college of forestry

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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When it comes to keeping streams cool, buffer strips help but geology rules

CORVALLIS, Ore. — Leaving a strip of trees along headwater streams during logging operations helps to keep the water cool, but researchers have now shown that the downstream impacts of such practices have more to do with geology than with the presence or width of buffer strips.

Using studies in three Oregon watersheds — Alsea, Trask and Hinkle Creek — scientists analyzed the impact of buffer strips on downstream temperatures. The researchers used data recorded in experiments carried out in 27 locations over 14 years. The results of the analysis, one of the most robust of its kind in the nation, were reported in the journal Hydrological Processes.

The Alsea and Trask watersheds are located in the Oregon Coast Range near Alsea and Tillamook respectively. The Hinkle Creek watershed is located northeast of Roseburg in the Cascade foothills.

“In Coast Range and Western Cascades catchments, where our study streams were located, streams that are small and non-fish bearing have no regulatory requirement for an overstory riparian buffer,” said Kevin Bladon, lead author and assistant professor in the College of Forestry at Oregon State University. “As a result, we observed some warming of the stream water. However, if the geology is permeable — where we have a lot of groundwater inputs into the system — that warm water didn’t persist downstream. As soon as it flowed back into a forested stream reach again, the temperature stabilized.”

Based on isolated research efforts, scientists have reached different conclusions about the impact of harvesting on stream temperatures and how far those impacts can be detected downstream. “This study, with 29 different sites across multiple catchments, upstream and downstream in different geologies, provides a lot of strong evidence” about how the environment determines the impacts of logging on downstream temperatures, said Bladon.

“Stream temperature is one of those things that people tend to think is simple and easy to measure,” he added. “However, the dynamics and all of the factors that influence it are quite complicated. Temperatures aren’t just influenced by exposure of water to the sun. They depend on things like whether the water flows through the stream bed or through a stream bank, the geometry of the stream channel, how much water there is in the stream channel, and how much groundwater input there is.”

In the experiments Bladon and his team analyzed, stream temperatures were recorded during low-flow conditions from July to September in headwater streams above and below locations where harvesting operations were conducted. The locations provided a variety of geology, landscape and forest-management circumstances.

All three watersheds contain fish-bearing reaches. While cutthroat trout are the primary fish species at Hinkle Creek, the Trask and Alsea watersheds are home to populations of coho salmon, steelhead, cutthroat trout and sculpin. Alsea also has runs of western brook and Pacific lamprey.

In Oregon, private forest regulations require loggers to leave buffer strips of trees along fish-bearing streams, medium and large non-fish-bearing streams and domestic water sources. The exact width depends on the size of the stream channel and the fish species present.

“We’ve been talking for a lot of years about riparian areas. The discussion can get really heated,” said Bladon. “I think a lot of folks would like to move toward a variable-width riparian area system. Right now, it’s categorized. If it’s a fish-bearing stream of a certain size, you will use a specific width riparian area.

“In terms of stream temperature, in some cases, it’s not enough, and in others, it’s overkill. But, we definitely need more research to figure out where those places are.”

While this research provides important insights into the downstream movement of warmed stream water, the experiments analyzed by Bladon and his team were not initially set up to directly address these types of questions. As a result, he and other Oregon State researchers are conducting additional studies. They are placing sensors at short intervals in undisturbed streams and in streams that will be harvested to determine precisely how temperatures change downstream from harvesting operations.

In addition to Bladon, co-authors on the paper included Catalina Segura at OSU, Nicholas Cook with Otak Inc. of Portland, Sharon Bywater-Reyes of the University of Northern Colorado and Maryanne Reiter of the Weyerhaeuser Company. Funding support came through the Watershed Research Cooperative at OSU from the College of Forestry, the Oregon Department of Forestry, the Oregon Forest & Industries Council, the National Council for Air and Stream Improvement, Weyerhaeuser Company, Roseburg Forest Products and Plum Creek Timber.

Story By: 

Kevin Bladon, kevin.bladon@oregonstate.edu, 541-737-5482


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Temporary Change in Leadership at College of Forestry

CORVALLIS, Ore. – Oregon State University’s College of Forestry Dean Thomas Maness announced this week his intention to begin immediately an approximate six-month change in responsibilities to attend to personal matters.

As a result, from January 17 to June 30, Executive Associate Dean Anthony S. Davis will serve as acting dean of the college 

The temporary changes occurs at a very important time within the college, as it continues to work on the Oregon Forest Science Complex and expand on the excellent teaching, research, and outreach and engagement that has built one of the finest forestry programs in the world and a source of great pride for Oregon State University.

Maness is expected to return to serving as dean by July 1, at which time, Davis will return to his executive associate dean role.

Media Contact: 

Sean Nealon, 541-737-0787, sean.nealon@oregonstate.edu


Steve Clark, 541-737-3808, steve.clark@oregonstate.edu

Complex, old-growth forests may protect some bird species in a warming climate

CORVALLIS, Ore. — Old forests that contain large trees and a diversity of tree sizes and species may offer refuge to some types of birds facing threats in a warming climate, scientists have found.

In a paper published today in Diversity and Distributions, a professional journal, researchers in the College of Forestry at Oregon State University reported that the more sensitive a bird species is to rising temperatures during the breeding season, the more likely it is to be affected by being near old-growth forest.

Researchers studied 13 bird species that have been tracked annually in the U.S. Geological Survey’s annual Breeding Bird Survey, one of the most comprehensive efforts of its kind in North America. Only two — the Wilson’s warbler and hermit warbler — showed negative effects from rising temperatures over the past 30 years, but actual counts of both species show that their populations are stable or increasing in areas that contain high proportions of old-growth forest.

A team led by Matthew Betts, professor in the College of Forestry, reached their conclusions by analyzing data for bird populations, forest structure and climate across northwestern North America. The researchers used satellite imagery to determine the amount of old-growth forest within about 450 yards of each 25-mile-long bird survey route.

The findings provide an additional reason for old-growth forest conservation, said Betts. “Managers hoping to combat the effects of climate change on species’ populations may now have an additional tool – maintaining and restoring old-growth forest.” He noted that this is important because management recommendations from biodiversity and climate studies have traditionally been sparse. Such studies have tended to focus on moving species to cooler climates or simply reducing carbon emissions. 

Wilson’s warbler winters in Mexico and breeds during the late spring and early summer along the West Coast and across northern North America from Alaska to New England and the Canadian Maritimes. Although it occurs in early-stage as well as mature forests, it is declining at a rate of about 2 percent per year in the Pacific Northwest.

The hermit warbler also winters in Mexico but breeds exclusively along the West Coast as far north as Washington. Its populations are relatively stable but declining in landscapes with low amounts of old-growth forest.

Additional research will be needed to identify the specific features of mature forests that buffer the effects of warming temperatures on birds. One possibility, the researchers said, is that the large trees themselves function as “heat sinks” during warm periods and thus moderate temperatures. Multiple canopy layers may also provide climate buffering effects.

 The study was supported by the National Science Foundation through the Long Term Ecological Research program at the H.J. Andrews Experimental Forest and the Department of the Interior’s Northwest Climate Science Center. Co-authors included Ben Phalen, Sara J.K. Frey, Josee S. Rousseau and Zhiquiang Yang, all at Oregon State. Phalen is also affiliated with the University of Cambridge in the UK. 

Note: The paper on which this story is based is available at http://onlinelibrary.wiley.com/doi/10.1111/ddi.12688/full (requires subscription).

See a video about this story.

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Matt Betts, matthew.betts@oregonstate.edu, 541-737-3841


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After a wildfire, attitudes about recovery vary with sense of place and beliefs about fire ecology

CORVALLIS, Ore. — How people who live close to burned forests feel about landscape recovery — whether they sense overwhelming loss or see positive signs in the growth of new vegetation — depends largely on their attachment to the area and on their appreciation for the ecological role of fire. 

In a survey of more than 800 people living in close proximity to 25 wildfires that occurred in 2011 and 2012 in Oregon, Washington, Idaho and Montana, researchers found that people had slightly positive attitudes about forest recovery within a year or two after the fire. A strong sense of place — a significant feeling of belonging or identification — and an understanding of the importance of fire in forest development tend to be associated with those attitudes.

“People have deeply rooted values that are affected by fires,” said Chad Kooistra, who led the analysis as a Ph.D. student in the College of Forestry at Oregon State University. “Wildfires are a very salient issue, even months or years after a fire. People who live nearby or go to that area for recreation care a lot about many different aspects of that landscape. Fires can change how they perceive and experience it.”

The survey results can assist managers of public forests in the aftermath of a fire, he added. “One way to help people have a positive view of forest recovery is to find ways to restore their attachment to the landscape that’s been affected. That could include volunteer activities and visiting places in the burned area. The concept of post-fire landscape recovery could be useful for talking to people about the ecological benefits and necessity of wildfires and how we can adapt to living with them without compromising important values.”

Kooistra reported the results in the journal Environmental Management with co-authors at Oregon State, the University of Idaho and Eastern Washington University.

Perceptions about forest recovery can vary dramatically among people in the same community, he added. Some residents can look at a burned landscape and regard fire as the first step in a process leading to a new forest, whereas other people can look at the same area and feel that their special place has been destroyed.

One surprise, said Kooistra, is that people who live farther away from the fire perimeter tend to feel more negative about the recovery process. It’s possible, he said, that people who live nearby may have more opportunities to see sprouting vegetation and other signs of growth.

Perceptions of landscape recovery were not affected by how long people had lived in the area or whether or not their income or livelihood depended on the forest, the researchers wrote.

Immediately after a fire, emergency response teams move in to address hazards such as the potential for erosion and trees at risk of falling, but such efforts do not usually address the psychological health of local residents. “Our research affirms the need to also address emotional and cognitive aspects related to how people experience the changing landscape after wildfires,” said Kooistra.

The researchers sent questionnaires to about 5,000 households within 9 miles of the perimeters of fires larger than 1,000 acres. They were asked to indicate their agreement or disagreement with statements such as: “The wildfire improved the health of the landscape,” and “I feel less of a connection to the landscape after the wildfire.” People were surveyed one to two years after the fires had occurred. Respondents had lived in their homes for an average of 20 years.

The survey was part of a larger project funded by NASA at the University of Idaho to understand the social and ecological dimensions of “extreme” wildfires. The researchers interviewed people in their homes and evaluated case studies of severe fires. They showed that post-fire landscape recovery is important for understanding connections between the social and ecological aspects of fires.

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Chad Kooistra, chadkooistra@gmail.com, 775-636-5145 

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Forest harvesting rules effectively protect water quality in the Alsea watershed

CORVALLIS, Ore. — Tree harvesting methods designed to protect streams from soil erosion and sedimentation can be effective in maintaining water quality, scientists have shown in a study in the Oregon Coast Range.

By following rules enshrined in the Oregon Forest Practices Act, research in the Alsea River watershed showed that a stream draining clear-cut slopes carried no more sediment after harvest than before. In fact, the clear-cut watershed had lower sediment concentrations than streams in two nearby uncut watersheds.

While the study shows what can theoretically be achieved, researchers are cautious about applying their results to actual harvesting activities elsewhere. The practices in this study may not represent the variety of conditions faced in forest management across the state, they said. For example, no new roads were constructed in the process of carrying out the study. That’s significant because previous studies have showed that road construction can be an important source of sediment.

The results of the study were published in Forest Ecology and Management, a professional journal.

“This and a number of other studies provide some very nice evidence that current best management practices are proving to be much more effective than historical practices,” said Jeff Hatten, lead author and associate professor in the College of Forestry at Oregon State University. Studies in other parts of Oregon and the West show that the impacts of such practices depend on landscape characteristics including geology, soil type, slope and historical landslides.

In the 1960s, the Alsea watershed was the site of one of the first comprehensive studies of tree harvesting and water quality in the nation. Located in southern Benton and Lincoln counties, the river empties into the Pacific at Waldport and supports runs of chinook and coho salmon as well as steelhead and cutthroat trout. Research results provided evidence for standards included in the landmark 1971 Oregon Forest Practices Act, among the first such laws in the United States to set rules to protect streams from impacts of tree harvesting.

In that study, forests were clear-cut above Needle Branch and Deer Creeks, and significant increases of sediment were recorded in each stream after harvesting. Another watershed, Flynn Creek, was left uncut as a control.

Tree cutting practices at that time included widespread burning of branches and other non-saleable materials. For the most part, trees were harvested down to the stream edge; few uncut vegetation buffers were left along the streams. Even where such buffers were left in Deer Creek, storm-driven road failures caused pulses of soil to enter the water.

By the time the latest project was begun in 2005, sediment concentrations in Needle Branch and Deer Creeks had returned to their pre-harvest states. Researchers began a new round of monitoring sediment, stream discharge (a measure of how much water is flowing per second) and precipitation. In 2009, after five years of data collection, the upper portion of Needle Branch was clear-cut. Similar harvest operations were conducted in the lower portions in 2014, and to meet annual clear-cut limits in the Oregon Forest Practices Act, the remainder was cut in 2015. No trees were cut in Flynn and Deer Creek, which were maintained as control sites for comparison purposes.

Over the course of the study, which ended in 2016, more than 4,400 water samples were collected and analyzed at the Forest Hydrology Lab at Oregon State.

“We found that there was no evidence of an effect of contemporary forest practices on suspended sediment concentrations,” the authors wrote. For all years, both the mean and the maximum sediment concentrations were higher in Flynn and Deer Creeks, where there had been no harvesting, than in Needle Branch, where trees had been cut.

Among the harvesting practices used in the study were 50-foot-wide buffers along fish-bearing portions of Needle Branch, which are required by law. No buffers were left along non-fish bearing stream segments. Residual materials were burned in discrete piles rather than broadly across the harvested areas. Tree-cutting equipment was not allowed in the stream channels.

Large pieces of wood that fell into the stream channel of Needle Branch were left where they lay. The researchers did not directly measure the impact of this material on sedimentation, said Hatten, “but there is evidence (from other studies) that large wood can increase the formation of pools and riffles, increasing sediment retention. There is also evidence that wood can cause channel widening and steepening.”

Other authors of the report included Catalina Segura and Kevin Bladon at Oregon State; V. Cody Hale at Nutter and Associates in Athens, Georgia; John Stednick at Colorado State University; and George Ice (retired) of the National Council for Air and Stream Improvement, a nonprofit research organization for the forest products industry.

The study was funded by members of the Watershed Research Cooperative at Oregon State University and the National Council for Air and Stream Improvement. More information about the study is available on the Watershed Research Cooperative website.

Story By: 

Jeff Hatten, jeff.hatten@oregonstate.edu, 541-737-8720


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Scientists dispute missing dryland forests

CORVALLIS, Ore. — Scientists are disputing the possibility that a significant portion of the world’s forests have been missed in an earlier accounting of ecological diversity.

Writing in the journal Science, a team led by Daniel Griffith, a postdoctoral scientist in the College of Forestry at Oregon State University, argues that dryland forests should not be confused with savannahs, which comprise valuable ecosystems in their own right.

Savannah ecosystems should be conserved as distinct habitats and not regarded as forests, Griffith and his co-authors wrote.

The authors responded to a paper published in May by a team led by Jean-Francois Bastin of the UN Food and Agriculture Organization. Bastin’s team had reported that, through an analysis of high-resolution satellite images on Google Earth, dryland forests had been underestimated across the world. Including regions with 10 percent or more tree cover, they wrote, results in a 40 to 47 percent global increase in the extent of such forests.

However, Griffith and his colleagues suggested that Bastin’s group “misclassify as dry forest many tropical regions that are in fact savannas. Savannas differ from forests in having a continuous grassy ground layer, which supports fire and grazing mammals.”

Many of the savanna ecosystems that Bastin proposed to be reclassified as forests have persisted for millions of years, they noted.

“We decided to take a closer look at this issue after reading a press release written by a co-author of the original paper,” said Griffith. “They claimed to have discovered ‘lost’ forests. We realized that the authors had applied an outdated and heavily criticized forest definition that greatly inflates forest estimates and assumes that high tree cover is a universal natural state. This misconception about tree cover is at the heart of conservation threats to savanna ecosystems, which have naturally variable tree cover.”

Managing savannas as forests, Griffith’s team wrote, could lead to changes in the way fires and the spread of trees are handled, with adverse consequences for these ecosystems. “Afforestation and fire suppression policies in savannas risk destroying a wealth of specialized and endemic savanna biodiversity that underpin unique ecological processes, and compromising ecosystem functions such as carbon cycling and water and energy exchange,” they added.

Moreover, classifying habitats on the basis of a single criterion such as dryness or tree cover ignores key differences between vegetation types. Using the approach that the Bastin team took, they wrote, would result in reclassifying some wet neotropical forests in Ecuador, Peru and Colombia as dry forest.

“We suggest that the Bastin team’s tree-cover analysis is a valuable contribution to understanding variation in woody cover, but we urge readers not to mistake the forest for the trees,” Griffith said.

Co-authors of the comment include Christopher Still, associate professor in the College of Forestry at Oregon State, and researchers representing organizations in Africa, Asia, Europe, North America and South America.

Story By: 

Daniel Griffith, griffith.dan@gmail.com, 541-737-8426

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Amrabad Tiger Reserve - India - Dr Jayashree Ratnam

Cerrado - Bolivia - credit Dr Joe Veldman

Isalo NP - Madagascar - Dr Caroline Lehmann

Kruger NP - South Africa - credit Dr Kate Parr

South Sahel - Mali - credit Dr Niall Hanan

Northwest forests are becoming denser and more vulnerable to fire

CORVALLIS, Ore. — While large fires have had dramatic impacts in some Pacific Northwest forests, only about 10 percent of the forested lands in the eastern Cascades have burned in the last 30 years, and young trees and dense forests are continuing to grow at a rate that outstrips losses from disturbance.

As a result, many forests across this region are becoming denser. Efforts to reduce their vulnerability to future high-severity fires — through tree thinning, prescribed burning and harvesting — have had little overall effect on forest structural conditions across the region as whole.

Those are among the results of a comprehensive analysis of forest structure and biodiversity based on satellite imagery and on-the-ground field work in the eastern Cascades of Washington, Oregon and Northern California from 1985 to 2010. Matthew Reilly, a former Ph.D. student in the College of Forestry at Oregon State University led the study, which was published in the journal Ecological Applications. Reilly is now a post-doctoral scientist at Humboldt State University.

Large fires in highly visible places such as the Columbia Gorge, Santiam Pass and the Northern California wine region capture public attention, said Reilly, but are not representative of what’s happening across the whole region. “We become fixated on losses associated with tree mortality and fire, but the gains from new growth are really important. They have the potential to offset those losses. This study zooms out beyond the perimeter of recent fires and considers them in the context of what else is going on in the forests and woodlands east of the Cascades.”

For forest managers, the findings emphasize the tradeoffs between two goals: dense forests that provide habitat for threatened species such as the northern spotted owl; and more open-canopy forest ecosystems that scientists call early seral (the youngest stage in forest development) with large, thick-barked trees that are considered less vulnerable to high-severity fire.

Reilly and his team analyzed patterns of landscape change and low-, medium- and high-intensity fire in three zones — the warm, dry zone dominated by ponderosa pine; areas comprised of mixed-conifer species such as ponderosa pine, Douglas fir and white and grand fir; and high-elevation subalpine forests with extensive areas of lodgepole pine. The study covered private as well as public lands, including the network set aside in 1994 by the Northwest Forest Plan, known as “late successional reserves.”

Forests in the reserves comprise about 8 percent of the 10.5-million-acre study area and burned at a higher rate than did forests outside that system. About 15 percent of the network burned during the study period.

Subalpine forests grow at the highest elevations and comprise only 9 percent of the study area. But among the three vegetation zones, these areas took a disproportionally large hit from fire. About 30 percent of that zone burned during the study period. Fires in Washington in 2006 accounted for most of the total area burned, about half of which was high severity. However, these sorts of events may be similar to historical fire activity, and some high-elevation species, especially lodgepole pine, are very resilient to fire, said Reilly.

In contrast, less than 10 percent of the mixed conifer and ponderosa pine forests burned. Although a third of the area burned was classified as high severity, one of the major threats to biodiversity in these zones continues to be a deficit of low- and moderate-severity fire, which historically maintained open, mature forest habitats and resilience to drought and high-severity fire.

“When you pull fire out of the picture, the forests are getting denser,” said Reilly. “There’s a push for restoration activities such as thinning and prescribed fire to make the forests more resilient. And there has been some really good work done on the ground, but it’s a drop in the bucket. It’s hardly enough to nudge things in the direction of the way we think things were historically and towards landscape-wide conditions that are likely to be more resilient to drought and fire.”

In the future, he added, scientists expect climate change to produce warmer and drier conditions, leading to decreased growth, a longer fire season and an increased risk of fire. “It’s very uncertain how much more, but as droughts increase in frequency and length, we’ll need to reassess the capacity of forests in the region to absorb these disturbances,” he said. “Continued monitoring will be essential to understand the impacts of these disturbances on our landscapes.” 

Reilly worked with scientists in the Pacific Northwest Research Station of the U.S. Forest Service, Michigan State University and University of Bari Aldo Moro in Italy. Funding was provided by the U.S. Forest Service Region 6 Inventory and Analysis program and the Pacific Northwest Research Station. 

Media Contact: 

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



Matthew Reilly, matthew.reilly@oregonstate.edu, 706-338-1372


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Low severity fire

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Ponderosa pine in the Fremont-Cinema National Forest (Photo: Matthew Reilly)

Dense forest stand in the Deschutes National Forest, Oregon (Photo: Andrew Merschel)

15,000 scientists in 184 countries warn about negative global environmental trends

CORVALLIS, Ore. — Human well-being will be severely jeopardized by negative trends in some types of environmental harm, such as a changing climate, deforestation, loss of access to fresh water, species extinctions and human population growth, scientists warn in today’s issue of BioScience, an international journal.

The viewpoint article — “World Scientists’ Warning to Humanity: A Second Notice” — was signed by more than 15,000 scientists in 184 countries.

The warning came with steps that can be taken to reverse negative trends, but the authors suggested that it may take a groundswell of public pressure to convince political leaders to take the right corrective actions. Such activities could include establishing more terrestrial and marine reserves, strengthening enforcement of anti-poaching laws and restraints on wildlife trade, expanding family planning and educational programs for women, promoting a dietary shift toward plant-based foods and massively adopting renewable energy and other “green” technologies.

Global trends have worsened since 1992, the authors wrote, when more than 1,700 scientists — including a majority of the living Nobel laureates in the sciences at the time — signed a “World Scientists’ Warning to Humanity” published by the Union of Concerned Scientists. In the last 25 years, trends in nine environmental issues suggest that humanity is continuing to risk its future. However, the article also reports that progress has been made in addressing some trends during this time.

The article was written by an international team led by William Ripple, distinguished professor in the College of Forestry at Oregon State University. The authors used data maintained by government agencies, nonprofit organizations and individual researchers to warn of “substantial and irreversible harm” to the Earth.

“Some people might be tempted to dismiss this evidence and think we are just being alarmist,” said Ripple. “Scientists are in the business of analyzing data and looking at the long-term consequences. Those who signed this second warning aren’t just raising a false alarm. They are acknowledging the obvious signs that we are heading down an unsustainable path. We are hoping that our paper will ignite a wide-spread public debate about the global environment and climate.”

Progress in some areas — such as a reduction in ozone-depleting chemicals and an increase in energy generated from renewable sources — shows that positive changes can be made, the authors wrote. There has been a rapid decline in fertility rates in some regions, which can be attributed to investments in education for women, they added. The rate of deforestation in some regions has also slowed.

Among the negative 25-year global trends noted in the article are:

  • A 26 percent reduction in the amount of fresh water available per capita
  • A drop in the harvest of wild-caught fish, despite an increase in fishing effort
  • A 75 percent increase in the number of ocean dead zones
  • A loss of nearly 300 million acres of forestland, much of it converted for agricultural uses
  • Continuing significant increases in global carbon emissions and average temperatures
  • A 35 percent rise in human population
  • A collective 29 percent reduction in the numbers of mammals, reptiles, amphibians, birds and fish

Ripple and his colleagues have formed a new independent organization, the Alliance of World Scientists, to be a collective voice on environmental sustainability and human well-being. Scientists who did not sign the warning prior to publication can endorse the published warning by visiting http://scientists.forestry.oregonstate.edu/.

Co-authors of the article include Ripple and Christopher Wolf at Oregon State University and Eileen Crist of Virginia Tech in the United States; Mauro Galleti of the Universidade Estadual Paulista in Brazil; Thomas Newsome of The University of Sydney and Deakin University and William Laurence of James Cook University in Australia; Mohammad Alongir of the University of Chittagong in Bangladesh; Mahmoud Mahmoud of the National Oil Spill Detection and Response Agency in Nigeria.

The BioScience article is publicly available online

Media Contact: 

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



William Ripple, bill.ripple@oregonstate.edu, 541-737-3056


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Field and Houses

Human activities are reshaping forest animal communities around the world


CORVALLIS, Ore. — Forest-dwelling animals don’t have to live right by a road, pasture or human settlement to be affected by what scientists call forest edges. Indeed, animals up to a kilometer (0.6 miles) from an edge show a measurable impact from their proximity to areas where trees have been removed to make way for other land uses.

In the largest-ever analysis of arboreal vertebrate species — 1,673 species on five continents — an international team of researchers has found that 85 percent are either attracted to or avoid the edges of forests. For 46 percent, the response is positive; edges provide these species with the resources they need to survive.

However, scientists are more concerned with the 39 percent that show negative effects. That’s because as intact forested landscapes diminish and become broken into smaller areas, species that prefer the deep woods face shrinking habitats and an increased threat of extinction. The findings emphasize the need for conservation programs to preserve large areas of forestland and prevent them from being divided into smaller fragments.

Adam Hadley and Urs Kormann, research associate and post-doctoral scientist respectively in the College of Forestry at Oregon State University, are co-authors of a paper announcing the team’s findings today in the journal Nature. Marion Pfeifer at Newcastle University in the United Kingdom is the lead author of a team of 32 researchers from the U.K, North and South America, Europe, Australia, Africa and Australia.

The study is the latest showing how the rapid fragmentation of the world’s forests is affecting animal extinctions and biodiversity. About half of the world’s forested acres are now thought to be within 500 meters — the length of five and a half football fields — of the edge of a road, pasture or other non-forest land use.

Examples of species that depend on unbroken swaths of forested landscapes include the Sunda pangolin (Manis javanica), the Bahia tapaculo (Eleoscytalopus psychopompus), the long-billed black cockatoo (Zanda baudinii) and Baird’s tapir (Tapirus bairdii). 

For this study, researchers assembled data for animal abundance across a range of mostly tropical landscapes, from open non-forested habitats to forest edges and deep within remote jungles. For each of the species included in the paper, the researchers calculated two measurements, which they call “edge influence” and “edge sensitivity,” in order to capture the complexity of relationships between species and habitats.

“I was shocked that we could find this effect for so many species going so deep into the forest,” said Hadley, who studies pollinators in forested areas of Costa Rica and Oregon. Studies of deep forest habitats are especially rare, he said, since such areas are difficult to reach. Nevertheless, the data show that edges really matter, he added. “There are few remaining areas where you don’t have intrusions into the forests, such as roads and other activities. Maybe we should consider not putting roads into them. It may be valuable just to keep them as remote as possible. There aren’t that many left.”

The study is the first to document universal patterns across many groups of animals, said Kormann. “This adds stark evidence to the idea that, if we are to conserve species diversity on this planet, there is no alternative to doing more to safeguard the last expansive tracts of rainforest.”

The study was funded by the European Research Council.

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