Cowles Bog
Located at Indiana Dunes National Lakeshore
Indiana Dunes National Lakeshore, authorized by Congress as a national park in 1966, is located on the southern rim of Lake Michigan. It includes a variety of wetlands such as bottomland swamps, interdunal swales, fens, pannes, and bogs.
The Cowles Bog Wetland Complex (CBWC) represents about 85 hectares of the western terminus of the largest interdunal wetland (The Great Marsh) present near the Lake Michigan shoreline. It was named after the University of Chicago plant ecologist, Henry Cowles, who conducted field studies there in the early 1900s. Plant inventory work conducted from 2002 through 2004 demonstrated that the complex is an exceptional composition of bog, fen, bottomland swamp forest, sedge-meadow, wet-prairie, shallow marsh, and a vegetated floating mat, all intertwined in a relatively small area.
The CBWC is an important segment of America's natural heritage as indicated by its designation in 1965 as a National Natural Landmark and by a subsequent congressional directive in 1977 for the NPS "to study and report concerning the following objectives...preservation and restoration of the watersheds of Cowles Bog and its associated wetlands." In 1976, the federal endangered Mitchell's Satyr butterfly was observed in the CBWC. As recently as 1990, 15 state listed plant species and 41 special floristic elements were present. The 2002-2004 inventory work indicated that invasive species, Typha spp.(hybrid cattails) and Phragmites australis (common reed) are present in over 90 percent of the CBWC; however, the abiotic signature of various plant assemblages remains intact.
Recent molecular biology studies conducted in 2003-2005 by NPS and USGS researchers indicate that the invasive hybrid cattail in Cowles Bog is a genetic mixture of the exotic narrow leaf cattail and the native broad leaf cattail. Genetic analysis indicates that more exotic cattail genes than native cattail genes are present in the population. The hybrid is fertile and the plants in Cowles Bog can interbreed with each other, creating what botanists call a hybrid swarm.
In much of the CBWC, the floristic resource present in the Cowles era (1900-1940) has been totally extirpated by the invasive species. However, there remain areas where the floristic vestiges from the Cowles era are still present. Current actions are being taken by park botanists to preserve much of the Cowles era vegetation and provide much needed habitat for native wildlife. Restoration work will include initiation of recovery of a 6-hectare nutrient rich fen, preserve floristically rich areas in mid- to early invasive stage, and convert hybrid cattail monoculture to a graminoid/forb community reflective of plant structure present in the Cowles era.
 |
 |
 |
Joy Marburger, PhD
Great Lakes Research and Education Center
Have you been to a wetland worth visiting? Contact the SWS webmaster if you have a brief story with photos you would like to submit.
