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Know the West

One scientist's forbidden fruit

 

Note: This article is a sidebar to this issue's feature story.

"This is the tree that started this mess," says Richard Keigley, kneeling for a closer look at the trunk of a scraggly juniper. The tree stands on a hillside above Mammoth, just inside the northern gate of Yellowstone National Park. Its base is as thick as my thigh, but a foot from the ground, it splits into two thin stems that rise eight feet straight up, ending in a plume of scaly needles. Bare of branches up as high as my head, the juniper looks like a lanky head of broccoli.

Keigley stumbled on the tree in 1992, while studying the effects of elk browsing on streamside willows. Its peculiar shape set him to wondering.

Using a tree corer, Keigley produced two thin cross-sections of the tree's trunk, one from its thick base, the other from one of its long stems. The base of the tree contained 58 annual growth rings, while the stems were just 30 years old. During the first 28 years of its life, from the 1930s to around 1960, he explains, the tree never grew taller than a foot. During the 30 years that followed, the tree sprouted seven feet.

What shaped the juniper?

Elk, says Keigley. When Yellowstone's managers allowed the northern elk herd to grow, the animals ate the tree back. When managers kept elk numbers down, the tree grew. "I can show you the history of the Northern Range in this tree," says Keigley.

And he does.

By 1930, when Keigley's juniper got started, more than 50 years of Army and Park Service management had made big changes on the Northern Range. Managers had cleared the park of hunters, coyotes, wolves and mountain lions. The result was booming herds of elk and bison that drew visitors from around the world. By 1930, there were about 15,000 elk spending part of the year on the Northern Range.

But park managers worried the elk were ruining Yellowstone's rangelands. In a 1932 report, Park Service biologist W.M. Rush said the elk were depleting grasses and eating aspen, willows and even sagebrush. Elk numbers stayed high for three decades, and seedlings such as Keigley's were eaten back year after year, leaving them dwarfed and split.

Then, in the 1960s, the Park Service culled more than 13,500 elk, knocking the herd down to about 4,500 animals. These reductions, says Keigley, were what allowed his juniper to achieve its present height. With few elk browsers around, the split trunk shot skyward.

In 1967, political pressure ended the killings, and the following year Yellowstone adopted natural regulation. Once again, the northern elk herd grew. By 1992, when Keigley first noticed the juniper, the northern elk herd numbered around 20,000 and the animals were eating the lower branches of many trees. This gave Keigley's juniper its "high-lined" broccoli look.

Keigley started seeing stories in trees everywhere. Junipers, cottonwoods, willows and firs all had things to tell. And the more trees Keigley looked at, the more he was convinced that the Northern Range was in trouble. Elk were damaging and killing older trees, and preventing younger trees from growing, he says.

Twice, Keigley approached Yellowstone's chief scientist John Varley about using the park's conifers to piece together a grazing history of the Northern Range. By using older trees, he believed he could see how the range looked before Euro-Americans arrived on the scene. The study would give park managers a picture of what the Northern Range looked like under "natural conditions." And if he was right, natural conditions were much different from what he saw in the juniper above Mammoth.

But both times Varley denied him a research permit. The first time, when Keigley was working for the Park Service, Varley told him he was deviating from his original assignment.

The second rejection came in 1994, when the National Biological Survey (now the Biological Resources Division of the U.S. Geological Survey or the "BRD') asked Keigley to study the impacts of elk browsing on conifers. Varley withheld the proposal, saying the research design was flawed. In a letter to Keigley's supervisors, Varley wrote that the project "has not appeared on your priority list or ours."

Despite Keigley's pleas to superintendent Michael Finley, the application was put on hold permanently. "We don't think (Keigley's) study design has merit. We don't think he can come up with reasonable answers," says John Varley. "(Keigley isn't) facing the real facts that he couldn't get his research design through peer review."

Actually, the study had undergone peer review before the BRD presented it to Varley, says Keigley, and the Park Service has never offered him any specific criticism of the project.

Keigley won't say how he thinks the northern elk herd should be managed, but he thinks the public and the Park Service need to consider all sides of the story. "There is nobody in this (debate) who doesn't have a point of view or a history," he says. "The best we can hope for is honesty."