Just 40 minutes north of the Twin Cities, Cedar Creek Ecosystem Science Reserve (CCESR) is a hidden gem filled with 2,200 hectares of biodiversity, natural history, and unique opportunities for education, outreach, and recreation. Today, the College of Biological Sciences’ affiliated reserve has some of the best-managed habitats in Minnesota. But this wasn’t always the case.
Before the University of Minnesota acquired CCESR’s acreage, some of the current reserve land was open pastureland for cows and agricultural use. Prairie was stripped of its teeming native plant life, and sections of Cedar Creek – the narrow water body that snakes through CCESR’s diverse landscape – became unrecognizable.
New efforts to renew and restore these disturbed habitats are being launched this summer by CCESR Scientist Maowei Liang and Bioproducts and Biosystems Engineering Associate Professor Chris Lenhart. Their work is supported by CCESR, The Nature Conservancy, the Anoka Conservation District, the Lessard Sams Outdoor Heritage Council, and the Cummins Foundation. It will support a vast range of the prairie and wetland ecosystems altered by agricultural activity.
Prepping the prairie
A northern section of CCESR contains many sections of abandoned pastureland, collectively known as “old fields.” Some were cleared for agriculture nearly one hundred years ago. Maowei Liang, a CCESR Scientist who monitors old fields as part of his long-term research, claims they have made significant recovery and could be an invaluable resource for carbon storage and pollinator habitat. But there’s room for improvement.
“There’s still almost a 30 percent deficiency of integral species for native prairie management,” says Liang, who hopes that number will change after he reseeds portions of the old fields with additional native species. “Some portions of the old field will be reseeded with nitrogen-fixing plants, and some with herbaceous, non-woody flowering plants,” he says.“Some with both.” Ecologists call these legumes and forbs, respectively.
Legumes and forbs play different roles in ecosystem functioning. Understanding how the addition of these different functional groups reshape abandoned pastureland could help land managers determine the best methods of restoring a landscape disturbed by agricultural use.
This year, Liang’s crew sowed the new seeds after a routine prescribed burn took place in select portions of his study area. Most native seeds require a season of “cold stratification” – i.e. cold, snowy weather – to germinate their seeds. Once they’ve taken root, disturbance like fire or grazing can boost plant growth and help native species out-compete non-native weedy species.
His team will also leave some areas untouched to compare how the restored plots contrast to the untouched areas in the long run. “I definitely see a lot of ecological questions we can experiment with,” says Liang. “We’ll have to wait a bit to see. It can take a long time for some of these plants to grow.”
Just around the creek bend
Close inspection of satellite imagery of CCESR reveals a lot about its historical land use. Near the old fields that Liang and his team plan to restore, is the is the reserve's namesake stream, Cedar Creek. Parts of the stream are more “straight” than the rest. Untouched sections of Cedar creek sporadically wind and bend through the landscape. The straight portion, says Lenhart, is the result of methods used to make terrain more suitable for agriculture.
“Most of the ditches in there were likely put in between 1900 and 1920 when it was too wet to farm,” says Lenhart. Straightening waterways typically alters the hydrology in such a way as to lower the water level in nearby terrain. Good for farming – not so great for unique wetland ecosystems. Think carnivorous plants, tall tamaracks, and expansive mats of thick moss or peatland.
Despite acquisition of the area after a push from conservation groups, the northern portion of Cedar Creek remained unrestored. Lenhart feels lucky to be part of efforts to change that. “It’s usually a massive battle to restore public ditches,” he says. “But a place that’s designated for science and nature preservation research is basically the perfect spot to do a stream ‘re-meander.’” It’s also not designated as a public ditch system by Isanti County, so Lenhart’s team doesn’t have to go through the mandated processes needed to naturalize a public ditch.
The project will take several phases.
“The basic idea is to add potentially over half a mile of stream,” says Lehnart. “That’s how much they cut off when they straightened it. It used to be very sinuous.” Re-meandering the stream will add more unique habitats, slow the water channels, and raise water levels slightly in the adjacent floodplain. In Cedar Creek’s case, these floodplains are peatlands – habitats known for their sponge-like carbon storage capacities – where spring water had dried up previously.
In the creek restoration project alone there’s opportunity to study ecology, hydrology, carbon and nutrient cycling. Since research and outreach is central to Cedar Creek’s wider mission, everyone benefits. “Cedar Creek is a unique place. There aren’t many undisturbed creeks in the southern half of the state. The wetlands have all sorts of benefits – for overall water quality, restoration, filtration, and reducing carbon dioxide emissions,” says Lenhart. “This is a pretty rare opportunity.” – Adara Taylor