Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Underlying cause of massive pinyon pine die-off revealed

11.10.2005


The high heat that accompanied the recent drought was the underlying cause of death for millions of pinyon pines throughout the Southwest, according to new research.


These photos show the massive die-off of pinyon pines that occurred during the recent drought. By October 2002, pinyons, normally evergreen, had reddish-brown foliage (left). By May 2004, the dead pinyons had lost all their needles, exposing their gray trunks. The photos were taken from the same vantage point in the Jemez Mountains near Los Alamos, N.M. Photo credit: Craig D. Allen, U.S. Geological Survey.



The resulting landscape change will affect the ecosystem for decades. Hotter temperatures coupled with drought are the type of event predicted by global climate change models. The new finding suggests big, fast changes in ecosystems may result from global climate change.

"We documented a massive forest die-off – and it’s a concern because it’s the type of thing we can expect more of with global warming," said research team leader David D. Breshears, a professor of natural resources in The University of Arizona’s School of Natural Resources in Tucson and a member of UA’s Institute for the Study of Planet Earth.


At study sites in Arizona, Colorado, New Mexico and Utah, the team found that from 40 to 80 percent of the pinyon trees died between 2002 and 2003. The researchers confirmed the massive regional dieback of vegetation through both aerial surveys and analysis of satellite images of those states’ pinyon-juniper woodlands.

"Scientists are concerned about how fast vegetation will respond to climate change, but we don’t have many examples to test our ideas," Breshears said. "Here we’ve clearly documented a case that shows how big and fast the die-off can be."

The drought coupled with particularly high temperatures set the trees up to be susceptible to insect infestations. Bark beetles delivered the knock-out punch.

"It was the drought – beetles don’t get trees unless the trees are really water-stressed," Breshears said.

Breshears, Neil S. Cobb, director of the Merriam-Powell Center for Environmental Research at Northern Arizona University in Flagstaff, Paul M. Rich, research scientist at Los Alamos National Laboratory in New Mexico, and their colleagues will report their findings the week of Oct. 10 in the online Early Edition of the Proceedings of the National Academy of Sciences. A complete list of authors and their affiliations is at the end of this release. Los Alamos National Laboratory (LANL), the National Science Foundation, the U.S. Forest Service, the U.S. Geological Survey, NASA and the National Institutes of Health funded the research.

Ecologists want to learn more about long-term changes in ecosystems that occur in response to climatic and other environmental variation.

So in 1987, researchers established a study site in the pinyon-juniper woodland zone at LANL. Roughly every two weeks, Breshears and his colleagues measured soil moisture on the 100-by-150 meter plot (about three times the size of a football field). Temperature and precipitation data were recorded at a nearby site. In 1992, the team began tracking tree mortality.

"I could see the plot from my office window," said Breshears, who used to work at LANL. When the recent drought hit, the scientists were well-positioned to compare how the vegetation fared before and during the drought.

Initially the trees managed, but in 2002 the pinyon pines began to die. By the end of 2003, more than 90 percent of the pinyons on the plot were dead. Breshears said, "I would see the trees go from vibrant green to pale, gasping green to pale brown to dropping all their needles."

Pinyon pines all over the Southwest were doing the same thing.

U.S. Forest Service’s aerial surveys of the region’s pinyon-juniper woodlands in 2002 and 2003 revealed significant tree die-off covering more than 4,600 square miles (12,000 square km).

The effect was so dramatic it could be detected by satellite.

Rich and his colleagues at LANL and the University of Kansas analyzed satellite images of the region’s pinyon-juniper woodlands for the years 1989 through 2003 using a measure of vegetation greenness known as Normalized Difference Vegetation Index (NDVI). The weekly composite images came from data collected by AVHRR (Advanced Very High Resolution Radiometer) sensors on National Oceanic and Atmospheric Administration satellites.

The region’s 60,000 square miles (about 155,000 square km) of pinyon-juniper woodlands became a lot less green starting in 2002, the team found. Moreover, the NDVI measurements for the site at LANL showed that the plot’s greenness dropped at the same time and in a similar way.

During a previous multi-year drought in the 1950s, not as many trees died. To see how the two droughts differed, the researchers compared the four driest consecutive years of the earlier drought, 1953-1956, with those of the recent drought, 2000-2003.

"By every measure we looked at, the recent drought was hotter," Breshears said, adding that, if anything, the 1950s drought was drier.

The high heat combined with the extreme dryness put the trees under so much water stress that the attacks from bark beetles finished them off. Under such conditions, the trees cannot make enough pine sap to defend themselves against the insects.

"These trees are slow-growing trees, so we aren’t going to have woodlands of this type back in this area for decades," Breshears said. He added that the lack of pinyon nuts will have negative effects on wildlife and on people who harvest the nuts for food and for sale.

Rich said, "The fate of the pinyon-juniper forest depends on what happens next, especially in terms of weather. If it’s wetter, the trees may come back. If not we’ll probably see shifts to species from drier ecosystems."

Having such a wealth of data and a range of expertise was crucial for figuring out what happened, said Cobb, leader of the Drought Impacts on Regional Ecosystems Network (DIREnet). "The NSF DIREnet project allowed us to bring all these researchers together."

Breshears said the team’s next step is developing ways to predict how bad a drought must be to cause such large-scale die-offs.

Breshears, Cobb and Rich’s coauthors include Kevin P. Price and Jude H. Kastens of the University of Kansas in Lawrence; Craig D. Allen of the U. S. Geological Survey in Los Alamos, N.M.; Randy G. Balice and Clifton W. Meyer of Los Alamos National Laboratory; William H. Romme of Colorado State University in Fort Collins; M. Lisa Floyd of Prescott College in Arizona; Jayne Belnap of the U.S. Geological Survey in Moab, Utah; Jesse J. Anderson of Northern Arizona University; and Orrin B. Meyers of the University of New Mexico in Albuquerque. The team’s paper, "Regional vegetation die-off in response to global-change type drought," will be published in an upcoming edition of the Proceedings of the National Academy of Sciences.

Mari N. Jensen | EurekAlert!
Further information:
http://www.arizona.edu

More articles from Ecology, The Environment and Conservation:

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Transport of molecular motors into cilia

28.03.2017 | Life Sciences

A novel hybrid UAV that may change the way people operate drones

28.03.2017 | Information Technology

NASA spacecraft investigate clues in radiation belts

28.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>