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

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

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: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

Hope to discover sure signs of life on Mars? New research says look for the element vanadium

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>