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Oregon State professors believe cougars key to thriving ecosystem

HOWLColorado : Science OSU professor Bill Ripple and colleagues have released a study which suggests large predators (cougars, wolves and bears – oh my!) are key to the thriving success of ecosystems, and the lack of said predators limits diversity.

Study: Cougars key to diverse ecosystem - Oregon State University

Study: Cougars key to diverse ecosystem - Oregon State University

The following appeared on Science Daily (citation at foot of article), and the research can likely be applied to any ecosystem balanced by an apex predator – such as wolves.

The general disappearance of cougars from a portion of Zion National Park in the past 70 years has allowed deer populations to dramatically increase, leading to severe ecological damage, loss of cottonwood trees, eroding streambanks, and declining biodiversity.

This “trophic cascade” of environmental degradation, all linked to the decline of a major predator, has been shown in a new study to affect a broad range of terrestrial and aquatic species, according to scientists from Oregon State University.

The research was just published in the journal Biological Conservation — and, like recent studies outlining similar ecological ripple effects following the disappearance of wolves in the American West — may cause land managers to reconsider the importance of predatory species in how ecosystems function.

The findings are consistent, researchers say, with predictions made more than half a century ago by the famed naturalist Aldo Leopold, often considered the father of wildlife ecology.

“When park development caused cougar to begin leaving Zion Canyon in the 1930s, it allowed much higher levels of deer browsing,” said Robert Beschta, an OSU professor emeritus of forest hydrology. “That set in motion a long cascade of changes that resulted in the loss of most cottonwoods along the streambanks and heavy bank erosion.”

“But the end result isn’t just loss of trees,” he said. “It’s the decline or disappearance of shrubs, wetland plants, amphibians, lizards, wildflowers, and even butterflies.” 

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