Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plant diversity threatened by climate change and buildup of greenhouse gas, study reveals

17.06.2003


Doubling the amount of carbon dioxide in the air significantly reduces the number of plant species that grow in the wild, according to a newly released study on climate change in California.




The results, published in the Proceedings of the National Academy of Sciences (PNAS), are the latest findings from the Jasper Ridge Global Change Project at Stanford University – a multiyear experiment designed to demonstrate how grassland ecosystems will respond to predicted increases in temperature and precipitation caused by the continual buildup of CO2 and other greenhouse gases in the atmosphere.

Writing in the June 16 edition of PNAS Online, researchers found that exposing open grasslands to large doses of CO2 gas for three years caused a nearly 20 percent reduction in wildflower species and an eight percent decline in plant diversity overall. The addition of excess nitrogen and other predicted climate changes caused diversity to plunge even further, the study found.


"I was surprised how quickly we lost species over such a short time," said the study’s lead author, Erika S. Zavaleta, a former Stanford doctoral student who recently joined the faculty at the University of California-Santa Cruz. "It only took three years in our experiment. What does that say about the impact global change will have on plant diversity in the longer term?"

Global changes

Located in the grassy foothills of Stanford’s Jasper Ridge Biological Preserve, the Global Change Project relies on a system of infrared heat lamps, sprinklers and emitters to simulate four conditions that climate experts predict could exist a century from now as a result of continued fossil fuel consumption and deforestation:

  • A temperature increase of 2 degrees F;
  • A 50 percent rise in precipitation;
  • Double the amount of CO2 in the air;
  • Higher concentrations of nitrogen pollutants in the soil.

To study the environmental impact of such future global changes, researchers monitored 36 circular plots of land, each about six feet in diameter, between 1998 and 2001. Four circles were left undisturbed as experimental controls. Each of the remaining 32 circles was divided into four quadrants – like a birthday cake cut into equal pieces – for a total of 128 experimental plots.

Different treatments were applied to different plots. Some were given a single application, such as excess carbon dioxide gas, while others received various combinations of elevated CO2, heat, water and/or nitrogen fertilizer.

Initially, each plot contained between five and 20 varieties of grasses and wildflowers. The goal of the experiment was to see how different combinations of treatments would affect species diversity over a three-year period.

Diversity loss

The results were dramatic. Plots that received all four treatments lost more than one-fourth of their wildflower species, while those given elevated nitrogen or CO2 suffered a 10 to 20 percent decline.

However, plots treated with excess water experienced a 10 percent increase in wildflower diversity and a 3 percent gain in the number of annual grass species.

"We found that elevated CO2 caused a loss in species, while added precipitation caused an increase. We were surprised they had such opposite effects," said study co-author Christopher B. Field, a professor by courtesy of biological sciences at Stanford and director of the Carnegie Institution’s Stanford-based Department of Global Ecology. "One hypothesis is that elevated CO2 added moisture to the soil, which tended to extend the growing season of the dominant plants, leaving less room for other species to grow."

On the other hand, he noted, increasing precipitation by 50 percent may have encouraged growth in late-season plants that normally stop growing during the dry California summer: "We think the effects of elevated CO2 and increased precipitation were more or less the same, but because they were separated in time by a couple of weeks, they actually produced opposite results. In our ecosystem here, things that happen at different times in the season are really important."

The study also revealed that heat in the absence of other treatments had no significant impact on diversity. However, when experimental plots were exposed to higher temperatures along with excess nitrogen, carbon dioxide and water, the number of wildflower species plummeted.

"One take-home message of our study is that certain kinds of species are much more sensitive to climate and atmospheric changes than others," Zavaleta observed.

"It turned out that wildflowers were much more sensitive to the treatments than grasses were, no matter what combination of treatments we tried," she added, noting that a large-scale change in diversity could diminish the ability of grasslands to support birds, deer, butterflies and other wildlife – as well as commercial grazing.

Additive response

The researchers discovered that they could make remarkably accurate predictions of species diversity in plots where multiple treatments had been applied simply by adding up losses and gains observed under single treatments. For example, in quadrants receiving excess nitrogen, heat and CO2, wildflower diversity decreased by about 27 percent -– almost exactly what would be expected if you added up the percentages of loss in quadrants given single treatments of CO2 (18 percent), nitrogen (8 percent) and heat (2 percent).

"One possible reason we see this overall additive response is that the mechanisms that are driving the changes are not interacting," Field said – a finding that could prove beneficial in forecasting how global environmental changes will affect plant diversity in other ecosystems.

"We hope to move into the domain where we can predict responses rather than just record them and report them," he added.

Other coauthors of the PNAS study are Harold A. Mooney, the Paul S. Achilles Professor of Environmental Biology at Stanford; Nona R. Chiariello, research coordinator of the Jasper Ridge Biological Preserve; and M. Rebecca Shaw of the Nature Conservancy.

The study was supported by the National Science Foundation, the David and Lucile Packard Foundation, the Morgan Family Foundation, JRBP, the Carnegie Institution of Washington, the U.S. Department of Energy, the U.S. Environmental Protection Agency, the Switzer Foundation, the A.W. Mellon Foundation and the Nature Conservancy.

Mark Shwartz | EurekAlert!
Further information:
http://www.stanford.edu/dept/news/

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

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | 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

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>