OREGON STATE UNIVERSITY

college of forestry

OSU scientists part of national APLU report outlining research challenges

CORVALLIS, Ore. – The national Association of Public and Land-grant Universities released a report today outlining six “grand challenges” facing the United States over the next decade in the areas of sustainability water, climate change, agriculture, energy and education.

The APLU project was co-chaired by W. Daniel Edge, head of the Department of Fisheries and Wildlife at Oregon State University. The report is available online at: http://bit.ly/1ksH2ud

The “Science, Education, and Outreach Roadmap for Natural Resources” is the first comprehensive, nationwide report on research, education and outreach needs for natural resources the country’s university community has ever attempted, Edge said.

“The report identifies critical natural resources issues that interdisciplinary research programs need to focus on over the next 5-10 years in order to address emerging challenges,” Edge noted. “We hope that policy-makers and federal agencies will adopt recommendations in the roadmap when developing near-term research priorities and strategies.”

The six grand challenges addressed in the report are: 

  • Sustainability: The need to conserve and manage natural landscapes and maintain environmental quality while optimizing renewable resource productivity to meet increasing human demands for natural resources, particularly with respect to increasing water, food, and energy demands.
  • Water: The need to restore, protect and conserve watersheds for biodiversity, water resources, pollution reduction and water security.
  • Climate Change: The need to understand the impacts of climate change on our environment, including such aspects as disease transmission, air quality, water supply, ecosystems, fire, species survival, and pest risk. Further, a comprehensive strategy is needed for managing natural resources to adapt to climate change.
  • Agriculture: The need to develop a sustainable, profitable, and environmentally responsible agriculture industry.
  • Energy: The need to identify new and alternative renewable energy sources and improve the efficiency of existing renewable resource-based energy to meet increasing energy demands while reducing the ecological footprint of energy production and consumption.
  • Education: The need to maintain and strengthen natural resources education at our schools at all levels in order to have the informed citizenry, civic leaders, and practicing professionals needed to sustain the natural resources of the United States.

 

Three other OSU researchers were co-authors on the report, including Hal Salwasser, a professor and former dean of the College of Forestry; JunJie Wu, the Emery N. Castle Endowed Chair in Resource and Rural Economics; and George Boehlert, former director of OSU’s Hatfield Marine Science Center.

Wu played a key role in the climate change chapter in identifying the need to better understand the tradeoffs between investing now in climate change adaptation measures versus the long-term risk of not adopting new policies.

Edge and Boehlert contributed to the energy chapter, which focuses primarily on renewable energy.

“The natural resources issues with traditional sources of energy already are well-understood,” Boehlert said, “with the possible exception of fracking. As the country moves more into renewable energy areas, there are many more uncertainties with respect to natural resources that need to be understood and addressed. There are no energy sources that do not have some environmental issues.”

Salwasser was an author on the sustainability chapter that identifies many issues associated with natural resource use, including rangelands, forestry, fisheries and wildlife and biodiversity. The authors contend the challenge is to use these resources in a sustainable manner meeting both human and ecosystem needs.

The project was sponsored by a grant from the U.S. Department of Agriculture to Oregon State University, which partnered with APLU and authors from numerous institutions.

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Dan Edge, 541-737-2810; Daniel.edge@oregonstate.edu

Scientists gather in Bend for “Week of Fire” April 7-10

CORVALLIS, Ore. – In what organizers have dubbed a “Week of Fire,” forest scientists and fire managers will meet in Bend April 7-10 to discuss the latest research on fire ecology and its implications for forest management.

The week will include a series of events: the 3rd biennial Central Oregon Fire Science Symposium, the first meeting of the newly formed Oregon Prescribed Fire Council and a four-day training course, The Ecological and Social Effects of Fire in Central Oregon.

All activities will be held at the Central Oregon Community College. The public is welcome to attend, but registration fees apply to the training course and to the symposium. Attendance at the prescribed fire council meeting on April 10 is free. Schedule and registration information are available at http://centraloregonfiresymposium.org/.

“Fire science and management experience are coming together to really allow our profession to be able to deal with the growing challenge of managing forest fires,” said John Bailey, a professor in the Oregon State University College of Forestry and one of the event planners. “The spatial extent and cumulative severity of wildland fires are unprecedented recently in much of the West and are likely to continue or increase. Fuel accumulations have and continue to markedly outpace treatment rates, feeding these fires.”

The fire-science symposium will run April 8-9. Bailey and speakers from Oregon State, the U.S. Forest Service, the Bureau of Land Management and other organizations will address fire ecology, fire science and the potential benefits of using prescribed fire as a tool to reduce future fire risk. 

“Forests in Central Oregon have evolved with fire,” said Bailey. “It’s not a matter of if they will burn; it’s when and how. The science is there to show that working with fire to steer it instead of trying to stop it is safer, cheaper and more ecologically fitting for the land.”

Since 2001, more than a million acres burned in Oregon alone during two fire seasons. Nationally, more than 8 million acres burned in six of those 12 years. Of particular concern is the growing number of large fires that burn uncontrollably and threaten life and property. In that same time, annual fire suppression costs have increased markedly and now consistently approach $2 billion.

“This is a bigger issue than the federal government can handle alone,” said Geoff Babb of the Bureau of Land Management, one of the symposium organizers. “These fires cross jurisdictional boundaries and require that we work together with local and state governments and university scientists.”

Highlights of the symposium include a presentation by Scott Stephens of the University of California, Berkeley, on the policy and management implications of last year’s Rim Fire in California. A special memorial will be held for Bob Martin, a pioneer of prescribed burning who inspired generations of fire managers in Central Oregon.

The Oregon Prescribed Fire Council’s inaugural meeting on April 10 will provide people with interests in prescribed burning — fire and fuels managers, natural resources specialists, private landowners, industry, air quality regulators, ranchers — to address a variety of issues. The council was founded in 2013 to address issues such as smoke management, worker training, legal liability and sharing of resources. Since the 1970s, such councils have been forming throughout the country, most recently in Washington and California.

“The opportunities and challenges in implementing prescribed fire are complex and in need of attention through collaboration,” said Amanda Stamper, chair of the Oregon council. “Ecological restoration and wildfire hazard reduction often depend upon the application of fire after treatments such as thinning and mowing, particularly in the dry forests and rangelands east of the Cascades.”

“Ultimately prescribed burning and wildfire management efforts need to focus on creating more resilient ecosystems and fire-adapted communities,” said Timothy Ingalsbee of the Association for Fire Ecology, a national nonprofit organization dedicated to fire ecology research, education and management. “The sooner we learn how to work safely and live sustainably with wildland fire, the better.

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Editor’s Note: Reporters are welcome at the Central Oregon Fire Science Symposium. To make arrangements, contact Timothy Ingalsbee, 541-338-7671, fire@efn.org.

Fire maps, risk ratings for Oregon communities and other information about forest fires in Oregon are available at Oregon Explorer’s Wildfire Risk Explorer, www.oregonexplorer.info/wildfire.

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Jean Nelson-Dean, U.S. Forest Service, 541-383-5561

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John Bailey, Oregon State University, 541-737-1497

Amanda Stamper, U.S. Forest Service and Oregon Prescribed Fire Council, 541-968-5851

Geoff Babb, Bureau of Land Management, 542-383-5521

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2013 prescribed burning operations on the Oregon State University’s McDonald Forest near Corvallis, Ore. OSU researchers and students conducted the burn with assistance from the Oregon Department of Forestry. Photo: Taylor Fjeran, Oregon State University

OSU selects public health leader, ecologist for Distinguished Professor Awards

CORVALLIS, Ore. – The leader behind what will become Oregon’s first accredited school of public health and a terrestrial ecologist who identified a new paradigm in wildlife research have been named 2014 recipients of the Distinguished Professor Award by Oregon State University.

Marie Harvey, a professor in OSU’s College of Public Health and Human Sciences, and William Ripple, a professor in the College of Forestry, will receive their awards this spring and give public lectures on campus.

The Distinguished Professor title is the highest designation Oregon State gives to its faculty.

Sabah Randhawa, OSU provost and executive vice president, said the two faculty members chosen for the honor share similar traits of innovative leadership, internationally recognized scholarship and service to the university and their respective fields.

“Marie Harvey and Bill Ripple exemplify what we hope all of our faculty will strive to become as they develop their careers,” Randhawa said. “They both have revolutionized their fields, drawing respect and admiration not only from their colleagues on campus, but from around the world.”

Harvey is widely known for her pioneering work in reproductive and sexual health, shifting the research from an exclusive focus on women to one that examines the relationship dynamics of couples as it applies to both pregnancy and disease prevention. That shift, along with Harvey’s work in diversity and equity, prompted the American Public Health Association to present her with its Lifetime Achievement Award.

“I am very pleased that Marie Harvey is being honored with the Distinguished Professor title,” said Tammy Bray, dean of OSU’s College of Public Health and Human Sciences. “In addition to her scholarly contributions to the field of public health, I most appreciate her leadership and partnership with me in the effort to transform our college to become the first accredited school of public health in Oregon.”

Harvey has been a faculty member at OSU since 2003 and associate dean of the college since 2011. Her title is Distinguished Professor of Public Health.

Ripple began his career studying old-growth forests and spotted owls and evolved his research to look at the impact of predators. His work led to a new field called “trophic cascades” – or how large predators exert powerful influences on ecosystem structure and function. Examples include the influence of wolves in Yellowstone Park on everything from the composition of hardwood forests to streamside erosion.

His prominence as an ecologist has led to consulting efforts with the National Academy of Sciences, The White House, President Clinton’s Forest Summit, the U.S. Fish and Wildlife Service and others. Ripple will be Distinguished Professor of Ecology.

“Bill Ripple has been a fantastic teacher and researcher in the College of Forestry and well deserves being named a Distinguished Professor,” said Thomas Maness, dean of the college. “He is an internationally known leader in the ecology of top predators and his studies on the impact of gray wolves in Yellowstone, along with co-author (OSU professor emeritus) Robert Beschta, have been featured in numerous scientific journals and in popular media. They have directly impacted conservation research and policies.”

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 Sabah Randhawa, 541-737-2111; Sabah.Randhawa@oregonstate.edu

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
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Dingo, credit Ken Shaw copy 2
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Gray Wolf, credit- Doug McLaughlin copy 2
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Sea otter, credit Norman S. Smith copy
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Eurasian lynx, credit Bodel Elmhagen copy
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puma also known as cougar, credit william ripple
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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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Small headwater streams export surprising amounts of carbon out of Pacific Northwest forest

CORVALLIS, Ore. — Scientists have tracked a higher-than-expected amount of carbon flowing out of a Pacific Northwest forest from month to month through a small headwater stream, suggesting that forested watersheds may not store quite as much carbon as previously thought.

In a paper published in the Journal of Geophysical Research — Biogeosciences, a team led by Alba Argerich, an assistant professor of research in the College of Forestry at Oregon State University, reported that a small headwater stream in the Cascades exports, on average, about 6 percent of what forests absorb from the atmosphere and store.

“Although we have a good understanding of the general global carbon cycle, there are still some details we haven’t quantified well,” said Argerich. “One of them is how carbon is stored and exported in small streams. Streams of this size drain three-quarters of the landscape, and when you add up their total influence, they may make quite a difference to the carbon budget.

Our work suggests that we may be underestimating their influence on carbon dynamics,” she added. 

In the past, researchers have generally ignored the role of small streams in the carbon cycle. As a result, a lack of data has prevented scientists from including these streams in computer models. The study by Argerich and her colleagues is one of the most detailed assessments yet of carbon exports in streams.

It was thought that most carbon is exported from streams as dissolved and particulate matter traveling downstream. However, Argerich and her team have shown that more than 25 percent of the carbon leaving streams goes into the atmosphere.

What we’re seeing is that these small streams export quite a bit of carbon, which we didn’t expect, Argerich said. A lot of it goes downstream, but some of it is in the form of carbon dioxide going into the atmosphere.               

Carbon is a critical element in the science of climate change, and the Pacific Northwest has some of the highest carbon storage of any forests in the world. Since streams represent a "leak" of carbon out of the forest, efforts to measure carbon stored in these systems should also account for carbon exported and lost by streams, said Roy Haggerty, co-author and interim dean of the College of Earth, Ocean, and Atmospheric Sciences at Oregon State.

The study was conducted by a collaborative team including Oregon State faculty and graduate students as well as scientists in the Pacific Northwest Research Station of the U.S. Forest Service. They analyzed data collected from 2004 to 2013 in a 50-year old second-growth forest at the H.J. Andrews Experimental Forest in the Cascades east of Eugene, where researchers monitor many forms of carbon.

Carbon flow in small streams has a distinct seasonal pattern. Like an exhaled breath lasting six months or more, the amount of carbon carried downstream starts to increase as rains arrive in the fall. By January, the carbon flowing out of small watersheds typically reaches a peak and then starts to decline. As water levels drop during the summer, little carbon moves out of the forests in streams, mostly through export to the atmosphere.

In general, carbon moves out of the forest in multiple forms — bits of leaves, seeds, branches and other detritus — as well as dissolved in stream water, carried in sediment and pumped back into the air as carbon dioxide gas. Altogether, the amount of carbon from small streams in the Pacific Northwest is similar to the average exported by large rivers globally, said Argerich.

Funding for the research was provided by the National Science Foundation’s Long-Term Ecological Research program and the U.S. Forest Service Pacific Northwest Research Station.

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Alba Argerich, alba.argerich@oregonstate.edu, 541-758-8856; Roy Haggerty, roy.haggerty@oregonstate.edu, 541-737-5195

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Studies confirm effect of wolves, elk on tree recovery in Yellowstone National Park

CORVALLIS, Ore. – An analysis of 24 studies over a 15-year period has confirmed that wolves and their influence on elk represent a major reason for the recovery of trees that had previously been declining for decades in Yellowstone National Park.

Despite long-term trends of increased temperatures and reduced precipitation, trees such as cottonwood, willow, aspen and other woody species have been showing signs of accelerated growth in many areas since wolves were restored to the park in 1995. Beavers and riparian songbirds are also showing signs of coming back to areas where they had been missing or in decline since the 1930s.

Still, it will likely take many years for established shrubs and trees to reach a size sufficient to produce the abundance of berries and seeds that support a diverse ecosystem.

Those are among the conclusions reported today in the journal Biological Conservation by Robert Beschta and William Ripple, two professors in the Oregon State University College of Forestry. They analyzed the results of 24 studies of streamside vegetation published since 2001 and reviewed long-term trends in temperature, precipitation, snowpack and stream discharge.

“When I first started studying this in 2001,” said Beschta, “I was skeptical that elk, a native ungulate, could stop nearly all cottonwood recruitment. But it was the elk that had damaged plant communities during the period when wolves were absent, and the reductions in elk browsing, since wolves have returned, are allowing them to begin recovering.”

In subsequent studies, Beschta and Ripple, as well as other researchers, measured the diameter of cottonwoods and aspen in the park’s northern range.  They found young trees almost completely missing.

“For decades, nothing had been growing into the smaller age classes of trees because of intensive elk browsing,” Beschta said.

In their latest assessment, Beschta and Ripple reviewed 11 published studies of willow, six of aspen and five of cottonwood as well as one each of service berry and thinleaf alder. All but two of the studies showed increases in height, diameter, canopy cover or recruitment for these species. The area of land covered by willow, for example, doubled between 1991 and 2006. By 2003, young aspen trees in many areas were starting to grow measurably higher.

More than half of the reviewed studies also measured browsing effects on plants, caused principally by elk. Those studies concluded that tree recovery had begun mostly because of a decrease in browsing.

“Climate may influence whether trees recover more quickly in some areas than in others to some degree, but the real issue for plants growing in Yellowstone is, how often are they browsed by ungulates?” Beschta added.

Elk numbers in Yellowstone have declined by more than two-thirds since 1995, from a high of nearly 20,000 to less than 5,000 today. The numbers and impacts of deer and pronghorn are relatively small, but in the past decade, bison herds have grown, and they tend to reside in valley bottoms much of the year. Bison grazing has prevented cottonwoods, willow and other plants from successfully recovering in parts of the Lamar Valley, he said.

Over the past 20 years, mean temperatures and precipitation in the northern range have changed in comparison to the long-term mean going back to 1895, when recordkeeping began. As measured at the Mammoth weather station in Yellowstone, annual mean temperatures today are more than 2 degrees Fahrenheit warmer than in 1895 and annual precipitation almost 3 inches lower.        

Research results following wolf reintroduction are generally supportive of the concept that the contemporary carnivore guild has, via a trophic cascade, mediated the effects of elk herbivory on riparian plant communities, the authors wrote. The ongoing reduction in elk herbivory has thus been helping to recover and sustain these plant communities in northern Yellowstone, thereby improving important food-web and habitat support for numerous terrestrial and aquatic organisms.

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Bob Beschta, robert.beschta@oregonstate.edu, 541-737-4292; William Ripple, bill.ripple@oregonstate.edu, 541-737-3056

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Increased heights of young aspen since wolves (1)

Fig. 1 -Riparian willow recovery

Tall willows with elk-winter

Carbon stored in Pacific Northwest forests reflects timber harvest history

CORVALLIS, Ore. – The amount of carbon stored in tree trunks, branches, leaves and other biomass — what scientists call “aboveground live carbon” — is determined more by timber harvesting than by any other environmental factor in the forests of the Pacific Northwest, according to a report published by researchers at Oregon State University.

In forests that are about 150 years old or less, live carbon above the ground is associated primarily with the age of a stand — reflecting how long ago it was harvested — rather than with climate, soil, topography or fire. However, as forests mature into “old growth,” the density of carbon is determined largely by factors other than harvesting.

The Pacific Northwest has some of the highest forest-carbon densities in the world. Understanding how much carbon is stored in growing forests is a critical component of international efforts to reduce climate change.

Researchers found that air temperatures, sun exposure and soils were also important in driving the variation in live carbon across the region. High-elevation forests tend to be cooler and contain lower amounts of carbon than do low-elevation forests.

Researchers conducted the study at the H.J. Andrews Experimental Forest in the Cascade Range east of Eugene. They combined data from two types of measurements: LiDAR (an aerial mapping technique that uses lasers) and ground-based forest inventories in which scientists measured aboveground live carbon in 702 forest plots. The study is one of the few to quantify carbon in living forest biomass in mountainous terrain.

Harold Zald, research associate in the College of Forestry, is lead author of the paper published in the journal Forest Ecology and Management.

“Very few studies have looked at above-ground carbon at a landscape scale with the combination of LiDAR and detailed disturbance history (logging and fire) that we have at the H.J. Andrews Forest,” said Zald. “These findings can be applied to the Douglas-fir dominated forests on the west slope of the Cascades in Oregon and Washington.”

The researchers found that fire was not a significant driver of carbon density in the H.J. Andrews. In the last century, these forests have experienced little severe “stand replacing fire,” but it’s possible that fire played a significant role in shaping the structure of old-growth forests and increasing carbon density over time. “Remnant old-growth trees resulting from non-stand replacing fires likely enhance the recovery of forest C (carbon) density,” they wrote.

The study was conducted by researchers at Oregon State, the Pacific Northwest Research Station of the U.S. Forest Service and the University of Natural Resources and Life Sciences (BOKU) in Vienna, Austria. 

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Harold Zald, 541-737-8719, harold.zald@oregonstate.edu

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Landscape_Sjohnson2