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 When corals eat plastics
24.05.2018 | Justus-Liebig-Universität Gießen

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

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: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>