Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Of mice, men, trees and the global carbon cycle

26.01.2006


A team led by a University of Minnesota researcher has found a universal rule that regulates the metabolism of plants of all kinds and sizes and that may also offer a key to calculating their carbon dioxide emissions, a number that must be known precisely in order to construct valid models of global carbon dioxide cycling. Emissions of the gas occur in both plants and animals through the process of respiration; Peter Reich, a professor of forest resources, and his colleagues have found that plant emissions can be deduced from the nitrogen content of any plant. The study also reveals that the respiration, or metabolic, rates of plants and animals follow different laws of scaling with respect to body size. The work will be published in the Jan. 26 issue of the journal Nature.



In revealing nitrogen content as the key to plant metabolic rates, the work uncovered a fundamental difference between plants and animals in how their metabolism varies with size. The larger an animal, the slower its metabolism on a per-weight basis. Thus, although an elephant burns many more calories per hour than a mouse, the mouse has a much higher rate per pound of body weight. An elephant with the same rate per pound as a mouse would generate so much heat it would have serious problems maintaining body temperature and eating fast enough to keep up. Instead of a one-to-one ratio between body size and metabolic rate, as an animal’s body weight quadruples, its respiration rate only triples.

In contrast, when Reich and his colleagues studied 500 plants from 43 species, they found that within a wide range of plant sizes, a quadrupling of weight leads to a quadrupling of respiration rate. The important variable was nitrogen content: The more nitrogen in a plant, the more it respired and the more carbon dioxide the plant emitted. Similarly, if two plants were the same size but had different concentrations of nitrogen in their tissues, the one with the higher nitrogen concentration had a higher respiration rate. Conversely, a big plant and a small plant with the same total nitrogen content would put out equivalent amounts of carbon dioxide over the same time period.


The universal rule linking plant metabolism to nitrogen can also assist efforts to measure the global carbon cycle. Through the process of photosynthesis, plants absorb and store more carbon dioxide than they emit through respiration. But global plant respiration is a huge variable that must be taken into account.

"If we estimate the nitrogen content of plants, we can model their metabolic rates, helping us to better assess the global plant metabolic rate," said Reich, a professor in the university’s College of Natural Resources. "The amounts of carbon dioxide given off by plants is one of the weak spots in models of global carbon cycling."

To predict how fast atmospheric carbon dioxide will rise in the future, it is important to know all the sources that emit the gas and all the sources that soak it up. The amount of carbon dioxide in the atmosphere is well known, as is the rate of emissions from fossil fuel burning. The rate of photosynthesis, in which carbon dioxide is absorbed and stored as plant tissue, is difficult to measure but can be estimated globally from satellites, based on the visible plant cover. The plant cover indicates how much light the plants will intercept. Even harder to calculate are the global amounts of carbon dioxide released by living, respiring plants; the amounts released as plants are decomposed by microbes; and the amounts being absorbed and emitted by oceans.

"If all the carbon dioxide emitted from fossil fuel burning were to stay in the atmosphere, its rate of accumulation in the atmosphere would be two-and-a-half times as fast as it actually is and climate would change two-and-a-half times faster," said Reich. "Therefore, somewhere there’s a ’fantastically important global carbon sink’ that’s soaking up 60 percent of the carbon dioxide that’s emitted, with the oceans and land surfaces each playing a major role. However, researchers have estimated that plant respiration releases five to 10 times as much carbon dioxide as fossil fuel burning. It’s crucial, therefore, to know the amount of plant emissions more accurately because that number makes a huge difference in calculating how much of the gas is being absorbed from the atmosphere and staying in the biosphere. This in turn will help scientists figure out what the carbon sink is and what its capacity might be."

Professor Peter Reich | EurekAlert!
Further information:
http://www.umn.edu

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>