Patrick Springer, Published July 07 2013
Researching the wetlands: North Dakota offers scientists a look at climate change
Consider the rivalry between the yellow-headed blackbird and red-winged blackbird.
During the drought of the late 1980s and early 1990s, the yellow-headed blackbird flourished. It did well in habitat rich with cattails, which thrived as wetlands receded in the drought.
Then, when the climate shifted dramatically to a wet pattern starting in 1993, the red-winged blackbird’s population soared, as the altered habitat allowed it to out-compete its rival blackbird species.
“It’s hard to find a yellow-head now,” David Mushet, a research wildlife biologist and wetland specialist, said of the flip-flopped fortunes of the two species.
Mushet and his senior colleague, Chip Euliss, have seen many such fluctuations play out in the more than two decades they have studied wetlands at the U.S. Geological Survey’s Northern Prairie Wildlife Research Center.
Drawing upon almost five decades of research at the center, their team is working on tools to predict how changes in climate will ripple throughout complex ecosystems.
It’s an area of growing interest given the volatile climate conditions – a rate of change researchers say is almost unparalleled in geological history.
Dry, then wet
Euliss arrived in 1990, joined by Mushet two years later, at the end of a drought comparable to the Dirty Thirties.
They watched the wetlands around Cottonwood Lake northwest of Jamestown go dry. The Cottonwood Lake Study Area, in fact, is the most extensively studied wetland complex in North America and perhaps the world.
“There was not a drop of standing water in Cottonwood towards the end of ’92,” said Mushet.
Then, a thunderstorm in July of 1993 launched the wet weather pattern that has dominated the area since. By 1994, conditions had rebounded to reach their peak for waterfowl production, with abundant aquatic food.
Cottonwood Lake was dry in September 1991, but by March of 1994, was deep enough to float a 50-foot boat.
“That’s how dynamic these things are,” Euliss said.
Researchers have documented how the yo-yoing climate conditions drive intricate changes in the web of plant and animal life of the prairies and marshes.
Some species are more adaptive than others, as shown by a pair of amphibians.
Salamanders, which can burrow underground and remain dormant during dry periods, quickly reappeared as the wetlands refilled from the rains.
But the leopard frog took three years to come back, spreading slowly from a deep pothole, traveling roughly a mile a year as it spread out under more hospitable conditions.
The wetlands of the prairie potholes are surprisingly dynamic. Fluctuating climate conditions work as a catalyst to promote the diversity of plant and animal species.
During more than two decades of research, Euliss has seen a cascade of changes in the Cottonwood Lake Study Area, more than 600 acres located roughly 30 miles northwest of Jamestown.
“I don’t think for sure we can say that under a drier climate it’s going to be bad,” he said. “We can say it’s going to be different.”
In fact, the changes triggered by fluctuating conditions actually spur new growth, with rejuvenation occurring when conditions shift from dry to wet, producing a cocktail of life that could be called “duck soup.”
“It’s the most productive phase in the cycle,” Euliss said. “Every piece of that wet-dry cycle provides something different.”
When the Northern Prairie Wildlife Research Center was established in the 1965, scientists didn’t have a deep understanding of the intricacies of prairie wetlands.
Almost half a century later, most of what scientists know about prairie wetlands was gleaned from comprehensive, ongoing studies at the Cottonwood Lake Study Area.
“It’s undoubtedly the most studied wetland on the globe,” Euliss said. It’s so famous, in fact, that visiting scientists have inquired about the availability of shuttle service from the Fargo airport, he added, chuckling.
The wetland research program was launched by George Swanson, with key assistance from hydrologist Tom Winter.
In a series of studies, they determined the movement of water, both on the surface and beneath the ground, as it flows in and out of the wetlands.
Water flows much more readily laterally than it does vertically. It takes a year for water to penetrate one meter, or about three feet. “It’s extremely slow,” Euliss said.
In the Cottonwood wetland complex, water in certain recharge wetlands, which cleanse water as it flows, is 10 times fresher than drinking water.
By contrast, in a discharge wetland, which receives discharge flows, minerals become concentrated over long periods of time. A prairie pothole in Saskatchewan is 10 times saltier than the ocean.
“It’s an incredibly diverse mix of habitat conditions that supports an incredible diversity of life,” Euliss said.
Certain sedge plants, for example, only tolerate flooding for two to three weeks. “Fairy shrimp” favor extremely fresh water, whereas brine shrimp like salty water.
Similarly, seaside arrow grass, normally found in western coastal marshes, can be found during dry periods, when wetlands can become very salty.
“This whole kaleidoscope of biology is changing,” Euliss said, responding to the dynamic conditions of the prairie marshes.
The prairie pothole region, which extends from Canada through a swath of North Dakota, South Dakota, Minnesota and Iowa, is home to more than half of North American waterfowl. It’s regarded as one of the world’s most important wetland regions.
“North Dakota is the most important state in the United States – in North America – for dabbling ducks,” species found in ponds, such as mallards.
In 2006, the Northern Prairie Wildlife Research Center published one of the first studies involving climate change in prairie wetlands.
The study found that prairie wetlands can serve as carbon “sinks,” with the ability to store twice as much carbon as no-till cropland, yet they occupy less than a fifth of the land area in the prairie pothole region.
Wetland restoration would be an effective way to replenish carbon storage lost due to cultivation. A restored semi-permanent wetland, for instance, would take an average of a bit more than three years to replenish lost carbon.
Although wetlands are a major landform source of methane, the study concluded wetlands can offset 2.4 percent of annual fossil carbon dioxide emissions.
In a major effort to apply what the center’s researchers have learned, an initiative headed by Mushet is working to provide a tool to predict the impacts changes in land use can have on a particular land area, including wetlands, grassland or cropland.
The service is called InVEST – Integrated Valuation of Ecosystem Service and Tradeoffs – and uses mapping technology to predict future scenarios.
The intent is to give policymakers, landowners and other stakeholders the ability to see the consequences of land use changes – converting conservation acres to a wheat field, for example.
The project also aims to show how land cover could change as a consequence of drought.
“It’s sort of like a weather forecast,” Euliss said, offering a range of extreme outcomes.
Readers can reach Forum reporter Patrick Springer at (701) 241-5522