Ecological Effects Of Forest Fires
April 10, 2001
More than 92,000 separate fires blackened an estimated 7.4 million acres of woodland in the U.S. last year -- one of the most severe years on record. Among the hardest hit states were Montana, New Mexico and Colorado.
Ever since fires blackened 739,000 acres in Yellowstone National Park in Wyoming in 1988, researchers have been studying the effect of fire on the park's ecosystem and how it responds in ensuing years. More than 250 experiments have been performed there. The findings should provide insights into how areas damaged last year might respond in the future.
Here are a few of the researchers' conclusions:
- Shifts in habitat fall along a spectrum -- from major to subtle -- depending on factors including a fire's intensity and soil conditions.
- The changes favor some species and increase their distribution and abundance (hawks, snowshoe hare, lynx), while hampering others (moose, pine martens) -- sometimes for the short term, and sometimes for much longer.
- Depending on wind and available fuel, a wildfire burns in a mosaic -- destroying some areas, while singeing other areas and leaving some untouched.
- Lightly burned or unburned areas provide a reservoir of seeds that revitalize more heavily burned acreage.
Three years after the Yellowstone fire, however, the boost from additional nutrients was largely over and regrowth was remarkably rapid.
In areas that burned last year, at lower elevations than the park, much more of the forests were in dryer ecosystems that are less resilient.
The researchers' findings are detailed in a new book, "Yellowstone in the Afterglow: Lessons from the Fire."
Source: Jim Robbins, "In Fires' Afterglow, Nature Runs Its Course, for Good and Ill," New York Times, April 10, 2001.
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