Emotional and social intelligence is not limited to us human animals............Bison, Musk Oxen, Dolphins, Crows, Ravens, Magpies, Elephants Baboons,Giraffes, Zebras and perhaps other creatures mourn their dead..............“As a human being, I can easily relate to animals’ suffering because another animal died".................“And maybe it is not so complicated"...................."Maybe it does have to do with the kind of grieving that we humans feel. It may not be exactly the same, but it looks like it is related"

https://www.nwf.org/en/Magazines/National-Wildlife/2018/Feb-Mar/Animals/When-Animals-Grieve

When Animals Grieve

Scientists are uncovering evidence that humans are not the only animals that mourn their dead

 A most extraordinary event in Yellowstone. A bison cow had earlier been killed by wolves. Just as we were driving past the carcass, 12 huge bulls began to surround her and pay homage. They grunted, pawed the ground and were visibly upset. Most faced towards her with heads bowed low. One male continuously licked her lifeless body. This circle of grief went on for half an hour. They mourned her death. Then, one by one, each slipped away. A professional photographer near us explained only few animal groups pay tribute to their dead in this way. One other is elephants. We all sat in silence and watched. It was a sacred, moving, somber and beautiful moment

Rich emotional lives

“The lower animals, like man, manifestly feel pleasure and pain, happiness and misery,” Charles Darwin wrote in 1871. “So intense is the grief of female monkeys for the loss of their young, that it invariably caused the death of certain kinds.”

An adult striped dolphin of unknown sex attends a dead adolescent female in the Gulf of Corinth, Greece, seemingly trying to keep it afloat.

Darwin’s view—that species beyond humans have rich emotional lives—did not evolve into scientific consensus. “In the 20th century, the predominant paradigm was human exceptionalism, the idea that animals are pretty robotic,” says Barbara J. King, emerita professor of anthropology at the College of William and Mary and author of the 2013 book How Animals Grieve, a comprehensive synthesis of animal mourning research. “The thinking was that animals live in the present; they’re solving their problems for survival; they don’t feel a whole a lot.”

The lifeless corpse belongs to a crow, and the dark-garbed group congregating nearby is a gathering of its fellow crows, sometimes referred to as a "murder."  That name is particularly apt in this case, as murder is what holds their attention. Their vigilance over a dead crow serves a purpose — one that's a matter of life and death, according to a new study in the journal Animal Behavior. By sticking close to a crow that was killed, other crows may improve their chances of learning about predators they need to avoid.

There were exceptions to this view. In 1972, the late Yale University biologist and anthropologist Ursula Moser Cowgill reported that two small captive primates called pottos, whom she described as “depressed,” set aside food for a dead companion even at the risk of starving themselves. Around the same time, in Tanzania, Jane Goodall observed how a young chimpanzee called Flint stopped eating and grew gaunt and lethargic after his mother Flo’s death. He died a month later. “His whole world had revolved around Flo,” the primatologist wrote, “and with her gone, life was hollow and meaningless.”

In Kenya’s Maasai Mara, an African elephant calf gently touches the skull of a dead adult. While most animals—even species thought to mourn—lose interest in a body after it decomposes, elephants famously pay homage to the bones of their kin. For two days, a western lowland gorilla (below) cradled and groomed her stillborn infant. “She tried to revive it, but she couldn’t,” says photographer Anup Shah. He and Fiona Rogers spent weeks documenting this gorilla’s family in the Central African Republic.

Even today, many researchers stay away from the language of emotion. “‘Grieving’ is a word that is perceived as illegal among scientists,” says biologist Giovanni Bearzi, president of Dolphin Biology and Conservation, a nonprofit research organization based in Italy. “Our capability of understanding what happens from an animal’s standpoint is pretty limited.”

Some scientists question whether a creature can mourn without a notion of mortality. “You have to understand ‘I am alive’ to understand that someone is dead,” says Alex Piel, a primate biologist at England’s Liverpool John Moores University. “That’s where we run into problems: Most animals, as far as we know, don’t have consciousness.”

After her calf died on a Kenyan savanna, this Rothschild’s giraffe stood vigil by the body, lingering for days without eating or drinking. “She was just standing guard over her dead baby,” says the biologist who observed and photographed the animal.

That argument exasperates Carl Safina, an ecologist at Stony Brook University and author of Beyond Words: What Animals Think and Feel. “There are many animals who, in an operative sense, understand death,” he says—for example, predators who must understand the difference between alive and dead when they kill their food. Besides, he says, “humans have many concepts of mortality—karmic wheels, eternal life and so on—most of which conflict, which indicates most of them are wrong.” Yet we all grieve.

King says that over the past few years animal-grief research has “exploded”—part of a larger “animal turn” among academics who advocate broadening the range of lives and cultures that are studied. Technology has helped, too, including remote monitoring cameras at wildlife sanctuaries. “We have access to behaviors that we didn’t before,” Piel says. In this changing climate, more scientists are publicly making the case for animal grief.

Upsurge of science

Zoe Muller, a University of Bristol wildlife biologist who founded the Rothschild’s Giraffe Project in Kenya, recalls a morning in 2010 when she came upon 17 female giraffes running haphazardly and looking distressed in a part of the savanna they don’t normally frequent. It turned out an injured calf had died, and the adults had gathered with its mother. They stayed with her for two days, frequently nudging the dead animal with their muzzles.

On the third morning, Muller returned. The mother appeared to be alone, standing alert in the shade of an acacia tree. On closer inspection, the biologist realized that hyenas had moved and fed on the calf’s carcass. “The mother was still standing over the body,” she recalls, “even though it was half-eaten.” Though giraffes feed almost constantly, “she wasn’t eating. She wasn’t drinking. She was just standing guard over her dead baby.”

Muller interpreted the giraffe’s behavior as grief. At the time, though, she was reluctant to say so publicly, knowing that “some scientists are very strict about not anthropomorphizing.” Since then, “my personal stance has changed. I would now be a lot more open about acknowledging nonhuman grief. Giraffes, humans, we’re all mammals. Our system of emotion is largely driven by hormones, and hormones are likely to have evolved similarly in all mammals.”

Nudging a dead female, a male Burchell’s zebra is “trying to wake her up,” suggests photographer Christophe Courteau. While scientists have not documented grieving in zebras, the number of such examples is growing.

One way to study grief, then, is to measure changes in hormone levels of survivors. That’s what behavioral ecologist Anne Engh realized when she was studying chacma baboons in Botswana’s Okavango Delta. One of those baboons, an older, high-ranking female called Sylvia, had earned the nickname Queen of Mean. “She went out of her way to be obnoxious to the other females,” says Engh, who now works at Kalamazoo College. “She would threaten somebody just because they’re there, and because she could.”

Sylvia did have one steady companion: her adult daughter Sierra. The duo spent most of their free time together, grooming each other and handling each other’s babies. One day, while Engh was present, lions attacked members of the group as they foraged for tubers in an area of tall grass. Sierra was killed, as was a male with whom she had been consorting. Afterward, Sylvia spent a lot of time alone, staring at her feet. “If she had been a human,” the ecologist says, “I absolutely would have said she was depressed.”

Chacma baboons groom one another more often after the death of a companion, a behavior that lowers stress hormone levels.

That led Engh to review hormonal data on Sylvia and other female baboons that had lost close female relatives—data her team had routinely collected using fecal samples for about a year. What she discovered, and reported in 2006 in the Proceedings of the Royal Society B, was that even a month after the deaths, females showed significant increases in stress hormones called glucocorticoids. After two months, the levels returned to normal.

Grooming and grief

Engh also discovered that, after their losses, the baboons groomed more frequently and with more partners. (Physical contact stimulates release of the hormone oxytocin, which inhibits glucocorticoid release.) “It seemed like they were actively trying to form new friendships,” she says.

That’s what Sylvia did: After her daughter died, she diversified her own grooming network. “In particular, she focused on a fairly low-ranking female who also didn’t seem to have a close friend at that time. “This is a female that she would have absolutely ignored before,” Engh says. “And along with that, her glucocorticoid levels decreased.”

Is it grief? “I still hesitate a little bit to say,” Engh says. “But you find something similar in humans. If women who lose spouses have support from close female friends, they do have increased glucocorticoid levels, but not as high as females who are more socially isolated. So, there is probably a parallel.”

Not every species lends itself to this type of quantitative research, so the question might ultimately remain unsettled. Still, it fascinates. In 2016, Bearzi was with a group of students from Texas A&M University in Greece’s Gulf of Corinth when they spotted an adult striped dolphin circling a dead adolescent and struggling to keep it afloat. “There was a sense of protecting and trying to resuscitate the animal,” he says— “as if to say, ‘Come on. Let’s swim together. Let’s go back to the group.’”

In moments like this, how do we know what’s really going on? Measuring stress hormones or brain activity might yield valuable data, Bearzi says. “But most of the time it is not possible, and I am not advocating that more invasive research be done on grieving cetaceans.” One alternative, he suggests, might be using underwater microphones to record changes in acoustic behavior.

What Bearzi most remembers from that afternoon in Greece was how visceral everyone’s reaction was. The students had not been trained to think about animal emotions, he says. Yet they described their observations in the language of psychicpain. “It’s becoming exhausted,” one of the students narrated on camera. “It’s putting itself in danger. Self-preservation seems to have momentarily left because it is grieving for its loved one.”

Bearzi had a similar reaction. “As a human being, I can easily relate to animals’ suffering because another animal died,” he says. “And maybe it is not so complicated. Maybe it does have to do with the kind of grieving that we humans feel. It may not be exactly the same, but it looks like it is related.”

In Kenya’s Maasai Mara, an African elephant calf gently touches the skull of a dead adult. While most animals—even species thought to mourn—lose interest in a body after it decomposes, elephants famously pay homage to the bones of their kin. For two days, a western lowland gorilla (below) cradled and groomed her stillborn infant. “She tried to revive it, but she couldn’t,” says photographer Anup Shah. He and Fiona Rogers spent weeks documenting this gorilla’s family in the Central African Republic

A new Penn State research report on the use of fire by Indians to enhance wildlife populations via encouraging certain mast bearing tree types such as oak and chestnut to thrive (as well as preparing the land for growing corn, squash and beans) states the following----"Tree census, paleopollen, fossil charcoal, hsman population, and climate data provide unique support for important anthropogenic use of fire over the last 2000 years in the eastern USA"......................."This includes multiple instances of climate fire anomalies that may be best explained by the role of human-caused burning"..............""The debate about whether forest composition has been largely determined by land use or climate continues, but this new study strongly suggests anthropogenic fire has been the major driver of forest change in the East"............“There are great smokes of fire rising from deep in the woods"...............“We marched to those smokes, recalled George Percy (upon navigating the Jamestown Virginia region in 1607), and found that the savages had been there burning down the grass as, we thought, either to make their plantation there or else to give signs to bring their forces together, and so to give us battle"...................."There are those who disagree as to the extent of fire use"............."Steve Pyne wrote that "even a decade ago the question of 'Indian burning' was a quaint appendix to fire management (Pyne 1995: 242)"................"One example of this can be found in the classic, college-level, forestry textbook on fire control by Art Brown and Ken Davis"---- "It is known that Indians at times set fires...[Yet] it is at least a fair assumption that no habitual or systematic burning was carried out by the Indians (Brown and Davis 1973: 16)".................."Hugh Raup, writing in 1937, noted that Indian caused fires in the northeast were uncommon and the idea that they burned the entire New England area every year , or even every 10 to 20 years “is inconceivable"................."Another author also called the idea that Indians purposely burned the forests to preserve them "preposterous" (Coman 1911)".................."Further, esteemed Historical Ecologist Emily Southgate Russell concluded that based on the 35 documents that describe vegetation or Indian life in the 16th or 17th centuries, only half mention any use of fire except for cooking"................. "Only six purportedly first—hand accounts might refer to purposeful, widespread, and frequent use of fire".............. "These six are all consistent with use of fire only locally near camps or villages, or with accidentally escaped fires".............."It is concluded that the frequent use of fires by the Indians to burn the forests was probably at most a local occurrence"................"The Indians' presence in the region and their use of fire for many purposes did, however, increase the frequency of fires above the low levels caused by lightning, and thus had some effect on the vegetation; for example, grasses characterized the ground cover at small, local, frequently burned sites"

A new report

Date:

May 21, 2019

Source:

Penn State

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 numbersof 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.

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Story Source:

Materials provided by Penn State. Original written by Jeff Mulhollem. Note: Content may be edited for style and length.

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Journal Reference:

1. 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

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https://esajournals.onlinelibrary.wiley.com/doi/abs/10.2307/1937331

Indian‐Set Fires in the Forests of the Northeastern United States

Emily W. B. Russell

First published: 01 February 1983

https://doi.org/10.2307/1937331

Abstract

The historical evidence for the Indians' burning the forests of the northeastern United States is reevaluated. Of 35 documents that describe vegetation or Indian life in the 16th or 17th centuries, only half mention any use of fire except for cooking. Only six purportedly first—hand accounts might refer to purposeful, widespread, and frequent use of fire. These six are all consistent with use of fire only locally near camps or villages, or with accidentally escaped fires. It is concluded that the frequent use of fires by the Indians to burn the forests was probably at most a local occurrence. The Indians' presence in the region and their use of fire for many purposes did, however, increase the frequency of fires above the low levels caused by lightning, and thus had some effect on the vegetation; for example, grasses characterized the ground cover at small, local, frequently burned sites.

Yesterday we examined how ridding forests of non-native invasive trees and plants can jump-start biodiversity............Today we involve ourselves with an Oregon State U. Study that reveals that by draining reservoirs, Fishery Managers can help revive populations of endangered Chinook Salmon by virtually causing non-native predatory fish to go extinct............"Draining the Oregon Fallcreek Reservoir led to its intended result—giving juvenile chinook salmon a way out of the reservoir"............. "At the same time, invasive crappie and largemouth bass numbers began declining until there were none"........"During the draining process, bass and crappie get pushed out and into the Willamette......."While filling the river with these exotic and invasive warm-water fish seems like a bad idea, they are in fact pushed downstream in the fall and winter when the water is cold and the flow is faster"........"This puts them at a disadvantage compared to when they leak out of the reservoir in the summer when the the Williamette runs warmer, allowing them to thrive and multiply"................"This extreme Reservoiir Draining Management paradigm lasts only a week in duration, but has long-term, positive implications for the whole ecosystem"..........."It makes the reservoir begin to act as a natural river again, positively affecting the entire native fish community"

https://phys.org/news/2019-05-extreme-reservoir-aids-young-salmon.html

MAY 21, 2019

Extreme draining of reservoir aids young salmon and eliminates invasive fish

by Chris Branam, Oregon State University(all photos credited to Oregon State)

A new study finds that the low-cost, extreme draining of a reservoir in Oregon aided downstream migration of juvenile chinook salmon—and led to the gradual disappearance of two species of predatory invasive fish in the artificial lake.

The study is published in the journal Ecohydrology.

The elimination of largemouth bass and crappie from Fall Creek Reservoir, about 30 miles southeast of Eugene in in the Willamette River basin, could have management implications for reservoirs that have been invaded by certain species of fishthat eat other fish, according to Christina Murphy, a recent Oregon State University doctoral graduate and lead author on the study.

"Even though the strategy appears extreme, it's both helping juvenile salmonids pass downstream and promoting a native species-dominated reservoir," Murphy said. "Bass and crappie, which are major predators in the reservoir, have been pushed out and into the Willamette. That can be worrying because filling the river with invasive, warm-water fish seems like a bad idea, but these reservoirs are leaking warm-water fish all the time.

"The good news is that they were pushed downstream in the fall and winter, when the water is cold and the flow is faster, so they should be at a disadvantage in the Willamette River—compared to when they leak out of the reservoir in the summer."

Fish passage out of reservoirs is a critical issue for downstream movement of juvenile salmonids and other migratory species. Because of their declining numbers through the decades, nine West Coast populations of Chinook salmon are federally threatened and endangered species.

In the Pacific Northwest, large dams and reservoirs have been constructed on many salmon-bearing rivers. Salmon are anadromous: they migrate from home streams to the ocean as juveniles and return a few years later as adults to spawn, so damming rivers can delay downstream migrations by juvenile salmon for months or years.

For the past several years, the U.S. Army Corps of Engineers has briefly drained Fall Creek Reservoir in the fall to help juvenile spring chinook salmon move out of the reservoir and continue their downstream migration.

Fall Creeek Reservoir indicated by lower red arrow

Williamette River indicated by red line

A team of researchers from Oregon State, the U.S. Forest Service Pacific Northwest Research Station and the Corps of Engineers analyzed fish capture data from 2006-2017—annual draining started halfway through this period—to examine changes in timing of passage out of the lake and to compare fish species composition.

The team found that draining the 50-year-old reservoir led to its intended result—giving juvenile chinook salmon a way out of the reservoir. At the same time, crappie and largemouth bass numbers began declining until there were none.

"We have also been sampling fish within the reservoir during the summer," Murphy said. "In 2012, we could capture 10 bass an hour. This went down each year. By the summer of 2015 we only caught one during all of our sampling and in 2016, we didn't capture any. This change was reflected in the data from the trap downstream too. The decline occurred with crappie, but faster."

"This extreme draining management is only about a week in duration, but has implications for the whole ecosystem. It makes the reservoir begin to act as a natural river again affecting the entire fish community," said Ivan Arismendi, an assistant professor in the Department of Fisheries and Wildlife in OSU's College of Agricultural Sciences and co-author on the study.

Sherri Johnson, a research ecologist with the U.S. Forest Service Pacific Northwest Research Station, said, "This type of research and monitoring before and after major changes in management of a reservoir is crucial for improving our ability to balance water availability while maintaining native species."

Gregory Taylor and Todd Pierce of the U.S. Army Corps of Engineers were co-authors on the study. Funding for the research was provided by the U.S. Army Corps of Engineers.

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More information: Christina A. Murphy et al, Short‐term reservoir draining to streambed for juvenile salmon passage and non‐native fish removal, Ecohydrology (2019). DOI: 10.1002/eco.2096

"Native plants in a Forest understory contribute to the health and stability of woodland ecosystems".............."It is a fact that native shrubs don't reach the same density in the understory as invasive, non-native shrubs do, having dire implications for bird, mammal, insect and forest amphibian communities"............"In eastern deciduous forests of North America, invasive, non-native shrubs are increasing in richness and abundance at the expense of native species".......... "Using an non-native shrub removal experiment over a 7 year span starting in 2009, Penn State Researchers have provided us with insight into the effect of repeated removal of a suite of 18 invasive shrub species dominated by border privet"............... "In a region in Pennsylvania known as Hartley Wood, non-natives were removed from five 20-m-diameter treatment plots"............. By 2016, there was an increase in native plant diversity, understory species abundance, and overstory tree species regeneration for individuals under a meter in height"..........."For plants 1 to 4 m in height, the non-native removal treatment has a positive effect on understory woody species, but did not result in the regeneration of native overstory trees"............. "A lack of overstory tree regeneration to greater heights is not surprising, given the time frame and the closed-canopy conditions, as well as other factors such as white-tailed deer over-browsing"................While this research is both relevant and illuminating, the question I pose is what is the cost, feasibility and reality of this type removal paradigm actually being implemented over large tracts of our species-compromised open space?

https://phys.org/news/2019-05-native-regenerate-invasive-shrubs.html

Native forest plants rebound when invasive shrubs are removed

by Pennsylvania State University

Removing invasive shrubs to restore native forest habitat brings a surprising result, according to Penn State researchers, who say desired native understory plants display an unexpected ability and vigor to recolonize open spots.

Seven years of invasive shrub removal from the Hartley Wood in The Arboretum at Penn State promoted plant diversity and facilitated passive natural regeneration of native canopy tree seedlings, understory woody species and woodland herbaceous species. Among them (top left to right) Indianpipe, mayapple and hepatica, (bottom left to right) spotted geranium, waxflower shinleaf and mapleleaf viburnum. Credit: Erynn Maynard-Bean

"The regeneration of native plants that we saw where invasive shrubs had been removed exceeds what we expected from looking at uninvaded parts of the forest," said researcher Erynn Maynard-Bean, who recently earned her doctoral degree in ecology.

"We believe that's because invasive shrubs take up residence in the best spots in the forest. They are most successful where there are the most resources—sunlight, soil nutrients and water. Then, when invasive shrubs are removed, the growth of native plants in those locations beats expectations."

She drew that conclusion after participating in a long-term project in the Arboretum at Penn State, which involved repeated removals of a suite of 18 invasive shrub species and closely monitoring the growth of native plants. That removal experiment was initiated by Margot Kaye, associate professor of forest ecology. In the experiment, after invasives were removed over seven years, plant diversity, native understory species abundance and overstory tree species regeneration, increased.

Non-Native Asian Kudzu on floor and climbing and 
"drowning" the Georgia Forest

The study took place in a woodlot known as the Hartley Wood, a unique old-growth tract of about 42 acres adjacent to what is now a municipal park, where the mostly oak, hickory and maple trees escaped the loggers' blades. A massive white oak that died there in 2000 was determined to have germinated around 1673. But likely because of its proximity to many landscaped homes, the Hartley Wood has been beset by an invasion of exotic plants, and Arboretum managers hope to eliminate them.

Significantly, Maynard-Bean noted, the research demonstrates that sampling the abundance of invasive shrubs and native plants in a forest can minimize negative impacts that invasive shrubs have on native plant numbers.

"We found that seven years of invasive shrub removal boosted natural regeneration of native plants that exceeded the abundance measured in unmanaged forest understories with low levels of shrub invasion," she said. "In this study, in which invasive shrubs have been prominent in the understory for more than 20 years, an ambient sampling approach underestimates the effect of invasive shrubs and the benefits of their removal."

Non-Native Asian Honeysucke(behind the man)
invading and taking over large expanses
of the northeastern forest understory

This research has allowed the native forest plant community to respond to invasive removal over nearly a decade, and highlights the capacity for that system to rebound, pointed out Kaye, whose research group in the College of Agricultural Sciences has been studying the impacts of woody shrub invasion on eastern forest dynamics for even longer.

The findings of the study, published recently in Invasive Plant Science and Management, are important, Kaye explained, because invasive shrubs are increasing in abundance at the expense of native species across eastern deciduous forests of North America. Interest in invasive shrub removal to restore native habitat is growing but forest managers are not sure about how much natural regeneration of native plants they can expect.

"A lot of people think that when you remove invasive shrubs you have to plant natives, and that is obviously helpful but difficult to afford on a large scale," Maynard-Bean said. "But there are native plants in the forest that are mixed with the invasives, and if you maintain the removal, the natives will come back in and take over."

The research is relevant because eastern deciduous forests are becoming more fragmented as urban and suburban areas extend into forests, and associated edges and open spaces have allowed invasive shrubs to make inroads. That does not bode well for wildlife, Maynard-Bean said.

"Native plants in the understory contribute to the health and stability of the forest ecosystem," she said. "Native shrubs don't reach the same density in the understory as invasive shrubs do, and that has implications for bird, insect and even forest amphibian communities."

more information: Erynn Maynard-Bean et al, Invasive shrub removal benefits native plants in an eastern deciduous forest of North America, Invasive Plant Science and Management (2019). DOI: 10.1017/inp.2018.35