Nav: Home

Yellowstone streams recovering thanks to wolf reintroduction

November 08, 2018

CORVALLIS, Ore. - In the first study of its kind, research by Oregon State University scientists shows that the return of large terrestrial carnivores can lead to improved stream structure and function.

The findings, published today in Ecohydrology, are important because they highlight the role big predators play in the health of aquatic and riparian ecosystems.

Robert Beschta and William Ripple of the OSU College of Forestry looked at stream-bank willows over a 13-year period along two forks of a creek in Yellowstone National Park, first in 2004 and again in 2017.

The study, funded in part by the National Science Foundation, began nine years after wolf reintroduction in Yellowstone and two decades after cougars had returned to the park.

Gray wolves and cougars had been hunted to extirpation in Yellowstone by the early 1900s, allowing for an abundance of elk that ate so much willow as to erode stream banks and damage waterways the shrubs had historically protected.

Beschta and Ripple examined willows along the west and east forks of Blacktail Deer Creek in the northern portion of the park.

"In the 1990s, elk were still keeping the willows short, usually less than 2 feet tall, and that led to stream widening - oversized cross sections of channel and a drastically reduced frequency of overbank flows," Beschta said. "But by 2017, willow heights greater than 6 feet were prevalent and canopy cover over the stream, which had essentially been absent in 1995, had increased to 43 percent and 93 percent along the west fork and east fork, respectively."

Increases in willow height, greater canopy cover, and stream-bank stabilizing courtesy of well-vegetated banks all point toward a recovering riparian/aquatic ecosystem, he said.

Beschta notes, however, that the healing is in its early stages and the recovery of stream channels may be slow in some areas.

"The over-widened streams that resulted when elk were able to browse on willows as they did when wolves and cougar were absent, that's a big change that's taken place and may become a legacy effect," he said. "In some areas these geomorphic changes to channels may not be quickly reversible and could be there for a long time."

Nevertheless, the ecosystem improvements that have already happened show the many positives of having a full guild of large carnivores present.

"The cougars had been back for a while, and the bears have always been there, but they were unable to control the elk populations or at least their browsing," Beschta said. "It wasn't until wolves were returned that we got this reshuffle in what elk were doing and we began to see improvement in plant communities and streams. This is the first study showing improving stream morphology in Yellowstone's northern elk range, or anywhere else in the U.S. as it relates to the return of a large predator."

With improvements in stream channels and to riparian vegetation, beavers are returning to parts of the study area, their dam building adding its own unique set of ecosystem enhancements.

"They reinforce and reconnect streams with floodplains in a way that only beavers do," Beschta said. "They irrigate riparian areas in ways that won't occur otherwise, and that's not only good news for riparian vegetation but also a host of wildlife species, such as songbirds, waterfowl, amphibians, fish and others."
-end-


Oregon State University

Related Yellowstone Articles:

Measuring the impact of a changing climate on threatened Yellowstone grizzly bears
A new analysis of Yellowstone grizzly bear diets reveals that grizzlies in the region continue to feed upon the products of an endangered tree species currently declining at the hands of climate change.
Seismic listening system offers new look at Old Faithful geyser
After deploying hundreds of seismometers around the Old Faithful Geyser in 2015 and 2016, scientists have a clearer picture of how the geyser erupts and what may lie beneath the popular tourist attraction in Yellowstone National Park.
ORNL scientists isolate, culture elusive Yellowstone microbe
A microbial partnership thriving in an acidic hot spring in Yellowstone National Park has surrendered some of its lifestyle secrets to researchers.
Hunting wolves near Denali, Yellowstone cuts wolf sightings in half
Visitors to Denali National Park and Preserve and Yellowstone National Park were twice as likely to see a wolf when hunting wasn't permitted adjacent to the parks, a new study finds.
Ancient super-eruptions in Yellowstone Hotspot track 'significantly larger' than expected
International team led by researchers from the University of Leicester report 12 giant eruptions around the Snake River Plain in the United States between 8 and 12 million years ago.
Study challenges widely accepted theory of Yellowstone formation
Understanding the complex geological processes that form supervolcanoes could ultimately help geologists determine what triggers their eruptions.
History shows more big wildfires likely as climate warms
If the warming trend continues as projected in the Northern Rockies of the American West, the large wildfires of recent years could be just the start of more extensive and devastating blazes.
First use of NanoSIMS ion probe measurements to understand volcanic cycles at Yellowstone
Super-eruptions are not the only type of eruption to be considered when evaluating hazards at volcanoes with protracted eruption histories, such as the Yellowstone (Wyoming), Long Valley (California), and Valles (New Mexico) calderas.
Creating a stopwatch for volcanic eruptions
According to new research at Arizona State University, there may be a way to predict when Yellowstone volcano will erupt again.
Recovering predators create new wildlife management challenges
A new study by scientists from NOAA Fisheries' Northwest Fisheries Science Center and the University of Washington examines recovering predator populations along the West Coast of the United States and in the Greater Yellowstone ecosystem, and the conflicts surrounding them.

Related Yellowstone Reading:

Yellowstone: Survival: A Post-Apocalyptic Survival Thriller (The Yellowstone Series Book 4)

Yellowstone: Fallout: A Post-Apocalyptic Survival Thriller (The Yellowstone Series Book 3)

Yellowstone: A Journey Through America's Wild Heart
by David Quammen (Author)

Yellowstone: Inferno: A Post-Apocalyptic Survival Thriller (The Yellowstone Series Book 2)

Moon Yellowstone & Grand Teton: Including Jackson Hole (Travel Guide)
by Becky Lomax (Author)

Yellowstone Treasures: The Traveler's Companion to the National Park
by Janet Chapple (Author)

Yellowstone: Hellfire: A Survival Thriller (The Yellowstone Series) (Volume 1)
by Bobby Akart (Author)

Death in Yellowstone: Accidents and Foolhardiness in the First National Park, 2nd Edition
by Lee H. Whittlesey (Author)

What I Saw in Yellowstone: A Kid's Guide to the National Park
by Durrae Johanek (Author), Christopher Cauble (Photographer)

Spectacular Yellowstone and Grand Teton National Parks
by Charles Preston (Author), Jim Robbins (Author), Dana Levy (Editor), Paul Vucetich (Editor), Letitia O'Connor (Editor)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Where Joy Hides
When we focus so much on achievement and success, it's easy to lose sight of joy. This hour, TED speakers search for joy in unexpected places, and explain why it's crucial to a fulfilling life. Speakers include inventor Simone Giertz, designer Ingrid Fetell Lee, journalist David Baron, and musician Meklit Hadero.
Now Playing: Science for the People

#500 500th Episode
This week we turn 500! To celebrate, we're taking the opportunity to go off format, talk about the journey through 500 episodes, and answer questions from our lovely listeners. Join hosts Bethany Brookshire and Rachelle Saunders as we talk through the show's history, how we've grown and changed, and what we love about the Science for the People. Here's to 500 more episodes!