Sunday, December 03, 2006

Trophic Cascade

I have written before about trophic cascade, specifically the research regard wolves of Yellowstone. Trophic cascade refers to the situation where the lack of a keystone predator has cascading consequences through the ecosystem. These cascades can ultimately impact species we would normally think to be outside the realm of influence, but the connections are eventually made. A new study has been published regarding the lack of Cougars in Zion National Park. Here is the full press release: Cougar predation key to ecosystem health.

The cascade extends far beyond the direct connections with deer and cottonwoods (what deer eat),  "It's the decline or disappearance of shrubs, wetland plants, amphibians, lizards, wildflowers, and even butterflies."  All can be linked back to the lack of the keystone predator - Cougars. The challenge here is that it cannot be resolved by simply reintroducing cougars.  Cougars have been chased away due to human activity.  This is an important lesson on the importance of maintaining intact eco-systems with a full complement of wildlife. As human intrusions further segment the wild lands, I expect we will see much more of this.

These local studies are only indicative of what has happened and continues to happen all over the planet. The World Wildlife Fund has recently released its latest Living Planet Report.  This report covers two indexes, the first is the Living Planet Index. This index reflects the health of the planet’s ecosystems.  This index has fallen by 29% in the past 30 years, indicating a 29% reduction in populations of terrestrial, marine, and freshwater vertebrate species. The second index is the Ecological Footprint Index.  This index indicates how much regenerative capacity is required to turn our waste back into resources. As of 2003, we are producing 25% more waste than the planet can possibly process.

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