, 20 percent. These are just data to give you some idea, but the numbers really are kind of irrelevant because it would depend on the types of fuel that youre burning.
Now, there are several reasons these are done. One reason is oftentimes, areas are burned to reduce fuel loads because of concerns of wildfires. For instance, I know the people at the Grand Canyon are real concerned with burning. They have such a dense stand of juniper that if a fire gets rolling in that stand, it would burn uphill, up to the rim, where all of the visitors are. They feel like they wouldnt be able to stop it, so they would like to reduce the fuel component. But at the same time, there is a lot of resistance saying, "Well, this is a park!" and they want to maintain it as natural. [But "natural" is a relative term, since] the density of the trees has increased since presettlement times. (We dont know to what extent though.) Weve been doing a lot of fire history in our more productive sagebrush type areas, where we have a lot of juniper moving in. In those areas, presettlement times used to burn about every, oh, an average of 15 to 25 years. Those would be wildfires from lightening, or could have been, you know, set by Native Americans. But because they were frequent, fuel loads were lower and so they were what we called "frequent but low intensity fires." So their thought at the Grand Canyon is, if they could actually do some thinning, burn some holes in the stands to reduce fuel, then a fire would be more easily controlled. So fuel reduction is one of the primary components of that.
Now another reason for possibly burning is to increase diversity of the landscape level for wildlife. Weve been working with U.S. Fish and Wildlife in Sheldon National Wildlife Refuge in Nevada. Theyve been doing prescribed burning to try to, basically, open up stands of dead sagebrush that havent burned in a long timenot to burn all of the sagebrush, but to basically create a mosaic. In good condition stands, you can get a tremendous increase in forage, wildflowers and grasses in those sites. If you have more of a mosaic, more diversity, such as more open areas, grassland and shrubsrather than a solid stand of junipers like at the Grand Canyonyou would have more of a broken fuel component. That would reduce the threat, at least, of the fires being very large.
Another real prime reason for burning is that were losing many of our Aspen stands in this Great Basin landscape, because theyre being invaded by conifers. Thats the case in the Rocky Mountains. You get these wet sites or sites that collect snow in the wintertime with a sagebrush stand and a pocket of Aspen, and they have an incredible amount of biodiversity on the landscape. The Aspen, however, were maintained by fire, because it kills the tops of the trees, but then they come back from the roots. So with a fire return interval of even once every 60 years, which is kind of what we suspected the Aspen probably burned in, they were maintained. If you remove that fire, youll have conifers moving in, dominating the stand and then you lose your Aspen. Right now, were working with the Bureau of Land Management on Steens Mountain in Oregon, which possibly will become a national monument. Weve lost or almost lost a number of Aspen stands in the gorge there. Were working in the gorge to try to restore some of the Aspen stands and that will involve a prescribed fire.
Now, about what happened in Los Alamos and Bandelier.... No matter how careful you are, if you do prescribed burning, you are eventually going to lose one. It sounds like there were several problems involved there. One was that there was some miscommunication between the park service and the meteorology people about the weather forecastin particular, with the winds. From what I hear, they didnt get reports that the winds were supposed to be unpredictable the following day.
I remember in Sheldon National Wildlife Refuge in Nevada, they were doing a burn a number of years ago, and they had a real unusual change in weather late in the day. Usually, they burn from afternoon late into the day. Usually, at night the humidity starts to go up and temperatures cool off a little bit, but they actually had a jump in temperature. There was a shift in weather which was not forecast, and it happenedan out-of-control burn. Humidity suddenly dropped, and it was the first time Id ever seen it. They lost it at night. Ive never seen a fire lost at night. Usually, the fire will kind of temper down and then itll take off again in the morning. Those kinds of things can happen.
But the other problem [at Los Alamos] is that you have urbanization going on in areas that used to burn very frequently and have high fuel loads. The area where they lost so many homes was in a high fire hazard area, where eventually fire was probably going to happen. We have a lot of areas like that all over the West. For example, west of Denver in the foothills of the Rocky Mountains, you have the pine zone, which probably burned in a fire return interval of every 10 to 20 years. Now, you have a lot of homes in there with 10 to 20 acres. They dont want to do any thinning, because they dont want to see their neighbors. There hasnt been any fire in there in a long time. Thats a fire just waiting to happen. In Oregon in the Bend-Redman area, we have Sunriver, which is growing in a large-pole Ponderosa pine forest and wood homes with cedar roofs that are sitting in an area that burned at 8 to 12 year return intervals prior to settlement. It hasnt burned since the turn of the century and so, you know, its a powder keg waiting to happen. There are examples like that all over the West. Probably, one of the greatest plays on words was in a Sierra Club article on fire right after Yellowstone occurred, and the title of the article was, "Only you can postpone forest fires."
The bottom line is that if we shut down all prescribed burning, thats fine, but were just going to increase the threat of wildfires. They might become less frequent, but when they happen theyre going to be much larger and they wont have near the heterogeneity or the variation, theyre going to be hotter and burn more completely large areas. Whereas, with a prescribed fire, you can burn under cooler conditions and create more of a mosaic, so you have burned and unburned areas, which again, can be real beneficial from a wildlife standpoint.
Of course, a lot of precations are taken. Its not something that they wake up and say "Were concerned about the fuel in this area. Lets go out and burn it!" There would have been some extensive planning before they went ahead and did the burning. When the federal government does it, they usually have their fire map unit laid out and they usually have some equipment on standby. I know that on the prescribed burns that Ive been on in California and Oregon, they were taking their own weather, continually checking, laying down fire line, putting down black line fire breaks, we know what areas we want to burn, and try to restrict the burning to those areas. and working off of natural firebreaks and having equipment and definitely having quite a bit of stuff on standby. The biggest precaution is burning within what we call "the window"of having limitations in terms of maximums and minimums on wind, temperatures and relative humidity. And again, what those are varies with the type of fuel that youre working with and it varies a lot with topography, too.
Overall weve shifted, big time, from my generation when we had Smokey the Bear and fire was "bad" and a major threat. We were sold that because fire was competing for timber resources for human use. Weve shifted, recognizing now that prior to the time of Europeans coming to the continent, that fire was a very major process in the system, in that, if you remove fire from that system, it can have some negative impacts. Burning is not a panacea.