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Crooked Lake Nature Preserve
Before agriculture became widespread, Indiana was quite a wet place. Thanks to glacial activity in the north we were endowed with thousands of lakes, ponds, marshes, swamps, and peat bogs. In the southern part of the state, floodplain and swamp forest were also widespread, particularly in the southwest lowlands. Even in the limestone counties of south-central Indiana, the dissolved bedrock has given us many sinkholes, springs, and lowland swamps.
When Indiana was originally surveyed (1799 to 1834), the surveyors found and described broad areas of poorly drained wetlands. The wetlands of northwestern Indiana were chiefly wet prairie, while those of the northeastern section were more often swamps or bogs, dominated by woody vegetation. In 1816, about half of the surface area of northwestern Indiana was ponded during 6 months of the year. Benton County was more than half wetland. In 1834, Beaver Lake, in Newton County, occupied 28,500 acres.
But the majority of these wetlands were not to last. More and more land was converted to agriculture, through dredging, draining, ditching, and damming. 1884 saw the start of major changes to the Kankakee River and its marshes by dredging, straightening the river, tiling and ditching the emergent lands. By 1917 Beaver Lake had shrunk from its 28,500 acres to 10,000 acres, and today exists in name only.
Today, the concentration is on preserving wetlands rather than destroying them. They are seen as places of beauty, as habitat for a variety of plants and animals and as replenishment and a cleaning filter for groundwater.
Wetland Communities include:
Bogs are the result of ponds filling up with dead plant matter – peat. They are usually found in glacial depressions, with restricted drainage. The peat deposits often float. Eventually shrubs and trees cover the area. Along the periphery of the bog is often a zone of open water, marsh, sedge marsh, or fen.
Dune & swale is a complex of linear and parallel east-to-west sand ridges interspersed with long ponds and marshes. It defines the beach and dune area of Lake Chicago, the precursor to Lake Michigan.
Fens occur in peat at the base of slopes where they receive calcareous water seepage. They generally occur in lake basins and stream valleys. Water is usually freely running at the surface. There is a diverse mix of plant species including grasses, shrubs, and trees.
Flatwoods occur on level or nearly level soil that has an impermeable or slowly permeable layer that causes a shallow water table. Spring ponds are common.
Floodplain forests are on the floodplain of rivers and streams. Diversity of plant species depends on how much and for how long flooding occurs.
Marshes are wetlands dominated by grasses. They have water near or above the surface for most of the year and occur in glacial potholes, river valleys, and lake plains. They have a wide variety of plant communities depending on the water depth – the deeper the water, the fewer the plant species.
Ponds are defined as permanent or semi-permanent small, still bodies of water, usually shallow enough to allow rooted aquatic plants across most of it. A lake differs by being big enough to have a barren wave-swept shore.
Sedge meadows are wetlands dominated by sedges on peat, muck, or wet sand. There is little plant diversity.
Seeps occur where soil is saturated from groundwater flowing to the surface in a diffuse flow. The soil makeup and water pH define the plant communities found around the seep.
Streams are defined as flowing waters that are permanent year round. They are divided into creeks and rivers by their gradient and size. A creek has a watershed smaller than 200 square miles, and a river has 200 square miles or more. A major river, with a wide and deep channel with a very large flow is actually a low-gradient stream – the difference is just in the name.
Swamps are permanent or semi-permanent bodies of water dominated by woody plants. Shrub swamps are dominated by shrubs; swamp forests by trees. They are often associated with ponds in wet floodplain forests.
Several Indiana dedicated Nature Preserves protect a variety of wetland communities. We invite you to explore these interesting and beautiful wetlands on our list of Nature Preserves page to learn more. Here are a few examples of nature preserves with wetland communities: