"We're showing this increased growth rate at treeline in a number of locations," said Matthew W. Salzer, a research associate at UA's Laboratory of Tree-Ring Research. "It's unique in several millennia, and it's related specifically to treeline."
Bristlecone pines live for thousands of years on dry, windswept, high-elevation mountain slopes in the western U.S. The scientists collected and analyzed tree rings from Great Basin bristlecone pines located in three mountain ranges in eastern California and Nevada that are separated by hundreds of miles.
Only trees growing within about 500 feet (150 meters) of treeline showed the surge in growth. In general, those trees were at or above about 11,000 feet (3,300 meters) in elevation.
"You can come downslope less than 200 vertical meters and sample the same species of tree, and it won't show the same wide band of growth," Salzer said.
Growth at the pines' upper elevational range is limited by cold temperatures. At the lower elevations, growth of the trees is limited by moisture more than temperature, Salzer said.
Co-author Malcolm K. Hughes said, "Something very unusual is happening at high elevations, and this is one more piece of evidence for that." One other example, he said, was the accelerated melting of small glaciers at high altitudes.
"There is increasingly rapid warming in western North America," said Hughes, a UA Regents' Professor of dendrochronology. "The higher you go, the faster it's warming. We think our finding may be part of that whole phenomenon."
Salzer, Hughes and their co-authors Andrew G. Bunn of Western Washington University in Bellingham and Kurt F. Kipfmueller of the University of Minnesota in Minneapolis will publish their paper, "Recent Unprecedented Tree-ring Growth in Bristlecone Pine at the Highest Elevations and Possible Causes," in this week's Early Online edition of the Proceedings of the National Academy of Sciences. The National Science Foundation funded the research.
Individual Great Basin bristlecone pines, Pinus longaeva, are the longest-living organisms known. The trees live at an elevation range of approximately 8,200 to 11,400 feet (about 2,500 to 3,500 meters). The oldest living bristlecone, almost 5,000 years old, is in California's White Mountains.
The trees' longevity coupled with the excellent preservation of trunks from even older dead trees has allowed some scientists to reconstruct regional climate 8,000 years into the past using tree-ring records from bristlecone pines.
The recent rapid growth of three species of pines at elevations close to treeline had been noticed more than 25 years ago by previous researchers from UA's Laboratory of Tree-Ring Research. The sudden growth surge was puzzling in trees hundreds to thousands of years old, well past adolescence."It means there has been some environmental change that affected the trees'
Salzer and his colleagues wanted to study trees whose growth was strongly affected by temperature.
"Where do you go to look for trees where ring width is related to temperature? You look for trees in high mountain ranges, where the mountain continues up and the trees don't follow," Salzer said. "As you go up, the main thing that's changing in these places is temperature."
He and his colleagues chose to extend the previous research efforts. The scientists used the previous researchers' data and also took new bristlecone pine cores to increase the number of samples available for analysis.The team analyzed the average and median width of tree rings for 50-year blocks of time, starting with the latter half of the 20th century, the years
1951 to 2000, and going backward in time to 2650 B.C. The analysis spans more than 4,600 years.
To see how the annual growth rings changed with temperature, the team used a new method of mapping climate data called PRISM that was unavailable to researchers 25 years ago.
PRISM combines weather records and knowledge of how topography affects weather and climate to provide state-of-the-art climate information going back 100 years for specific locations. PRISM stands for "Parameter-elevation Regressions on Independent Slopes Model."
The tree-ring researchers found that the chronological timing of the wider tree rings correlates with increasing temperatures from the PRISM climate map.
Hughes said that increasing temperatures high in the mountains could have significant effects elsewhere. In many areas of the western U.S., mountains are a key source of water for farms and urban areas at lower elevations.
"If the snow melts earlier, the mountains won't be able to hold onto water for as long," Hughes said. "They won't be as effective as water towers for us."
The same pattern of high-elevation growth increases has also been observed in Rocky Mountain bristlecone pines, including ones in Arizona's San Francisco Peaks, Salzer said. He plans to expand the research to investigate high-altitude trees at additional locations.
Contact information:Matthew Salzer, 520-621-2946.
Mari N. Jensen | University of Arizona
Forest Management Yields Higher Productivity through Biodiversity
14.10.2016 | Technische Universität München
Farming with forests
23.09.2016 | University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
26.10.2016 | Power and Electrical Engineering
26.10.2016 | Awards Funding
26.10.2016 | Power and Electrical Engineering