Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

At the root of nutrient limitation, ecosystems are not as different as they seem

13.11.2007
Anyone who has thrown a backyard barbecue knows that hot dogs are inexplicably packaged in different numbers than buns — eight hot dogs per pack versus 10 hot dog buns. Put in ecological terms, this means that weenie roasts are “hot-dog limited” — the extra buns are worthless without hot dogs to fill them.

Such limiting factors are a cornerstone of natural ecology, where phosphorus or nitrogen limits plant production in most ecosystems. According to the customary model, the relative importance of these two key nutrients varies by ecosystem; but a group of researchers led by Arizona State University professor James Elser has found that this view might need to be updated.

Their paper, “Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems,” is highlighted in the News and Views section of the October 25 edition of Nature. The most comprehensive study of its kind, this meta-analysis of more than 300 publications in the field of nutrient limitation in ecosystems was recently published online in the journal Ecology Letters.

Like all living things, plants require a number of chemical elements in order to flourish, including carbon, hydrogen and oxygen. They also need nitrogen, a building block of proteins; and phosphorus, used to make the nucleotides that compose DNA and RNA. The interplay of these elements affects the growth of the food web’s foundational plants, and so understanding their interplay is of vital environmental and commercial concern.

Nitrogen and phosphorus, both widely used in fertilizers, must be in proper balance to be effective. Adding nitrogen alone to an ecosystem is helpful only up to a point, after which plants stop benefiting unless phosphorus also is added. If such a system responds positively to the initial nitrogen addition, it is said to be “nitrogen-limited,” because the availability of nitrogen instantaneously constrains the productivity of the ecosystem. The converse is true in “phosphorus-limited” systems.

Plant production in both cases is limited by the nutrient in shortest supply, a principle known as von Liebig's law of the minimum. Because of their characteristic differences in size, makeup, geology and other factors, different kinds of ecosystems have long been thought to differ widely in the strength and the nature of their nutrient limitation; for example, conventional wisdom has held that freshwater lakes are primarily phosphorus-limited, while oceans along with terrestrial forests and grasslands were believed to be nitrogen-limited.

Yet that is not what Elser’s group found. Rather, their data reveals that the three environments are surprisingly similar, and that the balance of nitrogen and phosphorus within each ecosystem conforms to a different pattern than previously expected.

“Our findings don’t support conventional views of ecosystem nutrient limitation,” said Elser, a professor of ecology, evolution and environmental science at ASU. “They don’t, for example, confirm the rule of thumb that in freshwaters phosphorus is more limiting than nitrogen.”

Instead, Elser’s group found that nitrogen and phosphorus are in fact equally important in freshwater systems, and that phosphorus is just as important as nitrogen in terrestrial ecosystems as well.

“This is in contradiction to conventional wisdom, which seems to emphasize N on land while disregarding P,” Elser said.

The determining factor, according to Elser, is simplicity. Underlying all of the splendid diversity of the world’s ecosystems — whether soggy, arid, terrestrial, aquatic, arboreal or algal — is the simple unifying fact that all plants share a common core of biochemical machinery. That machinery is composed of proteins and nucleotides, meaning that all plants require nitrogen and phosphorus within a limited range of natural proportions.

“Thus, N and P both play a major role in limiting production, no matter where you look,” Elser said.

Skip Derra | EurekAlert!
Further information:
http://www.asu.edu

More articles from Ecology, The Environment and Conservation:

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

nachricht World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung

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: 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...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

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

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>