At the Chichaqua Bottoms Greenbelt in Polk County, near he town of Maxwell, researchers have developed a novel tool for restoring biodiversity to a landscape choked by invasive species: Set loose a herd of hungry goats.
The project began in 2008 when the Leopold Center for Sustainable Agriculture awarded a competitive grant to Iowa Heartland Resource Conservation and Development to study the benefits of incorporating livestock onto conservation lands. By dining on unwanted buckthorn, goats helped restore a rare swamp white oak savannah and created habitat for a wide array of native species, including Blanding's turtles, listed as threatened in Iowa.
Loren Lown, natural resource specialist for the Polk County Conservation Board, leads the project. Lown asked Deb and Eric Finch of State Center, Iowa, to let their herd of 30-plus goats browse at Chichaqua Bottoms, a 7,300-acre greenbelt along the Skunk River. The partnership allowed the Finches to raise healthy goats and rest their home pastures while Lown cleaned up the ecosystem.
Goats rotationally grazed, preferring to eat twigs, leaves, woody species
The goats, rotated through a 10-acre area divided into three paddocks, munched on invasive buckthorn and other unwanted plants. Goats prefer to eat twigs, leaves and woody species first, leaving the herbaceous layer alone. Lown described them as "little buckthorn bombs."
With the buckthorn gone, native plants begin to flourish again. Sedges and wildflowers appeared in formerly bare stretches of soil. The newly restored landscape supports a rare population of Blanding's turtles, indicating the presence of diverse wetland habitat. Recently a healthy, six-year-old turtle was found near the area where the goats browsed. Lown also noted other uncommon species in the area, such as the Graham's crayfish snake and Henslow's sparrow.
"We're getting a lot of use by animals that like the more open woodland," Lown says. "The diversity of the vegetation at the ground level has definitely increased. Prior to having the goats in there, the mid-story invasive species had shaded out almost everything on the ground floor."
Grazing, browsing were part of our natural ecosystem, which responds positively
"The bird life is phenomenal," he adds. "We have over 200 species of birds recorded at Chichaqua. We're doing something right for these species."
People have used Chichaqua Bottoms for a long time, not always for the best. Historic logging for railroad timber left only a few old oaks and agricultural fields replaced the prairies. But human land use can also provide disturbances that aid restoration efforts, as the project demonstrated. "Grazing and browsing were part of our natural ecosystem, so you would expect the ecosystem to respond in a positive way," Lown explains.
While goat browsing has helped restore the oak savannah, it's not a cure-all. Lown emphasizes the need to manage the landscape with multiple kinds of disturbances—browsing, grazing, mowing and fire—to give the native species a fighting chance. For example, some areas where goats knocked back buckthorn are now dominated by another exotic species, reed canary grass. Carefully timed controlled burns can help keep reed canary grass at bay.
"We used to just talk about prescribed fire," Lown says. "Now we speak about prescribed disturbance…. If you have a diverse disturbance regiment, then you get diverse plants and wildlife."
This project also studied the effects of cattle grazing on reconstructed prairie. Two scientists from Drake University, Keith Summerville and Tom Rosberg, are currently collecting and analyzing data from the project. Other partners include the USDA Natural Resources Conservation Service, Iowa Natural Resources Conservation Service, Practical Farmers of Iowa, Iowa Department of Natural Resources, Iowa State University Extension, Iowa Audubon Society, Iowa Prairie Network, Southern Iowa Forage and Livestock Committee, and the Iowa Forage and Grassland Council.