Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tropical plants go with the flow ... of nitrogen

08.05.2007
Tropical plants are able to adapt to environmental change by extracting nitrogen from a variety of sources, according to a new study that appears in the May 7 early online edition of The Proceedings of the National Academy of Sciences.

By demonstrating that not all plants specialize in one specific source of nitrogen, the result turns a commonly held theory on its head. It also provides a dose of optimism that tropical forests will be able to withstand environmental shifts in nutritional cycles brought on by global climate change.

Nitrogen is an essential nutrient that plants must absorb from the soil to survive. Most land plants outside the tropics appear to have evolved to rely on just one of three common sources of nitrogen: nitrate (NO3-), ammonium (NH4+), or dissolved organic nitrogen (DON). As a result of this limitation, they usually inhabit "niches" defined largely by the available nitrogen source. When that source crashes for any reason—often because of shifts in climate—the plants cannot adapt, with potentially disastrous consequences for natural ecosystems.

However, tropical species appear to be far more adaptable than their temperate kin when it comes to their nitrogen needs. A team of researchers* has found that, when confronted with shifts in nitrogen availability, these plants simply "flip a switch" and use whatever is handy.

"When it comes to nitrogen, the tropical plants we studied behave like kids at a pizza party—they may prefer pepperoni, but if only plain cheese is available, they'll still have a slice," said lead author and postdoctoral researcher Benjamin Houlton of the Carnegie Institution's Department of Global Ecology. "This result gives a glimmer of hope that tropical ecosystems may have the capacity to adjust to certain aspects of climate change."

Working in six well-known sites with variable rainfall on Hawaii's Maui Island, the researchers measured the soil content of nitrate, ammonia, and dissolved organic nitrogen. They also determined each source's relative contribution to the growth of a variety of plant species, from small floor-dwelling shrubs, to tree ferns, to tall canopy trees.

In dry areas, nitrate was most readily available, while in wetter areas, ammonium was the dominant source. The plants made use of whichever of these two sources was most common in their native soil. Dissolved organic nitrogen was plentiful, but did not make a significant contribution to plant growth at any of the sites.

To examine the plants' nutritional response to climate change, the researchers combined new measures and models of variations in the atomic masses of nitrogen compounds that occur naturally in plants and soils. By examining these different masses, known as isotopic ratios, across different rainfall climates, they discovered an abrupt shift in the nitrogen cycle and in the nutritional strategies of entire forest communities.

"It really is quite striking; once the soil gets wet and nitrate drops below a certain threshold, the tropical plants all begin using ammonium in near-perfect unison," Houlton explains. "If these diverse plant species can be flexible in their nitrogen metabolism—thought to be non-negotiable in many temperate ecosystems—then maybe they can react to other environmental stresses just as gracefully. Still, our results will need further testing in vast areas of the tropics before we will know how well they truly represent the entire ecosystem."

Dr. Benjamin Houlton | EurekAlert!
Further information:
http://www.stanford.edu
http://www.carnegieinstitution.org

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>