Posts tagged Rocky Mountains
2001-02 drought helped to shift Rocky Mountain pine beetle outbreak into epidemic
Nov 5th
The study, the first ever to chart the evolution of the current pine beetle epidemic in the southern Rocky Mountains, compared patterns of beetle outbreak in the two primary host species, the ponderosa pine and lodgepole pine, said CU-Boulder doctoral student Teresa Chapman. The current mountain pine beetle outbreak in the southern Rockies — which range from southern Wyoming through Colorado and into northern New Mexico –is estimated to have impacted nearly 3,000 square miles of forests, said Chapman, lead study author.
While the 2001-02 drought in the West played a key role in pushing the pine beetle outbreak into a true regional epidemic, the outbreak continued to gain ground even after temperature and precipitation levels returned to levels nearer the long-term averages, said Chapman of CU-Boulder’s geography department. The beetles continued to decimate lodgepole pine forests by moving into wetter and higher elevations and into less susceptible tree stands — those with smaller diameter lodgepoles sharing space with other tree species.
“In recent years some researchers have thought the pine beetle outbreak in the southern Rocky Mountains might have started in one place and spread from there,” said Chapman. “What we found was that the mountain pine beetle outbreak originated in many locations. The idea that the outbreak spread from multiple places, then coalesced and continued spreading, really highlights the importance of the broad-scale drivers of the pine beetle epidemic like climate and drought.”
A paper on the subject was recently published in the journal Ecology. Co-authors on the study include CU-Boulder geography Professor Thomas Veblen and Tania Schoennagel, an adjunct faculty member in the geography department and a research scientist at CU-Boulder’s Institute of Arctic and Alpine Research. The National Science Foundation funded the study.
Mountain pine beetles are native insects that have shaped the forests of North America for thousands of years. They range from Canada to Mexico and are found at elevations from sea level to 11,000 feet. The effects of pine beetles are especially evident in recent years on Colorado’s Western Slope, including Rocky Mountain National Park, with a particularly severe epidemic occurring in Grand and Routt counties.
Chapman said the most recent mountain pine beetle outbreak began in the 1990s, primarily in scattered groups of lodgepole pine trees living at low elevations in areas of lower annual precipitation. Following the 2001-02 drought, the outbreak was “uncoupled” from the initial weather and landscape conditions, triggering a rise in beetle populations on the Western Slope and propelling the insects over the Continental Divide into the northern Front Range to infect ponderosa pine, Chapman said.
The current pine beetle epidemic in the southern Rocky Mountains was influenced in part by extensive forest fires that ravaged Colorado’s Western Slope from roughly 1850 to 1890, said Chapman. Lodgepole pine stands completely burned off by the fires were succeeded by huge swaths of seedling lodgepoles that eventually grew side by side into dense mature stands, making them easier targets for the pine beetles.
“The widespread burning associated with dry years in the 19th century set the stage for the current outbreak by creating vast areas of trees in the size classes most susceptible to beetle attack,” said Chapman.
Veblen said a 1980s outbreak of the pine beetle centered in Colorado’s Grand County ended when extremely low minimum temperatures were reached in the winters of 1983 and 1984, killing the beetle larvae. But during the current outbreak, minimum temperatures during all seasons have been persistently high since 1996, well above the levels of extreme cold shown to kill beetle larvae in laboratory experiments.
“This implies that under continued warming trends, future outbreaks will not be terminated until they exhaust their food supply — the pine tree hosts,” said Veblen.
Chapman said there has been a massive and unprecedented beetle epidemic in British Columbia, which also began in the early 1990s and has now has affected nearly 70,000 square miles. “It is hard to tell if this current beetle epidemic in the Southern Rockies is unprecedented,” she said. “While warm periods in the 16th century may have triggered a large beetle epidemic, any evidence would have been wiped out by the massive fires in the latter part of the 19th century.”
Veblen said while the rate of spread of the mountain pine beetle in lodgepole pine forests has declined in the southern Rocky Mountains during the past two years because of a depletion of host pine population, U.S. Forest Service surveys indicate the rate of beetle spread in ponderosa pine forests on the Front Range has increased sharply over the past three years. “The current study suggests that under the continued warmer climate, the spread of the beetle in ponderosa pines is likely to grow until that food source also is depleted,” Veblen said.
“Our results emphasize the importance of considering different patterns in the population dynamics of mountain pine beetles for different host species, even under similar regional-scale weather variations,” said Chapman. “Given the current outbreak of mountain pine beetles on the Front Range, their impact on ponderosa pines is certainly something that needs further study.”
A 2012 study by CU-Boulder Professor Jeffry Mitton and graduate student Scott Ferrenberg showed some Colorado pine beetles, which had been known to produce only one generation of tree-killing offspring annually, are producing two generations per year due to rising temperatures and a longer annual warm season. Because of the extra annual generation of beetles, there could be up to 60 times as many beetles attacking trees in any given year, according to the study.
In addition, a 2011 study led by CU-Boulder graduate student Evan Pugh indicated the infestation of trees by mountain pine beetles in the high country across the West could potentially trigger earlier snowmelt and increase water yields from snowpack that accumulates beneath affected trees.
CU Boulder prof gets MAJOR cred
Feb 9th
National Academy of Engineering
Diane McKnight, professor of civil, environmental and architectural engineering and a fellow of the Institute of Arctic and Alpine Research at the University of Colorado Boulder, has been elected to the National Academy of Engineering.
McKnight is among 66 new members and 10 foreign associates of the academy announced today. She joins 16 other faculty from the campus who have been elected since the academy’s formation in 1962.
Election to the National Academy of Engineering is among the highest professional distinctions accorded an engineer. Academy membership honors those who have made outstanding contributions to “engineering research, practice or education” and to the “pioneering of new and developing fields of technology, making major advancements in traditional fields of engineering, or developing/implementing innovative approaches to engineering education.”
McKnight was recognized for making clear the interrelationship between natural organic matter and heavy metals in streams and lakes.
Her research expertise is in the interactions between freshwater biota, trace metals, and natural organic material in diverse freshwater environments, including lakes and streams in the Colorado Rocky Mountains and in the McMurdo Dry Valleys in Antarctica.
In the Rocky Mountains, she has focused on the impact of metal contamination in acid mine drainage streams and the influence of climate change and nitrogen deposition on alpine lakes and wetlands. McKnight has interacted with many state and local groups involved in mine drainage and watershed issues in the Rocky Mountains.
“Diane is a worldwide leader in the interactive effect of metals in our water system with natural organic matter,” said Professor Ross Corotis, who was dean of the College of Engineering and Applied Science when McKnight joined the faculty and the Institute of Arctic and Alpine Research in 1996. “In addition to her advanced research for protecting environments from the Antarctic to the Rocky Mountains, she is a leader in developing books for children to help them learn about the water cycle.”
McKnight has been working in Antarctica since 1987, and is a leading investigator studying extreme life at the McMurdo Dry Valleys Long Term Ecological Research site funded by the National Science Foundation. In the harsh polar environment, stream channels flow only a few weeks out of the year and the only life forms inhabiting the area are microorganisms, mosses, lichens and a few groups of invertebrates.
She wrote and published a children’s book, “The Lost Seal,” in 2006, that tells the true story of a wayward seal discovered near the research camp in 1990 and its eventual rescue. The story gives children an understanding of Antarctica’s extreme environment and the work of scientists there.
She earned three degrees from the Massachusetts Institute of Technology, including a bachelor’s degree in mechanical engineering in 1975, a master’s degree in civil engineering in 1978 and a doctorate in environmental engineering in 1979.
She was a research hydrologist with the U.S. Geological Survey’s National Research Program for 17 years before she came to CU-Boulder. She was named a fellow of the American Geophysical Union in 2004 and of the American Association for the Advancement of Science in 2009.
She is a former member of the National Research Council’s Water Science and Technology Board and Polar Research Board, and she received a Meritorious Service Award from the U.S. Geological Survey in 1995.
Other CU-Boulder faculty who have been elected to the National Academy of Engineering, and their years of election, are: Bernard Amadei, 2008; George Born and Kaspar Willam, 2004; Ross Corotis and Fred Glover, 2002; Frank Barnes, 2001; Delores Etter, 2000; Martin Mikulas, 1999; Valerian Tatarskii, elected a foreign associate in 1994; Earl Gossard, 1990; Don Hearth and Richard Strauch, 1989; Jacques Pankove, 1986; Richard Seebass (deceased), 1985; Klaus Timmerhaus (deceased), 1975; and Max Peters (deceased), 1969.
Mini quakes to shimmy the Rio Grand rift
Jan 11th
IN COLORADO AND NEW MEXICO, NEW STUDY SAYS
The Rio Grande Rift, a thinning and stretching of Earth’s surface that extends from Colorado’s central Rocky Mountains to Mexico, is not dead but geologically alive and active, according to a new study involving scientists from the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences.
“We don’t expect to see a lot of earthquakes, or big ones, but we will have some earthquakes,” said CU-Boulder geological sciences Professor Anne Sheehan, also a fellow at CIRES. The study also involved collaborators from the University of New Mexico, New Mexico Tech, Utah State University and the Boulder-headquartered UNAVCO. The Rio Grande Rift follows the path of the Rio Grande River from central Colorado roughly to El Paso before turning southeast toward the Gulf of Mexico.
Sheehan was not too surprised when a 5.3 magnitude earthquake struck about 9 miles west of Trinidad, Colo., in the vicinity of the Rio Grande Rift on Aug. 23, 2011. The quake was the largest in Colorado since 1967 and was felt from Fort Collins to Garden City, Kan.
Along the rift, spreading motion in the crust has led to the rise of magma — the molten rock material under Earth’s crust — to the surface, creating long, fault-bounded basins that are susceptible to earthquakes, said Sheehan, a study co-author and also associate director of the CIRES Solid Earth Sciences Division. The team studied the Rio Grande Rift region to assess the potential earthquake hazards.
Using Global Positioning System instruments at 25 sites in Colorado and New Mexico, the team tracked the rift’s miniscule movements from 2006 to 2011. “Questions we wanted to answer are whether the Rio Grande Rift is alive or dead, how is it deforming and whether it is opening or not,” said Sheehan.
The high-precision instrumentation has provided unprecedented data about the volcanic activity in the region. Previously, geologists had estimated the rift had spread apart by up to 2 inches or 5 millimeters each year, although the errors introduced by the scientific instruments were known to be significant. “The GPS used in this study has reduced the uncertainty dramatically,” Sheehan said.
Using the latest high-tech instrumentation, the scientists found an average strain rate of 1.2 “nanostrain” each year across the experimental area, the equivalent of about one-twentieth of an inch, or 1.2 millimeters, over a length of about 600 miles. “The rate is lower than we thought but it does exist,” Sheehan said.
The researchers also found the extensional deformation, or stretching, is not concentrated in a narrow zone centered on the Rio Grande Rift but is distributed broadly from the western edge of the Colorado Plateau well into the western Great Plains. “The surprising thing to come out of the study was that the strain was so spread out,” Sheehan said.
Results of the study are published in the January edition of the journal Geology.
The team plans to continue monitoring the Rio Grande Rift, probing whether the activity remains constant over time, said lead study author Henry Berglund of UNAVCO, who was a graduate student at CU-Boulder working at CIRES when he completed this portion of the research. Also, the team may attempt to determine vertical as well as horizontal activity in the region to tell whether the Rocky Mountains are still uplifting or not, Berglund said.
“Present-day measurements of deformation within continental interiors have been difficult to capture due to the typically slow rates of deformation within them,” Berglund said. “Now with the recent advances in space geodesy we are finding some very surprising results in these previously unresolved areas.”
As far as the potential for future earthquakes in the region, the study’s results are unequivocal, however. “The rift is still active,” Sheehan said.
The new study also is co-authored by CU-Boulder Associate Professor and CIRES Fellow Steven Nerem, Frederick Blume of UNAVCO, Anthony Lowry of Utah State University, Mousumi Roy of the University of New Mexico and Mark Murray of New Mexico Tech.
The National Science Foundation provided the funding for this study and the NSF-funded EarthScope program and UNAVCO provided instruments, equipment and engineering services. The Boulder-headquartered UNAVCO is a nonprofit, university-governed consortium that facilitates geosciences research and education.
–