OREGON STATE UNIVERSITY

college of forestry

OSU receives $4 million grant to identify mechanisms for control of genetic engineering in plants

CORVALLIS, Ore. — With a $4 million, five-year grant from the National Science Foundation, scientists at Oregon State University will develop new approaches to identifying genes that control the ability of a plant to be genetically engineered.

Researchers will create new methods to image and analyze plants undergoing the process of genetic engineering. Their goal is to identify the genes that promote or retard the process. 

Genetic engineering generally requires that DNA be inserted into cells. By modifying DNA, researchers can generate organisms with desired characteristics. 

“Many crop species, and many of the valuable varieties within them, remain extremely difficult to genetically engineer,” said Steve Strauss, OSU distinguished professor in the College of Forestry and project leader. “This greatly limits the ability of this method to be used for plant breeding and scientific research. There can be blockages at any of the several steps. Regeneration of modified cells into plants is usually the most difficult to overcome.”

In collaboration with Fuxin Li in the OSU School of Electrical Engineering and Computer Science, the investigators will develop state-of-the-art image analysis methods to visualize the genetic engineering process. This will include the use of machine vision where the computer learns how to recognize key plant organs and cell types. That would enable researchers to monitor and quantify the complex process through which a genetically engineered cell turns into a new plant.  

The research will focus on the cottonwood tree, a species whose DNA sequences have been previously determined by the U.S. Department of Energy (DOE). Oregon State researchers will collaborate with Wellington Muchero at the University of Tennessee and the Oak Ridge National Laboratory on genetic mapping and gene identification. 

OSU social scientist Troy Hall and other members of the project team will work with Jay Well of the Science and Math Investigative Learning Experiences (SMILE) program at Oregon State to develop education modules around genetic engineering in agriculture for middle- and high-school students. They will first analyze how youth approach the ideas and scientific concepts behind genetic engineering and then pilot the modules with underserved students in rural communities throughout Oregon.

This work will benefit from collaborations with the biotechnology industry, including Monsanto and Simplot, which will provide plant materials and methods of genetic analysis for student laboratory exercises.

“The research will shed new light on the mechanisms of genetic engineering so we can improve its efficacy and lower its costs,” said Strauss. “The work will also produce insights into how to effectively educate, both in Oregon and elsewhere, about the complex issues of crop genetic engineering.”

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Steve Strauss, 541-737-6578, steve.strauss@oregonstate.edu

    

Storing more carbon in western Cascades forests could benefit some wildlife species, not others

CORVALLIS, Ore. — Forest management policies that aim to store more carbon in the Pacific Northwest may benefit some wildlife species more than others.

According to a recently published analysis, increasing carbon storage could lead to more favorable conditions for northern spotted owls, pileated woodpeckers, olive-sided flycatchers, Pacific marten and red tree voles. These species may benefit from management policies that favor less intensive logging and longer periods between tree harvests.

However, mule deer and western bluebirds may not fare so well. Both species rely on open, early successional forests that could become less common under management policies that reduce harvesting.

The analysis of timber harvesting, wildlife habitat and the amount of carbon stored in vegetation and soils focused on a 400,000-acre landscape in the western Cascade Range. It is one of the most exhaustive studies of its type ever performed. Scientists at Oregon State University, Pacific Northwest Research Station of the U.S. Forest Service, and the University of Connecticut studied the consequences of 13 different logging intervals, from no harvest to removing all live and dead trees every 25 years. 

The results were published in Ecological Applications, a professional journal.

“Our analysis shows that implementing forest management strategies to store additional forest carbon will influence habitat for different species, improving or expanding it for some and reducing it for others,” said Jeff Kline, lead author and an economist with the U.S. Forest Service. “Although forest managers already know that intuitively, our study helps to put some numbers on the possible outcomes of an array of management options.”

The researchers used computer models to simulate the consequences of tree harvesting on wildlife habitat, as well as on the amount of carbon stored in forest ecosystems and in wood products. Their simulations did not focus on public versus private land ownership, but rather on the potential of the landscape to produce carbon storage, timber and habitat under management strategies of all types. They included harvesting operations but not other disturbances stemming from wildfire, storms or climate change.

Existing USDA policy directs the Forest Service to lead efforts to mitigate and adapt to climate change. This study is the first to broadly describe the consequences of one type of mitigation, carbon storage, for other benefits such as wildlife habitat. The results show that management aimed at one goal, such as carbon storage, may lead to trade-offs with other goals, such as wildlife habitat for specific species.

The study enables forest managers to consider the range of long-term outcomes that are possible under forest management scenarios, the scientists said. There may be opportunities to store additional carbon without reducing timber harvests, because current management practices represent only a small fraction of the outcomes that are possible in the western Cascades.

“The study will enable managers to consider more novel forest management possibilities that may be outside of the subset of current forest management strategies in widespread use,” said Kline.

Forest managers will need to account for other factors in actually implementing policies to increase carbon storage, the authors concluded. Natural disturbances, climate change and biological processes that might constrain wildlife populations should be considered.

The research was funded by the National Aeronautical and Space Administration (NASA) and the USDA Forest Service, Pacific Northwest Research Station.

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Mark Harmon, 541-737-8455, mark.harmon@oregonstate.edu; Tom Spies, 541-750-7354, tspies@fs.fed.us; Jeff Kline, 541-758-7776, jkline@fs.fed.us

    

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Public invited to groundbreaking celebration for Oregon Forest Science Complex

CORVALLIS, Ore. — The College of Forestry at Oregon State University will celebrate the construction of the new Oregon Forest Science Complex with a groundbreaking ceremony on Saturday, October 29.

The 95,000-square-foot project will encompass a new Peavy Hall and the A. A. “Red” Emmerson Advanced Wood Products Laboratory. It will showcase innovative uses for wood in building construction and design, including advanced wood products such as cross-laminated timber. The complex will also feature recycled wood beams from the old Peavy Hall to honor the college’s storied past.

“The complex will highlight materials grown and produced in the state of Oregon,” said Thomas Maness, the Cheryl Ramberg-Ford and Allyn C. Ford dean of the College of Forestry. “The state is perfectly positioned to produce products like cross-laminated timber. This complex is for the people of Oregon and represents the future of forestry in the entire region.”

The public is invited to the event, which will begin at 4:45 p.m. and feature remarks by Maness; Oregon State President Ed Ray; Governor Kate Brown; Allyn Ford, chairman of the board of directors for Roseburg Forest Products; and others.

The new buildings will serve a growing student population and meet the research needs of people working throughout the state and region toward a healthy forest landscape. In the last decade, the college has nearly doubled its enrollment of undergraduate and graduate students. In the last fiscal year, faculty researchers successfully competed for $11.4 million in research grants and contracts, up $2.9 million in the last decade.

To support Oregon’s wood-products industry, the A.A. “Red” Emmerson Advanced Wood Products Laboratory will serve as the hub for the National Center for Advanced Wood Products Manufacturing and Design. The center brings together expertise from OSU’s College of Forestry and College of Engineering and the University of Oregon’s School of Architecture and Allied Arts.

Oregon Governor Kate Brown worked with both universities to secure funds for this first-in-the-nation collaboration among forest-product scientists, engineers and architects. To support the mission of the center, a total of $2.6 million in state funds has been allocated and used to leverage an equal commitment in federal funds for research and wood-product testing.

“The complex is crucial to the future of our working forest landscapes,” Maness said. “The way we thought about forestry, natural resources and wood science in the past is very different from how we think about them now. This complex will help prepare our students to tackle our most complex landscape challenges, improve rural economies and establish a healthy forest landscape.”

In 2016, OSU was named the world’s 14th best university for forestry and agriculture by Quacquarelli Symonds (QS) World University Rankings, in a survey of more than 200 schools.

The new forest science complex has been supported by $29.7 million in state and $35 million in private funds, including lead gifts from Sierra Pacific, Starker Forests, Inc. and Roseburg Forest Products.

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Michael Collins, 541-737-3140, michael.collins@oregonstate.edu

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Wildlife migration routes for multiple species can link conservation reserves at lower cost

CORVALLIS, Ore. — Scientists have demonstrated a new technique for designing effective wildlife migration corridors while reducing the costs of conservation.

The method will assist managers of public and private lands that provide routes for animals to roam. Researchers have long known that such migration corridors are crucial for conserving rare and endangered species. For example, land has been set aside in Africa and India to enable elephants to migrate. In Canada, structures have been built to enable wolves and other animals to cross highways.

Focusing on one species at a time, however, has proved to be expensive. Developed by a team including researchers in the College of Forestry at Oregon State University, the new method can meet most of the migratory needs of two species simultaneously while reducing the total cost of buying land by about three quarters.

“We demonstrate that a lot of potential gain can be made at moderate increases in cost as you try to connect habitat areas,” said Claire Montgomery, a forest economist at Oregon State and one of the researchers on the project. “Looking at trade-offs between target species is something that no one has done, as far as I know, in terms of corridor design.”

Research such as this can help land managers who juggle competing priorities, including biodiversity, the scientists said. Species such as grizzly bears and wolverines range over large areas, some of which overlap. The animals need to be able to move between wilderness, parks and other reserves to avoid becoming inbred and losing genetic diversity.

The research was published in the journal Conservation Biology. Scientists at Oregon State, the Georgia Institute of Technology, the U.S. Forest Service Research and Development, Cornell University and the U.S. Geological Survey collaborated in a five-year effort to develop a computer model that could be applied to wildlife corridors.

“This approach could revolutionize the process of corridor design,” said lead author Bistra Dilkina at Georgia Tech. “By incorporating economic costs and multiple species needs directly into the planning process, it allows for a systematic exploration of cost-effective conservation plans and informs policy-makers about trade-offs, both between species as well as between costs and connectivity benefits.”

The researchers had been asked to help identify parcels of potential interest if opportunities arose to purchase land for wildlife corridor purposes. “If the scientific community were asked which land should be a priority to purchase for connectivity, the issue was whether or not we could answer that question,” said Montgomery.

The research team developed a method for combining two types of landscape data in a computer model: tax records that show the market values of land and ecological information about the ease with which animals can move across the landscape. They then applied the model to the design of corridors to serve grizzlies and wolverines. They compared corridors for bears and wolverines separately and together.

The cost of buying land to serve as ideal migration corridors for wolverines and grizzlies separately came to about $31 million. However, by combining corridors that meet most of the animals’ needs and including the cost of buying land in the analysis, the researchers cut that cost to about $8 million.

The corridors that the researchers identified pass through key breeding habitat for wolverines in western Montana. The routes connect the Greater Yellowstone Ecosystem in and around Yellowstone National Park with the Northern Continental Divide Ecosystem, which extends as far north as the Canadian border.

The closest points of the two reserves are 130 miles apart as the crow flies, but the corridors are longer, reflecting the animals’ complex habitat needs. A corridor that meets the ideal needs of grizzlies was calculated to be about 231 miles long. Since wolverines require snowpack for reproduction and tend to prefer high elevations, the researchers identified a network of pathways that served the elusive animals.

“Many efforts have tried to prioritize which lands to swap or purchase for connecting rare species given biological and economic realities. This new research leads the way in optimizing the use of scarce resources to achieve essential connectivity,” said Michael Schwartz, director of the U.S. Forest Service National Genomic Center for Wildlife and Fish Conservation and co-author of the study. “It provides a transparent solution for optimizing connectivity while taking into account economics.”

Implementing the new method requires a large amount of data about land values and barriers to animal movement. The researchers chose to work with the State of Montana because it maintains an exceptional database of land parcels for tax purposes.

For information about barriers to movement, the scientists calculated a “resistance” score for each parcel. Parcels with higher scores were judged to be more difficult to move through, so land with lower scores was more likely to be included in a potential corridor.

In each case, the corridors were presented as a potential example of connectivity, not an actual project involving a land purchase. More information would be useful to implement such a proposal. “Even with high-profile species like grizzly bears and wolverines, more data about habitat needs would be beneficial for long-term planning,” said Rachel Houtman, co-author on the paper and a research assistant at Oregon State.

Montgomery continues to evaluate ways to enable forest landowners to simultaneously achieve their management goals and to meet the habitat and migratory needs of wildlife. “Instead of saying we’re going to buy these lands, how can we protect the functionality that’s there or improve it? That’s a lot harder to analyze,” she adds.

Funding for the study was provided by the National Science Foundation and the U.S. Forest Service.

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Claire Montgomery, 541-737-5533, claire.montgomery@oregonstate.edu; Rachel Houtman, 541-737-4294, rachel.houtman@oregonstate.edu

    

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Successful control of reproduction could help address concerns about use of engineered trees

CORVALLIS, Ore. — Forestry scientists have found a way to arrest the development of flowers in poplar trees, paving the way for control of the unintentional spread of engineered or non-native tree species.

With this method, researchers raise the possibility of developing trees as crops for biofuel and other industrial purposes while preventing them from becoming established in nearby forests.

Our goal isn’t to make reproductively modified trees just to have that trait, said Amy Klocko, postdoctoral scientist in the College of Forestry at Oregon State University. It’s to prevent genetically modified or non-native trees from spreading, either to wild forests or to other plantations. This would help alleviate concerns over gene flow, whether for scientific or ethical reasons. 

Klocko is the lead author of a paper published today in Nature Biotechnology, reporting the results of more than a decade of research. She and her colleagues used a technique known as RNA interference to suppress a gene that is known to play a central role in the development of flowers in poplars and many other plants.

The gene, which scientists call LEAFY, is still present in the trees, but RNA interference acts like a brake to slow down the gene’s activity. Scientists grew trees containing the gene-slowing technology in experimental field trials authorized by the U.S. Department of Agriculture in the Willamette Valley. Before the trees flowered, researchers collected hundreds of small twigs containing flower buds and studied the flowers that emerged in the laboratory.

We noticed that some of the reproductive parts were tiny (and undeveloped), said Klocko. And we wondered if the flowers would have that same feature when they opened in the plantation. And they did.

By studying genetic activity in those trees, researchers then showed that the undeveloped flowers could be traced to the impact of RNA interference on the LEAFY gene.

In the future, the finding could be applied to commercial plantations of fast-growing hybrid poplars, which are not genetically engineered in the United States. Other reproductively modified trees — such as bananas, seedless oranges and many ornamentals — are commonly grown in agriculture and landscaping, but these trees have been produced using conventional forms of breeding such as hybridization and intentionally induced changes to DNA.

“People have made pollen-free male plants before, including trees,” said Steve Strauss, an OSU distinguished professor of forestry and a co-author on the paper. “But the approach we used is based on detailed knowledge of the genes that direct the production of flowers in nature, and the trees are designed to be completely incapable of producing pollen or seeds. We’ve turned down a gene that is essential for all flowering.” 

The use of RNA interference to change the expression of LEAFY is the first time genetic engineering technology has been used to produce a seedless forest tree of any kind, Strauss noted.

Strauss, Klocko and their team are analyzing tree growth rates and other characteristics to see if slowing down LEAFY has consequences beyond flower development. Their data show that the trees are identical in appearance and do not differ in growth rates from unmodified trees. They are hopeful that by modifying flowering, researchers might ultimately increase wood production.

The researchers are also studying similar gene containment mechanisms in apple, sweetgum and eucalypt trees.

“The principle applies everywhere,” said Strauss.

Scientists have known for more than two decades that LEAFY is key to flower development. This study is the first to show what would happen in a tree with modified LEAFY activity and grown in the field over several years.

“We are hopeful that this technology, or the related technology of gene editing applied to this gene, will reduce tensions and regulatory obstacles to the use of highly productive, genetically engineered or exotic trees, said Strauss.

There is no question that advanced genetic engineering methods, used responsibly, can increase productivity and sustainability of plantations, but the question of when and if to allow gene dispersal is a real point of contention for both scientists and society. We hope this technology helps us to get beyond this longstanding concern.”

Support for the research came from the USDA, the National Science Foundation, the J. Frank Schmidt Charitable Foundation and the Tree Genomics and Biosafety Research Cooperative, a two-decade-old consortium of university and tree growing industries based at OSU.

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Amy Klocko, 541-737-6897, amy.klocko@oregonstate.edu; Steve Strauss, 541-737-6578, steve.strauss@oregonstate.edu

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RNA silencing (RNAi) leads to catkin (flower) changes that show up in these photos.

Conservation scientists call for global strategy to halt threatened animal extinctions

CORVALLIS, Ore. Aiming to stop the looming extinction of large wild-animal species across the globe, a group of international conservation scientists has issued a call for actions to halt further declines.

In todays edition of the journal BioScience, 43 wildlife experts from six continents note that an extinction crisis is unfolding for large mammals, from those that are poorly known, such as the scimitar-horned oryx, to more familiar species such as gorillas and rhinoceroses.

They have issued a 13-point declaration that calls for acknowledgement of threats, a halt to harmful practices, a global commitment to conservation and recognition of a moral obligation to protect the planets large animals, or megafauna.

The more I look at the trends facing the worlds largest terrestrial mammals, the more concerned I am we could lose these animals just as science is discovering how important they are to ecosystems and to the services they provide to people, said William Ripple, distinguished professor of ecology in the College of Forestry at Oregon State University and lead author. Its time to really think about conserving them because declines in their numbers and habitats are happening quickly.

Ripple has studied the ecological effects of predators such as cougar and wolves in North America, and collaborated with other wildlife experts to analyze global trends facing large carnivores — wolves, lions, tigers and bears — as well as large herbivores, including elephants, rhinos, zebras and tapirs.

“Most mammalian megafauna face dramatic range contractions and population declines,” the authors wrote. “In fact, 59 percent of the world’s largest carnivores and 60 percent of the world’s largest herbivores are classified as threatened with extinction on the International Union for the Conservation of Nature Red List. This situation is particularly dire in sub-Saharan Africa and Southeast Asia, home to the greatest diversity of extant megafauna.”

Among the most serious threats to endangered animals, they wrote, are the expansion of livestock and crop operations, illegal hunting, deforestation and human population growth.

Human communities stand to lose key elements of their natural heritage if megafauna species are allowed to go extinct, said co-author Peter Lindsey of Panthera, a nonprofit organization dedicated to conserving wild cat species.

In addition, the disappearance of such species could significantly undermine the future potential for communities to benefit from tourism. In areas where people live with these species, there is a need for mechanisms to promote coexistence. We need to minimize the negative impacts on local communities that stem from human-wildlife conflict or risk to human life. 

The scientists call for action on two fronts: expanded interventions at scales that are relevant to animals habitat needs, and large-scale policy shifts to alter the ways in which people interact with large animals.

The authors emphasized that some conservation initiatives have had success.

The Range Wide Conservation Program for Cheetah and African Wild Dog provides a good model on how to enact conservation action across the massive scales required, said Sarah Durant, co-author and a wildlife biologist with the Wildlife Conservation Society and the Zoological Society of London.

This program has established a consensus across key stakeholders in multiple countries on a common conservation goal and plan of action to reverse declines in these species. Frameworks like these help everyone to work together most effectively towards a common goal of conservation.

However, they added, the resources for effective implementation of conservation strategies are seldom available in regions with the greatest needs. “Therefore,” they wrote, “the onus is on developed countries, which have long ago lost most of their megafauna,” to conserve their own species and to support initiatives in other regions.

The article is published in six languages in addition to English: Spanish, French, Chinese, Malay, Portuguese and Thai. “The translations were provided by some of the co-authors,” said Ripple.  

We must not go quietly into this impoverished future, the authors wrote. Rather, we believe it is our collective responsibility, as scientists who study megafauna, to act to prevent their decline. We therefore present a call to the broader international community to join together in conserving the remaining terrestrial megafauna.

Among Ripples co-authors are Oregon State colleagues Michael Nelson, Robert Beschta and Christopher Wolf, all in the College of Forestry; and Taal Levi in the College of Agricultural Sciences.

Some of the other organizations represented among the authors include the International Union for the Conservation of Nature; World Wildlife Fund; the University of Oxford; the Swedish University of Agricultural Sciences; the University of Pretoria and Nelson Mandela University in South Africa; the Chinese Academy of Sciences and Beijing Normal University in China; the University of Sydney and the University of New South Wales in Australia; the Universidad Estadual Paulista in Brazil; the Wildlife Conservation Society in Bangalore, India; and the University of Nottingham Malaysia Campus.

The study this story is based on is available online at http://bioscience.oxfordjournals.org/lookup/doi/10.1093/biosci/biw092.

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William Ripple, Oregon State University, 541-737-3056, bill.ripple@oregonstate.edu; Sarah Durant, Wildlife Conservation Society, sdurant@wcs.org

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Eastern gorilla by Peter Stoel

African Elephant_Amboseli Kenya_Photograph Varun R Goswami

Black rhino GFRNR 2009 G Kerley

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puma also known as cougar, credit william ripple

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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Old-growth forests may provide buffer against rising temperatures

CORVALLIS, Ore. – The soaring canopy and dense understory of an old-growth forest could provide a buffer for plants and animals in a warming world, according to a study from Oregon State University published today in Science Advances.

Comparing temperature regimes under the canopy in old-growth and plantation forests in the Oregon Cascades, researchers found that the characteristics of old growth reduce maximum spring and summer air temperatures as much as 2.5 degrees Celsius (4.5 degrees Fahrenheit), compared to those recorded in younger second-growth forests.

Landowners who include biodiversity as a management goal, the scientists said, could advance their aims by fostering stands with closed canopies, high biomass and complex understory vegetation.

Management practices that create these types of “microclimates” for birds, amphibians, insects and even large mammals could promote conservation for temperature-sensitive species, the authors wrote, if temperatures rise as a result of global warming.

“Though it is well-known that closed-canopy forests tend to be cooler than open areas, little is known about more subtle temperature differences between mature forest types,” said Sarah Frey, postdoctoral scholar in the OSU College of Forestry and lead author on the study. “We found that the subtle but important gradient in structure from forest plantations to old growth can have a marked effect on temperatures in these forests.”

Temperature is also strongly affected by elevation and even small changes in topography, but the way forests are managed was a critical factor in explaining temperature differences. Researchers at Oregon State and Pacific Northwest Research Station of the U.S. Forest Service conducted the study at the H.J. Andrews Experimental Forest east of Eugene.

Frey and her colleagues collected temperature data in 2012 and 2013 at 183 locations, just over one third of which were in plantations. The team also analyzed data on forest structure collected through LiDAR, an aerial mapping technique that uses lasers to detect very small-scale (less than six feet) structural differences in forests.

“To our knowledge, ours is the first broad-scale test of whether subtle changes in forest structure due to differing management practices influence forest temperature regimes,” they wrote.

“To the untrained eye, plantations might look similar to old-growth forest in terms of the aspects that are well known to influence temperature, particularly canopy cover,” said Matt Betts, Oregon State professor and co-author. “So, the magnitude of the cooling effect of old-growth structure is somewhat surprising.”

The researchers found that variations in the landscape, such as elevation and slope, helped to explain temperature differences over short distances of 100 feet or less. However, at broader scales, the characteristics of the forest itself exerted a significant influence.

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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Sarah Frey, 541-224-2115, sarah.frey@oregonstate.edu; Matt Betts, 541-737-3841, matthew.betts@oregonstate.edu

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