OREGON STATE UNIVERSITY

college of forestry

Loss of large carnivores poses global conservation problem

CORVALLIS, Ore. – In ecosystems around the world, the decline of large predators such as lions, dingoes, wolves, otters, and bears is changing the face of landscapes from the tropics to the Arctic – but an analysis of 31 carnivore species to be published Friday in the journal Science shows for the first time how threats such as habitat loss, persecution by humans and loss of prey combine to create global hotspots of carnivore decline.

More than 75 percent of the 31 large-carnivore species are declining, and 17 species now occupy less than half of their former ranges, the authors reported.

Southeast Asia, southern and East Africa and the Amazon are among areas in which multiple large carnivore species are declining. With some exceptions, large carnivores have already been exterminated from much of the developed world, including Western Europe and the eastern United States.

“Globally, we are losing our large carnivores,” said William Ripple, lead author of the paper and a professor in the Department of Forest Ecosystems and Society at Oregon State University.

“Many of them are endangered,” he said. “Their ranges are collapsing. Many of these animals are at risk of extinction, either locally or globally. And, ironically, they are vanishing just as we are learning about their important ecological effects.”

Ripple and colleagues from the United States, Australia, Italy and Sweden called for an international initiative to conserve large predators in coexistence with people. They suggested that such an effort be modeled on the Large Carnivore Initiative for Europe, a nonprofit scientific group affiliated with the International Union for the Conservation of Nature.

The researchers reviewed published scientific reports and singled out seven species that have been studied for their widespread ecological effects or “trophic cascades.” This includes African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.

Ripple and his Oregon State co-author Robert Beschta have documented impacts of cougars and wolves on the regeneration of forest stands and riparian vegetation in Yellowstone and other national parks in North America. Fewer predators, they have found, lead to an increase in browsing animals such as deer and elk. More browsing disrupts vegetation, shifts birds and small mammals and changes other parts of the ecosystem in a widespread cascade of impacts.

Studies of Eurasian lynx, dingoes, lions and sea otters have found similar effects, the authors reported.

Lynx have been closely tied to the abundance of roe deer, red fox and hare. In Australia, the construction of a 3,400-mile dingo-proof fence has enabled scientists to study ecosystems with and without the animals, which are closely related to gray wolves. In some parts of Africa, the decrease of lions and leopards has coincided with a dramatic increase in olive baboons, which threaten farm crops and livestock. In the waters off southeast Alaska, a decline in sea otters through killer whale predation has led to a rise in sea urchins and loss of kelp beds.

The authors call for a deeper understanding of the impact of large carnivores on ecosystems, a view that they trace back to the work of landmark ecologist Aldo Leopold. The classic concept that predators are harmful and deplete fish and wildlife is outdated, they said. Scientists and wildlife managers need to recognize a growing body of evidence for the complex roles that carnivores play in ecosystems and for their social and economic benefits.

Leopold recognized such relationships between predators and ecosystems, Ripple said, but his observations on that point were largely ignored for decades after his death in 1948.

“Human tolerance of these species is a major issue for conservation,” Ripple said. “We say these animals have an intrinsic right to exist, but they are also providing economic and ecological services that people value.”

Among the services that have been documented in other studies are carbon sequestration, riparian restoration, biodiversity and disease control.

Where large carnivores have been restored — such as wolves in Yellowstone or Eurasian lynx in Finland — ecosystems have responded quickly, said Ripple. “I am impressed with how resilient the Yellowstone ecosystem is. It isn’t happening quickly everywhere, but in some places, ecosystem restoration has started there.”

In those cases, where loss of vegetation has led to soil erosion, for example, full restoration in the near term may not be possible, he said.

“Nature is highly interconnected,” said Ripple. “The work at Yellowstone and other places shows how one species affects another and another through different pathways. It’s humbling as a scientist to see the interconnectedness of nature.”

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Bill Ripple, 541-737-3056

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Leopard. credit Kirstin Abley copy 2
Leopard


Dingo, credit Ken Shaw copy 2
Dingo


Gray Wolf, credit- Doug McLaughlin copy 2
Gray Wolf


Sea otter, credit Norman S. Smith copy
Sea Otter


Eurasian lynx, credit Bodel Elmhagen copy
Eurasian Lynx


puma also known as cougar, credit william ripple
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lion, credit kirstin abley
African Lion

Efforts to curb climate change require greater emphasis on livestock

CORVALLIS, Ore. – While climate change negotiators struggle to agree on ways to reduce carbon dioxide (CO2) emissions, they have paid inadequate attention to other greenhouse gases associated with livestock, according to an analysis by an international research team.

A reduction in non-CO2 greenhouse gases will be required to abate climate change, the researchers said. Cutting releases of methane and nitrous oxide, two gases that pound-for-pound trap more heat than does CO2, should be considered alongside the challenge of reducing fossil fuel use.

The researchers’ analysis, “Ruminants, Climate Change, and Climate Policy,” is being published today as an opinion commentary in Nature Climate Change, a professional journal.

William Ripple, a professor in the College of Forestry at Oregon State University, and co-authors from Scotland, Austria, Australia and the United States, reached their conclusions on the basis of a synthesis of scientific knowledge on greenhouse gases, climate change and food and environmental issues. They drew from a variety of sources including the Food and Agricultural Organization, the United Nations Framework Convention on Climate Change (UNFCCC) and recent peer-reviewed publications.

“Because the Earth’s climate may be near a tipping point to major climate change, multiple approaches are needed for mitigation,” said Ripple. “We clearly need to reduce the burning of fossil fuels to cut CO2 emissions. But that addresses only part of the problem. We also need to reduce non-CO2 greenhouse gases to lessen the likelihood of us crossing this climatic threshold.”

Methane is the second most abundant greenhouse gas, and a recent report estimated that in the United States methane releases from all sources could be much higher than previously thought. Among the largest human-related sources of methane are ruminant animals (cattle, sheep, goats, and buffalo) and fossil fuel extraction and combustion.

One of the most effective ways to cut methane, the researchers wrote, is to reduce global populations of ruminant livestock, especially cattle. Ruminants are estimated to comprise the largest single human-related source of methane. By reflecting the latest estimates of greenhouse gas emissions on the basis of a life-cycle or a “farm to fork” analysis, the researchers observed that greenhouse gas emissions from cattle and sheep production are 19 to 48 times higher (on the basis of pounds of food produced) than they are from producing protein-rich plant foods such as beans, grains, or soy products.

Unlike non-ruminant animals such as pigs and poultry, ruminants produce copious amounts of methane in their digestive systems. Although CO2 is the most abundant greenhouse gas, the international community could achieve a more rapid reduction in the causes of global warming by lowering methane emissions through a reduction in the number of ruminants, the authors said, than by cutting CO2 alone.

The authors also observed that, on a global basis, ruminant livestock production is having a growing impact on the environment:

  • Globally, the number of ruminant livestock has increased by 50 percent in the last 50 years, and there are now about 3.6 billion ruminant livestock on the planet.
  • About a quarter of the Earth’s land area is dedicated to grazing, mostly for cattle, sheep and goats.
  • A third of all arable land is used to grow feed crops for livestock.

In addition to reducing direct methane emissions from ruminants, cutting ruminant numbers would deliver a significant reduction in the greenhouse gas emissions associated with the production of feed crops for livestock, they added.

“Reducing demand for ruminant products could help to achieve substantial greenhouse gas reductions in the near-term,” said co-author Helmut Haberl of the Institute of Social Ecology in Austria, “but implementation of demand changes represent a considerable political challenge.”

Among agricultural approaches to climate change, reducing demand for meat from ruminants offers greater greenhouse gas reduction potential than do other steps such as increasing livestock feeding efficiency or crop yields per acre. Nevertheless, they wrote, policies to achieve both types of reductions “have the best chance of providing rapid and lasting climate benefits.”

Such steps could have other benefits as well, said co-author Pete Smith of the University of Aberdeen in Scotland. "Cutting the number of ruminant livestock could have additional benefits for food security, human health and environmental conservation involving water quality, wildlife habitat and biodiversity,” he explained. 

Agricultural researchers are also studying methane reduction through improved animal genetics and methods to inhibit production of the gas during digestion.

International climate negotiations such as the UNFCCC have not given “adequate attention” to greenhouse gas reductions from ruminants, they added. The Kyoto Protocol, for example, does not target ruminant emissions from developing countries, which are among the fastest-growing ruminant producers.

In addition to Smith and Haberl, co-authors include Stephen A. Montzka of the U.S. National Oceanic and Atmospheric Administration, Clive McAlpine of the University of Queensland in Australia and Douglas Boucher of the Union of Concerned Scientists in Washington D.C.

 

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Bill Ripple, 541-737-3056

Significant advance reported with genetically modified poplar trees

CORVALLIS, Ore. – Forest geneticists at Oregon State University have created genetically modified poplar trees that grow faster, have resistance to insect pests and are able to retain expression of the inserted genes for at least 14 years, a report in the Canadian Journal of Forest Research just announced.

The trees are one of the best successes to date in the genetic modification of forest trees, a field that is much less advanced than GMO products in crop agriculture. The advance could prove especially useful in the paper and pulp industries, and in an emerging biofuel industry that could be based on hybrid poplar plantations.

Commercial use of such trees could be done with poplars that also had been engineered to be sterile so they would be unlikely to spread their characteristics to other trees, researchers said.

Development of male sterile trees has been demonstrated in the field, which can be used for male varieties of poplar. Female sterility has not yet been done but should be feasible, they said. However, it is unclear if regulatory agencies would allow use of these trees, with sterility as a key mitigation factor.

“In terms of wood yield, plantation health and productivity, these GMO trees could be very significant,” said Steven Strauss, a distinguished professor of forest biotechnology in the OSU College of Forestry. “Our field experiments and continued research showed results that exceeded our expectations. And it is likely that we have underestimated the value these trees could have in improved growth and production.”

A large-scale study of 402 trees from nine “insertion events” tracked the result of placing the cry3Aa gene into hybrid poplar trees. The first phase was done in field trials between 1998 and 2001, and in 14 years since then study continued in a “clone bank” at OSU to ensure that the valued traits were retained with age.

All of the trees were removed or cut back at the age of two years before they were old enough to flower and reproduce, in order to prevent any gene flow into wild tree populations, researchers said.

With this genetic modification, the trees were able to produce an insecticidal protein that helped protect against insect attack. This method has proven effective as a pest control measure in other crop species such as corn and soybeans, resulting in substantial reductions in pesticide use and a decrease in crop losses.

“Insect attack not only can kill a tree, it can make the trees more vulnerable to other health problems,” said Amy Klocko, an OSU faculty research associate. “In a really bad year of insect attack you can lose an entire plantation.”

Hybrid poplar trees, which are usually grown in dense rows on flat land almost like a food crop, are especially vulnerable to insect epidemics, the researchers said. Manual application of pesticides is expensive and targets a wide range of insects, rather than only the insects that are attacking the trees.

A number of the GMO trees in this study also had significantly improved growth characteristics, the researchers found. Compared to the controls, the transgenic trees grew an average of 13 percent larger after two growing seasons in the field, and in the best case, 23 percent larger.

Some of the work also used a drought-tolerant poplar clone, another advantage in what may be a warmer and drier future climate. The research was supported by the Tree Biosafety and Genomics Research Cooperative at OSU.

Annual crops such as cotton and corn already are routinely grown as GMO products with insect resistance genes. Trees, however, have to grow and live for years before harvest and are subjected to multiple generations of insect pest attacks. That’s why engineered insect protection may offer even greater commercial value, and why extended tests were necessary to demonstrate that the resistance genes would still be expressed more than a decade after planting.

Some genetically modified hybrid poplar trees are already being used commercially in China, but none in the United States. The use of GMO trees in the U.S. still faces heavy regulatory obstacles, Strauss said. Agencies are likely to require extensive studies of gene flow and their effects on forest ecosystems, which are difficult to carry out, he said.

Strauss said he advocates an approach of engineering sterility genes into the trees as a mechanism to control gene flow, which together with further ecological research might provide a socially acceptable path for commercial deployment.

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Steven Strauss, 541-737-6578

Overgrazing turning parts of Mongolian Steppe into desert

CORVALLIS, Ore. – Overgrazing by millions of sheep and goats is the primary cause of degraded land in the Mongolian Steppe, one of the largest remaining grassland ecosystems in the world, Oregon State University researchers say in a new report.

Using a new satellite-based vegetation monitoring system, researchers found that about 12 percent of the biomass has disappeared in this country that’s more than twice the size of Texas, and 70 percent of the grassland ecosystem is now considered degraded. The findings were published in Global Change Biology.

Overgrazing accounts for about 80 percent of the vegetation loss in recent years, researchers concluded, and reduced precipitation as a result of climatic change accounted for most of the rest. These combined forces have led to desertification as once-productive grasslands are overtaken by the Gobi Desert, expanding rapidly from the south.

Since 1990 livestock numbers have almost doubled to 45 million animals, caused in part by the socioeconomic changes linked to the breakup of the former Soviet Union, the report said. High unemployment led many people back to domestic herding.

The problem poses serious threats to this ecosystem, researchers say, including soil and water loss, but it may contribute to global climate change as well. Grasslands, depending on their status, can act as either a significant sink or source for atmospheric carbon dioxide.

“This is a pretty serious issue,” said Thomas Hilker, an assistant professor in the OSU College of Forestry. “Regionally, this is a huge area in which the land is being degraded and the food supply for local people is being reduced.

“Globally, however, all ecosystems have a distinct function in world climate,” he said. “Vegetation cools the landscape and plays an important role for the water and carbon balance, including greenhouse gases.”

Even though it was clear that major problems were occurring in Mongolia in the past 20 years, researchers were uncertain whether the underlying cause was overgrazing, climate change or something else. This report indicates that overgrazing is the predominant concern.

Mongolia is a semi-arid region with harsh, dry winters and warm, wet summers. About 79 percent of the country is covered by grasslands, and a huge surge in the number of grazing animals occurred during just the past decade - especially sheep and goats that cause more damage than cattle. Related research has found that heavy grazing results in much less vegetation cover and root biomass, and an increase in animal hoof impacts.

Collaborators on this research included Richard H. Waring, a distinguished professor emeritus of forest ecology from OSU; scientists from NASA and the University of Maryland; and Enkhjargal Natsagdorj, a former OSU doctoral student from Mongolia. The work has been supported by NASA and OSU.

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Thomas Hilker, 541-737-2608

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Overgrazing in Mongolia

Grazing in Mongolia


Grazing in Mongolia

Mongolian herders

Media advisory: Oregon State wildfire experts

MEDIA ADVISORY

The following Oregon State University faculty members have expertise related to wildfire issues and are willing to speak with journalists. Their specific expertise, and contact information, is listed below.  For help with other OSU faculty experts, contact Mark Floyd, 541-737-0788, mark.floyd@oregonstate.edu.

OSU wildfire experts

John Bailey, 541-737-1497, john.bailey@oregonstate.edu

Bailey studies the role of forest management in accomplishing landowner objectives, including fire resilience, habitat and restoration. His areas of expertise include:

  • Fuels management for fire risk reduction
  • Wildland fire ecology
  • Prescribed fire

Stephen Fitzgerald, 541-737-3562, stephen.fitzgerald@oregonstate.edu

Amy Jo Detweiler, 541-548-6088, amyjo.detweiler@oregonstate.edu

Detweiler and Fitzgerald are faculty members in the OSU Extension Service and co-authors of a publication, Fire-Resistant Plants for Home Landscapes, published in 2006 and due to be updated next year. They can discuss ways for homeowners to reduce fire risk to their homes.

  • Types of shrubs and trees that are less likely to burn
  • Maintenance tips for fire resistant plantings
  • Bark mulches and other ground covers
  • Fuel reduction around homes

 

Beverly Law, 541-737-6111, bev.law@oregonstate.edu

Law is a professor in the OSU Department of Forest Ecosystems and Society and former Science Chair of the Ameriflux network. She studies carbon and water cycling in ecosystems and exchange with the atmosphere, including the forests of the Pacific Northwest. She has focused on, among other topics, the role of fire in the carbon cycle. She can comment on:

  • Modeling ecosystem responses to disturbances such as fire and insects
  • The effects of climate change, fire and forest management on carbon and water cycles
  • The combination of remote sensing and field observations to understand regional ecosystem processes

 

Claire Montgomery, 541-737-1362, claire.montgomery@oregonstate.edu

Montgomery studies the economic implications of fire management decisions, from the initial determination whether to let a fire burn or to put it out. She can address the likely impacts of fire management decisions on the value of timber and other forest resources in the future.

  • Incentives for cost-effective wildland fire management
  • Community considerations of forest fuel treatments
  • The opportunity costs of fire suppression

 

Roger Hammer, 541-760-1009, rhammer@oregonstate.edu

Hammer is a professor in the School of Public Policy and studies the interface between communities and undeveloped lands such as forests. He studies strategies to mitigate fire risk in the face of urban development. He can comment on:

  • U.S. demographic trends at the urban-wildland interface
  • Fire risk and development at the urban-wildland interface
  • New construction after a fire

Kathie Dello, 541-737-8927, kdello@coas.oregonstate.edu

Dello is the deputy director of the Oregon Climate Service and associate director of the Oregon Climate Change Research Institute. She studies Pacific Northwest weather patterns and compiles reports for use by businesses and government agencies. She can comment on weather patterns as they influence fire risk, including:

  • Long-term trends in Pacific Northwest weather
  • The impact of landscape features (mountains, forests) on weather
  • Weather data collection by citizens

 

Compiled by Nick Houtman

541-737-0783, nick.houtman@oregonstate.edu

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Nick Houtman, 541-737-0783

Rising fossil fuel energy costs spell trouble for global food security

CORVALLIS, Ore. – Ongoing efforts to feed a growing global population are threatened by rising fossil-fuel energy costs and breakdowns in transportation infrastructure. Without new ways to preserve, store, and transport food products, the likelihood of shortages looms in the future.

In an analysis of food preservation and transportation trends published in this week’s issue of the journal BioScience, scientists warn that new sustainable technologies will be needed for humanity just to stay even in the arms race against the microorganisms that can rapidly spoil the outputs of the modern food system.

“It is mostly a race between the capacity of microbe populations to grow on human foodstuffs and evolve adaptations to changing conditions and the capacity of humans to come up with new technologies for preserving, storing, and transporting food,” wrote lead author Sean T. Hammond, a postdoctoral researcher and interdisciplinary ecologist in the College of Forestry at Oregon State University.

Hammond developed the analysis with colleagues at the University of New Mexico, Arizona State University and Universidad Autónoma del Estado de Morelos in Mexico.

The authors note that increased energy use in food-preservation systems does not always prolong shelf life. For example, drying and canning tend to use less energy than freezing, which requires ongoing energy consumption. Moreover, as cities expand and food is produced by fewer people, dependence grows on fossil-fuel transportation systems. The cargo ships, trucks and trains that carry most of the world’s food run almost exclusively on oil.

“Getting food from the field to your table is a matter of production, storage and transportation,” said Hammond. “It sounds trivial to say that, but if there’s a problem with any of those – a drought, problems with roads or problems keeping foods cool and dry for storage during transport – the system breaks down and people starve.

“More people moving to cities means there are fewer people working to produce food, which means we need to use more energy in the form of machinery to grow and harvest things,” Hammond noted. “Problems with bridges, rail and port infrastructure increase the time needed to transport food and lead to even more energy needed to keep food from spoiling while it is transported.”

Technological advances in preservation and transportation systems have improved the diversity and nutritional qualities of food over what was available to pre-industrial societies. Nevertheless, it’s been estimated that up to 40 percent of the food produced in the United States is lost or wasted. The estimate is lower in developing countries, about 10 percent, due to different diets and cultural norms.

In their analysis, Hammond and his colleagues considered the growth of microorganisms on food products as temperatures increase in storage; the shelf life of foods such as fish, potatoes, strawberries and wheat; the amounts of energy used in preservation methods; and historical advances in the transportation of different foodstuffs.

“As humans push up against the limits of the finite Earth,” they wrote, “food security is a major concern.” To meet future needs, decreasing numbers of farmers, ranchers and fishermen will need to become more efficient and productive. In short, they will need to produce more food per acre and use less fossil-fuel energy, Hammond and his co-authors write.

Innovations that use other energy sources will be required in preservation, storage and transportation systems. The issue is particularly acute in tropical areas where higher average temperatures and humidity translate into faster rates of food spoilage than in temperate climates.

“We can transport any food, even foods that spoil quickly like fish or fruits, to any point on the surface of the planet before it goes bad,” Hammond said. “That’s pretty amazing, but I think we need to question whether we should. Maybe the local-food movement is less of a trend in modern society and more of a necessity.”

Researchers conducting the analysis received support from the National Science Foundation, the National Institutes of Health and the James S. McDonnell Foundation.

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Sean T. Hammond, 415-828-1674

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Sean T. Hammond

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Illustration by Trevor Fristoe

Scientists release predatory flies to protect eastern hemlocks from insect attack

CORVALLIS, Ore. – Scientists say that a West Coast fly no bigger than a grain of rice may hold the key to survival of a tree that is being devastated by an invasive insect.

The eastern hemlock grows from the Carolinas to Quebec and is threatened by the hemlock woolly adelgid, which is native to Asia and the Pacific Northwest. Through nearly a decade of research, scientists at Oregon State University and the USDA Forest Service have identified a predatory fly that kills the adelgid and may help to curb infestations.

In the southern Appalachians, hemlocks have been particularly hard hit, including a less-abundant species known as Carolina hemlock. As much as 80 to 90 percent of the mature trees in some stands have been killed. Researchers believe that without intervention, they could suffer the same fate as the American chestnut – a once-common eastern tree that was nearly wiped out by a fungal disease in the early 1900s.

A research team led by two entomologists – Darrell Ross in the Oregon State College of Forestry and Kimberly Wallin with the University of Vermont and the USDA Forest Service Northern Research Station – demonstrated that a type of fly in the Pacific Northwest known as a silver fly (species in the genus Leucopis) attacks adelgids on western and eastern hemlocks. And while silver flies in the East are known to prey on a species of adelgids in pine trees, those flies are not known to be attracted to hemlocks.

“Populations of flies in the West search for hemlock trees, and that’s where they find their hosts,” said Ross. “The same species in the East has evolved to look for pine trees. They probably use chemical cues from those trees to find their habitat and their hosts. That’s why it’s useful to take the flies from out here, because they’ll look for hemlock trees and feed on the hemlock woolly adelgid in the East.”

This past spring, scientists with the USDA Forest Service, the University of Vermont and Cornell University released silver flies from the Pacific Northwest in hemlock stands near Grandview, Tennessee, and along the shore of Skaneateles Lake in New York state. The researchers are monitoring the trees for evidence that the flies can successfully reproduce and prey on hemlock woolly adelgids. Early results indicate that the flies are mating, laying eggs and producing larvae that are growing to the adult stage.

“That is as good as we could have hoped for at this point,” said Ross. “It remains to be seen whether they will survive and if their populations will grow to densities that significantly impact the hemlock woolly adelgid populations and, ultimately, the survival of eastern hemlocks. We probably won't have answers to those questions for a year or two.”

“We don’t hope that the flies will eradicate all the adelgids,” added Wallin, but if they could provide a check on the pest’s population size and territorial expansion, it could allow some hemlocks to persist and recover.

The releases were done under a permit from the Animal Plant Health Inspection Service (APHIS). Forest Service scientist Albert “Bud” Mayfield and Extension researcher Mark Whitmore of Cornell led the release effort in Tennessee and New York respectively.

“It’s been a decade’s worth of research, first identifying the flies and then looking at their host breadth and then seeing if they would feed on the eastern hemlock woolly adelgid,” said Ross. “Now it’s a matter of waiting and seeing if they significantly contribute to controlling adelgid populations.”

In the West, adelgids and the silver flies that feed on them are difficult to find in the forest. “Where we find them is on street trees and in peoples’ yards and city parks,” said Ross. The Oregon State scientist travels to Washington state to collect silver flies on western hemlocks. He sends boxes of infested branches to Nathan Havill, a Forest Service entomologist in Hamden, Connecticut. In Havill’s lab, research technician Arielle Arsenault rears, collects and sorts the insects in growth chambers before they are released into the wild.

Although some species of adelgids are native to North America and do not pose a threat, the hemlock woolly adelgid currently present in the eastern United States is from East Asia. In the late 1970s, as infestations in Appalachian hemlock stands grew increasingly severe, scientists were unsure about the insect’s origins. In the early 2000s, Havill used genetic techniques to demonstrate that it had been introduced from southern Japan to the vicinity of Richmond, Virginia, in the 1950s.

He also showed that it is native to the Pacific Northwest. There, the insects appear to be controlled by silver flies and possibly by other predators as well.

Other researchers contributing to the project are Ross’ former OSU graduate students Glenn R. Kohler and Sarah M. Grubin. They received assistance from a leading taxonomic expert in silver flies, Stephen D. Gaimari of the California Department of Food and Agriculture. Their reports have appeared in Environmental Entomology and other professional journals.

Funding for the research was provided by the Hemlock Woolly Adelgid Initiative of the USDA Forest Service.

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Darrell Ross, 541-737-6566; Kimberly Wallin, 802-656-2517

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Kimberly releasing in a bag 2 TN release
Kimberly Wallin
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Hemlock woolly adelgids on a hemlock branch
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Silver fly larvae feed on adelgid eggs

Global decline of large herbivores may lead to an “empty landscape,” scientists say

CORVALLIS, Ore. – The decline of the world’s large herbivores, especially in Africa and parts of Asia, is raising the specter of an “empty landscape” in some of the most diverse ecosystems on the planet, according to a newly published study.

Many populations of animals such as rhinoceroses, zebras, camels, elephants and tapirs are diminishing or threatened with extinction in grasslands, savannahs, deserts and forests, scientists say.

An international team of wildlife ecologists led by William Ripple, Oregon State University distinguished professor in the College of Forestry, conducted a comprehensive analysis of data on the world’s largest herbivores (more than 100 kilograms, or 220 pounds, on average), including endangerment status, key threats and ecological consequences of population decline. They published their observations today in Science Advances, the open-access online journal of Science magazine.

The authors focused on 74 large herbivore species – animals that subsist on vegetation – and concluded that “without radical intervention, large herbivores (and many smaller ones) will continue to disappear from numerous regions with enormous ecological, social, and economic costs.” Ripple initiated the study after conducting a global analysis of large-carnivore decline, which goes hand-in-hand, he said, with the loss of their herbivore prey.

“I expected that habitat change would be the main factor causing the endangerment of large herbivores,” Ripple said. “But surprisingly, the results show that the two main factors in herbivore declines are hunting by humans and habitat change. They are twin threats.”

The scientists refer to an analysis of the decline of animals in tropical forests published in the journal BioScience in 1992. The author, Kent H. Redford, then a post-doctoral researcher at the University of Florida, first used the term “empty forest.” While soaring trees and other vegetation may exist, he wrote, the loss of forest fauna posed a long-term threat to those ecosystems. 

Ripple and his colleagues went a step further. “Our analysis shows that it goes well beyond forest landscapes," he said, “to savannahs and grasslands and deserts. So we coin a new term, the empty landscape.” As a group, terrestrial herbivores encompass about 4,000 known species and live in many types of ecosystems on every continent except Antarctica.

The highest numbers of threatened large herbivores live in developing countries, especially Southeast Asia, India and Africa, the scientists report. Only one endangered large herbivore lives in Europe (the European bison), and none are in North America, which, the authors add, has “already lost most of its large mammals” through prehistoric hunting and habitat changes.

The authors note that 25 of the largest wild herbivores now occupy an average of only 19 percent of their historical ranges. Competition from livestock production, which has tripled globally since 1980, has reduced herbivore access to land, forage and water and raised disease transmission risks, they add.

Meanwhile, herbivore hunting occurs for two major purposes, the authors note: meat consumption and the global trade in animal parts. An estimated 1 billion humans subsist on wild meat, they write.

“The market for medicinal uses can be very strong for some body parts, such as rhino horn,” said Ripple. “Horn sells for more by weight than gold, diamonds or cocaine.” Africa’s western black rhinoceros was declared extinct in 2011.

Co-author Taal Levi, an assistant professor in Oregon State’s Department of Fisheries and Wildlife, said the causes of the decline of some large herbivores “are difficult to remedy in a world with increasing human populations and consumption.”

“But it's inconceivable that we allow demand for horns and tusks to drive the extirpation of large herbivores from otherwise suitable habitat,” Levi said. “We need to intensify the reduction of demand for such items.”

The loss of large herbivores suggests that other parts of wild ecosystems will diminish, the authors write. The likely consequences include: reduction in food for large carnivores such as lions and tigers; diminished seed dispersal for plants; more frequent and intense wildfires; slower cycling of nutrients from vegetation to the soil; changes in habitat for smaller animals including fish, birds and amphibians.

“We hope this report increases appreciation for the importance of large herbivores in these ecosystems,” said Ripple. “And we hope that policymakers take action to conserve these species.”

To understand the consequences of large herbivore decline, the authors call for a coordinated research effort focusing on threatened species in developing countries. In addition, solutions to the decline of large herbivores need to involve local people. “It is essential that local people be involved in and benefit from the management of protected areas,” they write. “Local community participation in the management of protected areas is highly correlated with protected area policy compliance.”

In addition to Ripple and Levi, co-authors include Christopher Wolf and Luke Painter of Oregon State; Rodolfo Dirzo of Stanford University; Thomas M. Newsome of The University of Sydney in Australia; Kristoffer T. Everatt and Graham I.H. Kerley of Nelson Mandela University in South Africa; Mauro Galetti of the Universisade Estadual Paulista in Brazil; Matt W. Hayward of Nelson Mandela University and Bangor University in the United Kingdom; Peter A. Lindsey of Panthera (nonprofit organization) and the University of Pretoria in South Africa; David W. MacDonald, Yadvinder Malhi and Christopher J. Sandom of the University of Oxford in the United Kingdom; John Terborgh of Duke University; Blaire Van Valkenburgh of UCLA.

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Eastern gorilla by Peter Stoel
Eastern Gorilla
African elephant by Kristopher Everatt
African elephant
Black rhino GFRNR 2009 G Kerley
Western black rhinoceros

Lowland tapir by Thomas Newsome
Lowland tapir
Mountain Nyala by Halszka Hrabar
Mountain nyala
Mountain zebraHalszka Hrabar
Mountain zebra
The threatened European bison, Bison bonasus. Photo by Graham Kerley.
European bison
 Common hippopotamus by Kristopher Everatt
Common hippopotomus HerbivoreIllustration

Illustration of herbivore impacts

Cascades study may rewrite the textbook on forest growth and death

CORVALLIS, Ore. – A century-long study in the Oregon Cascades may cause scientists to revise the textbook on how forests grow and die, accumulate biomass and store carbon.

In a new analysis of forest succession in three Douglas-fir stands in the Willamette National Forest, two Oregon State University scientists report that biomass – a measure of tree volume – has been steadily accumulating for 150 years. In the long term, such a trend is not sustainable, they said, and if these stands behave in a manner similar to others in the Cascades, trees will begin to die from causes such as insect outbreaks, windstorms or fire.

“Mortality will occur in the future,” said Mark Harmon, professor and Richardson Chair in Forest Science at OSU. “It just hasn’t arrived.”

In 1910, pioneering forest scientist Thornton T. Munger established the research plots in stands that had, by that time, been recovering from a wildfire for about 50 years. Growth and mortality were measured in the plots every five years until 1955 and again starting in 1992.

Scientists generally treat mortality as a phenomenon that occurs at an average rate over many years, said Harmon. However, results from these stands show that mortality can proceed slowly for many years and then increase rapidly in sudden pulses.

Harmon and Rob Pabst, forestry research assistant at OSU, published their findings recently in the Journal of Vegetation Science.

“The way we have thought about mortality is wrong,” said Harmon, who is conducting long-term monitoring at 10 stands in the Cascades. “When we started measuring mortality, our goal was to come up with a long-term average, but it became clear that that’s misleading because its very nature is variable.”

After a disturbance such as a fire or a clear-cut harvest, “it takes a while for the machinery in the forest to get going,” Harmon said. “And then it starts to increase biomass and hits a point where a lot of the biomass isn’t being removed by tree death. But we know there are episodes of mortality: beetle kills, fire, wind storms.”

Continuous accumulation of biomass over many centuries is not realistic, he added. If the tree stands they analyzed were to continue to accumulate biomass over the next 200 years, they wrote, biomass would reach world-record levels, far exceeding “what has been observed in old-growth forests of the Pacific Northwest.”

“There must be some event waiting in the future that will knock them down,” Harmon said. “Whether that will become more frequent in the future because of climate change or something else, I don’t know.”

The findings have practical implications for management of public and private forestlands. For timber production purposes, it has been common practice to harvest trees at regular intervals, usually when the rate of biomass accumulation reaches a high point. In Douglas-fir forests, that interval is often 50 to 70 years.

However, since the stands in Harmon and Pabst’s study have continued to accumulate biomass steadily for 150 years, the optimum harvest cycle may be considerably longer than 50 years. It is likely, they wrote, that some Douglas-fir forests have been harvested many decades before they reached a point when the rate of biomass accumulation slowed.

The findings also suggest that these forests can continue to sequester carbon from the atmosphere well past typical harvest intervals. “While we suspect that live biomass accumulation will eventually slow down and perhaps cease, this is likely to occur many decades in the future, barring a major disturbance in these plots,” they wrote. “This implies substantially more live carbon can be accumulated in this type of forest if harvest rotations are extended past the 50- to 100-year age.”

The research was supported by the National Science Foundation and the Pacific Northwest Research Station of the USDA Forest Service. The paper is available online (http://onlinelibrary.wiley.com/doi/10.1111/jvs.12273/full).

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Pioneering forest scientist T. T. Munger established long-term monitoring stands in the Oregon Cascades in 1910.

Satellites give scientists unprecedented views of insect outbreaks in forests

CORVALLIS, Ore. – Scientists for the first time have simultaneously compared widespread impacts from two of the most common forest insects in the West – mountain pine beetle and western spruce budworm – an advance that could lead to more effective management policies.

By combining data from satellites, airplanes and ground-based crews, the researchers have shown in unprecedented detail how insects affect Western forests over decades.

In the past, forest managers relied on airplane surveys to evaluate insect damage over broad areas. However, satellites can reveal patterns at a much finer scale. By combining both types of data, scientists are refining estimates of damage and showing how they may relate to other factors that determine forest structure and composition.

“This is the first time anyone has compared the impacts from these two insects in consistent units of change going all the way back to 1970,” said Garrett Meigs, a post-doctoral researcher at the University of Vermont. Meigs conducted his analysis while he was a Ph.D. student in the College of Forestry at Oregon State University. He worked with Robert Kennedy, an expert in landscape analysis and an assistant professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences.

They published their findings in this week’s issue of Forest Ecology and Management, a professional journal.

Outbreaks of both insects occur in cycles and can affect millions of acres of forest lands from year to year. The mountain pine beetle has killed lodgepole pine trees across much of western Canada and the United States in recent decades. Western spruce budworm defoliates – but does not normally kill – Douglas-fir, spruce and true firs. However, repeated years of western spruce budworm attack can weaken trees and make them vulnerable to other stresses, which may eventually kill them.

“Mortality from bark beetles is only the beginning of long-term change,” said Helen Maffei, a U.S. Forest Service scientist in Bend, Oregon, who supported the study. “Dead trees fall and decay, and forest regrowth begins and continues over many decades. This new technique can help us understand not only how insect outbreaks are initiated and spread but also address the question, ‘What comes next’? It can help us better understand the process of recovery.”

The new method of using satellites, aerial surveys and forest inventory data enables scientists to identify hotspots of insect activity that may need special attention from forest managers in the future.

“By blending the richness of the Forest Service data with the robustness of the satellite signal, I think we have a really useful new approach to understanding insect patterns on the landscape,” said Kennedy.

The new methods aren’t yet available to businesses, government agencies and other organizations, but through a partnership between Oregon State and Google, that may change. Kennedy is working with the company to use satellite data and new analytical procedures in a system that would be accessible to land managers. The system will be freely available on Google’s Earth Engine, a platform for planetary data and analysis.

“If successful, it would mean that agencies could begin working with the satellite data and potentially take the next step in merging with the Forest Service observation data directly,” said Kennedy.

The report is online in OSU’s Scholar’s Archive, http://hdl.handle.net/1957/55196. Support was provided by the NASA Earth and Space Science Fellowship Program and the USDA Forest Service.

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Mountain pine beetle larvae borrow under bark.

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Mountain pine beetle damaged forests in the Oregon Cascades.

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Trees defoliated by western spruce budworm in Washington.