Scientist documents wetland losses

May 29, 2013
SDSU scientist documents wetland losses
Professor Carol Johnston of the South Dakota State University Natural Resource Management Department measures the height of common reed grass in a Lake Michigan wetland. The researcher says wetlands are important to wildlife and human beings.

( —Wetlands in eastern North and South Dakota are shrinking at a rapid pace, according to professor Carol Johnston of the South Dakota State University Natural Resource Management Department.

The and expert compared Department of Agriculture crop maps with wetland maps from the U.S. and the U.S. Geological Survey. She identified those areas that were once wetlands but are now cropland to determine the amount of loss and verified her findings using aerial photos.

The study focused on the Prairie Pothole Region in the eastern Dakotas, Johnston explained. "That's where most of the wetlands and are." Her article was published in Wetlands, the Journal of the Society of Wetland Scientists. The Prairie Pothole region extends from Iowa through the Dakotas into Canada and provides habitat for more than 50 percent of North American migratory waterfowl.

She compared wetlands maps from the 1980s and 2001 to cropland maps from 2011. If the area on the earlier wetlands maps was identified as cropland in 2011, Johnston explained, "it was no longer a wetland."

Comparing wetlands mapped 30 years ago with those areas in 2011, she documented a yearly loss of nearly 13,000 acres of wetlands. Considering only the changes in the last decade, those losses increased to 15,377 acres per year.

The 2012 data came out this spring and, Johnston said, "the rate just keeps going up."

These changes in land use affect not only wildlife but human beings. "Wetlands provide many ecosystem services," Johnston explained. Wetlands improve water quality downstream by trapping sediment and filtering out pollutants such as phosphorus.

"Wetlands are called the kidneys of the landscape," Johnston said. The in wetlands convert nitrate, a form of nitrogen dissolved in the water, into harmless . Nitrates can pollute well water, making it unfit to drink. Without the filtering effects of wetlands, these nitrates can also encourage the growth of algae. When these algae decompose, they decrease the oxygen available for fish and other aquatic organisms.

Wetlands help recharge groundwater supplies in many places, Johnston explained. Because these shallow reservoirs hold excess water, they can also reduce flooding downstream. Johnston cited an instance in which wetlands along the Charles River in Massachusetts were bought and maintained specifically for the purpose of reducing floods in the city of Boston.

Near Hillsboro, N.D., a 160-acre area that was once a shallow pond is now completely cropland, Johnston explained. "Many wetlands dry up naturally during droughts like we had last year, but I did my study at the end of a three-year wet period, so I'm sure the wetland loss was not due to drought."

The combination of higher commodity prices and a drop in the number of acres enrolled in the Conservation Reservation Program, known as CRP, have contributed to the conversion of wetlands into croplands. This program pays landowners to set aside land as wetlands and grasslands.

"Many acres are going off of CRP in both the Dakotas," Johnston said. Contracts on 105,387 acres of land in South Dakota and 253,746 acres in North Dakota are set to expire in September, and U.S. Department of Agriculture officials expect that many of these acres will be converted to cropland.

Johnston explained that wetland losses in the Dakotas affect a much larger area.

"Loss of nutrients as a result of wetland drainage can increase the amount of nitrogen going downstream," she explained. "What we do in South Dakota impacts people all the way down to the Gulf of Mexico."

Explore further: Rising sea levels threaten migratory birds

add to favorites email to friend print save as pdf

Related Stories

Losing wetlands to grow crops

Mar 24, 2013

Getting enough to eat is a basic human need – but at what cost to the environment? Research published in BioMed Central's journal Agriculture & Food Security demonstrates that as their crops on higher ground fail due to ...

Rising sea levels threaten migratory birds

May 06, 2013

Millions of birds that stop at coastal wetlands during annual migrations could die as rising sea levels and land reclamation wipe out their feeding grounds, researchers warned Monday.

Targeted action needed to protect waterbirds

May 01, 2013

( —Researchers from our Biodiversity Lab have identified specific areas around the world where conservation efforts could best be targeted to safeguard inland-breeding waterbirds.

Recommended for you

US delays decision on Keystone pipeline project

Apr 18, 2014

The United States announced Friday a fresh delay on a final decision regarding a controversial Canada to US oil pipeline, saying more time was needed to carry out a review.

New research on Earth's carbon budget

Apr 18, 2014

( —Results from a research project involving scientists from the Desert Research Institute have generated new findings surrounding some of the unknowns of changes in climate and the degree to which ...

User comments : 0

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...