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The Importance Of A Good Burn

Jessika Walsten |
September 24, 2009 | 8:00 a.m. PDT

Staff Reporter

The Angeles Forest begins the long post-fire recovery process.
(Photo by Ashley Ahearn)
It's burned over 160 thousand acres and killed two firefighters.
It's destroyed 89 residences and more than 100 vehicles.
The Station Fire has been raging for nearly a month, only recently reaching near full containment, according to the United States Forest Service. Area residents now face the daunting task of assessing the damage and rebuilding lost homes. Like people, plants and animals of the region have also begun the recovery process. However, for some of them, fire is necessary for their survival.
Smoke from fires like the station fire serves as a chemical trigger for several species of sagebrush, said Jon Keeley, a research ecologist who has worked for the United States Geological Survey for 11 years. Keeley said these plants produce seeds that lie dormant in the soil until the nitrous oxide in the smoke germinates them.
Sagebrush communities are diverse ecosystems, and while the sagebrush itself needs smoke, other plants such as Deerweed and other legumes need heat, often relying on fires to trigger seed germination, Keeley adds.
The Big-cone Douglas-fir doesn't germinate after a fire, it resprouts. Buds form on the trunk and branches of the tree instead of the base, as is usual with resprouters. They "can resprout from their burned out skeleton," said Keeley, who thinks the trees have adapted to do this after thousands of years in a fire-stricken ecosystem. However, he adds that more research needs to be conducted before any conclusions can be made.
The arroyo toad is another California species that does well after fire, said Robert Fisher, a conservation biologist who has worked with the U.S. Geological Survey since 1998.  Fire destroys the underbrush that crowds the sandy areas beside rivers and creeks, important habitat for the toad. However, this increase in population lasts only a few years. Plants like the sand too, and soon reclaim the habitat, Fisher said.
While the arroyo toad, sagebrush, Deerweed, and the Big-Cone Douglas-Fir are species native to Southern California, there are other species across the country that need fire. The boreal ecosystem houses several of them. 
Researchers at the University of Minnesota have studied Bicknell's geranium. This flower, which exists primarily in the boreal forests of Canada and Northern Minnesota, disperses seeds that remain dormant in the soil. The sun then germinates these seeds after fire exposes them to sunlight.  As a result these are some of the first plants to come back after a fire - covering the ground and preventing soil erosion. 
black-backed
The black-backed woodpecker. (Creative Commons Licensed --
garyirwin)
The Black-backed Woodpecker favors northern areas that have recently burned, according to The Cornell Lab of Ornithology, because recently burned areas attract bark beetles, the bird's primary source of food. 
Boreal toads are a group of closely related species that also seem to do better with a little fire in their lives. These are some of the only species of toad that occur at high elevations in the West, said Steve Corn, a researcher for the U.S. Geological Survey who has been studying amphibians for 23 years. Because these toads live in an environment that many other amphibians could not survive in, they are particularly important to study, Corn said.
Steve Corn and Blake Hossack, also a researcher for the U.S. Geological Survey, have found evidence linking population surges of boreal toads to wildfires. Results from a 2009 study currently in press with Forest Ecology and Management by Hossack et al. indicate that recently burned habitats increase the growth and fertility of boreal toads. 
"We still do not have a good explanation for the increased occurrence after fire, or why this increase only lasts a year or two," Corn said. Researchers have hypothesized, however, that an increase in soil and water temperature may play a role. 
borealtoad
The Boreal Toad. (photo by Steve Corn, USGS)
"One of the most interesting, but frustrating, things about boreal toads is that the more we study them, the less we seem to understand them," said Corn. While the many years of research have yielded fascinating results, there's much more work to be done in order to fully understand the importance of fire for plants and animals. 
One thing researchers in the Southern California chaparral region do agree on, however, is that the frequency and intensity of fires is higher than ever before and there is only so much burning any ecosystem can handle. 


 

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