Wolves bring aspens back to Yellowstone

CORVALLIS, Ore., July 27 (UPI) -- U.S. researchers said the return of wolves to Yellowstone National Park has allowed aspen trees to grow there for the first time in decades.

A study published in the journal Biological Conservation says "the ecology of fear" is keeping elk from eating aspen shoots.

The young trees are the first in Yellowstone's northern range in more than 50 years, Oregon State University said Friday in a release.

Researchers said elk populations have shown a steady decline since wolves were reintroduced to Yellowstone Park in 1995. The presence of a natural predator appears to have altered the behavior of the remaining elk, which tend to avoid browsing in areas in which they feel most vulnerable.

"This is really exciting, and it's great news for Yellowstone," said William Ripple, a professor in the Oregon State University College of Forestry. "We've seen some recovery of willows and cottonwood but this is the first time we can document significant aspen growth, a tree species in decline all over the West. We've waited a long time to see this but now we're optimistic that things may be on the right track."