Keystone Species of the High Country in Peril
Whitebark Pine being considered for Endangered Species status
High on the ridges of the surrounding mountains stand the often-twisted and gnarled whitebark pine. The harsh, wind-blasted environment makes survival difficult but these trees have another battle: mountain pine beetles and white pine blister rust.
The combination of mountain pine beetles and white pine blister rust can be deadly. Mountain pine beetles feed and reproduce under the bark of pine trees which eventually disrupts the flow of water and nutrients within the tree and kills it. White pine blister rust is a fungus that enters through the needles, grows down the branches and into the trunk and eventually girdles the tree. “The mountain pine beetle wouldn’t usually kill all the trees because of the tree’s resistance,” said Robert Keane, research ecologist at the U.S. Forest Service Rocky Mountain Research Station. “But the mountain pine beetle epidemic is killing all the trees because they are infected with white pine blister rust.”
The mountain pine beetle and white pine blister rust are two reasons the Natural Resources Defense Council petitioned the United States Fish and Wildlife Service to list the whitebark pine under the Endangered Species Act. In July, the USFWS announced that the whitebark pine may warrant protection under the ESA, but a year-long status review will determine if it is truly warranted.
In their petition, the NRDC stated that other factors affecting the whitebark pine included climate change and changes in fire regimes. According to the NRDC petition, climate change will limit the range of the whitebark pine, increase the range of competing tree species, increase the range of pests and increase the frequency and intensity of stand-replacing wildfires. Additionally, the NRDC petition states that current fire suppression practices have allowed competing trees to thrive among whitebark pines and have allowed fewer openings for whitebark pine seed germination.
The whitebark pine’s thick bark, deep root system and thin crown allow it to withstand frequent fires. Fire creates the open spaces necessary for seed germination and kills competing trees that are not fire-resistant, such as sub-alpine fir.
Locally, the U.S. Forest Service is working on reintroducing fire to whitebark pine communities. In 2006, the Bonners Ferry Ranger District burned over 1,000 acres to help restore whitebark pine. Prescribed burns were conducted near Russell Peak, Ball Lakes, Big Fisher, Farnham Ridge, Burton and Cutoff Peak. The burning project is an experiment to reduce the mountain pine beetle population according to Jamie Wynsma, USFS Silviculture Forestry Technician. “Fire is Mother Nature’s way of giving it a bath,” said Wynsma. “We are anticipating visiting the plots next year to see if they worked and to inventory new whitebark pine seedling.”
New seedling trees are the future of whitebark pine stands. Since mountain pine beetles target large, mature trees, the seedlings have a chance to thrive as the cyclic nature of mountain pine beetles takes it course. Mountain pine beetle outbreaks are correlated to periods of warmer temperatures, such as from 1909 to the1930s and during the 1970s and 1980s according to the NRDC petition. Wynsma mentioned that the Selkirk Crest is the hardest hit area by mountain pine beetles. “We have to let it [the mountain pine beetle] run its course yet protect the whitebark pine,” said Wynsma.
The USFS is protecting the best whitebark pine trees in regards to genetics. “We are trying to keep individual trees alive,” said Wynsma. The genetically best trees have small, white pheromone packets attached to them to discourage mountain pine beetles. The packets contain the same pheromone that mountain pine beetles emit to signal to other beetles that the tree is at capacity. Therefore, the packets cause the mountain pine beetles to pass over that tree.
While mountain pine beetles can be tricked, white pine blister rust cannot. As a fungus spread by wind-blown spores, white pine blister rust is not specific; it affects all age classes of five-needled white pines in North America. Currently, white pine blister rust is detected across the whitebark pine’s entire range except for a few isolated stands in the interior of the Great Basin ranges. Locally, the Forest Service is pruning whitebark pines to reduce white pine blister rust infection rates.
A combination of projects is important for the survival of whitebark pine communities. In 2008 and 2009, after the mountain pine beetle outbreak of 1999-2005, aerial surveys were completed in three areas of the Selkirks: Russell Ridge, Pyramid Lake and Trout Lake. Of the mature whitebark pines, 78 to 94 percent were killed by mountain pine beetles and of the remaining trees, 69 to 89 percent were infected with white pine blister rust. In addition, 15 to 23 percent of the smaller trees were infected with blister rust. In regards to theses three areas, USFS Entomologist Sandy Kegley said: “They will most likely convert to another cover type without intervention.” Interventions include fire or other restoration work.
“The Selkirks were one of 42 stands surveyed in Montana, Idaho and Yellowstone,” said Kegley. “Twenty-four of the 42 stands are likely to convert to another cover type without intervention. The remaining 18 sites will most likely remain whitebark pine because of the low rate of rust or sufficient numbers of regens [small trees] that were not affected or there was not a lot of competing vegetation.” According to Kegley, one of the reasons the Selkirks will convert to another cover type, most likely alpine fir or spruce, is that the Clark’s nutcracker has few open areas to cache seeds.
The Clark’s nutcracker is one of the main dispersal agents of whitebark pine seeds because the cones do not open upon drying and, therefore, are not wind-dispersed. The nutcracker caches thousands of seeds every year throughout its territory. The birds prefer to cache seeds in open sites, such as burns, where the caches will be accessible throughout the winter and spring. Forgotten caches are the beginning of seedling whitebark pines.
Even though the whitebark pine is in peril, natural and human restoration efforts will continue regardless of whether or not it becomes listed under the Endangered Species Act.