Characteristics of Whitebark Pine (Pinus albicaulis)

The whitebark pine has been classified as endangered by the IUCN Redlist. Severe population declines in whitebark pine communities are associated with a variety of causes, the most significant of which are white pine blister rust infection, recent mountain pine beetle outbreak (2000-2014), wilderness fire ecological disturbances (including fire suppression), forest succession, and climate change. A study in the mid-2000s showed that whitebark pines had declined 41 percent in the western Cascades due to two main threats, namely blister rust and pine beetles. Deaths of whitebark pine trees in North Cascades National Park doubled from 2006 to 2011.
 

WHITEBARK PINUS MASS DEATH

Many whitebark pines in their natural habitat are infected with white pine scald rust disease (Cronartium ribicola), a fungal disease that is native to Europe. In the northern Rocky Mountains of the United States, whitebark pine mortality in some areas exceeds 90 percent, where the disease affects nearly 143,000 hectares (580 km2). White pine scald rust fungus grows on whitebark pines to the species’ northern limits in coastal areas of British Columbia and the Canadian Rockies. This fungus has also destroyed the commercially valuable western white pine in this area and also infected the Limber pine (Pinus flexilis) population. Nearly 80 percent of whitebark pines in Mount Rainier National Park are infected with blister rust.

There are currently no effective methods for controlling the spread and effects of scald rust. However, a small number of trees (less than 5%) in most populations have genetic resistance to scald rust. Restoration efforts undertaken by the U.S. Forest Service, Bureau of Land Management, and National Park Service in the northern Rocky Mountains involve harvesting cones from known and potential whitebark pine, growing seedlings, and planting seedlings in suitable locations.

Outbreaks of the unusually large mountain pine beetle (Dendroctonus ponderosae), a species of bark beetle native to western North America, have also significantly contributed to the destruction of whitebark pines. INI beetles lay their eggs and introduce pathogenic fungi to their host trees, which include many other pine species, and a combination of larval feeding and fungal colonization is usually sufficient to kill old or otherwise unsanitary trees.

In 2007, the U.S. Fisheries and Wildlife Service estimated that beetles had killed whitebark pines on 500,000 acres in the West, while in 2009, beetles were estimated to have killed trees on 800,000 acres. The pine beetle resurgence has killed nearly 750,000 whitebark pines in the Greater Yellowstone Ecosystem.

Fire suppression has led to slow population declines over the last century by changing health dynamics and stand composition without fire ecology balancing their habitats and suppressing the threat of insect disease. In the absence of a low-grade fire cycle, whitebark pines in this stand are replaced by more shade-tolerant and non-fire-tolerant species such as subalpine spruce (Abies lasiocarpa) and Engelmann fir (Picea engelmannii).
 

PROTECTION FOR WHITEBARK PINE

On July 18, 2011, the US Fish and Wildlife Service reported that whitebark pines needed protection and, without it, the tree would soon be extinct. However, the agency announced it would not be able to register the tree as endangered or protect the organism, as it lacked the necessary staff and funds to do so. In June 2012, the Canadian federal government declared the whitebark pine critically endangered under the Species at Risk Act. As such, it is the first federally registered endangered tree in western Canada.

In response to the ongoing tree decline throughout its range, the Whitebark Pine Ecosystem Foundation was formed. Their mission is to raise awareness and promote conservation by sponsoring restoration projects, publishing a newsletter called “Nutcracker Records”, and hosting annual science and management workshops for anyone interested in whitebark pine. This US group works closely with the Whitebark Pine Ecosystem Foundation of Canada.