Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

K-State researchers study response of prairie ecosystem

13.12.2002


In face of changes in precipitation variability, climatic extremes



What does Kansas’ weather and life have in common? In the words of Forrest Gump, both are like a box of chocolates. "You’re never sure what you’re going to get." Rain or drought. Drought or rain.
Concerns about future climate changes resulting from human activities often focus on the effects of increases in average air temperatures or changes in average precipitation amounts. But climate models also predict increases in climate extremes such as more frequent large rainfall events or more severe droughts. This aspect of climate change can lead to an increase in climatic variability without accompanying changes in average temperatures or total precipitation amounts, according to a report by a team of researchers at Kansas State University.

The team, headed by Alan Knapp, a university distinguished professor of biology, and John Blair and Phil Fay, professors of biology, has been studying how grasslands respond to increases in the variability of rainfall patterns to better understand how rapidly and to what extent ecosystems might respond to a future with a more extreme climate. Their findings appear in the latest issue of Science.



A key feature of the four-year field study is that the team was able to construct 12 rainfall "shelters" on the Konza Prairie -- essentially greenhouses with clear plastic roofs but without sidewalls -- that allowed the researchers to collect and store rainfall as it occurred and use it in turn to manipulate rainfall patterns in large grassland plots.

The research team was able to alter the rainfall variability by using the collected rainfall to increase the size of individual rainfall events and lengthen the periods of time between rainfall events by 50 percent, thus effectively increasing the severity of dry periods between storms without altering the total amount of precipitation received during the growing season in their experimental plots.

"All plots get the same amount of rain, but there are different durations in the dry periods between events and the size of the storms is different," Knapp said of the. "We’re changing just the distribution of rain and the intensity of the rain, but we’re not changing the amount that occurs on the prairie."

After four years, researchers discovered "a host of changes" in the tallgrass prairie as a result of just altering the patterns of rainfall and not the amount of rainfall. When intact, native grassland plots exposed to more variable rainfall patterns were compared to plots that received natural rainfall patterns, the researchers found that the physiological vigor of the grasses decreased as did the overall productivity or growth of all plants combined. More variable rainfall patterns led to lower amounts of water in the soil in the upper 30 centimeters of soil. Since this is the soil depth where most plant roots occur and where soil microbes are most abundant, grasses were more water stressed and the activity of below ground organisms was reduced. Overall, more extreme rainfall patterns reduced the rate of carbon cycling in this grassland by lowering the uptake of carbon dioxide by the plants above ground and slowing carbon dioxide release by roots and microbes below ground.

"We found a significant reduction in the amount of grass growth and productivity, just by changing the pattern of rainfall but not by changing the total amount," Knapp said. "We saw significant reductions in below ground activity of the roots and microbes; we found significantly more stress in the grasses -- they experience longer dry periods between storms.; they can’t use the big rainfall events as effectively as they can the more frequent smaller ones and so we see greater water stress in the dominant grasses."

The group’s study as part of the Long-Term Ecological program at Konza Prairie, is the first to focus on and manipulate climate variability in an intact ecosystem without altering the climate average. Because all of the responses measured are similar to those that would occur under drought conditions, the results suggest that increased rainfall variability when combined with projected higher temperatures and decreased rainfall amounts may lead to even greater impacts on ecosystems than previously anticipated.

"This is a phenomenon of global importance, not just Kansas," Knapp said. "An increase in precipitation extremes is likely to occur everywhere. The kinds of climate changes that are likely to occur here and elsewhere will have measurable effects upon the resources that we depend upon. Those resources can be grassland resources or they can be cropland resources but it’s very likely that this change in climate, this increase in extreme storm events, this increase in rainfall variability will have measurable effects in a fairly short period of time."

Alan Knapp | EurekAlert!
Further information:
http://www.ksu.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society

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

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: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

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...

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

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>