Help for the Whitebark Pine
By Margaret Buranen
Millions of acres of whitebark pines grow from the Canadian coastal mountains in British Columbia to the Sierra Nevada, Cascades, Pacific Coast ranges and northern Rockies, including the greater Yellowstone ecosystem. These trees offer unique benefits to people, animals and the land. Because whitebark pines grow on rocky, windy ledges where other trees can’t, they stabilize soil and slow snowmelt in high elevations, ensuring sufficient water flow and preventing flooding in lower elevations. Whitebark pine seeds sustain birds and other animals. They provide essential nourishment to grizzly and black bears and keep them from having to search for food in populated areas. But whitebark pines are threatened on a number of fronts.
White pine blister rust, a European import, has long plagued the pines. Management has focused on encouraging the establishment of trees that are genetically resistant to the rust. Now, another enemy is challenging those efforts: mountain pine beetles.
“Mountain pine beetles kill both resistant and nonresistant trees, which reduces the genes available for both natural selection and genetic restoration programs,” says Diana Tomback, professor of evolutionary ecology at the University of Colorado Denver and director of the Whitebark Pine Ecosystem Foundation.
The best way to combat the mountain pine beetle is to apply verbenone (a pheromone that tricks the beetles into thinking other beetles have already eaten the tree) or carbaryl (an insecticide) to individual trees before the beetles’ annual flights. But because such applications have to be done every summer until the beetle outbreak ends, the work is costly and time-consuming.
Another threat to the whitebark pine is the policy of suppressing forest fires, followed for decades. This practice encouraged the growth of shade-tolerant trees, such as spruce and fir. As more of these trees grew, whitebark pine seedlings dwindled for lack of sun.
Whitebark pine is better adapted to survive and regenerate after fires. The species has somewhat thicker bark, thinner crowns and deeper roots than do other conifers.
Because the tree requires sunlight, available only in more open areas, some researchers and government officials suggest that allowing controlled fires would help the whitebark pine regenerate. Manual removal of faster-growing trees would also help, though it would be labor intensive.
An obvious strategy to help the whitebark pine is replanting, especially in burned areas. Governmental and environmental organizations have been doing this for years.
Collecting seeds from disease-resistant whitebark pines and growing them into seedlings for planting offers the best hope for the tree’s future. The U.S. Forest Service has several such projects.
After locating rust- and beetle-free trees, workers climb 30 to 40 feet to attach wire mesh to the seed cones to keep birds and squirrels from eating them. Then they return to collect the seeds and plant them in a greenhouse.
A year or more later, when the seedlings have grown, they’re tested for rust resistance by exposing them to spores of the fungus. If healthy, they are then planted. The labor-intensive process takes two to three years.
Research recently published by the U.S. Forest Service’s Pacific Northwest Station suggests that conserving the ponderosa pine will help the whitebark pine. That is because the Clark's nutcrackers that disseminate whitebark pine seeds rely heavily on ponderosa pine seeds for food.
In 2008 the Natural Resources Defense Council petitioned to have the whitebark pine added to the federal Endangered Species List. Government officials agreed that the evidence warranted a thorough review, which takes a year. The final decision is due this July.
If listed, the whitebark pine will be the first broadly distributed tree species to be so designated. The listing would consolidate current research, monitoring and conservation projects and make available more resources, all part of a major recovery plan for this beleaguered tree.
MARGARET BURANEN, of Lexington, Ky., writes about the environment, animals, business and medicine. Her articles have appeared in Stormwater, American Forests and other publications.
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Last modified on January 23, 2012