How humans, vanishing cougars changed Yosemite

SF Chronicle ^ | May 2, 2008 | David Perlman

[jazusamo]

Agile, fast and fierce, cougars once hunted their prey throughout Yosemite National Park, but as human invasions and hunting began about 80 years ago, the predators steadily disappeared, and the entire ecology of the fabled valley was disrupted, researchers say they have discovered.

With fewer cougars to prey on them, Yosemite's mule deer multiplied and browsed on the tasty shoots of young black oak trees. The oaks disappeared, pines and firs replaced them, and even the wild evening primrose, known for its nutritious roots and its perfumed oil, grew rare among the altered plant growth in the valley's moist meadow soils.

A new study by Oregon State University scientists says the vanishing of the cougar had long-term effects on Yosemite that closely resemble the ecological impact of the disappearance of wolves in Yellowstone.

"The loss of top predators, whether it's wolves in Yellowstone or cougars in Yosemite, is having a severe and degrading impact on plant communities," says William Ripple of Oregon State's department of forest resources, the lead author of a report published online in the journal Biological Conservation.

The study by Ripple and his Oregon State colleague Robert Beschta is the first of its kind ever conducted in Yosemite. It is an effort to find evidence confirming a still-controversial theory about how the loss of a breed of predatory animal can affect an entire ecological system.

"There are interactions everywhere in nature," Ripple said Thursday. "In Yosemite, the predators like cougars are tightly linked to the herbivores, like deer. The herbivores browse on the young oak shoots and keep their numbers down so that other trees, like pines and firs, can invade. They, in turn, are linked to other plants - all along the line."

But scientists at Yosemite, who - like most Californians - refer to cougars...

[cherry]

mule deer nationwide are declining in numbers in alarming rates.....its good to hear they are doing well in Yosemite....they are an awesome animal....