Mann Wilderness Area State Preserve

Mann Wilderness Area is a rugged forested area along the Iowa River Greenbelt. This 103-acre preserve is located five miles north of Steamboat Rock in northeastern Hardin County. The Hardin County Conservation Board purchased the rugged area from Joe and Flossie Mann in 1960. It was dedicated as a biological and geological state preserve in 1979. 

About the Land

Located near the eastern edge of the Des Moines Lobe landform region, the topography of this preserve is dominated by a long, narrow ridge paralleled by deep ravines draining into the entrenched course of the Iowa River, which forms most of the preserve’s southern border. This highly dissected landscape was formed by downcutting streams that eroded through soft glacial deposits to the underlying limestone bedrock. Rugged topography with frequent outcrops of these Mississippian (350- million-years-old) limestones along the valley walls contribute to the scenic character of the Iowa River Greenbelt. 

Directions

1. From the intersection of Highway 175 and Highway 215 in Eldora, take Highway 175 east 1 mile to County Road S56. 
2. Turn north (left) and drive on this winding road for 4 miles to the town of Steamboat Rock. 
3. Continue north through the town on County Road S56 for 4.5 miles, then turn west (left) onto 160th Street. 
4. Drive west on 160th Street for 2.5 miles to a dead end at the preserve entrance (sign: Mann Wilderness Area).

Vegetation

Forest vegetation within this preserve varies greatly from place to place, reflecting the influences of slope, aspect, and past land use. Mature deciduous forest of white oak, red oak, and shagbark hickory prevails on the steepest slopes where logging and grazing were infrequent. Several large white oaks over 130 years old can be found along the edge of the ridge top. A large population of paper birch indicates sites where past logging and grazing were more recent and more intense. Ironwood, basswood, and ash are common in the understory of these communities. A large plantation of thirty- to forty-year-old pines is also found on the ridge top where the land was previously cleared for agriculture. Black walnut is the dominant tree in the narrow floodplain of the Iowa River where small patches of alluvium have formed. Other woody plants in the preserve include blue beech, bitternut hickory, hazelnut, wahoo, chokecherry, and downy arrowwood.

Plants & Wildflowers

 Over 170 plants occur here. Spring-blooming plants are abundant here with snow trillium, bloodroot, spring beauty, and rue anemone. By summer, starry false Solomon’s seal, honewort, tall sunflower, and white snakeroot can be seen. The forest is also rich with ferns including northern maidenhair fern, dissected grape fern, and creeping fragile fern. Woodland sunflower begins blooming in July followed by zigzag aster and blue wood aster in the fall. 

Wildlife

Chorus frogs, gray tree frogs, and cricket frogs can be found here. Raccoon, opossum, fox squirrel, and white-tailed deer are commonly seen. The Iowa River is a migration corridor for many raptors, including bald eagles, Cooper’s hawks, and Swainson’s hawks. Blue-winged warbler and scarlet tanagers are found here during the nesting season, and woodcock can infrequently be found during spring migration. Pileated and other woodpeckers can be frequently seen and heard, as well as many other songbirds and migrants. 

Archaeological Significance

Hardin County is rich in archaeological sites spanning at least 11,000 years. Ancient people used the Iowa River Greenbelt extensively, as evidenced by many mound groups and campsites in the valley along this part of the river. Several prehistoric sites dating between 3000 b.c. and a.d. 500 (Archaic through Middle Woodland time periods) are located within or adjacent to this preserve. 

Regulations

Hunting is permitted. 

Nearby Natural Areas

Other natural areas along the Iowa River Greenbelt include:

• Hardin City Woodland State Preserve
• Fallen Rock State Preserve 
• Pine Lake State Park
• Wildcat Cave.