Illinois Natural History Survey - University of Illinois

INHS Reports January-February 1996

Wetland Restoration at the Middle Fork River Forest Preserve

Over the past several decades, dramatic losses in wetland acreage have occurred across the United States. More than half of the country's original wetland area has been lost, and over 200,000 more acres disappear each year. Illinois, in particular, has been devastated, losing more than 90% of its original wetland acres. This loss is of special concern because of the important functions that wetlands perform.

Many people now realize the value of wetlands in helping contain and disperse floodwaters, as illustrated by the 1993 flood along the Mississippi and Illinois rivers. Wetlands are also of great importance as habitat for plants and animals. In Illinois, more than 40% of the state's threatened and endangered species use wetland habitats. This increasing realization of the great importance of wetlands, combined with their dramatic recent losses, has led to the rapid development of the science of wetland creation and restoration.

INHS researchers sampling vegetation at the Middle Fork River Forest Preserve.
(Photo by staff of INHS Center for Wildlife Ecology.)

In east-central Illinois, Survey researchers, in cooperation with the Champaign County Forest Preserve District, the Grand Prairie Friends, and The Nature Conservancy, have worked to restore a kettle marsh along the Middle Fork of the Vermilion River. Historically a wetland, this area had been drained by underground field tiles and had been previously used as pasture. In 1990, the drainage tile system was dismantled, restoring the natural hydrology. Almost immediately, wetland vegetation began to return, emerging from the existing seedbank, as well as establishing from nearby seed sources and from seeds brought in by wildlife. Forty-six species were recorded in the first year alone, dominated by native plants, such as spikerush, water plantain, beggar-ticks, and marsh yellow cress. Little vegetation was planted. Natural revegetation and community development were allowed to proceed at their own pace.

As documented by yearly vegetation sampling since 1991, wetland plants, such as duckweed, smartweed, sedge, and millet, established and flourished almost immediately, while others, like arrowhead and rice cutgrass, did not reach prevalence for a couple of years. Although rare at first, problematic, aggressive species, such as cattail and reed canary grass, became more dominant in the passing years. This growing and diverse wetland plant community encouraged the immigration of wildlife. Songbirds, shorebirds, rails, waterfowl, muskrats, coyotes, rabbits, deer, turtles, frogs, and snakes have all found this new wetland. Two birds listed as endangered in Illinois have been observed in the wetland, specifically the pied-billed grebe and the northern harrier (or marsh hawk). In 1994, a pied-billed grebe nested successfully in the marsh, producing several offspring.

Research, monitoring, and management of the wetland are continuing with the help of Illinois State Geological Survey researchers. In addition to continued vegetation sampling, water levels both above and beneath the ground are being monitored with staff gauges and groundwater wells. Researchers are investigating the development of the plant community over time and hope to relate these changes to the hydrology of the wetland. Initial results indicate that certain plant species, such as beggar-ticks, spikerush, and ragweed, fluctuate dramatically between wet and dry years. Monitoring of potentially problematic, aggressive plant species is continuing and, when necessary, control measures are taken. In November 1994, a controlled burn was conducted in an effort to help control cattail and reed canary grass. In response to this action, plant species diversity increased sharply, to over 60 species. Unfortunately, both target species increased slightly, while two highly desirable species (arrowhead and water plantain) decreased greatly. Based on these conflicting results, the use of fire as a management tool to control problem vegetation in the wetland is still being studied.

A restored wetland at the Middle Fork River Forest Preserve.
(Photo by staff of INHS Center for Wildlife Ecology.)

Finally, taking the restoration process one step further, surrounding areas are being restored to native prairie and oak savanna habitats. This continuing process involves many aspects of vegetation establishment and management, including the seeding and planting of prairie species and the regular use of fire to control problem vegetation and encourage the growth of fire-adapted prairie and savanna species. Continued monitoring of the entire restoration will ultimately allow the effectiveness of various habitat management techniques to be evaluated. Although restoration and management are ongoing, the overall goal of this project is to develop a natural, functioning, wetland-centered ecosystem that contributes to the natural resources of Illinois. Researchers also hope to gain valuable knowledge about the science of restoration and apply it successfully to similar types of restoration and management projects in the future.

Brian Wilm, Scott Simon, and Marilyn Morris, Center for Wildlife Ecology

Charlie Warwick, editor