Mingo Swamp

• Category: Inland Aquatic Biomes.
• Geographic Location: North America.
• Summary: In an epic story of environmental ruin and renewal, conservationists have revived the Mingo Swamp ecosystem that was once reduced to a burnt and eroded wasteland.

Lying within an abandoned channel of the Mississippi River, and nestled between the Ozark Escarpment on the west and the limestone bluffs of Crowley’s Ridge on the east, the Mingo Swamp sits squarely within the Boot Heel of southeastern Missouri, approximately 150 miles (240 kilometers) south of St. Louis. Alluvial fans formed by tributaries to the old Mississippi River channel act as natural levees here, slowing drainage through the basin that also is interrupted by several small sand ridges. These may be riverine deposits or, alternatively, may have been forced to the surface by earthquakes. Indeed, the region lies within the New Madrid seismic zone, the source of some of the most powerful earthquakes recorded in North America.

The Mingo Swamp was once part of a 25-million-acre (10.1-million-hectare) complex of forested wetlands extending along both sides of the Mississippi River from Illinois to Louisiana. The seasonal flooding of the Mississippi created a shifting mosaic of dynamic habitats that supported a diverse and abundant array of fish and wildlife species. Native Americans used the area seasonally for hunting and fishing, attracted by its abundant wildlife. The area was later included in the 1803 Louisiana Purchase, but remained relatively unpopulated until the 1880s, when lumber companies began intensively harvesting its vast forests of cypress and tupelo. By 1935, the majority of the venerable trees had fallen—mainly for railroad ties and building materials—and the lumber companies were forced to look elsewhere for supplies.

Seeking to reap additional revenues through agricultural production, landowners constructed a system of drainage ditches to divert water from the swamp and into the nearby St. Francis River. However, periodic flooding of the river and the region’s poorly-drained acidic soils, combined with falling land prices during the Great Depression, dashed any remaining hopes of commercially farming the Mingo.

What followed was a free-for-all of unregulated land uses. Timber was cut indiscriminately without regard to ownership, wildlife and waterfowl were rampantly over-harvested, and lands were burned with impunity to maintain open grassland conditions for cattle and hogs. Wildlife populations were decimated. The region’s once-abundant deer and beaver populations were locally extirpated; wild turkey nearly so.

Nevertheless, deforested, drained, and over-exploited, the Mingo was designated a National Wildlife Refuge (NWR) in 1944, with a primary mandate to preserve Mississippi Lowland Forest habitats and to provide resting, feeding, nesting, and brooding habitat for waterfowl and other migratory birds traveling the Mississippi Flyway. The western portion of the refuge was designated a Wilderness Area in 1976. Together, the Mingo NWR and Mingo Wilderness Area preserve and provide opportunities to study the unique ecosystems and natural features of the region.

Biodiversity

Nearly 70 percent of the 21,592-acre (8,737-hectare) Mingo NWR is composed of Mississippi bottomland hardwood forest, complemented by marsh and open water habitats (23 percent) and grassy openings (3 percent). Flanked by bluffs, the swamp floods seasonally. Vegetation communities vary along a narrow elevational gradient that corresponds to the degree of inundation. Three upland community types are recognized, as well as four bottomland community types, the most extensive being Oak Hardwood Bottoms that occupy shallowly inundated areas between drainage ditch levees and floodplains.

Bottomland hardwood forests are one of the lowest and wettest types of hardwood forests. They serve as a transition area between the drier upland hardwood forest, and wet floodplains and forested wetlands. The trees located in this area are cherrybark oak, swamp white oak, swamp chestnut oak, Shumard oak, pin oak, willow oak, overcup oak, shagbark hickory, and water hickory. Also in the swamp forest ecosystem are bald cypress and water tupelo, species that have adapted to the flooded conditions of their environment.

A total of 279 resident and migratory bird species use the Mingo’s refuge habitats throughout the year, including tens of thousands of migrating waterfowl. Hundreds of thousands of migrating ducks can be seen at any one time, as can masses of herons, ibises, swans, grebes, geese, gulls, loons, rails, and terns. Whooping crane, an endangered species, finds haven in the Mingo Swamp, as do the bald eagle and peregrine falcon.

Thirty-eight mammal species occur here, including the swamp rabbit, a relative of the eastern cottontail that regularly takes to water to move about and escape predators. Other mammals include deer, bobcat, and beaver.

More than 30 species of amphibians and reptiles can be found, including three species of venomous snakes, such as the cottonmouth, which hibernates in the cracks and crevices of the bluffs surrounding the refuge. While a complete list of fish species has not yet been compiled, at least 46 species are known to occur in the area’s ponds and ditches.

Environmental Protection

Preservation and restoration of Mississippi Bottomland Forest remnants is a top priority for conservation planners, and the Mingo NWR is an important part of this strategy. Areas of concern include enhancing the natural productivity of the swamp and its surroundings; improving drainage through the use of water control structures, ditches, and dikes, providing habitat, and producing food for wildlife, including preserving open marsh areas that nurture aquatic invertebrates and high-energy seeds.

Wildfires are managed with prescribed fire where appropriate to restore natural ecological processes and minimize greenhouse gas emissions. Ongoing reforestation using native plants helps increase carbon sequestration, a natural way to ward off climate change.

Various natural populations here—including groups as diverse as mussels, moths, and mushrooms—are monitored as part of local and national surveys. Careful monitoring and management of invasive plants and animals is an ongoing need, as is maintaining environmental controls over contaminants, such as mercury, to minimize their potential effects on wildlife and human health.

Through careful management, the majority of plant and animal species historically present in the Mingo Swamp are being restored to the biome, and ecological succession to a complex mosaic of mature forested wetlands is occurring. Ongoing challenges include keeping swamp forces in balance in the face of climate change-induced alterations in rainfall patterns, temperature, and humidity. One of the biggest threats from climate change is the alteration of precipitation patterns. Changes could lead to more frequent and extreme flooding, as well as periods of drought that could cause water level drops. Both situations could negatively impact plant growth and the health of aquatic species that rely on stable water conditions for their well-being. Fluctuating water levels could also create a loss of habitat and breeding grounds for various wildlife species.

Bibliography

Conservation Fund. “Restoring a Forest Legacy at Mingo National Wildlife Refuge.” s3.amazonaws.com/CCBA/Projects/Restoring‗a‗Forest‗Legacy‗at‗Mingo‗National‗Wildlife‗Refuge/The‗Conservation‗Fund‗Mingo+NWR‗Project‗Implementation‗Report.pdf. Accessed 18 Nov. 2024.

Heitmeyer, Mickey E., et al. Water and Habitat Dynamics of the Mingo Swamp in Southeastern Missouri. Washington, DC: U.S. Fish and Wildlife Service, 1989.

“Mingo National Wildlife Refuge.” U.S. Fish and Wildlife Service, 27 Oct. 2022, www.fws.gov/refuge/mingo. Accessed 18 Nov. 2024.

Rundle, W. Dean and Leigh H. Fredrickson. “Managing Seasonally Flooded Impoundments for Migrant Rails and Shorebirds.” Wildlife Society Bulletin 9, no. 2 (1981).

U.S. Fish and Wildlife Service. “Mingo, Pilot Knob, and Ozark Cavefish National Wildlife Refuges Comprehensive Conservation Plan.” . Accessed 18 Nov. 2024.