|2/5/2016 10:36:00 AM|
Wetlands' vital role in habitats, clean water explained by ecologist
Denise Thornton and Doug HansmannThe quality of Wisconsin's groundwater, streams, rivers and lakes has long been a highly-prized natural resource, but our wetlands are often undervalued. In many cases they have been drained or filled with little regard for their environmental value, but as Pat Trochlell, Wetland Ecologist for the Wisconsin DNR told an audience of over 50 people on Thursday evening, wetlands throughout the state play a vital role in keeping our water clean and providing habitat for native plants and animals. And in particular, the wetlands of the Driftless Area have their own distinct characteristics and challenges.
Trochlell detailed what makes wetlands in the southwestern part of the state exceptional in the first of four Winter Conservation Conversations sponsored by the Blue Mounds Area Project, a community-based organization with a 20 year record of promoting the biodiversity of our region.
When the glaciers that covered much of Wisconsin finally melted away about 14,000 years ago, they left behind thick deposits of sand, silt, clay, gravel and rocks collectively know as glacial drift. But the last three glacial advances missed the southwestern part of state, leaving a landscape of steep ridges and deep valleys unscathed and uncovered by glacial drift for perhaps the past 500,000 years.
While they dodged the Driftless area, the glaciers still had an affect on its wetlands. Trochlell described how glaciers dammed up rivers in the area and turned the valleys into lakes where sediment collected.
"When the glaciers retreated, tremendous amounts of water flowed down these waterways," Trochlell said. "They formed the wide valleys with steep sides that now have streams running through them. You can actually see the broad valleys that were formed when you bike along the Military Ridge Trail."
One of Trochlell's favorite Driftless wetland types is floodplain forest, like the Tiffany Bottoms State Natural Area, part of the river delta at the mouth of the Chippewa River system, which in the 1800s is thought to have carried more water than the Wisconsin River.
She said the wetlands along the streams feeding into the Wisconsin River provide a travel corridor from northern Wisconsin for animals like bears and bobcats. The wetlands also provide important habitat for rare wetland birds and migrating flocks.
Trochlell described many rare native plants that require wetlands to survive, like Nodding Rattlesnake Root and Prairie Indian Plantain. She urged the audience to visit some of our state wetlands, but warned them to make sure they know what poison ivy and poison sumac look like before they do.
A good way to find out where to go is to visit the website of the Wisconsin Wetlands Association. Check out their section on Wisconsin's Wetland Gems, which provides descriptions and directions to some of the best preserved wetlands in the state.
Though people usually imagine broad marshy areas when they think of wetlands, in the Driftless Area most wetlands are found around streams in the bottom of winding valleys.
Driving the country roads, you can see streams everywhere that have cut deeply into the soil around them. These wetlands are in trouble, said Trochlell.
"European settlers broke the prairie sod on the hill tops and farmed with no erosion control.That cut off the ground water source from plants that needed it."
Tracy Hames, director of the Wisconsin Wetlands Association, agrees with Trochlell that Driftless Area wetlands are in trouble. Many agricultural practices and other types of development have changed the way rain water flows down the steep valley slopes.
"Instead of seeping slowly into the soil on its way down the hillsides, most of the water flushes off quickly into channels that were formed over thousands of years to handle a slower type of water flow," said Hames. "When water starts moving down a channel that is too small for it, it starts digging itself in deeper and deeper becoming entrenched."
"Wisconsin has lost half its wetlands in the last 150 years," Hames continued. "We need those wetlands to collect flood water, process sediments, provide fish and wildlife habitat and keep our lakes and rivers clean."
Trochlell said that invasive species are the biggest threat to our wetlands today. Plant species like Reed Canary Grass are degrading them. One in four Wisconsin wetlands is now dominated by Reed Canary Grass.
"It's having a destructive effect on our state natural areas," she said. "Avoca Prairie State Natural Area is being filled by this invasive. When it floods, the plant expands its range. It's hard to get rid of."
Global climate change is also affecting Driftless Area wetlands.
"We are going to see more extreme precipitation events," Trochlell said. "We will have more soil washing down to the valleys."
But the news is not all bad. Efforts to restore wetlands are underway, and some of them are doing very well, Trochlell said.
She described a successful wetland restoration project on a piece of property called Shea Prairie that was purchased by the Wisconsin Department of Transportation (WDOT) to mitigate an impact to wetlands in Iowa County. The WDOT gave the property to the Prairie Enthusiasts to restore its wetland. It is now part of a recovering natural habitat that includes 11 acres of cold water trout stream and stream bank habitat, two acres of degraded spring seeps and an ephemeral pond.
Wetland monitoring is an important part of this kind of restoration effort, and next summer Trochlell will be sampling nearby wetlands.
"We have 36 sites to visit in the Driftless area," she said. "We will be looking at high quality wetlands, sampling the vegetation and soil. It's a really great way to determine the conditions and diversity of the undisturbed plant communities so we can learn how to restore wetlands in the Driftless by having a plant list of what should be there."
Blue Mounds Area Project will be presenting three more Conservation Conversations this winter on Thursdays at 7 p.m. at the Mount Horeb branch of the State Bank of Cross Plains, 1740 East Main St. in Mount Horeb.
On, February 4, Dr. Karen Oberhauser of the University of Minnesota will talk about the biology and conservation of Monarch butterflies. February 18, Dr. Rebecca Christoffel, Iowa State University Extension wildlife specialist, will speak on reptile denizens of the Driftless Area. March 3, Amy Alstad the Blue Mounds Area Project outreach ecologist will speak on the 60-year record of changes in Wisconsin's prairie remnants.
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