Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sediment samples suggest how plants would fare in hotter, drier future

14.01.2004


Sediment samples dating back thousands of years and taken from under the deep water of West Olaf Lake in Minnesota have revealed an unexpected climate indicator that can be factored into future projections.



In the Jan. 13 issue of the Proceedings of the National Academy of Sciences, scientists at the University of Illinois at Urbana-Champaign report that native C4 plants did not fare well during prolonged periods of severe drought that occurred in the middle Holocene (4,000 to 8,000 years ago).

C4 plants, so designated because of their biochemical pathway of photosynthesis, are generally expected to do well in warmer, drier climates driven by rising levels of carbon dioxide. Elevated carbon dioxide concentrations alone should favor C3 plants, which use another photosynthesis pathway. While the middle Holocene had much lower levels of carbon dioxide, the general climate conditions of that time provide a good model for study, said Feng Sheng Hu, a professor in the plant biology and geology departments at Illinois.


The sediment from West Olaf Lake, which contains residue of plant life, indicates that weedy C3 plants such as Ambrosia (ragweed) adapted well during severe-drought episodes because of their ability to exploit very limited amounts of water available during the growing season, said David M. Nelson, lead author of the paper and a doctoral student in ecology and evolutionary biology working with Hu.

The findings suggest that even C4 plants could face disastrous consequences during long periods of drought, despite the fact that they use water more efficiently than C3 plants, Nelson said. Barren areas unsuitable for agriculture may be much more extensive in the Midwest under warmer, drier conditions predicted for the future, he said.

"Previous studies of past grassland change have been hampered by the fact that pollen grains of grasses cannot be separated into species, making it difficult to understand climate adaptations of C3 and C4 plants during the middle Holocene," Hu said. "This study offers a new details about grassland responses to long periods of severe drought."

The researchers analyzed and compared sediment from West Olaf Lake with samples from Steel Lake, about 75 miles northeast in Hubbard County. Today West Olaf Lake is along the border of the Great Plains and the more hilly deciduous forest of west central Minnesota. Steel Lake is in more geographically diverse terrain that features a dense coniferous forest that was less susceptible to long-term drought.

The middle Holocene C3 and C4 estimates of the two lakes were based on an analysis of carbon isotopes in charcoal particles produced by fires and well preserved in the stratified layers of sediment. Because of the presence of aragonite, a carbonate mineral, at West Olaf Lake, climate data were extracted by using X-ray diffraction. Climate conditions at Steel Lake came from oxygen-18 isotope levels.

"These analyses gave a picture of precipitation and aridity over time," Nelson said. "At West Olaf Lake, during the most severe, long droughts in the early years of the middle Holocene, C4 plants were low in abundance. Only as temperatures cooled and moisture availability rose later in the middle Holocene did C4 plants increase in abundance."

The West Olaf Lake area was rich in weeds such as Ambrosia during the Holocene’s drier middle years. During the period’s early years, severe droughts limited plant productivity, reducing the accumulation of flammable fuels. During the milder, wetter later years of the period, rising C4 plant productivity coincided with an increase of fires.

At Steel Lake, C4 plants were abundant in the middle Holocene. Researchers did not see the inverse relationship between C4 plants and drought, which were not as severe.


The study was funded by a Packard Fellowship in Science and Engineering and by a National Science Foundation grant to Hu. Carbon dating was done under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory in California.

Other contributing authors on the paper were Jian Tian, a doctoral student in geology at Illinois, Ivanka Stefanova of the University of Minnesota and Thomas A. Brown of the Lawrence Livermore National Laboratory.

Jim Barlow | UIUC
Further information:
http://www.news.uiuc.edu/news/04/0113minnesota.html
http://www.uiuc.edu/

More articles from Life Sciences:

nachricht 'Lipid asymmetry' plays key role in activating immune cells
20.02.2018 | Biophysical Society

nachricht New printing technique uses cells and molecules to recreate biological structures
20.02.2018 | Queen Mary University of London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>