Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wolves’ top-down effect

01.08.2005


Presence of canine predator cascades through populations of elk, trees, beavers, and songbirds



Willow trees, riparian willow warblers and beaver dams once were bountiful in an area near the town of Banff, Alberta, Canada. But once wolves left this area, elk grew more plentiful, browsing heavily on young willows. Today, there is little trace of beavers, and sparrows have replaced the warblers in what is now a grassland meadow. These profound changes were driven by the absence of the wolf, a top predator. That’s the compelling finding of the paper, "Human Activity mediates a Trophic Cascade caused by Wolves" that appears in the August issue of Ecology by Mark Hebblewhite (University of Alberta) and colleagues.

Top-down effects of predators are called trophic cascades. While studies have demonstrated this phenomenon in aquatic environments, the Hebblewhite et al study is one of the first terrestrial, large-scale studies that so clearly exemplifies the strong role played by a top predator.


In the mid-1980s, wolves naturally recolonized the Bow Valley of Banff National Park in Alberta, Canada. The nearby town of Banff has been steadily growing and prevented wolves from fully recovering in areas surrounding the town while wolves fully repopulated adjacent areas. Hebblewhite and his fellow researchers were able to examine the effects of wolf exclusion on elk--wolves’ preferred prey--on plants such as willow, which are favored by the ungulates, and on other species that depend on the willow habitat.

Hebblewhite and his colleagues found that in the low-wolf area of Bow Valley elk populations were 10 times as high as in the high-wolf area.

"We also found that as elk populations climbed, active beaver lodges declined, probably because beavers could no longer find sufficient trees with which to build their dams," says Hebblewhite.

In addition, songbirds, such as the American Redstart, which is strongly dependent on willow, also vanished from the wolf-excluded area.

Although the presence of people in the Bow Valley area also kept away other large predators, such as grizzly bears, Hebblewhite and colleagues believe their large-scale natural experiment demonstrates a wolf-driven cascade effect. Only wolves were completely eliminated from the study area and subsequently recovered. Bears and other large carnivores were never completely extirpated. In addition, the researchers traced elk deaths in the high-wolf area to wolves, which also supports the major role wolves have in this trophic cascade.

"Our study findings strongly bolster the use of conservation and restoration strategies which are based on the key role of large predators," says Hebblewhite.

Annie Drinkard | EurekAlert!
Further information:
http://www.esa.org

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>