 Radio Script 2001
Alaska Fire Research INTRO: While massive forest fires have so far ravaged more than two million acres across the American West in one of the worst fire season in years, wildfires in Alaska have scorched just over 200,000 acres across the state. Typically, Alaska fires are among the nation's largest, with single burns blackening hundreds of thousands of acres. As Sonya Senkowsky reports in this week's Arctic Science Journeys Radio, northern forest fires could be a significant source of the greenhouse gas, carbon dioxide. STORY: It's been seven years since lightning triggered the fire that torched a 22,000-acre swath of boreal spruce forest in Interior Alaska, about 90 miles south of Fairbanks. Fire ecologist Eric Kasischke (Kaz/ISS/kee) of the University of Maryland has come to see how the forest is regrowing. KASISCHKE: "This site's coming back like a gangbuster now." A shovel-full of earth gives him basic information about the site, from growing conditions and drainage, to the kind of soil left behind after a burn. Seven years ago, this area was covered by a stand of mostly black spruce trees, with a forest floor carpeted in thick moss. Then came the fire. Researcher Scott Goetz, also from the University of Maryland, says the blaze destroyed almost everything in its path. GOETZ: "The ground fire came through and basically smoldered through here and consumed all the organic layer and then the roots of the trees, and the trees fell over. So we're walking through a lot of snags with this meter-high deciduous regrowth coming in." When this kind of northern forest burns, the trees aren't the only things to go up in smoke, says Kasischke. KASISCHKE: "Part of what burns are these organic soils. And these organic soils form over hundreds to thousands of years. So when they burn, it's going to take hundreds to thousands of years for them to re-accumulate." Contained in these soils is a storehouse of organic carbon, the result of hundreds of years of accumulated forest litter, which in the boreal forest is kept from decomposing by the moist soil and frozen ground•called "permafrost." Burning the carbon-rich soil releases carbon dioxide, which, when released into the atmosphere, is believed to contribute to global warming. Traditionally, models of climate change haven't accounted for boreal forest fires as a major source of greenhouse gases. It was thought low-fire years would cancel out the negative effects of high-fire years. Many models, in fact, still count on the boreal forest, which stretches across Alaska, Canada and Russia, as a "sink," or a repository, for carbon. That's because the carbon dioxide that trees absorb from the air ends up in their roots, wood fiber and leaves. Kasischke has found evidence that the effects of low-fire and high-fire years do not cancel each other out. His research indicates a pattern: Big fire years in the boreal forest come in cycles, and they are increasing in severity as the northern climate warms. KASISCHKE: "When you're looking at changes in amounts of greenhouse and other gases in the atmosphere that originate from fires on a global basis, these large fire years in the boreal forest are very significant." Just how significant is the question that Kasischke and other researchers are still seeking to answer. At one burn site, called the "Buffalo Field" site because of the bison that graze nearby, Scott Goetz looks over an array of solar cells networked among a maze of burned and toppled trees along the ground. Here and there, tree saplings and fireweed poke up through the charred forest. GOETZ: "Every 10 seconds it'll click off a measurement. Then it's all recorded and we come out and download it." The data-logging instrument records the amount of light reaching the ground. The measurement helps scientists estimate the amount of photosynthesis and carbon uptake taking place in the new plants. GOETZ: "So we get a pretty good handle on the amount of light that's absorbed and then we're able to relate that to the production and carbon uptake of these stands." These and other readings from both burned and unburned sites will be compared to those collected by NASA satellites that measure plant growth from space. In the long run, Kasischke hopes to better understand the relationships between northern fires and climate. KASISCHKE: "The weather in this region has been changing. It has warmed significantly over the last 20 to 30 years. The increase in temperature, combined with the increase in fire frequency, is just going to change the boreal forests up here. And that's what we're trying to understand. How are they going to change, or how are they changing?" OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Sonya Senkowsky. Audio version and related Web sites (sidebar at top right) Thanks to the following individuals for help preparing this script: Scott Goetz, Associate Research Professor Eric Kasischke, Associate Professor Sonya Senkowsky, Science Writer Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
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