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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

August 2000

The seedhead on a stalk of reed canary grass. © Robert Queen

Grappling with the green giant

Reed canary grass grows in tall, dense stands of bright green, but it's hardly a sign of a healthy wetland.

Amy Groshek

The seedhead on a stalk of reed canary grass.

© Robert Queen

"Look at all that purple," said my friend, his forehead wrinkled in frustration. The highway skirted a large marsh, and I followed his gaze out the window. Surrounding the occasional purple streak of loosestrife flower were huge swaths of a bright green, thick-growing grass. Unnoticed, reed canary grass (Phalaris arundinacea) had invaded and subdued this wetland long before the purple loosestrife arrived.

"Reed canary grass has more influence over more acres than purple loosestrife, but because it's green and not showy, we don't notice it," says Dan Spuehler, management specialist for Wehr Nature Center in Milwaukee and former member of the State Natural Areas Management Crew for the DNR Bureau of Endangered Resources. Reed canary grass is native to North America, but a European subspecies has become an invasive pest in American wetlands, Spuehler says.

English farmers began cultivating the grass around 1824 and brought the cultivar to the eastern U.S. in the 1850s. The plant was hardy, grew in waterlogged marginal soils, spread easily and provided forage early in the growing season. The grass was promoted nationwide and farm workers were photographed planting and harvesting reed canary grass in Coos County, Oregon in 1885.

A United States Department of Agriculture pamphlet from 1929 describes the grass as "an excellent hay and pasture plant, both succulent and palatable that deserves a wider use...particularly on wet lands." Botanists, however, were already noting the invasive character of the plant. In 1940 C.C. Deam, in Flora of Indiana, wrote " observation with reed canary grass is that it is wise not to plant it if one wishes ever to get rid of it."

Wetland managers and scientists alike repeat Deam's sentiments today. DNR's Horicon Marsh Naturalist Bill Volkert notes that the stems of canary grass tend to lie down late in the summer season. The plant fails to shelter nesting wetland birds and pheasants. Young birds and mammals have difficulty navigating the dense stands reed canary grass forms. The stems are also too weak to serve as singing perches and nesting sites for songbirds. Further, the seeds do not provide much nutrition for small mammals.

Joel Trick of the U.S. Fish and Wildlife Service in Green Bay, conducting a 1997 study for the U.S. Environmental Protection Agency, found that small Wisconsin wetlands dominated by reed canary grass were rarely used by migratory birds.

And botanists statewide lament the loss of plant diversity in areas where reed canary grass has successfully invaded.

Wetlands ecologist Alice Thompson studied reed canary grass for her master's project. "I had this grand idea I was going to figure out what would control it," she said. The grass invades wetlands easily because it grows early in spring and shades out native plants that don't grow until later in the season. Its seeds shatter and spread through the air or by floating on water, so that any disturbed area downstream of a reed canary grass stand is at risk. The plant also loves nitrogen, and flourishes where urban runoff or siltation raises nutrient levels.

But high urban runoff and siltation are not factors in stable wetlands. Reed canary grass needs help to invade an area. "Disturbance is the real factor," says Thompson. Again and again, the cause of invasions is disturbance of some sort, whether it's fluctuating water, a change in nutrient levels, siltation or devegetation.

As botanist C.C. Deam suggested, removing established reed canary grass is very difficult. Each invaded area differs in size and ecology, and each requires careful planning and follow-through. Thompson is writing a landowners' guide to wetland restoration, which will set out basic techniques that can be adapted to a site's individual needs.

To help those working privately and through government organizations to control the plant, Joanne Kline of DNR's Southeast Region formed a Reed Canary Grass Task Force. "The task force pulls together people from all areas – research, education, landscape design, landowners, and managers," says Kline. "Effective control takes both getting the information out to people who will use it and getting feedback to come up with even better ideas."

The task force published guidelines, "Reed Canary Grass Control Methods in Herbaceous Wetlands," that outlines and discusses various management strategies. Members also serve as contacts for those seeking advice or information.

One member, Joy Zedler, the Aldo Leopold Professor of Restoration Ecology at UW-Madison, tried control techniques on an invaded portion of the UW-Madison Arboretum's Greene Prairie. On seven wetland acres, Zedler is investigating which native species can compete with reed canary grass when combined with prescribed burning.

Methods to check the spread of reed canary grass include controlled burning and planting of hardy native species. © Alice Thompson
Methods to check the spread of reed canary grass include controlled burning and planting of hardy native species.

© Alice Thompson

A main component of the study, says Zedler, will be the human community's response. Some properties might have to be flooded or drained to restore original hydrology. A genuine attack on the invasion also requires changing the flow of storm runoff from homes and public properties within the watershed. Zedler is curious about how much people are willing to pay to preserve the wetland. As invasive control efforts increase, public sentiment becomes crucial.

Even with so much attention on the harmful aspects of reed canary grass, some soil stabilization and stream bank restoration experts say the plant does have a few redeeming qualities. In disturbed areas vulnerable to erosion, few other plants grow as quickly and hold soil as well as reed canary grass. Trout stream restoration would become difficult without reed canary grass – thick, matted root structure to stabilize banks and provide habitat.

But there are alternatives to reed canary grass. "Anywhere it effectively controls erosion there are native plants that can take its place," says Dan Spuehler, listing several native grasses and sedges in potential mixtures. "It's an easy option." Spuehler supports using affordable native plant species and keeping reed canary grass out of as many wetland areas as possible.

Controlling exotic species is challenging and time-consuming, but restoring native plant diversity is a rewarding experience. Learning to identify native and exotic species greatly enriches one's understanding of natural systems. Reed canary grass is not the first invasive plant to grow its way into our native habitats, and it will not be the last, but information and options are available to check its progress.

Amy Groshek studies botany and writing at the University of Wisconsin-Stevens Point.