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 research—which is featured in the February issue of Science Findings, a monthly publication of the U.S. Forest Service's Pacific Northwest Research Station—suggests, 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 tree—which is threatened today by outbreaks of the mountain pine beetle and blister rust—would 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 of her master's degree studies at Utah State University. "You can see the cone chips flying."
In the study, aimed at determining how effective the birds are in regenerating whitebark pine, the researchers fitted 54 Clark's nutcrackers in the Olympic and Cascade Mountains with radio collars and tracked them for three seasons. They found that:
• The nutcrackers foraged widely for whitebark pine seeds, but transported nearly all of them back to their home ranges for caching, which suggests that natural generation of the tree would be greatest within the birds' home ranges
• The nutcrackers transported seeds over much longer distances than previously observed, sometimes up to 20 miles, which suggests that the birds facilitate a great amount of genetic mixing of the tree
• The nutcrackers tended to cache their seeds in sheltered locations at the driest, lowest elevation sites within their range—areas unsuitable for successful whitebark pine germination
"One of the most important things this study helped us to understand is how unlikely it is that whitebark pine seeds will end up in good germination spots," Raphael said. "Birds placed only about 15 percent of the seeds they gathered in places where germination is actually possible."
In addition to revealing that Clark's nutcracker caching alone, while critical, would not be sufficient to recover populations of whitebark pine, the study also is the first to document the role of the birds in disseminating the seeds of ponderosa pine. The nutcrackers not only routinely gathered ponderosa pine seeds within their home ranges, but were more effective in dispersing them to suitable germination sites than they were at dispersing whitebark pine seeds.
"Because we found ponderosa pine seeds to be an important food for nutcrackers in Washington and Oregon, the success of whitebark pine restoration may be irrevocably linked to the conservation of low-elevation ponderosa pine," Lorenz said. "What we've found can help managers focus restoration efforts and may help them refine seed boundaries and identify the likeliest regeneration sites."
To read the February issue of Science Findings online, visit http://www.treesearch.fs.fed.us/pubs/37291.
The PNW Research Station is headquartered in Portland, Oregon. It has 11 laboratories and centers located in Alaska, Oregon, and Washington and about 425 employees.
Yasmeen Sands | EurekAlert!
Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University
New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction