The caching of whitebark pine seeds by the Clark's nutcracker in late summer and early fall may not be enough to regenerate populations of the imperiled conifer in most of its range, scientists have found.
Their researchwhich is featured in the February issue of Science Findings, a monthly publication of the U.S. Forest Service's Pacific Northwest Research Stationsuggests, for the first time, that the success of whitebark pine restoration may be linked to the conservation of another tree species: ponderosa pine.
"Whitebark pine is a keystone species in the high-mountain ecosystems of the northern Rockies, Cascades, Olympics, and eastern Sierra Nevada because it plays a major role in creating suitable conditions for the growth of other plants and in supplying seeds, which are consumed by a number of animals," said Martin Raphael, a research wildlife biologist with the station and one of the study's collaborators. "But the species is in trouble and is experiencing declines of 45 percent across some of its range."
Regeneration of the high-elevation treewhich is threatened today by outbreaks of the mountain pine beetle and blister rustwould seem intimately tied to the foraging behavior of the Clark's nutcracker, a crow-sized bird that propagates the tree by removing its large seeds from its cones and caching them in the ground. Unlike most other pines, the cones of whitebark trees do not open on their own to release their seeds, but must be forced open by Clark's nutcrackers. The birds' spatial memory allows them to retrieve seeds from many of their caches throughout the year; those that remain are left to germinate.
"The nutcrackers flock around whitebark pine stands in autumn as the cones ripen and use their sharp, strong bills to hammer into the tightly closed cones and dig out the seeds," said Teresa Lorenz, a doctoral student who led the study, along with Raphael and Forest Service geneticist Carol Aubry, as part
|Contact: Yasmeen Sands|
USDA Forest Service, Pacific Northwest Research Station