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Changing face of wildfire detailed by Gavin
Predicting and preventing wildfire involves a detailed analysis of the complex relationships among climate, vegetation and land, says geography professor Dan Gavin, who recently was the lead author of a review on the subject.
Climate change and the amount and type of vegetation in a forest can influence wildfire, but no single factor is enough to explain both past fluctuations and the current increase in frequency and magnitude of wildfire, said University of Oregon geography professor Dan Gavin, the lead author of a review on the subject's literature in the November issue of Frontiers in Ecology and the Environment.
"Rather it is a complex combination of those factors working in concert with a variety of variables that explain and ultimately might allow us to help forest managers with predictions of fire and its effects," said Gavin.
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Paleofire research, the focus of Gavin's review, is helping to piece together not only a history of fire, but also factors that influence the amount of fire on the landscape. By analyzing charcoal in lake sediments, researchers can determine the amount of burning and when fires occurred over thousands of years. A similar analysis of ancient pollen paints a detailed picture of what types of vegetation dominated an area at a given time, while water levels and sediments from ancient lakes provide a picture of climatic conditions over thousands of years.
When data from all sources are combined, researchers can address cause and effect between fire and vegetation and how changes may have paralleled those in the climate. "Ultimately we desire a model of wildfire that explains how these factors have interacted in the past and how they might in the future," said Gavin, who teaches "Fire in the Environment," an upper-level special topics course. "What we're seeing is that fire -- not climate -- can explain the actual boundaries for some ecosystems. For example, we may find grasslands that could support a forest, but fire prevents it. Through time we may see a threshold where grasses give way to different fuel."
Determination of such thresholds is complicated by environmental factors in specific locations, as well as a century of warming trends capping what had been a 4,000-year cooling-off period, Gavin said.
"Conventional wisdom shows that global warming should contribute to increased wildfire," Gavin said. "But mechanistic models may show that warmer, drier climates in some places may show a decrease in fires because of reduced vegetation, essentially leaving nothing to burn and no fire," Gavin said. "While climate change has always been a factor in fires, we can't let that precedent lull us into a false sense of security. Recent climate changes have significantly outpaced those in the past."
UO geography professor Patrick Bartlein was among the eight co-authors of the review.