Wednesday, September 14, 2011

Wolves in Yellowstone again under peril


A letter to the editor in the August 26, 2011 issue of Science from Bradley J. Bergstrom informs us that:
In May 2011, the Northern rocky mountain gray wolf was removed from the federal List of Endangered and Threatened Wildlife in the first legislative delisting of an endangered species since the 1973 U.S. Endangered Species Act (1) was passed into law.
 Delisting of wolves is described as the result of pressure by western politicians, ranchers and hunters.
(E)lk in Yellowstone National Park increased substantially before wolf reintroduction in 1995 and have decreased substantially since, but they have not been extirpated. In fact, state biologists say that Wyoming's elk herd should be reduced in order to maintain the health of the herd and the habitat. Meanwhile, the park's wolf population has not increased exponentially but rather declined 44% since 2003 and stabilized at fewer than 100. Critics' concerns about livestock are also unfounded: Confirmed cattle deaths due to wolves in Wyoming, as well as the number of wolf packs responsible for cattle deaths, have declined steadily from 2006 through mid-2011, even as Wyoming's wolf population has increased. Overall, protecting the wolves has positively affected the ecosystem), which was a key intent of the 1973 Endangered Species Act.
Yellowstone National Park is a World Heritage site, and its value as part of the natural heritage of mankind would seem to be reduced by the decision to allow hunting of wolves in Wyoming. I value having wolves in the wild per se. I am happy just thinking of the Yellowstone ecosystem, recalling the park as one of the most inspiring places I have ever visited. I also think that the United States should live up to its treaty obligations, and we are obligated under the World Heritage treaty to protect the sites which we have nominated that have been accepted as World Heritage sites.

A second letter to the editor, this by Werner T. Flueck, states:
J. A. Estes and coauthors highlight the far-reaching changes to ecosystems that result from the loss of apex consumers. In particular, they point out large reductions in vegetation brought about by unregulated herbivore populations in such systems. This leads me to point out yet another important consequence of losing large terrestrial predators and their top-down effects (1). When photosynthetic capacity is reduced, not only does atmospheric CO2 increase, but heat dissipation through evapotranspiration is reduced. Some models estimate that evapotranspiration's contribution to global warming is greater than that of CO2 by one to two orders of magnitude (2, 3). The trophic downgrading discussed by Estes et al.thus not only alters ecosystems as they describe, but reduces the rate of entropy production, which increases surface temperature variation. These indirect effects may have substantial consequences for biodiversity and ecosystem functions.
In simpler terms, killing the wolves leads to increases in the elk population; the elk graze more plants and the loss of plants increases CO2 and decreases the heat used in vaporizing water. This contributes to global warming, which in turn adds to global warming and further deterioration of the environment and loss of biodiversity.

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