Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

An exotic grass kills trees by hijacking their water

02.08.2004


Foothill palo verde trees at the University of Arizona’s Desert Laboratory surrounded by buffelgrass. Photo credit: J. Alex Eilts.


Buffelgrass snatches water away from nearby palo verde trees, ultimately killing them.

Scientists thought deep-rooted plants such as desert trees did not compete with grasses for water. Now researchers from the University of Arizona in Tucson report that buffelgrass, an invasive non-native species, grabs water before foothill palo verde trees can.

The situation does not bode well for the trees, said J. Alex Eilts, a doctoral candidate in UA’s department of ecology and evolutionary biology. Native to the Sonoran desert, foothill palo verde trees, or Cercidium microphyllum, cope with drought by shedding branches to reduce the amount of water needed to survive. "It’s as if the trees are self-pruning themselves to death," he said.



Eilts will give his presentation, "Effects of a non-native grass on a dominant woody Sonoran desert tree," at 9:50 a.m. on Thursday, Aug. 5 in the Oregon Convention Center in Portland, Ore., at the annual meeting of the Ecological Society of America. His coauthor, Travis Huxman, is an assistant professor in UA’s department of ecology and evolutionary biology.

Buffelgrass, or Pennisetum ciliare, thrives in arid and semi-arid climates. Ecologists are increasingly concerned about buffelgrass, a native of Africa often introduced for livestock grazing or to control erosion, because it spreads quickly and outcompetes native species. Buffelgrass now is found in Texas, New Mexico, Arizona, Mexico, Venezuela, Argentina, Hawaii and Australia.

First planted in the Tucson area shortly before 1940, the exotic grass now is found in the Tucson Mountains, on A Mountain and on nearby Tumamoc Hill, home of UA’s century-old Desert Laboratory. Researchers believe that buffelgrass first invaded the laboratory grounds in the mid-1980s.

One focus of the laboratory is long-term research on the ecology of Sonoran desert plants. While working on a class project, Eilts noticed that, unlike other parts of the laboratory grounds, there were almost no palo verde trees within the patches of buffelgrass.

Historic photographs taken by Ray Turner of the U.S. Geological Survey showed foothill palo verde trees on the laboratory grounds in locations which now have only buffelgrass. Such trees can live more than 100 years, so Eilts suspected that buffelgrass had something to do with the palo verdes’ disappearance.

To study how buffelgrass affects the trees, Eilts used an instrument called a pressure chamber to find out how much water stress the trees were experiencing. First he tested foothill palo verde trees surrounded by buffelgrass. The next year, he removed the grass from under some of those trees and repeated the experiments. Removing the buffelgrass significantly reduced the trees’ water stress.

The grass is reducing the water available to the trees, he said. "This means that in any given year the water deficit experienced by the trees with grass at their bases is greater compared with those trees free of the influence of buffelgrass."

Eilts also measured how much of their branches the trees shed.

Palo verdes self-prune little during an non-drought year, said Huxman. But when times are tough, buffelgrass makes it tougher. Eilts found that in a drought year, trees surrounded by buffelgrass lost about 24 percent of their total branches, whereas trees free of buffelgrass shed only about 16 percent. Huxman said, "Buffelgrass takes the drought and accentuates it."

The ecologists’ findings contradict current hypotheses about the relationship between trees, grasses and water in arid climates. Eilts said, "One would predict that the presence of buffelgrass would have the least affect on the deep-rooted woody plants such as the palo verde trees."

Instead, the buffelgrass reduces water available to the trees’ deep roots. "Effectively, what is happening to the trees in the grass is that they are experiencing a biotically induced drought," he said. "They seem to be responding to this the same way they do to normal drought, by self-pruning." Eilts said there is no reason why the grass couldn’t affect other plant species in a similar manner. He said, "What makes buffelgrass a potential threat to the foothill palo verdes and other native plants is that it can move into undisturbed habitats and effectively compete for water."

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

More articles from Ecology, The Environment and Conservation:

nachricht When corals eat plastics
24.05.2018 | Justus-Liebig-Universität Gießen

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

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: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>