Yellowstone - With Growing Season 20 Days Longer Than In Mid-1990s, Ecosystems Shifting Rapidly

[hatrack]

The grassy sweep of the Lamar Valley in the northeastern corner of this park is famous for its wildlife, especially its vast herds of elk and bison and the wolves that hunt them. But while walking across the Lamar last fall, Robert L. Crabtree, chief scientist with the Yellowstone Ecological Research Center in Bozeman, Mont., pointed out a cascade of ecological changes under way. The number of grizzly bears and gophers in the valley has increased, Dr. Crabtree said, an increase supported by the spread of an invasive plant from the Mediterranean that a warming climate benefits.

“It’s the early stages of a new ecosystem,” he said, “one that hasn’t been seen here before.” The plant, Canada thistle, provides food for grizzlies in more than one way but may also be squeezing out native plants that cannot compete. Canada thistle first appeared in North America several hundred years ago and has been present in Yellowstone at least since the 19th century, Dr. Crabtree said. Because of its extensive root system, the plant defies spraying, and park officials have largely abandoned efforts to control it. Warming temperatures have helped its fortunes.

Areas along the Lamar River that were once marshy have dried out because of a drought that began around 2000. As the ground becomes drier, the thistle invades. Dr. Crabtree theorizes that its range in the valley has doubled since 1989, when he started research on the ecosystem here. Enter the pocket gopher, a half-pound dynamo that tunnels into the ground near the surface. The gophers love the abundant, starchy roots of the plant and burrow beneath it to harvest the tubers. What they do not eat they stockpile under plants or rocks.

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Tom Oliff, chief scientist for Yellowstone, confirms that the growing season for the park has expanded 20 days a year since the mid-1990s, which may explain the spread of Canada thistle. Mr. Oliff said the park reduced control efforts because evidence showed that the plant ebbed and flowed and that the range would probably shrink on its own. About the idea a new ecosystem, Mr. Oliff said: “It’s an interesting hypothesis. Is it true? That’s a good question.” Charles C. Schwartz, leader of the Interagency Grizzly Bear Study Team, said his agency had no way to tell whether there were more bears in the valley. “I think what he’s seeing is real,” Dr. Schwartz said of Dr. Crabtree. “It wouldn’t be surprising to see individuals shift and take advantage of an abundant food supply.”

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http://www.ecoearth.info/shared/reader/welcome.aspx?linkid=95019

[havocmom]

1. 20 days earlier , AT LEAST, in my corner of eastern MT

Lots more birds much earlier for the past 3 years. Bugs out and about at least a month earlier than back in 2000.

[DCKit]

2. A plant from the Mediterannean called "Canada thistle"?

Have Terrance and Philip been taken hostage by the Amurikan military in retaliation?