July 02, 2006

Yellowstone NP and the "Trophic Cascade"

An article in Yellowstone Discovery suggests that reintroducing wolves to Yellowstone National Park started a "trophic cascade*," with positive effects on beavers, trout, and plant life.

I wanted to say something about the politics of the Rocky Mountain National Park elk cull--and I will--but meanwhile this fell into my lap, thanks to Mike Beagle of Backcountry Hunters and Anglers.

Here's the "nut graf," as we newsies like to say:

The apparent decline of biodiversity and biomass in Yellowstone’s northern range has confounded biologists for years. Yes, over-browsing remains a viable explanation. But was that the whole story? Couldn’t drought conditions and changes in climate, as well as gradual changes in the region’s hydrology explain why the cottonwoods, willows, and aspens weren’t regenerating, and why riparian zones were disappearing? Was it due, at least in part, to decades of fire suppression? What effects, if any, did the fires of 1988 have on the northern range? According to some prominent biologists, it wasn’t until 31 gray wolves were reintroduced in Yellowstone National Park in 1995-1996 that ecological diversity began to increase in the northern range, and, consequently, some of the answers to these questions were possible.

To read it, go here and scroll halfway down to the headline, "Yellowstone’s Trophic Cascade: Evidence of an Ecosystem on the Mend?

* Trophic cascade: "Three or more trophic levels linked by either predation or threat of predation that results in alternating increases or decreases in abundance or biomass."

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