Wildlife and People

The “Natural Regulation” Debacle at Yellowstone NP

W.I.S.E. is pleased and honored to present a review of Dr. Fred Wagner’s excellent book, Yellowstone’s Destabilized Effects, Science, and Policy Conflict, in our Wildlife Sciences Colloquium [here].

Fred Wagner is former associate dean of the Natural Resources Dept. at Utah State University. The review was written by Cliff White of Parks Canada, Banff, Alberta. Both men are world-recognized environmental scientists, managers, and greatly accomplished experts.

From Cliff White’s (also excellent) review:

For those unfamiliar with the Yellowstone situation, removal of native peoples from the park in the 1800s and reduction in large carnivores in the early 1900s provided favorable conditions for the population of elk (Cervus elaphus), a generalist herbivore, to increase dramatically. After government biologists observed the effects of high densities of elk on soil and vegetation in the 1920s, park rangers routinely culled the herd for over 4 decades. In the 1960s, recreational game hunters lobbied to take over the cull. Given the potential political incompatibility of sport hunting with conservation in one of the world’s premier national parks, the federal government made the decision to cease elk culling. Park managers and senior scientists then carefully selected a generation of researchers to evaluate the revised policy. The result was a new paradigm of “natural regulation” that was underlain by 4 key hypotheses:

1) long-term human hunting, gathering and burning had not substantially influenced the ecosystems of North America’s Rocky Mountains;

2) ungulate populations in Yellowstone were, over the long term, generally high;

3) carnivore predation was a “non-essential adjunct” having minimal influence on elk numbers; and

4) high elk numbers would not cause major changes in plant communities, ungulate guilds, and other long-term ecosystem states and processes.

Although the natural regulation paradigm seems rather farfetched today, remember that it was born in the 1960s, a time of antiestablishment flower children, when wilderness was untrammeled by Native Americans, when biologist and author Farley Mowat’s wolves subsisted on mice (Mowat 1963), and the only “good fires” were caused by lightning. Moreover, an excellent argument can be made that ecological science needs large “control ecosystems” with minimal
human influences.

In the 40 or so years since the implementation of the national regulation policy, both the National Park Service and outside institutions conducted many ecological studies. These culminated in 1997 with a congressionally mandated review by the National Research Council. It is this wealth of research and documentation that Fred Wagner uses to evaluate changes over time in the Yellowstone ecosystem. He provides meticulous summaries of research in chapters on each of several different vegetation communities, the ungulate guild, riparian systems, soil erosion dynamics, bioenergetics, biogeochemistry and syntheses for the “weight of evidence” on the primary drivers of ecological change. This background allows readers to develop their own understanding on the results of this textbook case of applied ecological science.

Wagner clearly shows that most studies did not support the hypotheses of natural regulation. In cases where studies did seem to support a hypothesis, methods and results were suspect. The elk population clearly grew beyond predictions, some plants and animals began to disappear, and the importance of Yellowstone’s lost predators and Native Americans should have become undeniable. However, faced with these incongruities, park managers still supported the natural regulation policy. Some researchers closely affiliated with management then began to invoke climate change as a potential factor for observed ecosystem degradation, but the evidence for this was similarly tenuous. On the basis of the almost overwhelming evidence, Wagner concludes that much of the park-sponsored science on the natural regulation paradigm “missed the mark” and that “Yellowstone has been badly served by science.”