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The Early Stages of a New Ecosystem in Yellowstone

By Matthew Frank, 3-18-08

In Yellowstone National Park's Lamar Valley there's a "cascade of ecological changes under way," writes Jim Robbins of the New York Times, particularly the spread of the invasive plant Canadian thistle supported by a warming climate, and the plant in turn supports larger numbers of grizzly bears and gophers.

“It’s the early stages of a new ecosystem,” says Robert L. Crabtree, chief scientist with the Yellowstone Ecological Research Center in Bozeman, “one that hasn’t been seen here before.”

Robbins writes that areas along the Lamar River that were once marshy have dried out and increased the thistle's range. Pocket gophers love the abundant, starchy thistle roots and burrow to harvest the tubers. As they do they churn surface soil and create a perfect habitat for more thistle -- a rapid positive-feedback loop. And bears, naturally, eat both gophers and their stashes of thistle.

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