|In the Mountain West, five-needle white pines play a critical role in ecosystem stability. Of the six five-needle pine species that inhabit high-elevation forests, the whitebark pine stands out as the species most in need of protection and restoration because of its significant contributions to the ecosystem and its unique susceptibility to invading threats.
Importance of the Whitebark Pine
- As a foundation species, whitebark pine is the initial colonizer of high-elevation forests after major disturbances. They grow first and act as “nurse” tree, providing a protected, stable environment for numerous other plants to repopulate these areas with difficult growth conditions.
- A keystone species, whitebark pine plays a significant role in animal biodiversity of western forests. In harsh mountain conditions, they provide nesting habitat and shelter for myriad animals. In addition, their large, nutritious seeds serve as an energy-rich food source for a number of animals, including grizzly and black bears, Clark’s nutcracker and other small birds and mammals. Whitebark pine communities have actually been designated by the U.S. Fish and Wildlife Service as critical habitat for the threatened grizzly bear.
- The whitebark pine is found at the highest elevations where the majority of snowfall occurs. Through the shade provided by their large crowns, they help reduce snow melt, avalanche potential and soil erosion. The snow on these ridges feed the headwaters of the Greater Yellowstone Area providing water resources for more than 33 million people in 16 states.
- Take a minute to read Taza Schaming’s article Importance of Whitebark Pines and Clark’s Nutcrackers in Western Ecosystems discussing the fascinating million-year-old relationship between the whitebark pine and Clark’s nutcracker and how it is being impacted due to high mortality of whitebark pines.
Challenges to the Whitebark Pine
- Whitebark pine seeds are not dispersed by wind. Thus, the species relies primarily on the Clark’s nutcracker to collect its seeds and bury them to spur regeneration.
- Whitebark pine is highly vulnerable to infection by white pine blister rust. Only 28 percent of the species’ trees have shown genetic resistance to the disease.
- Mountain pine beetles are attacking whitebark pine at an unprecedented rate. Uncharacteristically high temperatures and unusual precipitation patterns in the last 13 years have increased the population and survival rate of the mountain pine beetle in the highest elevations where whitebark communities are found. These beetles also attack and reproduce in whitebark pines as small as 13 cm in diameter, but need other pine to have at least a 20 cm diameter.
- Whitebark pine is shade intolerant. It needs fire and other natural disturbances to create openings for it to grow. Years of fire suppression have limited suitable habitat for whitebark pine regeneration.
Approximately half of the remaining grizzlies in the U.S. are located in the Greater Yellowstone Area.