03 Jan 2012:
Return of Wolves Has Helped
Ecosystem Recovery in Yellowstone Park
The return of wolves to Yellowstone National Park has caused significant ecosystem recovery
by curbing populations of elk that for decades had over-browsed young aspen and willow trees, according to a new
U.S. Fish & Wildlife
study. In an analysis conducted by Oregon State University
, researchers found that tree stands and shrubs have recovered along some streams, improving habitat for beaver and fish and providing more food sources for birds and bears. In the 15 years since wolves were reintroduced to Yellowstone after being killed off last century, northern elk populations have decreased from more than 15,000 in the early 1990s to about 6,000 last year, according to the study published in the journal Biological Conservation
. By 2006, some aspen trees had grown tall enough that they were no longer susceptible to browsing by elk. As a result, along four streams in the Lamar River basin, less than 20 percent of the tallest young aspen sprouts were being browsed last year compared with 100 percent in 1998. “Yellowstone increasingly looks like a different place,” said William Ripple, an Oregon State professor and lead author of the study.
Yale Environment 360 is
a publication of the
Yale School of Forestry
& Environmental Studies
Yale Environment 360
articles are now available in Spanish and Portuguese on Universia
, the online educational network. Visit the site.
Business & Innovation
Policy & Politics
Pollution & Health
Science & Technology
Antarctica and the Arctic
Central & South America
A three-part series Tainted Harvest
looks at the soil pollution crisis in China, the threat it poses to the food supply, and the complexity of any cleanup. Read the series.
is now available for mobile devices at e360.yale.edu/mobile
The Warriors of Qiugang
, a Yale Environment 360
video, chronicles a Chinese village’s fight against a polluting chemical plant. It was nominated for a 2011 Academy Award for Best Documentary Short.
Watch the video.
Top Image: aerial view of Iceland
. © Google & TerraMetrics.
, winner of the Yale Environment 360 Video Contest, documents the work of African researchers monitoring wildlife in Uganda's remote Bwindi Impenetrable National Park. Watch the video.