Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tree die-off triggered by hotter temperatures

12.02.2013
A team of scientists, led by researchers at Carnegie's Department of Global Ecology, has determined that the recent widespread die-off of Colorado trembling aspen trees is a direct result of decreased precipitation exacerbated by high summer temperatures.

The die-off, triggered by the drought from 2000-2003, is estimated to have affected up to 17% of Colorado aspen forests. In 2002, the drought subjected the trees to the most extreme growing season water stress of the past century.

While often not killing the trees directly, the drought damaged the ability of the trees to provide water to their leaves, leading to a decline in growth and increased mortality that has continued for a decade after the drought. The research is published on-line in Global Change Biology. Another related study appeared earlier this year in the same journal.

Until recently, there has been little attention paid to what drought characteristics (seasonal differences, severity, or durations) actually cause trees to die. Scientists additionally have lacked a sufficient understanding of the processes that lead to die-offs, which inhibits the ability to predict how climate change can affect different ecosystems.

The recent study was led by brothers Leander and William Anderegg.* William was a Ph.D. student while Leander was an undergraduate at the time of the research at Carnegie. The team looked at the dynamics of water availability to the trees by examining the ratio of oxygen isotopes in the sap contained in the tree "veins" that transport water. Isotopes are atoms with the same number of protons, but different numbers of neutrons and their ratios are signatures of where and when water originates, among other features.

"Mother nature provides us with natural fingerprints in the ratio of oxygen isotopes," explained Leander. "They tell us about the type of water available to the trees. For instance, summer rain has different isotopic ratios than winter snow. So we can use these markers to figure out where and when the water found in tree veins was taken up, which in turn helps us determine drought impacts."

The scientists examined the isotopes in the aspen sap during natural and experimental drought in an area in Colorado that had heavy tree casualties. It turns out that aspens generally use shallow soil moisture, which evaporated quickly with increased temperatures during the summer drought of 2002. They then looked at climate data finding that these high temperatures were part of a long-term increasing trend, likely linked with climate change, a unique feature of this drought that separates it from earlier less damaging droughts.

"Forests store about 45 percent of the carbon found on land," remarked William. "Widespread tree death can radically transform ecosystems, affecting biodiversity, posing fire risks, and even harming local economies. Rapid shifts in ecosystems, particularly through vegetation die-offs could be among the most striking impacts of increased drought and climate change around the globe."

In a previous study the brothers, with colleagues, looked at two competing theories for how forest trees die during a drought. One hypothesis was that the trees starved due to decreased photosynthesis. Another was that the system for transporting water within a tree was damaged beyond repair. They looked at both carbon starvation and water-transportation stress and found no evidence of significantly decreased carbon reserves. They did find a notable depressed function in the trees' water-transport systems, especially in the roots—some 70 percent loss of water conductivity.

This study pinpoints the trigger of this loss—summer temperature was the most important climate variable for explaining aspen death by drying out surface soil and stressing the trees' water-transport system. Joe Berry, a co-author and Carnegie staff scientist, noted that understanding how and where the trees get their water was key to unraveling cause and effect in this study.

"Since there is a very strong upward trend in Colorado summer temperatures, they could link tree death to climate change," said Chris Field, director of the Carnegie department. This study is a milestone in linking plant-level physiology measurements with large-scale climate to predict vulnerability to climate change in these forests.

Interestingly, this type of climate-change hot summer drought actually occurred again in 2012, which could indicate more tree die-offs are in the pipeline for the near future.

*Other researchers on the paper are John Abatzoglou, University of Idaho; Alexandra Hausladen, Stanford University; and Joseph Berry, Carnegie. The work was supported by Carnegie, the Bill Lance Center for the American West, Morrison Institute, Phi Beta Kappa Northern California Association, Jasper Ridge Biological reserve, Stanford VPUE Program, NSF DDIG Program, and THE Stanford Biology SCORE Program.

Published related work includes:

Anderegg, W.R.L., Plavcova, L., Anderegg, L.D.L. Hacke, U.G., Berry, J.A., Field, C.B. (2013) Drought's legacy: multiyear hydraulic deterioration underlies widespread aspen forest die-off and portends increased future risk. Global Change Biology. doi: 10.1111/gcb.12100,

Anderegg, W. R. L. (2012). Complex aspen forest carbon and root dynamics during drought. Climatic Change, 111(3-4), 983–991. doi:10.1007/s10584-012-0421-9.

Anderegg, W. R. L., Kane, J. M., & Anderegg, L. D. L. (2012). Consequences of widespread tree mortality triggered by drought and temperature stress. Nature Climate Change, 3(1), 30–36. doi:10.1038/nclimate1635.

The Department of Global Ecology was established in 2002 to help build the scientific foundations for a sustainable future. The department is located on the campus of Stanford University, but is an independent research organization funded by the Carnegie Institution. Its scientists conduct basic research on a wide range of large-scale environmental issues, including climate change, ocean acidification, biological invasions, and changes in biodiversity.

The Carnegie Institution for Science has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

Leander Anderegg | EurekAlert!
Further information:
http://carnegiescience.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

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

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>