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, email@example.com (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 firstname.lastname@example.org.)
William Mitsch | EurekAlert!
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy