Chichaqua Greenbelt - Turtlehead Fen

About Turtlehead Fen

Turtlehead Fen is owned and managed by the Polk County Conservation Board and is part of the Chichaqua Greenbelt Complex. Fens are a rare and unique wetland type, with groundwater the primary source of hydrology. Fens are scattered throughout northern and eastern Iowa, with the density of fens greatest in the northern part of the state. Iowa's fens are thought to be 2,000 to 10,000 years old; relatively young systems that have developed since the end of the Wisconsin Glacial Period.

Hillside seepage fens, such as Turtlehead Fen, can be found where groundwater flowing through porous soil above a restrictive layer surfaces as seepage along hill slopes above stream terraces. The groundwater seepage is copious, consistent, cold, and devoid of oxygen, which decreases rates of decomposition. As a result, dead plant matter accumulates forming an organic soil that looks similar to the composted peat commonly used in vegetable and flower gardening. In Iowa, it is the depth of this organic layer that distinguishes fens from hillside seeps, with fens having an organic or muck soil horizon greater than 18 inches in depth. In fens that receive significant and consistent groundwater flow, it is possible for this organic layer to float on top of the water. Walking on these fens is similar to walking on a waterbed, and traversing on thin areas could cause visitors to break through to a shockingly brisk bath to the knee and the risk of a lost boot.

As is the case for most fens, Turtlehead Fen is small in size and exhibits a noticeably different plant community than the surrounding landscape. Fens are dominated by hummock forming sedges and can be difficult to navigate. Where the mineral content of the groundwater is high, fens are minerotrophic and can be highly alkaline. Under such conditions, rare plants called calciphiles can be found, including Grass of Parnassus, Golden Ragwort, Sterile Sedge, Bog Birch, and Shrubby Cinquefoil. Less commonly, Iowa fens can be acidic, creating conditions suitable for the existence of acidophiles, such as sphagnum moss.

Due to their rarity and complex mode of development, fens are the only wetland type that cannot be drained and mitigated for in Iowa under the Swambuster provision of the 1982 Food Security Act. Furthermore, fens are a high conservation priority, with several programs available to aid in the restoration, management, and preservation of these unique wetland systems. Please contact your local Natural Resources Conservation Service, County Conservation Board, Iowa Department of Natural Resources or US Fish and Wildlife Service Private Lands Biologist for more details.

Amenities

This site offers off road parking. There are no restroom facilities or maintained trails.

How to Get There:

On Highway 65 North, continue north of the 118th Avenue intersection for 2.2 miles. At the N 75th Avenue W intersection, make a u-turn and head south on Highway 65 for one mile. The unmarked entrance to the parking area will be on the right side of the highway.

From Highway 65 South, the entrance of the unmarked parking area will be one mile south of the N 75th Avenue W intersection.

Nearby Sites of Interest:

• Chichaqua Greenbelt

• Engeldinger Marsh

• Franklin Cemetery Prairie Remnant

• Hartley Heritage Fen

Interesting literature concerning Fens in Iowa

Amon, James P., Carol A. Thompson, Quentin J. Carpenter, and James Miner. Temperate Zone Fens of the Glaciated Midwestern USA.

Anderson, W. A. 1943. A Fen in Northwestern Iowa. American Midland Naturalist 29(3):787-791.

Bedford, Barbara L. and Kevin S. Godwin. 2003. Fens of the United States: Distribution, Characteristics, and Scientific Connection Versus Legal Isolation. Wetlands 23(3):608-629.

Bryan, Georgia. 1993. Managing Iowa Habitats: Fen Wetlands. Iowa State University Extension Pm-1351f. 8 pages.

Nekola, Jeffrey C. and Thomas G. Lammers. 1989. Vascular Flora of Brayton-Horsley Prairie: A Remnant Prairie and Spring Fen Complex in Eastern Iowa, Castanea 54(4):238-254.

Nekola, Jeffery C. 1990. Rare Iowa Plant Notes from the R. V. Drexler Herbarium. Journal of the Iowa Academy of Sciecne 97(1):55-73.

Nekola, J. C. 1994. The environment and vascular flora of northeastern Iowa fen communities. Rhodora 96:121–169.

Nekola, Jeffery C. 2004. Vascular plant compositional gradients within and between Iowa fens. Journal of Vegetation Science 15(6):771-780.

Pearson, John A. and Mark J. Leoschke. 1992. Floristic and Conservation Status of Fens in Iowa. Journal of the Iowa Academy of Science 99(2-3):41-52.

Prior, J. C. 1991. Landforms of Iowa. University of Iowa Press, Iowa City, IA, US.

Rosburg, Thomas R. 2006: Autumnal floristic surveys of potential fen sites; Iowa Geological Survey.

Thompson, C. A., E. A. Bettis III, and R. G. Baker. 1992. Geology of Iowa fens. J. Iowa Acad. Sci 99:53–59.

Thompson, C., Prior, J., Quade, D. 1991. Quaternary Landforms and Hydrogeology of Fens in Clay and Dickinson Counties or Mucing about in Northwest Iowa. Geological Society of Iowa Guidebook 54. 35 pp.

van der Valk, A. G. 1975. Floristic composition and structure of a fen in northwest Iowa. Proc. Iowa Acad. Sci 82:113–118.

Wilson, Tre. 2007. Floristic Survey of Fens at Proposed Fox Valley Subdivision Johnson County, Iowa. Report submitted to the Iowa Department of Natural Resources. 6 Pages.

Websites:

Fens one of Iowa’s Unique Habitats – Iowa State University

Iowa’s Peatlands – Iowa Department of Natural Resources

Wet and Wild in Iowa’s Fens – Iowa Natural Heritage Foundation

Silver Lake Fen – Wild Sites Watchable Wildlife of Northwest Iowa

Delaney Fen Protected by INHF Conservation Project – Iowa Natural Heritage Foundation

Fens of Iowa – Iowa’s Water Ambient Monitoring Program

Becky’s Fen: Unique Property Features Some of Iowa’s Rarest Plants – WCF Courier.com