COLORADO—Whitebark pine is currently experiencing high mortality due to multiple stressors across its range. This species continues to die off in alarming numbers. In 2016, 51 percent of all standing whitebark pine trees in the United States were dead, a huge increase from 12 percent standing dead trees in 1999. Mortality is due to factors including white pine blister rust, wildfire and mountain pine beetle outbreaks.
In August, the journal Forest Science published “A Landscape-level Assessment of Whitebark Pine Regeneration in the Rocky Mountains, USA,” where lead author Sara Goeking, Rocky Mountain Research Station biological scientist, and her team assessed whitebark pine seedling densities throughout the Rocky Mountains. The team identified stand, site and climatic variables related to seedling data based on over 1,400 Forest Service Forest Inventory and Analysis plots. While previous studies have documented whitebark pine decline and factors determining regeneration, this study examined all forest types throughout the West, including forests where most researchers do not expect to find whitebark pine. That led to a surprising finding. The study found that the highest densities of seedlings were not in predominantly whitebark pine forests—they were in lodgepole pine forests.
“The challenge for forest managers is to figure out how to encourage whitebark pine seedlings in lodgepole pine forests to grow into mature trees,” said Goeking.
Whitebark pine is an ecologically important species in high-altitude areas of the western United States. Its ability to reach cone-producing age is important not only for the survival of the species, but for the animals depend on it. Its large, nutritious seeds are a critical food source for Clark’s nutcrackers, red squirrels, grizzly bears and other animals.
More information is available in a news release, an RMRS Science Spotlight, and in a story map, “Vital Signs of a Species in Decline: Mortality and Regeneration of Whitebark Pine,” developed by Goeking and biological scientist Chuck Werstak.