Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Increase in rainfall variability related to global climate change

13.12.2002


Impacts on ecosystems are greater than previously anticipated



Projected increases in rainfall variability resulting from changes in global climate can rapidly reduce productivity and alter the composition of grassland plants, according to scientists funded by the National Science Foundation (NSF). Although the diversity of plant species is increased in this scenario, the most important or dominant grasses were more water-stressed and their growth was reduced. Carbon dioxide release by roots and microbes below ground also was reduced.

Results of the experiment, conducted at NSF’s Konza Prairie Long Term Ecological Research (LTER) site, are published in this week’s (December 13th) issue of the journal Science.


The biologists, Alan Knapp, Philip Fay, and John Blair and colleagues of Kansas State University, Scott Collins of NSF, and Melinda Smith at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara, found that more extreme swings in rainfall patterns, without any changes in the total amount of rainfall received in a growing season, reduced the biomass of plants but increased the variety of species able to live in a particular experimental plot of land.

"This study is the first to focus on and manipulate climate variability in an intact ecosystem, without altering the average climate," said Quentin Wheeler, director of NSF’s division of environmental biology, which funded the research along with the U.S. Department of Agriculture and the U.S. Department of Energy. "Because these responses are similar to those that would occur under drought conditions, the results suggest that increased rainfall variability combined with projected higher temperatures and decreased rainfall amounts, may lead to even greater impacts on ecosystems than previously anticipated."

In this study of how grasslands respond to more variation in rainfall patterns, the scientists hoped to better understand how rapidly and to what extent ecosystems might respond to a future with more climate extremes. In the four-year field study, the researchers altered rainfall variability by increasing the amount of precipitation that falls in one storm, and lengthened the periods of time between rainfalls by 50 percent. That effectively increased the severity of dry periods between storms without altering the total amount of precipitation received during a growing season.

"When these native grassland plots, exposed to more variable rainfall patterns, were compared with plots that received rainfall in a natural pattern, the overall growth of all plants decreased," said Knapp. "More variable rainfall patterns led to lower amounts of water in the soil in the upper 30 centimeters. Since this is the soil depth where most plant roots occur, and where important soil microbes are most abundant, grasses there were water-stressed and the activity of below-ground organisms was reduced."

In contrast, said Collins, "the diversity of plants in plots with greater variability in rainfall patterns increased." Collins cites two possible explanations for this finding: "A high degree of variability in resources can lead to a greater number of co-existing species. Or reduced total productivity may have allowed less common species to increase in abundance." Regardless of the mechanism, said Collins, these results show that plant community structure can be significantly changed, and the cycling of carbon slowed, in as little as four years when grasslands are exposed to a more variable climate.

Concerns about predicted climate changes resulting from human activities often focus on the effects of increases in average air temperatures or changes in average precipitation amounts. But widely used climate models also predict increases in climate extremes, said Knapp, such as more frequent large rainfall events or more severe droughts. "It’s important that we look at variability in a new way: not only from year to year or decade to decade, but from storm to storm."


###
NSF PR 02-98

Media Contact:
Cheryl Dybas
703-292-8070, cdybas@nsf.gov

Program Contact:
Henry Gholz
703-292-7185, hgholz@nsf.gov




Cheryl Dybas | EurekAlert!

More articles from Ecology, The Environment and Conservation:

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>