OREGON STATE UNIVERSITY

college of forestry

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.

Story By: 
Source: 

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

Multimedia Downloads
Multimedia: 

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. 

Story By: 
Source: 

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

Multimedia Downloads
Multimedia: 

Landscape_Sjohnson2

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.


Story By: 
Source: 

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

Multimedia Downloads
Multimedia: 

plantation_oldgrowth_LiDAR

Betts3

OG_Sjohnson3

Ancient bones point to shifting grassland species as climate changes

CORVALLIS, Ore. – More rainfall during the growing season may have led to one of the most significant changes in the Earth’s vegetation in the distant past, and similar climate changes could affect the distribution of plants in the future as well, a new study suggests.

In a report in Science Advances, an analysis was done of mammoth and bison hair, teeth and bones, along with other data. It concludes that a changing climate — particularly increasing rainfall and not just atmospheric carbon dioxide — explains the expansion of grassland plants during the latter part of the Neogene, a geologic era that includes the present.

The research was led by Jennifer Cotton as a post-doctoral researcher at the University of Utah and in the College of Forestry at Oregon State University. She is now an assistant professor at the California State University, Northridge.

Scientists have long known that some grassland species became more abundant during this period, including the ancestors of corn, sugar cane and sorghum. Known as C4 grasses, they use a different method of metabolism via photosynthesis from most other types of vegetation, called C3 grasses. They tend to thrive under warm, moist conditions, in addition to low levels of carbon dioxide in the atmosphere.

“The point of the work was to understand what drove one of the most dramatic biological transitions in the past 65 million years, and also to better understand the past so that we can make predictions about the future,” said Cotton. “We know that the balance between C3 and C4 grasses is controlled by both atmospheric CO2 and climate, but the relative influence of each of these factors has not been clear.

To understand what drove that transition, the researchers analyzed carbon isotopes in 632 samples of bison and mammoth tissues from across North America over the past 18,000 years, corresponding to the time between the peak of the last ice age to the present. The researchers were able to show that, over time, the animals’ diets shifted toward more C4 plants and those plants gradually spread north.

By combining their findings with data on climate, temperature and changing carbon dioxide concentrations, the researchers showed that increasing precipitation during the growing season was the single most important factor in the spread of C4 grasses. In recent years, increases in rainfall and temperature have enabled farmers to grow corn in the upper Midwest in areas dominated by wheat.

“Both atmospheric CO2 and climate have been changing and will continue to change in the future,” said Cotton, “and many have suggested that additional CO2 in the atmosphere will benefit C3 grasses, causing them to outcompete C4 grasses. Our results suggest that climate, rather than CO2 fertilization, will drive future changes to C3 and C4 grass distributions, which will likely benefit C4 grasses in much of the Great Plains.”

The National Science Foundation provided funding for the research. Cotton’s co-authors included Christopher J. Still and Thomas M. Mosier at Oregon State, Thure E. Cerling at the University of Utah and Kathryn A. Hoppe at the University of Washington.

The paper is online at http://advances.sciencemag.org/content/2/3/e1501346.

Story By: 
Source: 

Jennifer Cotton, jen.cotton@csun.edu, 818-677-7978

Multimedia Downloads
Multimedia: 

Corn

Advanced wood products center receives economic development grant

CORVALLIS, Ore. – The federal Economic Development Administration has approved a grant of nearly $450,000 to Oregon State University to jump-start the use of new engineered wood products in the building industry.

The National Center for Advanced Wood Products Manufacturing and Design, a collaboration between Oregon State and the University of Oregon, will develop testing to help integrate mass timber construction into Oregon’s building code standards, while maintaining a close working relationship with the Oregon Building Codes Division.

The goal of the center is to develop new wood products, such as cross laminated timber, or CLT panels, that can be manufactured and certified for use in Oregon. It will also try to create economic opportunities for rural communities that have lost jobs to globalized commodity markets and dramatically reduced harvest levels.

“Code approval for new uses of wood products in these markets requires dedicated performance testing,” said Geoff Huntington, director of strategic initiatives for the OSU College of Forestry. “This testing is key to unlocking the engineered wood supply chain to meet growing demand.”

Developers in the Northwest and Pacific Rim countries may use CLT for its resilient, energy-efficient properties. The D.R. Johnson Lumber Company in Riddle, Oregon, has become the nation’s first certified manufacturer of CLT for construction purposes.

“We will use funds to work with manufacturers and commercial developers to complete performance testing of Oregon-manufactured wood building components for specific projects,” said Huntington. “Our objective is to make CLT and other innovative uses of mass timber products technically feasible, economically viable and accessible alternatives for architects and developers seeking to use Oregon products to meet growing consumer demand for healthy, sustainable buildings.”

Projects using innovative mass timber projects are already in the planning stages in Portland and Corvallis. In Portland, LEVER Architecture is designing a 12-story CLT building in the Pearl District, and in Corvallis, OSU plans to use the material in constructing new teaching and research facilities for the College of Forestry.

Story By: 
Source: 

Geoff Huntington, 541-737-9103

Multimedia Downloads
Multimedia: 

LeverArch-Ptld

Illustration courtesy of LEVER Architecture

Fungal pigments provide commercial opportunity for paint and dye manufacturers

CORVALLIS, Ore. Oregon State University researchers have developed a new method for producing stable pigments from fungi, a process they say can be scaled up to match the needs of manufacturers of paints, wood finishes and textile dyes.

Scientists have known for some time that fungi make pigments with blue-green, reddish-orange, yellow and brown hues, and since the Middle Ages, artists have used woods colored by fungal pigments, a process known as spalting.

But while the microorganisms can be grown in solution, capturing the pigments has required the use of toxic solvents, said Sara Robinson, an assistant professor in the OSU College of Forestry. Robinson has now found a way to use oils to harvest the pigments, and OSU has applied for a provisional patent on the technique.

Fungal pigments are stable and sticky, qualities that make them commercially useful.

Their role in nature is to persist, to preserve the resource for the fungus, said Robinson, who conducts research on fungi and their impacts on wood.

In a past research study in the Journal of Coatings, she compared the effects of spalting on 16 Pacific Northwest woods by inoculating them with three different fungi. In a study in the journal Coloration Technology, she reported the results of testing three fungal pigments on fabrics such as bleached cotton, spun polyester and worsted wool.

All three pigments utilized in this study show signicant potential for use as textile dyes,"  she and her co-authors wrote. 

The pigments extracted from spalting fungi can be carried in oil and water-based wood finishes and wood stabilizers. Wood workers would go nuts about having a finish that is spalted,Robinson said.

Information about licensing the use of the pigment production process is available from Denis Sather in the Oregon State Office for Commercialization and Corporate Development.

Story By: 
Source: 

Sara Robinson, 541-737-4329; Denis Sather, 541-737-8806

Multimedia Downloads
Multimedia: 

Close up of Chlorociboria species fruiting bodies (Elf’s Cup) (Photo by Sara Robinson, Oregon State University)

Chlorociboria species on malt agar, five point inoculation. (Photo by Sara Robinson, Oregon State University)

Mutated Chlorociboria species on malt agar, five point inoculation (Photo by Sara Robinson, Oregon State University)

Chlorociboria species fruiting bodies on log (Elf’s Cup) in the McDonald-Dunn Forest, Oregon (Photo by Sara Robinson, Oregon State University)

Increasing urban and rural wildfire risks featured in Starker Lecture Series

CORVALLIS, Ore. — With wildfires increasing in frequency and threatening urban as well as rural communities, Oregon State University’s annual Starker Lecture Series will tackle trends in living with fire in the Pacific Northwest.

The series, “Burning Questions: People, Forests, and Fire,” is hosted by the OSU College of Forestry. It begins Thursday, Jan. 28, at 7 p.m. with a film, “Legacy of Fire: The Story of the Tillamook Burn,” followed by a talk by Doug Decker, state forester, at the Whiteside Theater, 361 S.W. Madison Ave. in downtown Corvallis.

Told through the voices of the men and women who lived through a series of severe wildfires in the 1930s and 1940s, the film also shows the dramatic forest that grew from the ashes. Following the film, Decker will offer some historic perspective of the significance of the fire; its impact on the development and direction of the Oregon Department of Forestry and Oregon State College of Forestry; and how people in Oregon and across the West need to adjust to new realities.

Other events in the series include:

  • Feb. 18: “Fire Ecology, Management and Policy in the Western United States,” with Scott Stephens, University of California, Berkeley, 3:30 p.m. in the LaSells Stewart Center, C&E Hall, at OSU.
  • March 3: “Exposure of Buildings to Wildfire,” with Steve Quarles, Insurance Institute for Business and Home Safety, 3:30 pm at the River House in Bend, Ore.
  • April 7: “Living with Fire,” with Ed Smith, University of Nevada Cooperative Extension, 3:30 p.m. in the LaSells Stewart Center, C&E Hall, at OSU. Smith will follow his presentation with a workshop for community fire prevention educators on April 8.

A reception and discussion will be held after each lecture. In addition, at the March 3 and April 7 lectures, vendors will offer services and information about fire safety and prevention.

The Starker Lecture Series is sponsored by the Starker family in memory of T.J. and Bruce Starker, prominent leaders in the development of the Oregon forest products industry. The series is also supported by the OSU College of Forestry and the Oregon Forest Resources Institute.

More information on the series is available at http://starkerlectures.forestry.oregonstate.edu

Story By: 
Source: 

 Jessica Fitzmorris, OSU College of Forestry, 541-737-3161

Multimedia Downloads
Multimedia: 

Fire in the urban fringe

Water deficits and rising temperatures increase stress on Pacific Northwest forests

CORVALLIS, Ore. — Rising temperatures and late summer dryness are teaming up to push some types of forests beyond their ability to cope with stress, according to a new analysis of forest response to climate change across the Pacific Northwest.

Particularly vulnerable forests include those in drier areas such as the east side of the Cascade Range, the Blue Mountains and the Rocky Mountains of northeast Washington. High-elevation forests in these areas are poorly adapted to increasingly hot, dry conditions. Sensitive species include lodgepole pine, subalpine fir, spruce and mountain hemlock.

Over the last decade, increasing stress has peaked in August and September as greater water deficits and rising temperatures combined to affect forests across the region. This has created conditions potentially lethal to trees in some highly vulnerable areas, according to a report published this week in the journal Remote Sensing of Environment.

In those two months, the region’s extensive Douglas-fir forests saw an increase in the area subject to stressful conditions, from about 1 percent in August to almost 8 percent in September, said David Mildrexler, a doctoral student in the Oregon State University College of Forestry, and lead author of the report. Areas of high Douglas-fir vulnerability were largely concentrated in the southern portion of the Oregon Coast Range and western Cascade Range.

In ponderosa pine forests, the area of vulnerability rose from 5 percent in August to 33 percent in September. These forests are more adapted to drought but could be affected if prolonged stress continues.

Instead of focusing on air temperatures — the numbers commonly heard in daily weather reports — the analysis uses the actual temperature of surfaces, such as leaves and soil. Trees cool themselves by pumping water from the ground through their leaves, much as humans reduce heat stress by sweating on a hot summer day.

When moisture is lacking, that natural air conditioning shuts down.

“As soon as that stops, the canopy starts to heat up,” Mildrexler said. “When there is no water available to cool the leaves, at about 104 degrees Fahrenheit photosynthesis starts to decline in many plant species. At about 122 degrees, we start seeing effects that are lethal, even with fairly short time exposure. Higher temperature droughts really start to stress trees fast. And it’s projected to get much worse in the future, pushing more forests to the edge.

“You don’t see many places on Earth where forests get that hot,” he said. “It’s why forests are so important for cooling the Earth. With their deep roots that can access groundwater, forests help regulate high temperatures in the summer. The increasing dieback of forests globally is very concerning for this reason.”

In their analysis, Mildrexler and his colleagues tracked the month-to-month difference between water availability and surface temperature starting in 2003, using data from the Terra and Aqua satellites launched by NASA. These two satellites generate images of the entire Earth’s surface every day.

The scientists created a mathematical model — what they call the forest vulnerability index — that captures the relationship between water and temperature trends from one month to the next. In the Pacific Northwest, late-summer stress shows up clearly across the region.

In areas where seasonal dryness occurs regularly, forests have evolved mechanisms to cope with these conditions. Drought in the West isn’t that unusual, but the combination with higher surface temperatures makes this trend a concern, said Mildrexler.

By providing a way to monitor forest stress, the research will help managers in government agencies and private companies focus their efforts on vulnerable areas. Among the options that forest managers can pursue are removal of less drought-tolerant species such as grand fir from drier forests, and prescribed burning to improve fire- and drought-adapted stands.

Other actions include improving water retention in soils, retaining streamside vegetation and restoring beavers, whose dams can raise water tables and retain summer water flows.

“This monitoring method allows managers to better prioritize their activities,” Mildrexler said. “Right now, it isn’t always so clear, but we’re showing where on the landscape vulnerability is increasing and how it varies in each forest type. There is a lot of forest land out there, and the Forest Service has limited budgets for treatments across the landscape, so there’s a real need to get the maximum benefit for what they are doing.”

Co-authors of the Remote Sensing of Environment report include Zhiqiang Yang in the OSU College of Forestry and Warren B. Cohen and David M. Bell in the Pacific Northwest Research Station of the U.S. Forest Service.

 

Story By: 
Source: 

David Mildrexler, 541-786-9354

Multimedia Downloads
Multimedia: 

September_FVI

Art and science in the life of a dead tree

CORVALLIS, Ore. – We may value forests most for timber, wildlife and scenic beauty, but the real treasure may lie largely hidden in the soil.

At the Nov. 9 Corvallis Science Pub, an Oregon State University forest researcher and four visual artists will discuss their efforts to understand the “life” of dead trees through science and the arts. They are all participating in a project, The Afterlife of Trees, organized by the Corvallis Arts Center in partnership with the Spring Creek Project for Ideas, Nature and the Written Word at OSU.

The Science Pub presentation is free and open to the public. It begins at 6 p.m. at the Old World Deli, 341 S.W. 2nd St. in Corvallis.

 

“In many cases, dead trees are more alive than living ones,” said Mark Harmon, professor and holder of the Richardson Chair in the Oregon State College of Forestry who will speak at the event. “Dead trees are used by almost every group of major organisms in forests – plants, animals, microbes, protozoans and lichens.

 

“We need to make informed decisions about dead trees,” Harmon added. “In the past, we have not, and it has been costly economically and ecologically.”

 

Artists Leah Wilson, David Paul Bayles, Bob Keefer and Andries Fourie will describe their visual interpretations of tree decomposition. Their work will be part of a show at the Arts Center, which is scheduled to run from Jan. 15 to Feb. 25.

 

Sponsors of Science Pub include Terra magazine at OSU, the Downtown Corvallis Association and the Oregon Museum of Science and Industry.

Story By: 
Source: 

Mark Harmon, 541-737-8455

Prehistoric predators kept large animals in check, shaped ecosystems

CORVALLIS, Ore. – Our prehistoric ancestors may have had large carnivores – giant lions, sabertooth cats, bears and hyenas up to twice the size of their modern relatives – to thank for an abundance and diversity of plants and wildlife.

Likewise, modern ecosystems, from tropical forests to the American West, may depend on the ability of large carnivores to control grazing animals.

Those are among the conclusions of scientists who used ice-age fossils and historical data from modern surveys of animal populations to investigate the nature of predator-prey relationships. Researchers led by Blaire Van Valkenburgh of UCLA published their findings today in the Proceedings of the National Academy of Sciences. William Ripple, distinguished professor in the Oregon State University College of Forestry, is among the co-authors.

“Large predators can have a major role in limiting their prey and in determining the structure and function of ecosystems,” said Ripple. “But scientists have thought that the largest herbivores, such as elephants, were immune from predation. We now know that’s not the case, and based on these data from the Pleistocene (the epoch which lasted from about 2.5 million to 11,700 years ago), we now think that large carnivores did limit the large herbivores at that time.”

Using Pleistocene fossils, Ripple and his colleagues concluded that juvenile members of large herbivores – such as woolly mammoths and giant bison, sloths and camels — were well within the size range of prey available to the carnivores that roamed the landscape.

“Imagine a large population of herbivores: If they had not been under control, they could have eaten themselves out of house and home,” Ripple added. “It would not have been sustainable.”

The researchers synthesized data on predator and prey body masses, historical data on group size in large carnivores and paleontological data on ancient carnivores. Their analysis of data on more than 50,000 individual kills in the wild enabled them to predict the probable prey sizes of the extinct predators using a mathematical model derived from modern data. They estimated the body mass of young mammoths and mastodons using data on the relationship between shoulder height and age and, for living elephants, shoulder height and mass.

Today in Africa, lions do prey on young elephants, but since lions have declined dramatically in pride size and geographic range, they are not thought to provide an ecologically effective control on elephant populations. Safari hunting parties and explorers recorded prides containing an average of 24 and as many as 40 animals in the late 1800s, but today, lion prides have dwindled to an average of nine animals, based a recent analysis of 27 African reserves.

In African national parks, elephants can be destructive to the landscape, said Ripple, knocking down trees and tearing up vegetation.

“There’s evidence that larger prides had more success at killing elephants,” said Ripple. “Sometimes a group of lions will run down a fairly young elephant, some jumping on its back and others nipping at its sides. They’ll just wear it out and bring it down. We tallied 173 elephant kills by lions and hyenas, and 75 percent of these elephants were younger than nine years old.”

The findings have implications for modern wildlife management policies, the authors said. “Recreating these (Pleistocene) communities is not possible, but their record of success compels us to maintain the diversity we have and rebuild it where feasible (e.g., rewilding),” they write.

“If a manager’s goal is to have sustainable predator prey relationships in highly functional ecosystems, it can be important to have predators at ecologically effective population sizes,” Ripple said.

In addition to Van Valkenburgh and Ripple, co-authors include Matthew Hayward, a senior lecturer in conservation with the UK’s Bangor University College of Natural Sciences; Carlo Meloro, a vertebrate palaeontologist with the UK’s Liverpool John Moores University; and V. Louise Roth, professor of biology at Duke University.

Story By: 
Source: 

Bill Ripple, 541-737-3056

Multimedia Downloads
Multimedia: 

Pleistocene_hippo

Pleistocene_mammothattack

Illustrations by Mauricio Anton