a new plant grows in ashes after a small forest fire has burnt out


There have been news stories all summer about wildfires destroying thousands of acres of forest in the West and elsewhere. Most of the time we hear about the devastation, but our guests says that fires actually help forests stay healthy and can even bring them back to their natural states by removing non-native plants.

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Guests: Dr. Nancy French, is a senior scientist at the Michigan Tech Research Institute in Ann Arbor, part of Michigan Technological University

Dominick DellaSala is chief scientist at the Geos Institute in Ashland, Oregon, and author of the book, The Ecological Importance of Mixed-Severity Fires: Nature’s phoenix


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The Benefits of Wildfires

Marty Peterson: The recent wildfires in the West have made countless residents of California homeless and devastated thousands of acres of land this summer. The drought there and the dry, hot winds make that area susceptible to fires that can move quickly through the forests and shrub land. It’s difficult to see any benefit through all of that tragedy, but believe it or not there is. Foresters have used fire to create healthy forests and destroy low-lying vegetation so that huge fires like the ones in the West don’t get started. We talked to two forest experts about how fire can be a tool in growing healthy forests, if it’s used correctly. First, the term “wildfires” to describe the situation in California is a popular term, not a scientific one. Dr. Nancy French, a senior scientist at the Michigan Tech Research Institute in Ann Arbor, part of Michigan Technological University, explains.

Nancy French: We don’t use wildfire because it implies that fires are dangerous and bad and tend to be “wild.” The term wildfire is very well known, though, so we use it when we’re communicating. Typically it means that it’s a fire that wasn’t put in a place that we want it as opposed to “prescribed fire.”

Peterson: There’s also another term that the professionals use – “mixed-severity fires.” Dominick DellaSala is chief scientist at the Geos Institute in Ashland, Oregon, and author of the book, The Ecological Importance of Mixed-Severity Fires: Nature’s phoenix. He says that fires don’t burn consistently over the landscape, burning everything in their path to the ground.

Dominick DellaSala: If you were flying over these forest fires after they’ve burned, you wouldn’t see a uniform tree kill across the landscape. What you would see is more of a patchwork mosaic, a variety of different burn intensities that kills some of the vegetation in places, kills most of the vegetation in places and misses spots. And in Nature, we know that variety is the spice of life so when we see that kind of variation on the landscape, there’s habitat for all kinds of critters from deer and elk to species that require old-growth forests. And so that mixture of intensities gives you this patchwork mosaic that is really healthy and it’s part of Nature’s phoenix.

Peterson: It’s hard to believe that a fire – no matter if it’s “wild” or planned – can help a forest grow, but it can. French says that woodlands and other wild areas are uniquely adapted to the occasional fire, such as the shrubby chaparral areas of Southern California.

French: That’s a fire-prone and fire-adapted ecosystem. It means that fire’s always been in that ecosystem and it’s part of the structure and the way that the landscape functions. It allows nutrients to be cycled in and out; it gets rid of pests. There’s a lot of evidence that Aboriginal and Indians in North America set fires in order to get rid of pests. In Africa now, in fact, there’s a lot of studies looking at how Aboriginal people would put fire on the land mainly because then their cattle could graze better. Things like that.

Peterson: In fact, many fires are started by Mother Nature – through lightning strikes in wooded areas and dry shrub and grasslands. DellaSala says that those fires and others don’t really destroy all the vegetation like a fire destroys a manmade structure. Instead, it gives new vegetation a chance to grow…

DellaSala: There are all kinds of seeds that are in the soil, down beneath the initial layer, that are shielded by the heat of the burn. And so as soon as those flames go out, those seeds start to germinate and you get life right out of the ashes, whether or not they’re shrubs or flowering plants or eventually conifers. Those plants are uniquely adapted to fire. This has been going on since before the time of the dinosaurs, when plants began to evolve 400 million years ago they developed at a close association with fire and many of them have special adaptations for taking advantage of the newly-created habitat when a burn comes through an area.

Peterson: French says that forests don’t all burn the same, either because burn rate and the extent of the damage depend on the type of tree and ground cover. The jack pine in the Midwest, for example, is a fire-adapted species.

French: They have a strategy to actually burn and burn completely by having what we call “ladder fuels.” So they’ve got branches that come right down to the level of the ground or just above so when the fire flames come through on the, maybe on the ground through the grassy understory, the fire will ladder up and actually crown out the fire. Other types in the Southeast, loblolly pine forests, have very high canopies and that means that if there are moderate-level fires that go through, the flames never get up to the canopy so you end up with a good surface fire with very little crowning. And those types of trees will have very thick barks.

Peterson: Speaking of thick bark, DellaSala and French say that the Giant Sequoia in the Pacific Northwest have an amazing ability to live through fires to reach ages of hundreds and even thousands of years old.

DellaSala: In the state of California you know a lot of folks have been to the Giant Sequoia Forest in the Sierra Mountains, and Sequoia is the most fire-resistant tree species in the world. It can withstand flames into its tree crowns and after about 100 years or so of growth, those trees develop a natural asbestos layer in their bark so they can withstand a forest fire and still live through it. And the ones that die just create an opening for seedlings to take advantage of the new space. So they are a lot different than if a fire went through a hardwood forest where you don’t necessarily have those properties or a fire goes through a tree farm where the trees aren’t big enough or old enough to have that natural insulation that protects them from forest fires.

French: They’ve got a huge space and the fire just can’t really girdle them properly because bark doesn’t allow it, so they oftentimes, most often, will live through a fire because they’ve got thick enough bark that can’t get girdled and they end up just living through the whole thing.

Peterson: Trees and vegetation aren’t the only living things that are touched by forest fires. There are insects and animals that also have to contend with smoke and flames. DellaSala says that they, too, have strategies for living through even the biggest blazes.

DellaSala: Most wildfires burn through an area at a very slow pace. You do get occasional movements of flames that go through an area quickly, so there’s time for most of the species to move out when the flames are coming in. Some of them will burrow into the ground and stay cool while the flames are passing over them. And as soon as those fires are out, many of them have new habitat to come back in. To give you another example, when the shrub layers start to come back, all kinds of small mammals come into that area taking advantage of new plant growth. And with those small mammals come predatory birds like hawks and owls that all of a sudden have a new food supply. So it’s really a rebirthing where Nature is just hitting the reset button.

Peterson: The other living thin – humans – don’t fare as well as the animals and insects, though. With their homes burned to the ground and all of their belongings destroyed, residents of wooded areas where wildfires are common are understandably distraught at their losses. French says that in California where there are so many fires, the state and local governments are promoting “fire wise” communities where residents can lessen the chance that their homes will be ravaged by fire.

French: There’s a lot of work to train people how to keep the vegetation away from their houses, and make sure their house is safe, but some people find that to be not as attractive. And I think, again, it depends on the setting. In California we’re building our houses right up into the chaparral shrub lands that are there. It’s just a really nice setting for a home, but those chaparral shrub lands are fire-prone, they live by fire, that’s part of what their ecology is all about.

Peterson: French says that the U.S. Forest Service is trying to lessen the occurrence of out-of-control fires by setting some of their own to rid the forests of excess fuel that can easily catch fire when lightning strikes or a careless camper doesn’t follow safety procedures. These “fuels reduction” strategies not only keep big fires at bay, they also regenerate the environment.

French: Putting prescribed fire in place or sometimes it’s mechanical removal of fuels to make it so we have a forest that’s a little bit more like what you would have in a natural fire regime. Because for many, many years we kept fire out of our forests for reasons that we thought were the right thing to do and we’ve learned since then that we need to have fire in some of these types to keep the fuels down to make the fires less catastrophic. So fuels-reduction work that’s happening by the Forest Service, by the California fire people, those are very important things to work on so we can really reduce the amount of catastrophic fire that we have.

Peterson: Dr. Nancy French says that you can find out more about forest fires and how they can benefit the environment by visiting the Michigan Tech Research Institute’s site at mtri.org. For information on the effect of climate change on the environment and forests, Dominick DellaSala invites listeners to log onto the Geos Institutes sites at geosinstitute.org and forestlegacies.org. To find out more about all of our guests, log onto our site at Viewpointsonline.net. You can find archives of past programs there and on iTunes and Stitcher. Our show was written and produced by Pat Reuter. Our production directors are Sean Waldron and Reed Pence. I’m Marty Peterson.