Penn State University study: Eastern forests shaped more by Native Americans’ burning than climate change

26 May

The United States Department of Agriculture (USDA) wrote about the benefits of prescribed burning:

Definition Prescribed burning is the deliberate use of fire to help manage a forest. It is a complex management tool and should be used by only those who are trained and experienced in its use.

Benefits Hazard Reduction Prescribed burning helps to eliminate fuels such as pine needles, hardwood leaves, fallen branches, and herbaceous vegetation that accumulate on the forest floor. These fuels increase the chance of destruction of young stands if a wildfire erupts.

Control of Understory Vegetation Prescribed burning helps control low-quality hardwoods and shrubs. Understory vegetation competes with pines for moisture and nutrients, and may interfere with regeneration….

Definition Prescribed burning is the deliberate use of fire to help manage a forest. It is a complex management tool and should be used by only those who are trained and experienced in its use.

Benefits Hazard Reduction Prescribed burning helps to eliminate fuels such as pine needles, hardwood leaves, fallen branches, and herbaceous vegetation that accumulate on the forest floor. These fuels increase the chance of destruction of young stands if a wildfire erupts.

Control of Understory Vegetation Prescribed burning helps control low-quality hardwoods and shrubs. Understory vegetation competes with pines for moisture and nutrients, and may interfere with regeneration. https://efotg.sc.egov.usda.gov/references/public/AL/338_js_PrescribedBurning.pdf

Native Americans used prescribed burning as a forest management practice. See, Indian Use of Fire in Early Oregon https://oregonencyclopedia.org/articles/anthropogenic_fire/#.XOte93dFzIU

Science Daily reported in Eastern forests shaped more by Native Americans’ burning than climate change:

Native Americans’ use of fire to manage vegetation in what is now the Eastern United States was more profound than previously believed, according to a Penn State researcher who determined that forest composition change in the region was caused more by land use than climate change.
“I believe Native Americans were excellent vegetation managers and we can learn a lot from them about how to best manage forests of the U.S.,” said Marc Abrams, professor of forest ecology and physiology in the College of Agricultural Sciences. “Native Americans knew that to regenerate plant species that they wanted for food, and to feed game animals they relied on, they needed to burn the forest understory regularly.”
Over the last 2,000 years at least, according to Abrams — who for three decades has been studying past and present qualities of eastern U.S. forests — frequent and widespread human-caused fire resulted in the predominance of fire-adapted tree species. And in the time since burning has been curtailed, forests are changing, with species such as oak, hickory and pine losing ground.
“The debate about whether forest composition has been largely determined by land use or climate continues, but a new study strongly suggests anthropogenic fire has been the major driver of forest change in the East,” said Abrams. “That is important to know because climate change is taking on an ever larger proportion of scientific endeavor.”
But this phenomenon does not apply to other regions, Abrams noted. In the western U.S., for example, climate change has been much more pronounced than in the East. That region has received much more warming and much more drought, he explained.
“Here in the East, we have had a slight increase in precipitation that has ameliorated the warming,” said Abrams.
To learn the drivers of forest change, researchers used a novel approach, analyzing both pollen and charcoal fossil records along with tree-census studies to compare historic 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. Those forest types encompass two distinct floristic zones — conifer-northern hardwood and sub-boreal to the north, and oak-pine to the south.
The researchers found that in the northernmost forests, present-day pollen and tree-survey data revealed significant declines in beech, pine, hemlock and larches, and increases in maple, poplar, ash, oak and fir. In forests to the south, both witness tree and pollen records pointed to historic oak and pine domination, with declines in oak and chestnut and increases in maple and birch, based on present-day data.
“Modern forests are dominated by tree species that are increasingly cool-adapted, shade-tolerant, drought-intolerant pyrophobes — trees that are reduced when exposed to repeated forest burning,” Abrams said. “Species such as oak are largely promoted by low-to moderate-level forest fires. Furthermore, this change in forest composition is making eastern forests more vulnerable to future fire and drought.”
Researchers also included human population data for the region, going back 2,000 years, to bolster their findings, which recently were published in the Annals of Forest Science. After hundreds of years of fairly stable levels of fire caused by relatively low numbers of Native Americans in the region, they report, the most significant escalation in burning followed the dramatic increase in human population associated with European settlement prior to the early 20th century. Moreover, it appears that low numbers of Native Americans were capable of burning large areas of the eastern U.S. and did so repeatedly.
After 1940, they found, fire suppression was an ecologically transformative event in all forests…. https://www.sciencedaily.com/releases/2019/05/190521162443.htm

Citation:

Eastern forests shaped more by Native Americans’ burning than climate change
Date: May 21, 2019
Source: Penn State
Summary:
Native Americans’ use of fire to manage vegetation in what is now the Eastern United States was more profound than previously believed, according to a researcher who determined that forest composition change in the region was caused more by land use than climate change.

Journal Reference:
Marc D. Abrams, Gregory J. Nowacki. Global change impacts on forest and fire dynamics using paleoecology and tree census data for eastern North America. Annals of Forest Science, 2019; 76 (1) DOI: 10.1007/s13595-018-0790-y

Here is the press release from Penn State:

Eastern forests shaped more by Native Americans’ burning than climate change

Jeff Mulhollem

May 21, 2019

UNIVERSITY PARK, Pa. — Native Americans’ use of fire to manage vegetation in what is now the Eastern United States was more profound than previously believed, according to a Penn State researcher who determined that forest composition change in the region was caused more by land use than climate change.
“I believe Native Americans were excellent vegetation managers and we can learn a lot from them about how to best manage forests of the U.S.,” said Marc Abrams, professor of forest ecology and physiology in the College of Agricultural Sciences. “Native Americans knew that to regenerate plant species that they wanted for food, and to feed game animals they relied on, they needed to burn the forest understory regularly.”
Over the last 2,000 years at least, according to Abrams — who for three decades has been studying past and present qualities of eastern U.S. forests — frequent and widespread human-caused fire resulted in the predominance of fire-adapted tree species. And in the time since burning has been curtailed, forests are changing, with species such as oak, hickory and pine losing ground.
“The debate about whether forest composition has been largely determined by land use or climate continues, but a new study strongly suggests anthropogenic fire has been the major driver of forest change in the East,” said Abrams. “That is important to know because climate change is taking on an ever larger proportion of scientific endeavor.”
But this phenomenon does not apply to other regions, Abrams noted. In the western U.S., for example, climate change has been much more pronounced than in the East. That region has received much more warming and much more drought, he explained.
“Here in the East, we have had a slight increase in precipitation that has ameliorated the warming,” said Abrams.
To learn the drivers of forest change, researchers used a novel approach, analyzing both pollen and charcoal fossil records along with tree-census studies to compare historic 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. Those forest types encompass two distinct floristic zones — conifer-northern hardwood and sub-boreal to the north, and oak-pine to the south.
The researchers found that in the northernmost forests, present-day pollen and tree-survey data revealed significant declines in beech, pine, hemlock and larches, and increases in maple, poplar, ash, oak and fir. In forests to the south, both witness tree and pollen records pointed to historic oak and pine domination, with declines in oak and chestnut and increases in maple and birch, based on present-day data.
“Modern forests are dominated by tree species that are increasingly cool-adapted, shade-tolerant, drought-intolerant pyrophobes — trees that are reduced when exposed to repeated forest burning,” Abrams said. “Species such as oak are largely promoted by low-to moderate-level forest fires. Furthermore, this change in forest composition is making eastern forests more vulnerable to future fire and drought.”
Researchers also included human population data for the region, going back 2,000 years, to bolster their findings, which recently were published in the Annals of Forest Science. After hundreds of years of fairly stable levels of fire caused by relatively low numbers of Native Americans in the region, they report, the most significant escalation in burning followed the dramatic increase in human population associated with European settlement prior to the early 20th century. Moreover, it appears that low numbers of Native Americans were capable of burning large areas of the eastern U.S. and did so repeatedly.
After 1940, they found, fire suppression was an ecologically transformative event in all forests.
“Our analysis identifies multiple instances in which fire and vegetation changes were likely driven by shifts in human population and land use beyond those expected from climate alone,” Abrams said. “After Smokey Bear came on the scene, fire was mostly shut down throughout the U.S. and we have been paying a big price for that in terms of forest change. We went from a moderate amount of fire to too much fire to near zero fire — and we need to get back to that middle ground in terms of our vegetation management.”
Also involved in the research was Gregory J. Nowacki, with the Eastern Regional Office, U.S. Department of Agriculture Forest Service.
The Agricultural Experiment Station of Penn State funded this research.
(MEDIA CONTACTS)
Jeff Mulhollem
jjm29@psu.edu
Work Phone:
814 863-2719
A’ndrea Elyse Messer
aem1@psu.edu
Work Phone:
814-865-9481
Last Updated May 21, 2019

The Royal Parks of the United Kingdom summarized the benefits of urban trees. The Royal Parks wrote in Why are trees so important?

Trees are vital. As the biggest plants on the planet, they give us oxygen, store stabilise the soil and give life to the world’s wildlife. They also provide us with the materials for tools and shelter.
Not only are trees essential for life, but as the longest living species on earth, they give us a link between the past, present and future.
It’s critical that woodlands, rainforests and trees in urban settings, such as parks, are preserved and sustainably managed across the world….
Trees benefit health
The canopies of trees act as a physical filter, trapping dust and absorbing pollutants from the air. Each individual tree removes up to 1.7 kilos every year. They also provide shade from solar radiation and reduce noise….
Trees benefit the environment
Trees absorb carbon dioxide as they grow and the carbon that they store in their wood helps slow the rate of global warming.
They reduce wind speeds and cool the air as they lose moisture and reflect heat upwards from their leaves. It’s estimated that trees can reduce the temperature in a city by up to 7°C.
Trees also help prevent flooding and soil erosion, absorbing thousands of litres of stormwater.
Trees boost wildlife
Trees host complex microhabitats. When young, they offer habitation and food to amazing communities of birds, insects, lichen and fungi. When ancient, their trunks also provide the hollow cover needed by species such as bats, woodboring beetles, tawny owls and woodpeckers.
One mature oak can be home to as many as 500 different species. Richmond Park is full of such trees, which is one of the reasons it has been designated a National Nature Reserve and Site of Special Scientific Interest.
Trees strengthen communities
Trees strengthen the distinctive character of a place and encourage local pride. Urban woodland can be used as an educational resource and to bring groups together for activities like walking and bird-watching. Trees are also invaluable for children to play in and discover their sense of adventure.
Trees grow the economy
People are attracted to live, work and invest in green surroundings. Research shows that average house prices are 5-18% higher when properties are close to mature trees. Companies benefit from a healthier, happier workforce if there are parks and trees nearby.
Trees protect the future
Soon, for the first time in history, the number of people with homes in cities will outstrip those living in the countryside. Parks and trees will become an even more vital component of urban life. We must respect them and protect them for the future…. https://www.royalparks.org.uk/parks/the-regents-park/things-to-see-and-do/gardens-and-landscapes/tree-map/why-trees-are-importantcarbon,

See, Envisioning a Great Green City: Nature needs cities. Cities need nature. https://www.nature.org/en-us/what-we-do/our-insights/perspectives/envisioning-a-great-green-city/

Resources:

Urban Forestry & Energy Conservation Bibliography https://articles.extension.org/pages/71120/urban-forestry-energy-conservation-bibliography

Urban Forestry Bibliography Created by the Forest Service … https://www.milliontreesnyc.org/downloads/pdf/urban_tree_bib.pdf

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