Yet restricted and carefully controlled fires can benefit forest ecosystems, Raeburn said. Fires clean forest floors of a heavy buildup of leaves, twigs, and dead vegetation that might otherwise accumulate and help fuel fires to potentially hazardous levels, he noted.
For most of the past 70 years, staff in national parks and forests suppressed the majority of fires. After assessing the ecological benefits of fire, forest officials began to change that policy.
Now, officials at U.S. parks and forests around the country authorize limited burning in areas that are seen as likely to benefit from controlled fires, according to Valerie Baca of the U.S. Forest Service.
"There might be some short-term death," said Raeburn, "but the new life that comes from it is more vigorous and more diverse."
A more sensitive form of fire management is prescribed natural fires, which allow fires started by lightning to burn under specific conditions. Shenandoah National Park and the George Washington National Forest are now writing specific guidelines for such fires.
Boost to Growth
Bourg, a Ph.D. candidate at the University of MarylandCollege Park, has been investigating turkeybeards in the Appalachians to study how fire affects them ecologically. His major adviser, Douglas Gill, had started tagging the plants in 1990, before park and forest officials began setting limited fires to prune the undergrowth and reduce fuel loads.
In the absence of fires, turkeybeards are easily overlooked in forests and seldom produce flowers. The situation was much different after the sanctioned fires in 1996.
By 1998, the plants had resprouted vigorously and hundreds of spectacular flowering stalks had appearedfar more than had ever been recorded. Two additional prescribed fires in 1999 set the stage for the turkeybeards' rejuvenation and growth to their "super-plant" status this year. The plants need a year after a fire to recover before achieving maximum growth and blooming, Bourg said.
Massive fire-induced blooming may be a fire-adapted characteristic of the species, he said, and could explain the multiple stalk production seen on the lilies.
Fire also increases opportunities for pollen exchange among turkeybeard plants as a result of the mass-flowering. Bourg's experimental results have shown that flowers that receive pollen from other plants are more fruitful than those fertilized by their own pollen. Therefore, they produce more seeds, which leads to higher reproduction.
But burns indirectly benefit the plants as well. Fire literally paves the way for the lilies to enjoy a growth spurt, Bourg said. Forest fires reduce competition from other vegetation, open up tree canopies to admit more sunlight, and recycle nutrient-rich organic material by returning it to the soil.
During the recovery period after a fire, this extra sun and added nourishment enable turkeybeards, as well as other forest plants, to grow stronger and then initiate mass production and blooming.
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