Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Planted, unplanted man-made wetlands are similar at year 15, and function as effective carbon sinks

A 15-year experiment in an outdoor "laboratory" on Ohio State University's campus shows that naturally colonizing wetlands can offer just as many, if not more, ecological services as will wetlands planted by humans.

Researchers at Ohio State have been comparing the behavior of two experimental marshes on the campus, one that was planted in 1994 with wetland vegetation and another that was left to colonize plant and animal life on its own. The 2 ½-acre marshes are part of the Wilma H. Schiermeier Olentangy River Wetland Research Park, a 30-acre complex that functions as a "living laboratory" in ecological science.

After year 15, the two wetlands contained nearly the same number of plant species, and their rates of retaining phosphorus and nitrates – nutrients that can become potential water contaminants – were almost identical. Both wetlands also hold carbon in their soil, with this carbon sink function increasing steadily over the years.

Plant productivity and greenhouse gas emissions were two ways in which the wetlands differed at this stage in their lives: The naturally developing wetland produced more plant biomass and emits more of the greenhouse gas methane, the latter because it contains more decayed organic material from the higher biomass production. Bacteria that produce methane during that decaying process cause wetlands to release the gas into the atmosphere.

"These experimental wetlands have enabled us to start new ecosystems from scratch. You don't get to do that very often," said William Mitsch, an environment and natural resources professor at Ohio State and director of the wetland research park. "I consider these two wetlands after 15 years as standards. If people who create wetlands compare them to ours and find them to behave in the same way, then their wetlands are in pretty good shape."

Mitsch presented the 15-year wetland report Friday (8/6) at the annual meeting of the Ecological Society of America in Pittsburgh.

Often called the "kidneys" of the environment, wetlands act as buffer zones between land and waterways. In addition to absorbing carbon and holding onto it for years – a process called sequestration – wetlands filter out chemicals in water that runs off from farm fields, roads, parking lots and other surfaces.

When the two experimental wetlands were created in 1994, researchers planted 13 common wetland species in one marsh and left the other to develop as a natural wetland. Water from the nearby Olentangy River has been continually pumped into both marshes at rates to mimic water flow in a freshwater river wetland setting.

Within five years, both wetlands contained almost 100 different species each, and that plant diversity was maintained through the study period's end in 2008.

"I was surprised that the vegetation, the types of species and diversity of the plants, jumped up very fast, by year five," Mitsch said. By 1998, the planted wetland hosted 96 species and the naturally developing marsh was home to 87 species. Those numbers increased to 101 and 97 species, respectively, by 2008.

Seven dominant plant types were growing in year 15 in the created wetland: bur-reed, a variety of cattails, river bulrush and softstem bulrush, American lotus, sago pondweed and rice cutgrass. The three dominant plant types in the natural wetland at year 15 were the rice cutgrass, softstem bulrush and cattails.

"The naturally developing wetland was more powerful, the planted wetland still slightly more diverse," Mitsch said.

Even with that growth, Mitsch calls the wetlands "unfinished." He and his colleagues expect these two experimental marshes to be followed for a total of at least 50 years by university scientists of the future to tell the whole story of the similarities and differences between man-made and natural wetlands.

"I foresee that they will become more and more tree-like every year," Mitsch said. "We've got forest developing on the edges. We think they will be much more dominated by woody vegetation in 50 years."

The researchers have predicted that both wetlands' ability to sequester carbon in their soil will increase at a steady pace through year 50. At the 15-year mark, these two wetlands were sequestering carbon about 40 percent faster than was a similar reference natural wetland – 200 grams of carbon per square meter per year vs. 140 grams of carbon per square meter per year. This could be because of the high biomass production in the created wetlands, Mitsch said.

Though almost all freshwater wetlands are known to release methane, a greenhouse gas, into the atmosphere, Mitsch asserts that wetlands are valuable carbon dioxide sinks and that more than compensates for the methane emissions. Methane oxidizes in the atmosphere while carbon dioxide does not, tipping the balance of value for protection against greenhouse gases in favor of wetlands because of their carbon storage capacity, he said.

"I think wetlands' value as carbon sinks is gigantic, but it is still under-appreciated," Mitsch said. "This study and other work we've done suggests that wetlands can be cost-effective tools to reduce the effects of carbon emissions while they perform their other ecosystem functions, such as water quality improvement and flood control."

The Ohio State wetlands tell a different tale about their ability to retain nutrients, which helps prevent certain substances from fouling adjacent bodies of water.

Phosphorus is problematic in inland freshwater systems, where, in excess, it can stimulate the growth of algae. The experimental wetlands at Ohio State started strong at retaining phosphorus, but the retention rate has declined over time, from 60 percent to 10 percent over the course of the 15 years of study.

For nitrates, which can lead to algae blooms and kill some fish species in coastal waters, the rate of retention in the wetlands has decreased some from the early years but remains consistent, from about 35 percent to 25 percent.

"In the long term, it looks like the wetland gets less effective at retaining phosphorus. For nitrates, it's different. That retention is controlled by microbes, and they are becoming stronger every year, so we expect the removal of nitrates to level off, or maybe even get better," Mitsch said.

Perhaps the greatest value of the wetland research park, Mitsch said, is that "It teaches us a lot about how nature does things."

This work has been supported by the U.S. Department of Agriculture, the U.S. Environmental Protection Agency, the Wilma H. Schiermeier Olentangy River Wetland Research Park, and Ohio State's School of Environmental and Natural Resources, Environmental Science Graduate Program, and Ohio Agricultural Research and Development Center.

Co-authors of the presentation include Li Zhang, Kay Stefanik, Blanca Bernal and Amanda Nahlik of the ORWRP; Christopher Anderson of the Auburn University School of Forestry and Wildlife Sciences; and Maria Hernandez of the Environmental Biotechnology Unit, Institute of Ecology, Xalapa, Veracruz, Mexico. Anderson and Hernandez completed their Ph.D.s at the ORWRP a few years ago.

Contact: William Mitsch, (Mitsch will be at the ESA meeting in Pittsburgh through Friday and is accessible by e-mail there. To reach him by phone at the meeting, contact Emily Caldwell, (614) 292-8310 or

William Mitsch | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

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

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

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: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>