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Eastern forests are more affected by the burning of Native Americans than by climate change



  Eastern forests are more affected by the burning of Native Americans than by climate change
Pollen and Tree Survey Map. Picture credits: Marc Abrams, Penn State

The use of Native American fire to manage vegetation in what is now the eastern United States was, according to a Penn State researcher, who noted that the change in forest composition in the region is due to land use rather than climate caused far more widely than assumed change.

"I believe the Native Americans were excellent vegetation managers and we can learn a lot about how to best manage US forests," said Marc Abrams, Professor of Forest Ecology and Physiology at the College of Agricultural Sciences. "The Native Americans knew that in order to regenerate the plant species they needed as food and to feed the wildlife they rely on, they had to regularly burn the undergrowth of the forest."

At least in the last 2000 years, Abrams said ̵

1; who For three decades, the past and present qualities of forests in the eastern US have been studied. Frequent and widespread man-made fires have led to the prevalence of fire-adapted tree species. And in the time of burning, the forests are changing and species like oak, hickory and pine are losing ground.

"The debate over whether forest composition was largely determined by land use or climate continues, but a new study strongly suggests that anthropogenic fire was the main driver of forest change in the east," Abrams said. "This is important to know because climate change is taking up more and more of the scientific effort."

However, this phenomenon does not apply to other regions, according to Abrams. In the western US, for example, climate change was much more pronounced than in the East. This region has experienced much more warming and drought, he explained.

"Here in the east we have a slight increase in rainfall, which has improved warming," Abrams said.

To learn the drivers of From a novel approach, the researchers analyzed pollen and coal fossils and tree-count studies to compare the historical and modern tree composition in the forests of eastern North America. They looked at seven forest types in the north and central regions of the eastern United States. These forest types include two distinct floristic zones: northern coniferous and subboreal in the north and oak in the south.

Researchers found that today's pollen and tree survey data are available in the northernmost forests. Beech, pine, hemlock and larch decreased significantly, and maple, poplar, ash, oak and fir increased. In forests to the south, both witness tree and pollen records indicated a historic dominance of oaks and pines, with a decline in oaks and chestnuts, and an increase in maple and birch, based on current data.

"Modern forests are dominated by trees Species that are increasingly adapted to cool conditions, can tolerate shadows and tolerate drought – trees that are reduced when exposed to repeated forest fires," said Abrams. "Species such as oak are largely fueled by forest fires of low to moderate levels, and this change in forest composition makes the forests in the east more vulnerable to future fires and droughts."

Researchers also took 2000-year human population data back to the region to support their findings recently published in the Annals of Forest Science (19459014). After hundreds of years of relatively stable fire caused by a relatively small number of Native Americans in the area, the most significant escalation of incineration followed the dramatic increase in human population associated with European settlement prior to the early 20th century. In addition, it appears that a small number of Native Americans have been able to burn large areas of the eastern United States, and this is repeated.

After 1940, they discovered that firefighting was an environmentally transformative event in all forests.

"Our analysis identifies several cases where changes in fires and vegetation are likely to have been caused by shifts in human populations and land use beyond those anticipated solely on account of the climate," Abrams said. "After Smokey Bear came on the scene, most of the fire in the US was shut down, and we paid a high price for the forest change, moving from a modest amount of fire to an excessively high amount of fire to near zero fire . " and we have to return to this middle ground in terms of our vegetation management. "


Eastern US forests are more susceptible to drought than before 1800


Further information:
Marc D. Abrams et al., Global Change Affects Forest and Fire Dynamics by Using Paleoecology and Tree Counting Data for Eastern North America (19459014). Annals of Forest Science (19459015) (2019). DOI: 10.1007 / s13595-018-0790-y

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Pennsylvania State University




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Eastern forests are more affected by Native American burning than climate change (2019, 21 May)
retrieved on May 22, 2019
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