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The use of fire by Native Americans to manage vegetation in what is now the eastern United States was deeper than previously thought, according to a Penn State researcher who determined that the amendment The composition of forests in the region was more caused by land use than climate change.
"I think Native Americans were excellent managers of vegetation and we can learn a lot about the best way to manage the forests of the United States," said Marc Abrams, professor of ecology and forestry. Forest Physiology at the College of Agricultural Sciences. "Amerindians knew that to regenerate the plant species they needed to feed and feed the game animals they relied on, they had to burn the undergrowth of the forest regularly."
For at least the last 2,000 years, according to Abrams – who has been studying the past and present qualities of the forests of the eastern United States for three decades – frequent and widespread man-made fires have led to the predominance of forest species adapted to fire. And since the burning has been reduced, forests are changing, with species such as oak, hickory and pine losing their land.
"The debate over whether the composition of the forest was largely determined by land use or climate continues, but a new study strongly suggests that fires of anthropogenic origin have been the Main factor of forest change in the East, "said Abrams. "It is important to know, because climate change is a growing part of science."
But this phenomenon does not apply to other regions, noted Abrams. In the western United States, for example, climate change has been much more pronounced than in the east. This region has experienced much more warming and drought, he explained.
"Here in the east, we had a slight increase in precipitation that eased warming," said Abrams.
Researchers used a new approach by analyzing pollen and charcoal archives as well as tree census studies to compare the historical and modern composition of trees in the eastern forests of Canada. North America. They examined seven forest types in the north and central eastern United States. These forest types encompass two distinct floristic zones: northern hardwoods and subboreal forests in the north, and green oak pines in the south.
The researchers found that in the northernmost forests, current pollen and tree survey data revealed significant declines in beech, pine, hemlock and larch, as well as an increase in maple, poplar, ash, oak and fir. In the southern forests, records of control trees and pollen indicated historic dominance of oaks and pines, with declines of oaks and chestnuts and an increase in maple and birch stocks, based on current data. .
"Modern forests are dominated by species increasingly adapted to the cold, drought-resistant and drought-intolerant pyrophobes – reduced trees when exposed to repeated forest fires," said Abrams. "Species such as oak are largely favored by low to moderate forest fires, and this change in forest composition makes eastern forests more vulnerable to future fires and droughts."
The researchers also included data on the 2,000-year-old human population of the region to support their findings, which were recently published in the Annals of Forest Science. After hundreds of years of relatively stable fires caused by relatively low numbers of Native Americans in the area, the largest increase in fires followed from the dramatic increase in the human population linked to European colonization prior to the beginning of the 20th century. In addition, it appears that low numbers of Native Americans have been able to burn large areas of the eastern United States on several occasions.
After 1940, they found that fire suppression was an event of ecological transformation in all forests.
"Our analysis identifies many cases in which fires and vegetation changes were likely caused by changes in human population and land use beyond those expected from the only climate," Abrams said. "After the arrival of Smokey Bear, the fires were almost completely extinguished in the United States and we paid a heavy price for the change of the forest." We went from a moderate amount of overfire to almost zero – – and we have to go back to that middle ground in terms of vegetation management. "
Gregory J. Nowacki, from the US Regional Office of the US Forest Service for Agriculture, was also involved in the research. The Penn State Agricultural Experiment Station funded this research.
Source of the story:
Material provided by Penn State. Original written by Jeff Mulhollem. Note: Content can be changed for style and length.
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