Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

An ecosystem being transformed – Yellowstone 15 years after the return of wolves

22.12.2011
On the 15th anniversary of the return of wolves to Yellowstone National Park, a quiet but profound rebirth of life and ecosystem health is emerging, scientists conclude in a new report.

For the first time in 70 years, the over-browsing of young aspen and willow trees has diminished as elk populations in northern Yellowstone declined and their fear of wolf predation increased. Trees and shrubs have begun recovering along some streams, providing improved habitat for beaver and fish. Birds and bears also have more food.

“Yellowstone increasingly looks like a different place,” said William Ripple, a professor in the Department of Forest Ecosystems and Society at Oregon State University, and lead author of the study.

“These are still the early stages of recovery, and some of this may still take decades,” Ripple said. “But trees and shrubs are starting to come back and beaver numbers are increasing. The signs are very encouraging.”

The findings of this report, based on a recent analysis done by OSU researchers and a review of many other studies as well, were just published in Biological Conservation, a professional journal. They outline an ecosystem renaissance that has taken place since wolves were restored to Yellowstone after being extirpated in the 1920s.

Along four streams studied in the Lamar River basin, 100 percent of the tallest young aspen sprouts were being browsed in 1998, compared to less than 20 percent last year. Heavy browsing by elk on this favorite food had caused new aspen tree recruitment to essentially grind to a halt in the mid-to-late 1900s, when wolves were absent, but new trees are now growing again in places.

Among the observations in this report:

Since their reintroduction in 1995-96, the wolf population generally increased until 2003, forcing changes in both elk numbers and behavior due to what researchers call the “ecology of fear.”

The northern range elk populations decreased from more than 15,000 individuals in the early 1990s to about 6,000 last year, and remaining elk now have different patterns of movement, vigilance, and other traits.

By 2006, some aspen trees had grown tall enough they were no longer susceptible to browsing by elk, and cottonwood and willow were also beginning to return in places.

Improved willow growth is providing habitat that allows for a greater diversity and abundance of songbirds such as the common yellowthroat, warbling vireo and song sparrow.

The number of beaver colonies in the same area increased from one in 1996 to 12 in 2009, with positive impacts on fish habitat.

Increases in beaver populations have strong implications for riparian hydrology and biodiversity – Wyoming streams with beaver ponds have been found to have 75 times more abundant waterfowl than those without.

The coyote population decreased with the increase in wolf numbers, potentially allowing more small mammals that provide food for other avian and mammalian predators, such as red foxes, ravens and bald eagles.

Evidence of improved ecosystem health following the return of wolves is “becoming increasingly persuasive,” the scientists said in their report, though they also note that an increasing population of bison is continuing to impact young woody plants in the Lamar Valley.

“The wolves have made a major difference in Yellowstone,” said Robert Beschta, a professor emeritus of forestry at OSU and co-author on the study.

“Whether similar recovery of plant communities can be expected in other areas, especially on public lands outside national parks, is less clear,” Beschta said. “It may be necessary for wolves not only to be present but to have an ecologically effective density, and mechanisms to deal with human and wolf conflicts also need to be improved.”

But at least in America’s first national park, the return of this large predator is having an impact.

“Predation and predation risk associated with large predators appear to represent powerful ecological forces,” the researchers concluded in their report, “capable of affecting the interactions of numerous animals and plants, as well as the structure and function of ecosystems.”

Note: YouTube video in Yellowstone:
http://www.youtube.com/watch?v=AGnIYrsF4bk&feature=youtu.be
About the OSU College of Forestry: For a century, the College of Forestry has been a world class center of teaching, learning and research. It offers graduate and undergraduate degree programs in sustaining ecosystems, managing forests and manufacturing wood products; conducts basic and applied research on the nature and use of forests; and operates 14,000 acres of college forests.

The study this story is based on is available in ScholarsArchive@OSU: http://hdl.handle.net/1957/25603

William Ripple | EurekAlert!
Further information:
http://www.oregonstate.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>