In today's New York Times, there's an article about the changes in Yellowstone National Park's ecosystem which have been brought about by a warming climate. The story is fascinating to anyone interested in ecosystem shifts (which should be everybody, not just science types and econerds like yours truly).Apparently a plant called the Canada thistle, which is, counterintuitively, actually an invasive species from the Mediterranean, has begun to colonize the park, aided by warmer temperatures, which dry out marshy land and provide habitat for the invader. Then, following on the plant's footsteps comes an increased population of pocket gophers, who like to eat the thistly roots. Finally, the omnivorous grizzly bear comes along and eats both the roots and the pocket gophers, to boot.
Result: more grizzly bears, but also an array of native plants have been out-competed, which is not so good. Will there soon be so many bears that we return to the bad old days, when park visitors used to gather to watch the bears feed at garbage dumps and do tricks for treats? Hopefully not.
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