The pine and the nutcracker - U.S. Forest Service is cross-breeding whitebark pine to produce trees resistant to blister rust

American Forests, Jan-Feb, 1992 by Tad Brooks

Montana forester Lars Halstrom squints into the sun and eyes a pair of Clark's nutcrackers atop a whitebark pine tree high in the mountains of the Absaroka-Beartooth Wilderness.

The birds are busy jackhammering through pitch-soaked pinecones, eating some of the meaty seeds, stashing some on the forest floor for later. That the nutcrackers are present means that the cones are ripe and that new whitebarks will grow, thanks to the birds' Johnny Appleseed-like habits.

But the hungry nutcrackers are unwelcome competition for Halstrom. He's searching for perfect cones as part of a first-ever genetic experiment aimed at saving the whitebarks from blister rust, a killer disease imported to this country.

The blister-rust fungus has been bringing slow death to whitebarks and other five-needle pines from British Columbia to Wyoming since it landed in Vancouver 81 years ago aboard a freighter full of French-grown pine. In northwestern Montana, the disease has killed 90 percent of whitebark stands, and biologists fear environmental side effects that include quickened snowpack melt and increased erosion.

Seedlings from 5,000 cones collected by Halstrom and others will be deliberately infected with blister rust, and the survivors cross-bred to produce disease-resistant trees. The first batch of super whitebarks could be ready for replanting in 25 years.

The experiment is a longterm gamble: The Forest Service has little experience in regenerating whitebarks, which take 75 to 100 years to mature. But the program is modeled after agency geneticists' successful production of blister-rust-resistant western white pines, a bread-and butter timber tree being replanted by the millions.

"Mother Nature can do it on her own," says experiment leader Ray Hoff, a genetic engineer at the Intermountain Research Station at Moscow, Idaho. "But we can speed up the process a bit."

The new program comes at a critical time for Yellowstone grizzly bears, which in spring and fall feed almost exclusively on whitebark seeds, says Dave Mattson, a habitat specialist for the Interagency Grizzly Bear Study Team. Drought and the fires of 1988 wiped out up to 25 percent of Yellowstone's cone-producing trees, and a blister-rust epidemic would be a major catastrophic event here for the grizzly-bear population. "

During boom cone years the big bears stay at high elevations, raiding cone caches gathered by squirrels. In bust years they are forced to find food at lower elevations and come into conflict with humans. "If the blister rust wipes out a large percentage the trees, we can predict more bear problems," says Kerry Gunther, a wildlife biologist on the grizzly team.

Hoff suggests that selective clear-cutting and burning in the field, along with planting the nursery stock, could hasten the process of natural selection so that someday Clark's nutcrackers will be stashing disease-resistant whitebark seeds.