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  1. Illinois DNR
  2. Conservation
  3. Wetlands
  4. Wetland Communities in Illinois

Wetland Communities in Illinois

 You may view a larger picture.  Just click on it.  Below the wetland communities is a description of the habitat and soil information      

      
 
     

 

       Swamp

      Forested

      Wet Meadow

        Intermittent Stream

   

    Lower Perennial Stream

​   

     Pond 

       Marsh                                       

     

      Bog    

    ​

      Scrub-Shrub 

        Open Lake

    ​

     Fen  

    ​   

      Lake Shore                               

 

​   

    Upper Perennial Stream

 
 
Swamp - *PF06F, PF02F, PF02G
The swamp communities of Illinois are the northernmost remnant  of vast network that once covered much of the southern United States. Many  plant and animal species that occur here are at the northernmost edge of their range.
The characteristics of this community are the presence of permanent to semipermanent water, and a greater than 30 % areal canopy cover of tall (over 20 feet) woody vegetation.  In many areas, the canopy cover exceeds 80%. The dominant trees include bald cypress, some more than 1,000 years old, with knees up to 10 feet high.  These trees typically occur as scattered individuals, or in small groves
.
The classification code PF06F represents a mixed class and is only used in areas where broad-leaved and needle-leaved deciduous trees cannot be distinguished on aerial photography; for example, where bald cypress and water tupelo trees are growing together in  approximately equal numbers.
 
The soils in this community consist of silt and clayey materals. They range in reaction from very strongly acid to neutral.  The major soils include undrained phases of Okaw silt loam, Darwin silty clay, and Jacob clay.
 
Forest - *PF01A, PF01C
Forested wetlands differ from true swamps in that they lack continuously standing water, although repeated flooding is common.  Differences in the length of inundation give rise to a variety of community types within this classification.  For example, large timbered areas bordering swamps or rivers with frequent flooding (PF01C) often have a poorly developed, very open understory.  Silver maple, sycamore, and cottonwood are common, and the forest floor is littered with rotting logs and woody debris deposited by flood water. In contrast, drier areas (PF01A), where flooding is not as prolonged, have a greater diversity of plant species, with oaks, elms, and hickory common in the canopy.  The forest floor in these areas is often covered by a variety of annual and/or perennial plants.
 
The soils in this community consist of silty and clayey alluvial materials.  They are subject to annual flooding with brief to long duration.  Reaction of the materials ranges from strongly to slightly acid.  The major soils include Bonnie silt loam, Birds silt loam, Piopolis silt loam, Petrolia silty clay loam, Karnak silty clay, and Sharon silt loam.
 
Wet Meadows - *PEMA, *PEMC, PEMAf, PEMAd, PEMCf
Wet meadows are characterized by moist to saturated soils with standing water present for only brief to moderate periods during the growing season. Vegetation includes a wide variety of herbaceous species, from sedges and rushes to forbs and grasses. Woody vegetation, if present, accounts for less than 30% of the total area cover.
 
Wet meadows were once common through Illinois, but now only small remnants remain. They were often found associated with wetland types, especially at the drier fringes of a lake, pond, or marsh. In some areas, wet meadows are often partially drained and farmed , and therefore lack the vegetation typical of this community.
The soils in this community consist of silty and clayey materials in depressional areas. The reaction is typically neutral. The major soils are dominantly wet phases, or undrained phases of Peotone silty clay loam, Rantoul silty clay, Booker clay, Edinburg silty clay loam, Brooklyn silt loam, and Denny silt loam.
 
Intermittent Stream - *R4SBF, R4SBC
In this wetland type, the channel contains flowing water  for only a portion of the year. When not flowing, the water may remain in isolated pools, or surface water may be absent.n this wetland type, the channel contains flowing water  for only a portion of the year. When not flowing, the water may remain in isolated pools, or surface water may be absent.

The substrate consists of organic deposits, sand, gravel, cobble, rubble, bedrock, or pioneering plants. There are generally no named soils in this community, although some areas may be listed as mixed alluvial land.
Vegetation is dependent on the length of inundation, as well as the substrate type. In many cases, streambeds are not vegetated because of the scouring effect of the moving water, but occasionally "pioneering" annuals or perennials may colonize the area during low flow. Many small drainage ditches are included with this type.
 
Lower Perennial Stream - *R2UBH, R2EM2H, R2RBH
The majority of Illinois' Large streams and rivers can be categorized as lower perennial. Permanent water usually flowing over a bottom of silt, sand, clay, or fine gravel, and a well developed floodplain characterized this type of wetland. As in the upper perennial streams, there are not named soils in this community.

Oxygen deficits sometimes occur, and true planktonic organisms exist. Faunal diversity is largely dependent on water quality, with the more heavily polluted streams supporting less variety. Wetland vegetation consists mostly of rooted emergents, with floating leaved or submerged vascular plants and algae occurring rarely. Extensive wetland marshes, swamps, or bottomland forests may be found along the perimeter, or within the channel of the stream, but these areas will be classified in the palustrine system when the vegetation comprises greater than 30% of the areal cover, and the area is dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens.
 
Pond -  *P0WG, *PUBG, PUBH, PABG
This Community type is characterized by the presence of nearly permanent open water a minimum of one-half acre in size to a maximum of 20 acres(8 hectares). Although free of vegetation throughout the non-growing season, floating vascular plants and/or algae often comprise a majority of the vegetation mass during the mid-summer months. Rooted vegetation is generally restricted to the shallows. Bottom sediments consist of mud, sand, cobble, gravel, and organic debris.
Many Illinois ponds are man-made and include farm ponds, borrow pits, and small reservoirs, as well as natural open water areas which may occur within a marsh or swamp.
 
The soils of this community consist of silty and loamy materials. Reaction of the materials ranges from strongly acid to moderately alkaline. Typically, ponds are constructed in Ava silt loam, Hosmer silt loam, and Hickory loam in southern Illinois. Some of the larger ponds have Belknap silt loam in the bottom.  In central and northern Illinois, the major sloping soils include Fayette silt loam, Miami silt loam, and Morley silt loam. La*PEMF, PEMGrger ponds would typically have Lawson silt loam in the bottom.
 
 Marsh - *PEMF, PEMG
The marsh community overlaps somewhat with the wet meadow, but includes species that prefer standing water for prolonged periods throughout the growing season.  Woody vegetation accounts for less than 30% of the areal cover.
Marsh vegetation consists of a variety of herbaceous species,  with cattails representing one of the most common plants. The presence of standing water throughout the growing season contributes to an extremely high level of productivity. Hundreds of species of fish, birds, and other wildlife spend all or part of their lives in marshes. Marshes were once common throughout Illinois, but today, only a few remnants remain.  Many of these areas are part of larger wetland complexes, occurring along the border of a pond or within the floodplain of a stream.
 
The soils in this community consist of silty, loamy, and clayey materials. Some organic soils are included. The reaction is typically neutral. The major soils include ponded phases of Karnak clay, Comfrey loam, Palms muck, Adrian muck, and Darwin silty clay.
 
The bog communities of Illinois are found almost exclusively in glaciated depressions of the northeast corner of the state. Drainage is usually restricted, and this, coupled with an abundance of sphagnum moss, results in conditions which are highly acidic.  The bog communities of Illinois are found almost exclusively in glaciated depressions of the northeast corner of the state. Drainage is usually restricted, and this, coupled with an abundance of sphagnum moss, results in conditions which are highly acidic.

The soils of a bog are saturated throughout the growing season in most years, and small open water areas are common. Vegetation consists of a variety of emergents with shrubs and/or small trees occurring on more consolidated peat.  Soils acidity and low nutrient levels inhibit the invasion of competing species. No specific classification code exists for these areas so therefore the wetland maps cannot be used exclusively to locate bogs.  However, the saturated water regime (B) will provide a clue to the presence of a bog, since this regime was used most commonly in describing these areas.
 
The soils in this community consist of organic materials.  The principal soil is Houghton peat.  Other associated organic soils which are not highly acidic are Houghton muck, Aurelius muck, and Muskego muck.
  
Scrub-Shrub -*PSS1C, PSS1A, PSS1F
A scrub-shrub wetland typifies a community in transition and exemplifies the dynamic nature of wetlands in general. Many emergent wetlands, left undisturbed, will gradually be replaced through succession by woody vegetation that will in time develop northeastern Illinois, which climax with the scrub-shrub phase.

The scrub-shrub wetland is often found grading shoreward from an emergent wetland which borders a lake, stream, or pond. The woody vegetation accounts for at least 30% of the vegetation present, and must be less than 20 feet (6 meters) tall.
 
Species composition is dependent on the length of inundation, with willows and dogwood growing in the temporarily to seasonally wet areas (PSS1A, PSS1C) and buttonbush in semipermanently flooded areas (PSS1F).
The soils in this community typically are wet phases of alluvial soils. They may have been cropland at one time, particularly where they border large constructed reservoirs. Most of the materials range in reaction from strongly acid to neutral. The major soils include Wakeland silt loam, Birds silt loam, Belknap silt loam, Bonnie silt loam, Karnak silty clay, and Sawmill silty clay loam.
 
Open Lake - *L10WH, *L1UBH
This community includes wetlands and deepwater habitats with all the following characteristics: 1. Situated in a topographic depression or a dammed river channel; 2. Lacking trees, shrubs, persistent emergents, emergent mosses, or lichens with greater than 30% areal coverage; and, 3. Total area exceeds 20 acres (8 hectares). Some areas less than 20 acres may be included if the depth is greater than 6.6 feet (2 meters) at low water, or if an active wave-formed or bedrock shoreline makes up all or part of the boundary.

In general, this wetland type includes all permanently flooded, natural or artificial lakes and reservoirs. Typically, there are extensive areas of deep water with moderate to considerable wave action. Vegetation is limited to the shallow edges from shore to a depth of approximately 2 meters.
 
The soils in this community consist of silty, loamy, and clayey materials in man-made lakes, and loamy materials in antural lakes. Reaction of the materials ranges from strongly acid to moderately alkaline. Some major soils inundated by construction of lakes in southern Illinois include Belknap silt loam and Bonnie silt loam on floodplains, and Hickory loam on side slopes.
 
In central and northern Illinois, the major soils include Lawson silt loam and Sawmill silty clay loam on floodplains, and Hennepin loam on the side slopes. Soils on the bottom of natural lakes are not named.
 
A fen is a type of wet meadow fed by an alkaline water source such as a calcareous spring or seep. The deposition of calcium and magnesium in the soil results in an elevated soil pH, and gives rise to a variety of unique plants adapted to surviving these conditions.

Fens are most commonly found in the northeast corner of the state, and in isolated areas along the Illinois River valley.  The vegetation is normally comprised of herbaceous emergents, although woody shrubs or even trees sometimes occur.As is the case with bogs, no specific classification code exists for fens, so the wetland maps cannot be used to pinpoint their location.  In general, they will most often be listed as an emergent wetland.
 
The soils in this community consist of calcareous silts, clay, and organic materials.  The major soils include Calco silty clay loam, Mound prairie silty clay loam, and Lena muck.
  
Lake Shore - *L2USJ, L2RSJ
The lake shore community is generally restricted to the edges of large rivers, and wave-affected lakes such as Lake Michigan, Carlyle Lake, and Rend Lake. Erosion and sediment deposition by waves produce a number of landforms such as beaches, bars, and flats, all of which are included in this type.

Vegetation is generally lacking except for pioneering plants that become established during brief favorable growing conditions. The substrate and water regime are the important factors that determine the types of plant and animal communities present. For example, rocky shores (L2RSJ) tend to support fewer plant species than a sandy beach or mud bar (L2USJ). The amount of vegetation is also dependent on the strength of the wave action as well as the length of inundation.
 
Upper Perennial Stream - *R3UBH, R3RBH, R3ABH
The typical soil material along the lake shores is beach sand. Sand bars along major rivers are similar; however, these materials are called riverwash.
 
*Used throughout the community descriptions to indicate the most commonly occurring code in Illinois
This wetland community is characterized by the presence of swiftly moving, permanent water and usually a poorly developed floodplain.  The bottom sediments consist of gravel,  cobble, rubble, boulders, or bedrock.  Riffles and rapids are interspersed with pools along the length of the stream. There are no named soils in this community although, in large areas, some soil maps may list them as riverwash.

Great diversity exists in the fish and aquatic invertebrate faunna due to the abundance of oxygen, the variety of habitat types, and generally good water quality.
Water willow is one of the most common and abundant plants of gravel bars between pools, and in the finer soils within shallow water areas.
 
Other wetland vegetation is limited to a few species that can survive in the shallows or along the stream bank.
Some headwater streams in Illinois can be placed in this class.
 
 
 *      Used throughout the community descriptions to indicate the most commonly occurring code in Illinois Used throughout the community descriptions to indicate the most commonly occurring code in Illinois