environment and natural resources

Forecast: After Slow Start, Western Oregon May be Cooler, Wetter – and Snowier?

CORVALLIS, Ore. – In his years of producing a fall and winter weather forecast for the state, George Taylor has rarely if ever predicted snow for western Oregon – and true to form, he won’t go too far out on a limb this year.

But Taylor, who manages the Oregon Climate Service at Oregon State University, concedes that it is a good likelihood this year.

“The stars are lined up that way,” he said with a laugh.

Taylor and colleague Cadee Hale have just issued the Oregon Climate Service’s forecast for October through March and the bottom line is that once we get through October, temperatures are expected to be slightly cooler than average in western Oregon, with average to above-average precipitation. And, they say, there is “a good chance” for low-elevation snow in western Oregon.

Oregon residents east of the Cascades, on the other hand, will see warmer-than-average temperatures and average precipitation through the fall and winter.

The brightest forecast may be for skiers and ski resort owners: Snowpack in the Cascade Mountains is expected to be well above-average this year.

“We anticipate a very good ski season,” Taylor said.

One of the reasons for predictions of cooler temperatures and a higher possibility of snow in western Oregon is the development of La Niña-like conditions near the equatorial Pacific. While it is too early to conclude that a La Niña event will take place this winter, cooler temperatures in the tropical Pacific and stronger trade winds suggest it is a possibility.

La Niña events usually result in cooler, wetter winters for the western portions of the Pacific Northwest.

Every year Taylor makes a prediction for fall and winter weather based on a number of factors, culminating in selecting "analog years" that most closely resemble current conditions. He takes into account long-term wet and dry cycles (known as the multi-decadal phase), El Niño and La Niña episodes, sea level pressures, temperatures, wind speeds, solar cycles and even hurricanes, which have a surprisingly strong correlation to Northwest climate.

"Based on a composite of analyses, we are usually able to identify four or five analog years that had similar conditions during the first several months of the year, which helps us predict what the weather may be like in the fall and winter," Taylor said.

Taylor and Hale were able to find four analog years with conditions comparable to this winter. Each had some extreme weather events during those years.

• 1952-53 – A major flood hit western Oregon in January, and a major windstorm that same month caused significant damage;

• 1953-54 – A heavy rainstorm fell in western Oregon in November; two strong windstorms followed in December, and three major storms – with wind, rain and snow – struck in January.

• 1970-71 – A major windstorm in March affected the entire state. December was wet with snow in the low elevations. A heavy snowstorm struck the entire state in January, dumping 11 inches of snow in Salem and nine inches in Portland.

• 1988-89 – There was heavy rain with localized flooding in November, followed by an extremely dry month in December. Record low temperatures and heavy snow arrived in February, resulting in five deaths. Central Oregon was hit by flooding in March, the same month a major windstorm killed three people.

It is difficult to predict extreme weather events based on analog years, Taylor pointed out, and there is a possibility of heavy rains, windstorms and even heavy snow. Three of the four analog years included snowstorms and two of those years had heavy snow, even in western Oregon.

“I will say that there is a good chance of at least one low-elevation snow event,” Taylor said. “And the mountains should see a lot of snow after a slow start. We expect mountain snows to accumulate quickly in November and become significant in January and February.”

The entire forecast and background on how Taylor and Hale arrive at their conclusions is available at the Oregon Climate Service website at: http://www.ocs.oregonstate.edu/index.html

Story By: 

George Taylor,

New Tools Available to Tackle Epidemic of Swiss Needle Cast

CORVALLIS, Ore. – Forestry researchers at Oregon State University have developed a computerized risk analysis system to help predict the vulnerability of specific sites to Swiss Needle Cast, a serious problem in Coast Range forests that can cut tree growth and causes losses of more than $200 million a year.

The model, which is now in prototype form and should be fully available to landowners by early next year, may be an important tool to help address a resurgence of the Swiss Needle Cast epidemic that has occurred just in the past couple years, almost doubling from its level in 2004.

Other initiatives are also under way in the Swiss Needle Cast Cooperative based at OSU, which was founded 10 years ago as a cooperative effort of private industry, academia and other government agencies.

“This new risk-rating model should be a reliable predictive tool so that landowners can make more informed decisions on what tree species to plant,” said David Shaw, an assistant professor in the Department of Forest Science at OSU, and director of the cooperative. “Some of our co-op members are pretty excited about its potential to help address this problem.”

Swiss Needle Cast, a fungal disease of Douglas fir that is native to the Pacific Northwest, is mostly a problem in areas within 20 miles of the ocean, where warm, wet conditions favor its growth. It’s a cyclical problem that is made more severe by warmer winters, wetter springs and extended drizzle.

Historically, the fungus was a minor concern in this region, which was dominated by hemlock and Sitka spruce trees, with only smaller amounts of Douglas fir. But with intensive forest management during the past century, the varied tree species were often harvested and replaced with a monoculture of Douglas fir, which grew well and commanded higher market prices.

“Other than with the concerns about Swiss Needle Cast, Douglas fir grows exceptionally well in the Coast Range, and in past decades a couple million acres were converted to it,” Shaw said. “But now we have a perfect storm of conditions favoring this fungus, with dense plantations of the trees it infects and favorable climate conditions.”

At its worst, Swiss Needle Cast can cut Douglas fir growth by up to 50 percent, causing new-growth tree needles to turn yellow and be “cast off.” As recently as 2004, efforts to change the mix of tree plantations had shown some success and cut the acreage of significant infection in half, to less than 200,000 acres. But a new survey shows the disease has made a dramatic recovery and once again is nearing peak levels, affecting 338,000 acres. A particular hot spot is the low elevation areas and hills around Tillamook, where conditions appear optimal for the disease.

“Most of what we’re seeing is probably variation driven by weather,” Shaw said. “This is not a problem we’re going to eradicate any time soon, so we have to develop ways to deal with it.”

The new model is being developed at OSU with funding from the Swiss Needle Cast Cooperative, by Jeff Stone, an associate professor of botany and plant pathology, and Len Coop of the Integrated Plant Protection Center. It can tell landowners whether a very specific plot of land will be at low, moderate or high risk to develop significant Swiss Needle Cast infection. This can help guide decisions on what to plant for future tree rotations. The model incorporates a diverse range of data about topography, climate, local weather patterns, historic disease problems and other relevant issues.

For those with existing problems, there are fewer options. Use of fungicides is effective but too expensive to use on a broad scale. OSU studies in the Swiss Needle Cast Cooperative have determined that thinning of the weakest Douglas-fir and replacement with hemlock or spruce can be of some value. It helps to avoid nitrogen fertilization, which favors the growth of fungus. And in extreme cases, some landowners may even consider conversion of their existing forest to different species.

Within five to 15 years, Shaw said, other research may produce Douglas fir varieties with improved Swiss Needle Cast tolerance, through studies that are now under way.

A series of workshops will be conducted next year to help private and industrial landowners learn more about the new risk-rating model and other steps to address this problem, Shaw said.

Story By: 

David Shaw,


CORVALLIS - Work done in an upgraded and improved test facility in the Department of Nuclear Engineering and Radiation Health Physics at Oregon State University has helped create the "next generation" of nuclear power reactors that many experts believe will herald the future of nuclear energy.

This fall, tests done in this facility, along with much other work in a massive, international project, led to the final approval by the Nuclear Regulatory Commission of the AP 1000 Generation III-plus, an advanced nuclear reactor design from Westinghouse that will soon be available for international and domestic orders.

For its work in this field, the Advanced Thermal Hydraulic Research Laboratory at OSU, in collaboration with TIC The Industrial Company, received two awards from the Associated Builders and Contractors. The awards recognize their achievements in upgrading the testing facility from the AP600 design to the AP1000 design.

These reactor designs are much simpler, less costly to build, and based on "passively safe" concepts that take advantage of natural forces such as gravity, natural circulation, convection and evaporation for improved safety. They have fewer pumps, piping, valves, and cables, and overall less items to install, inspect or possibly fail than a traditional plant.

At OSU, these processes and design elements were built in one-quarter scale in the test laboratory, and tested repeatedly under varying conditions. The recent major upgrade to the facility involved construction and design of new electrical, mechanical, and pipe components, new data acquisition hardware, tracking instrumentation, and state of the art computer hardware and software.

"OSU is very proud of the important research we contributed to assist Westinghouse and the Nuclear Regulatory Commission in their determination that this reactor design concept meets the design requirements of reducing costs and enhancing safety," said Andrew Klein, professor and head of the Department of Nuclear Engineering and Radiation Health Physics.

This project is one of OSU's largest collaborative research efforts with private industry. Many nuclear industry officials say that power reactors of the type created by this research should be the safest, most economical nuclear power plants ever designed, and could lead to a re-birth of the nuclear power industry both in the U.S. and around the world.

Leaders of the OSU Thermal Hydraulics and Reactor Safety team include Jose Reyes, Qiao Wu, Brian Woods, John Groome and Teresa Culver, as well as both graduate and undergraduate students.


Teresa Culver, 541-737-2644

Extreme Weather Stresses Douglas-Firs

CORVALLIS, Ore. – Driving through forested regions surrounding Oregon's Willamette and Umpqua Valleys this summer, you may have noticed reddish dead branches, tops or whole dead Douglas-fir trees.

These trees may be reflecting physiological stress from the effects of extreme swings in weather over the past year and a half, says Rick Fletcher, forester with the Oregon State University Extension Service.

After experiencing months of saturated soils in the winter, then bone dry periods in the spring and summer, some Douglas-firs planted in less than ideal situations are showing what some foresters call "flare out," the occasional dead branch, top or the entire tree.

So far, most of the stressed trees seem to be limited to Douglas, Lane, Benton, Linn, Yamhill, Polk and Marion counties, from the areas surrounding McMinnville, south to Roseburg, according to local OSU Extension foresters. Douglas-fir in western Oregon's northern and westernmost counties, including Clackamas, Washington and the coast seem relatively unaffected. So far, economic impacts of this stress on forestry are unknown.

"Starting in December, 2005 and January, 2006, we experienced 44 days of straight precipitation, an all time record of consecutive days," said Fletcher. "These conditions left many Valley foothill sites with water logged soils for weeks on end, a recipe for disaster for wet-intolerant species like Douglas-fir."

In waterlogged soils, many fine roots die, leaving the tree to try and regrow these roots in the spring, stressing the trees, Fletcher explained.

"The summer of 2006 was very hot, with three separate periods of temperatures in excess of 100 degrees," said Fletcher. "These hot, dry conditions were with us for 110 straight days, putting trees in severe moisture stress.

"This one, two, three punch was devastating for trees on marginal soil types, leaving them easy picking for a host of insects and diseases," Fletcher said. "Samples I have examined are suffering from a range of problems such as twig weevils, coneworms, root rot and bark beetles. It would be too easy to point fingers at one of these problems as being the cause, when in reality, it is the weather conditions that are much more to blame."

Typically, species like Douglas-fir find these extremes in soil conditions marginally acceptable for growth, under more average climate conditions, said Fletcher. But this series of events during the past 17 months have just been too harsh for Douglas-fir on these sites.

While many different tree species seem to be affected, young Douglas-fir on marginal growing sites are taking the worst of the damage, he said. "Around the Willamette Valley foothills, Douglas-fir has been planted and comes in naturally on soils that are shallow and droughty, seasonally wet, or in some cases both."

Flare-out is common to the south as well, in the Umpqua Valley, according to John Punches, OSU Extension forester in Douglas County. "The situation is most common here on lower elevation, south and west facing slopes that tend to be hotter and drier, where moisture stress is exacerbated by unmanaged competition from grass and brush," he said. "Local landowners often assume that Doug-fir will grow on these sites. They may under optimum weather conditions, but these less than ideal conditions invariably result in significant branch, top and whole tree mortality."

Some commercial Christmas trees are being affected as well, said Dave Shaw, Extension forest health specialist at OSU. But Shaw thinks the stress seems to be limited to those trees growing in soils that are less productive—those waterlogged in the winter and dry as a bone in the summer.

"Across any given property it is likely that the problem is patchy and not evenly distributed," said Shaw. Once the rains come in, the extent of impacts will be clearer, he said. Then, healthy trees will green up and stressed parts will not.

These OSU Extension foresters say that the growing conditions for Doug-fir are looking more moderate this year.

"Even though our spring was short on precipitation, overall, the growing conditions we have been experiencing in 2007 are much more average than what we experienced in 2006," said Fletcher. "But it will take time for the trees to recover from 2006."

Similar Douglas-fir die-off occurred in other recent years, especially in 1998-99, said Fletcher.

For more information and photos of these problems, visit the Oregon Department of Forestry publication entitled: "Dead Branches, Dead Tops, and Dead Douglas-fir Trees - The Interaction of Water Stress, Insects and Disease," at http://egov.oregon.gov/ODF/PRIVATE_FORESTS/docs/fh/deadbr99.pdf


Rick Fletcher,
(Linn, Benton)

200-year experiment changes face of forest management

CORVALLIS - A 200-year study of rotting logs in the Oregon Cascade Range is only 10 percent complete, but findings from this research have already helped save hundreds of millions of dollars, improved forest health and shattered conventional wisdom about the decay of woody debris.

It also has attracted the interest of forest managers from around the world.

This work was begun 20 years ago by scientists from the College of Forestry at Oregon State University with 530 logs at the H.J. Andrews Experimental Forest near Blue River, Ore. The research was seen as a way to more rigorously document the process of wood decay and the value it provides in nutrient release, soil enhancement and other issues.

Even though the study is far from complete, it has already achieved many of these goals and raised other important questions that will continue to affect modern silviculture and the understanding of forest ecology, said Mark E. Harmon, the Richardson Chair and Professor of Forest Science at OSU. The work has been funded by the National Science Foundation and the U.S.D.A. Forest Service.

"Much of what we've found has run contrary to the conventional wisdom and is not what we expected," Harmon said. "And this long-term, intensive study of the decay of forest debris and logs has raised considerable awareness of this issue among forest managers."

Two decades ago, forest harvest operations usually "cleaned up" a site after logging, removing most of the debris at considerable cost and effort. As this and other studies showed the compelling ecological value of that material, the debris is now largely left where it is, making the forest healthier in the long run and saving hundreds of millions of dollars in unnecessary work.

"When this study began, we still assumed that most debris and logs decayed in more or less the same way, only releasing their stored-up nutrients after decades or centuries of decay," Harmon said. "It's now understood that there are large differences between the decay rate caused by different decomposers of different tree species, and that some nutrients from dead wood begin to enrich the forest almost immediately.

"That's a huge change in our thinking, and there are still a lot more changes to come," he said.

Among the other findings of the first 20 years of this work:

  • As much as one-third of the nitrogen in Pacific Northwest forests, one of the key nutrients that limit vegetation growth, appears to come from nitrogen fixation processes within rotting logs, in addition to that being slowly released from the wood itself.
  • Nutrient release begins far more quickly than ever anticipated, from both decaying fungi and the leaching effects of persistent rains.
  • The "brown rot" fungi that cannot break down lignin in trees leaves structural material behind to help form the next generations of forest floor and ultimately soil. White rot fungi, by contrast, degrade all parts of the wood, leaving almost nothing behind and decaying far more rapidly but only on some tree species.
  • Although some wood (such as Douglas-fir) resists decay, mechanisms such as mushroom growth on downed logs work to drain nitrogen from these logs, much more than had been understood.
  • There is a 10-fold difference in wood decay rates among dead trees. True firs such as silver fir will decay far more rapidly than other species, as much as 5-6 percent a year and may be gone in 60 years or less. Other species such as western red cedar or Douglas-fir may persist for hundreds of years.
  • Some parts of a log will decay and release nutrients much more quickly than other parts, leading to complex patterns that cannot be predicted by considering just the "average" condition of the wood.
  • Decay processes are dynamic and constantly changing, and they affect everything from nutrient release to soil changes, stream sedimentation, and plant, animal and fish habitat.

    "In the past we just didn't pay much attention to what was decaying, and how, and what the ecological implications of that were," Harmon said. "We now know there are huge differences between tree species, that some fungi decay some species and not others, and that all of these factors will play a role in sustainable forestry and overall forest health."

    In the future, Harmon said, trees increasingly will be planted that are never meant to be harvested - by design, they will be left to decay and play certain roles in forest ecology, for the health of plants, trees, microbes and wildlife. With large trees that have commercial value, it's still not certain exactly how many must be left for the complete range of forest benefits, he said, and findings on that issue will continue to emerge from studies such as this.

    Oddly enough, some of today's evolving forest management systems may seem more similar to those in the early days of the Pacific Northwest forest products industry - when large amounts of less-valuable wood was left behind in practices that were later deemed "wasteful" and changed dramatically after the 1940s, in order to harvest more of the wood and leave a clean site behind.

    The findings of these studies and their temporal scope have been so compelling, Harmon said, that they have attracted not only forest scientists but artists.

    "We originally began this work assuming it would be of interest only to forest researchers and ecologists," Harmon said. "Now people from all over the world are watching these studies, and many experts think of nutrient release as one of the last frontiers in understanding the role of dead trees in forest ecology.

    "Writers have done features on the work in national publications. Even artists and sculptors have worked with us to portray the fascinating, natural processes of forest growth and long-term changes."

  • Story By: 

    Mark E. Harmon, 541-737-8455

    DVD project helps land managers plan for the future

    CORVALLIS - Rural land managers reflect on their past and plan for the future in a new DVD produced by the Oregon State University Extension Service.

    "Landmarks in Conservation" is designed to help rural landowners, farmers, ranchers and foresters devise sustainable natural-resource management plans for their operations. The interactive multimedia project utilizes both DVD and web technologies.

    "This project draws on the experiences of nearly 30 land managers from across our state," said Bill Braunworth, agriculture program leader for the OSU Extension Service. "It demonstrates the importance of resource management planning, whether you operate a five-acre farm near Portland or a 100,000-acre ranch in southeast Oregon."

    The DVD and its companion website are a cooperative effort funded by the OSU Extension Service, the USDA Natural Resources Conservation Service and a private gift to the OSU Foundation. The DVD holds nearly two hours of video clips, while the website serves as a gateway to more than 120 print, video and online resources.

    "We are excited about the scope and potential impacts of this project," said Sara Magenheimer, public affairs specialist with the Natural Resources Conservation Service. "It presents technical, research-based information in an understandable, user-friendly fashion."

    The project's non-linear structure helps educators customize classroom, workshop or field instruction to meet the needs of specific audiences. It also empowers individuals to select the learning pace, media formats and content that work best for their own situation.

    "The insights and stories of these Oregon land managers are really what bring this project to life," Braunworth said. "They help viewers understand that connection between healthy natural resources and a profitable, sustainable operation."

    "Landmarks in Conservation" (DVD-1) is available from OSU Extension and Experiment Station Communications for $19.95 per copy plus $4 shipping and handling. Discounts are available when purchasing 10 or more copies. To order the DVD, visit http://extension.oregonstate.edu, call toll-free, 1-800-561-6719, or fax your request to 541-737-0817.


    Bill Braunworth, 541-737-1317

    Multimedia Downloads

    New DVD

    Scientists develop groundbreaking new model for impacts of dams

    CORVALLIS, Ore. – Scientists have developed a new system to help policy makers better assess the costs and benefits of building dams – the first system of its kind to use an interdisciplinary approach to simultaneously evaluate the distribution of biophysical, socio-economic and geopolitical impacts of dams, according to one of the study’s co-authors.

    “We as scientists tend to look at things through our own tiny little drinking straw, studying our one narrow field,” said Bryan Tilt, an assistant professor of anthropology at Oregon State University and one of the study’s authors. “When it comes to dams, we felt a broader perspective was needed. Because when you put up a dam, it affects whole ecosystems and whole communities.”

    The study, which was funded by the National Science Foundation, is part of a special issue on dams featured in the summer edition of the Journal of Environmental Management. The entire special issue was edited by Tilt and Desiree Tullos, an assistant professor in the Department of Biological & Ecological Engineering at OSU. Tullos is another co-author on the study and the principal investigator on the National Science Foundation grant.

    Each scientist was brought in for their piece of the dam puzzle. Lead author Philip H. Brown of Colby College is an economist who studies microeconomic issues in economic development. Tullos is an environmental engineer with expertise in ecohydraulics and hydraulic modeling. Tilt is an environmental anthropologist who studies the social and environmental impacts of rural development, with a special focus on China, where dam construction far outpaces any other nation. Darrin Magee of Hobart and William Smith Colleges is a geographer specializing in energy and water issues in China. And OSU’s Aaron Wolf studies water resources policy and conflict resolution.

    The scientists have developed what they call an Integrative Dam Assessment Modeling tool, or IDAM. The model was designed as a decision-support tool that policy makers can use to understand holistically the impacts, costs and benefits of building a dam in any area.

    “It can be used anywhere, with some modifications,” Tilt said, adding that the researchers have used the tool to study the impact of dams in China and are continuing that research through a new National Science Foundation grant this summer.

    The dam assessment tool measures the costs associated with a proposed dam development project and also measures the possible benefits. Each of the diagrams in the tool consists of 27 individual indicators of the effects of dam construction, divided into socio-economic, geopolitical and biophysical themes.

    In the published study, the authors illustrated the use of the IDAM tool by testing it on two hypothetical dams with different design characteristics.

    This summer the research team travels to China again where it will put the IDAM tool into practice on real dams. Tilt said they will collect data on two rivers: one that has several dams on it already (the Upper Mekong River) and one that is slated for dam development in the near future (the Nu River, also called the Salween).


    Story By: 

    Bryan Tilt, 541-737-3896

    International climate change researchers to convene at OSU July 8-11

    CORVALLIS, Ore. – Some of the world’s leading climate change researchers will gather July 8-11 at Oregon State University for a conference that will examine past changes in the Earth’s systems in order to better predict what may happen in the future.

    The conference is part of an international effort called PAGES (Past Global Changes), a core project of the International Geosphere-Biosphere Programme, which is funded by the National Science Foundation and NOAA in the United States and Switzerland.

    A keynote lecture by Jim Hansen, director of the NASA Goddard Institute for Space Studies, will be free and open to the public. His lecture, “Global Warming Time Bomb: The Path from Science to Action,” will begin at 6:30 p.m. on Thursday, July 9, at OSU’s LaSells Stewart Center, 26th Street and Western Boulevard in Corvallis.

    Hansen is a pioneer in the field of climate modeling and an internationally regarded expert in human-caused changes in climate. In his lecture, he will discuss the implications of climate inertia and how we have only recently become aware of the dangers of “climate tipping points.” A question-and-answer session and discussion will follow his lecture.

    Some 330 climate change scientists from around the world will discuss their research, representing institutions in the United States, China, France, Sweden, Argentina, Switzerland, Mexico, Chile, United Kingdom, Finland, Morocco, Germany, Japan and elsewhere.

    Among the paleoscience topics to be discussed are the global hydrological cycle and abrupt changes; reconstruction of past climates; human-environmental interactions; interglacial climate variability; and the stability of polar ice sheets and sea levels.

    Four designated “hot topic” presentations are highlighted. They include:

    • “The Role of Paleoscience in IPCC (Intergovernmental Panel on Climate Change),” by Jonathan Overpeck, University of Arizona, 5 to 6 p.m., Wednesday, July 8;
    • “Past Ocean Acidification: Biogenic Impacts and Climate Feedbacks,” James Zachos, University of California-Santa Cruz, and Ros Rickaby, University of Oxford, 5 to 6 p.m., Thursday, July 9;
    • “Transient vs. Rapid Change in the Sahara,” by Zhengyu Liu, University of Wisconsin, and Brahim Damnati, Abdelmalek Essaadi University in Morocco, 5 to 6 p.m., Friday, July 10;
    • “How Abruptly Can Sea Level Rise?” by Richard Alley, Pennsylvania State University, 5 to 6 p.m., Saturday, July 11.

    The entire scientific program can be found online at: http://www.pages-osm.org/osm/program_full.html. Registration information for the conference is at: http://www.pages-osm.org/osm/registration.html

    Prior to the conference, The PAGES Project will hold its first Young Scientist Meeting July 6-7 at Oregon State. Nearly a hundred early-career scientists and students will meet to discuss their paleoscience research and to network with senior researchers.


    Story By: 

    Andreas Schmittner, 541-737-9952

    Fear of Wolves Allows First Aspen Recovery in Yellowstone in More Than 50 Years

    CORVALLIS, Ore. – The wolves are back, and for the first time in more than 50 years, young aspen trees are growing again in the northern range of Yellowstone National Park.

    The findings of a new study, just published in Biological Conservation, show that a process called “the ecology of fear” is at work, a balance has been restored to an important natural ecosystem, and aspen trees are surviving elk browsing for the first time in decades.

    The research, done by forestry researchers at Oregon State University, supports theories about “trophic cascades” of ecological damage that can be caused when key predators – in this case, wolves – are removed from an ecosystem, and show that recovery is possible when the predators are returned. The results are especially encouraging for the health of America’s first national park, but may also have implications for other areas of the West and other important predators.

    After an absence of 70 years, wolves were re-introduced to Yellowstone Park in 1995, and elk populations began a steady decline, cut in half over the past decade. Also, the presence of a natural predator appears to have altered the behavior of the remaining elk, which in their fear of wolves tend to avoid browsing in certain areas where they feel most vulnerable. The two factors together have caused a significant reduction in elk browsing on young aspen shoots, allowing them to survive to heights where some are now above the animal browsing level.

    “This is really exciting, and it’s great news for Yellowstone,” said William Ripple, a professor in the OSU College of Forestry. “We’ve seen some recovery of willows and cottonwood, but this is the first time we can document significant aspen growth, a tree species in decline all over the West. We’ve waited a long time to see this, but now we’re optimistic that things may be on the right track.”

    The study found significant numbers of aspen, especially in streamside “riparian” zones, that have grown from tiny shoots in the past decade to heights of more than seven feet – a key point in their long-term survival, placing their crowns above the height easily browsed by elk and other animals. Tree growth in some stands has been particularly apparent just in the past 4-5 years.

    The long-term decline, to the point of localized extinctions, of aspen and cottonwood trees in Yellowstone National Park dates to the extirpation of the last known wolf packs in the 1920s. Prior to the re-introduction of wolves, scientists found there were many small sprouting shoots of these important tree species, and numbers of large trees 70 years old or more – but practically nothing in between. High populations of grazing ungulates, primarily elk, had grazed on the small tree shoots at leisure and with little fear of attack.

    But the ecological damage, researchers say, went far beyond just trees. The loss of trees and shrubs opened the door to significant stream erosion. Beaver dams declined. Food webs broke down, and the chain of effects rippled through birds, insects, fish and other plant and animal species.

    Aspen, a beautiful hardwood tree with golden fall color, a key to ecosystem biodiversity and a hallmark feature of mountain areas across the West, has been the focus of concern. Unlike willows, aspen are more easily killed or suppressed by browsing and have been the slowest to show any recovery. In some areas of the West, up to 90 percent of the aspen have disappeared.

    “When I first looked at these degraded ecosystems in the mid-1990s in Yellowstone, I had doubts we would ever be able to bring the aspen back,” said Robert Beschta, a professor emeritus of forestry at OSU and co-author on the study. “There were so many elk, and the stream ecosystems were in such poor shape. The level of recovery we’re seeing is very encouraging.”

    The OSU researchers say they believe there are two forces at work – both the lower populations of elk, and their changed behavior due to fear of wolves – but it’s difficult to determine exactly which force is the most significant.

    Of note, they say, is that elk populations now are actually higher than they were in the mid-1960s, when aspen trees were still in significant decline. The major change from that period of time is the presence of wolves. The effect of behavioral changes “may be equal to or even greater than” lower elk population levels in allowing tree survival, the researchers said in their report.

    “In riparian zones, where wolves can most easily sneak up on elk, and gullies or other features make it more difficult for elk to escape, we’ve seen the most aspen recovery,” Ripple said. “We did not document nearly as much recovery in upland areas, at least so far, where elk apparently feel safer. But even there, aspen are growing better in areas with logs or debris that would make it more difficult for elk to move quickly.”

    This element of fear, the OSU scientists said, is a concept that is now getting more attention in ecology – it factors in not just the numbers or species of animals, but also their behavior and the reasons for that behavior. Predators such as wolves or cougars, OSU researchers have shown, have the ability to strike fear into their prey and significantly change their behavior as a result.

    The recovery of aspen, the researchers said, appears to have no link to climate or local terrain, since unbrowsed aspen in upland sites are growing just about as much as those in riparian zones. More details on this research and the findings can be found on the web at www.cof.orst.edu/cascades

    “The issue of aspen decline in the American West is huge, and their recovery will depend on local conditions and issues in many areas,” Ripple said. “In northern Yellowstone, we finally have some good news to report. It’s just a start, but it’s a pretty good start.”

    Story By: 

    William Ripple,

    Invasive parasite destroying fish species in Europe

    CORVALLIS, Ore. - Researchers have discovered that a parasite carried by an invasive species of minnow is responsible for the dramatic declines and localized extinctions of a different minnow species in Europe during the past 40 years.

    This parasite, which scientists have found can almost totally destroy the spawning success of the small sunbleak minnow, Leucaspius delineatus, may pose threats to the diversity and stability of freshwater ecosystems, and is genetically very similar to a parasite that can be deadly to salmon, researchers say.

    The findings were published today in the journal Nature by researchers from Oregon State University, the Centre for Environment, Fisheries and Aquaculture Science in England, Idaho State University, and the Centre for Ecology and Hydrology in England.

    "This solves a mystery that fisheries researchers have been studying for decades, about why sunbleak minnows have been disappearing from Europe, where they were once quite common," said Michael Kent, a professor of microbiology and director of the Center for Salmon Disease Research at OSU.

    "And to find a parasite that can have such a devastating effect on spawning success is a little alarming," Kent said. "There are still a lot of unanswered questions here, including knowledge of the host range of the parasite. It's unknown if it would be pathogenic to other groups of fishes, such as salmonids."

    The minnows involved, both the invasive species and those dying out, are rather small, grey, innocuous fish no more than a few inches long that do not by themselves have any major commercial value, Kent said. But they are an integral part of the biodiversity of freshwater streams and lakes across Europe, and form an important part of the food chain for other fish, he said. The European sunbleak is now listed as a threatened species among European freshwater fish.

    "This is another aspect of the concerns about invasive species that you always have to watch for," Kent said. "The new minnows that moved in did not seem to be a big issue by themselves, but the parasite they carried was deadly to the minnows native to these waters."

    The invading species, researchers say, was a fish called Asian gudgeon, and it carried parasites closely related to an odd group of fungus-like organisms called choanoflagellates. The Asian gudgeon was first introduced into Romanian ponds and the Danube River in 1960, and has since spread rapidly throughout Europe.

    The fungal-like parasite carried by this species can infect the internal organs of fish, causing organ failure, severe anemia and death in susceptible species. The mortality rate of infected fish is very high, and they can get easily infected by direct transmission of the parasite during a free-swimming stage in its life cycle.

    "As high as the direct mortality is from this parasite, it's nothing compared to the effect on spawning success," Kent said. "It appears that in sunbleak, infection with the parasite causes near 100 percent failure in successful spawning. Over a few generations that can wipe out a local population."

    Other fish in the cyprinid family, including carp, may also be susceptible to this parasite, researchers say. And the parasite is remarkably similar to the "rosette agent" found occasionally in salmon, including chinook salmon, which can also cause mortality.

    This is one of the first times that introduction of an invasive fish species has resulted in the almost-total suppression of spawning success in a native species, researchers said. The host fish, Asian gudgeon, is only a carrier and does not appear to be affected by the parasite.

    The presence of this parasite in fish may also be a concern in aquaculture trade, they said.

    This research was supported by grants from the Centre for Environment, Fisheries and Aquacultural Sciences and the Centre for Ecology and Hydrology in England.

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    Michael Kent, 541-737-8652