Natural Resources
Conservation Service
Ecological site F113XY920IL
Silty Floodplain Forest
Last updated: 5/17/2024
Accessed: 12/21/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 113X–Central Claypan Areas
The eastern Illinois portion of the Central Claypan Areas MLRA is in the Till Plains Section of the Central Lowland Province of the Interior Plains (USDA-NRCS, 2006) and includes the Southern Till Plain Natural Division of the natural divisions of Illinois (Schwegman, 1973; 1997; IDNR, 2018) in south-central Illinois. South-central Illinois is a dissected Illinoisan till plain south of the terminal Wisconsin moraine. This region consists of nearly level to gently sloping, old till plains. Stream valleys are shallow and generally are narrow. Elevation is about 660 feet (200 meters), increasing gradually from south to north. Local relief is generally low on the broad, flat till plains and flood plains and high on the dissected hills bordering rivers or drainage systems. The Kaskaskia, Little Muddy, Little Wabash, Embarras, and Skillet Fork rivers are part of this area. This region is covered with loess, which overlies old glacial drift (Illinoisan till) that has a high content of clay. Fragipans are also present. Pennsylvanian limestone and shale bedrock underlay the glacial till. The dominant soil orders in this region are Alfisol and Mollisol. The soils in the area predominantly have a mesic soil temperature regime, an aquic or udic soil moisture regime, and mixed or smectitic mineralogy. They generally are very deep, well drained to poorly drained, and loamy or clayey. (USDA-NRCS, 2006).
Classification relationships
Major Land Resource Area (MLRA) (USDA-NRCS, 2006):
113 – Central Claypan Areas, Eastern Part
U.S. Forest Service Ecoregions (Cleland et al. 2007):
Domain: Humid Temperate Domain
Division: Hot Continental Division
Province: Eastern Broadleaf Forest (Continental)
Province Code: 222
Section: Central Till Plains, Oak-Hickory Section
Section Code: 222G
Ecological site concept
The historic pre-European settlement vegetation on this site was dominated by a variable canopy cover of deciduous trees with an understory of shade-tolerant shrubs and ground flora (LANDFIRE 2009; Nelson 2010; White 1978). They occur on nearly level to gently undulating flood plains of rivers and large streams. Soils are moderately well to well drained and very deep, formed in silty alluvium (SSS NRCS OSD, 2018).
Silty Floodplain Forests resemble Loamy Floodplain Forests, except they lack the variety of oak species (Quercus spp.). Stands are dominated by American sycamore (Platanus occidentalis L.)*, with a mixture of other species, including silver maple (Acer saccharinum L.), white ash (Fraxinus americana L.), green ash (Fraxinus pennsylvanica Marshall), black walnut (Juglans nigra L.), American elm (Ulmus americana L.), and slippery elm (Ulmus rubra Muhl.). Shrubs include pawpaw (Asimina triloba (L.) Dunal) and northern spicebush (Lindera benzoin (L.) Blume). Vines may be abundant, including Virginia creeper (Parthenocissus quinquefolia (L.) Planch.) and eastern poison ivy (Toxicodendron radicans (L.) Kuntze). Herbaceous species include Jack in the pulpit (Arisaema triphyllum (L.) Schott), Canadian wildginger (Asarum canadense L.), smallspike false nettle (Boehmeria cylindrica (L.) Sw.), Virginia wildrye (Elymus virginicus L.), Canadian clearweed (Pilea pumila (L.) A. Gray), jumpseed (Polygonum virginianum L.), and others. (LANDFIRE 2009; Nelson 2010; NatureServe 2018; Voigt and Mohlenbrock 1964). Historically, seasonal flooding was the primary disturbance factor, while windthrow events and beaver alterations were secondary factors.
*All plant common and scientific names in this document were obtained from the U.S. Department of Agriculture – Natural Resources Conservation Service National PLANTS Database (USDA NRCS, 2018).
Associated sites
F113XY911IL |
Loamy Till Backslope Forest This ecological site is located on steep backslopes above Silty Floodplain Forests. |
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F113XY919IL |
Wet Silty Floodplain Forest This ecological site is located in the floodplain on silty water sediments in low lying areas. |
F113XY922IL |
Loamy Floodplain Forest This ecological site has well drained coarse-loamy water sediments found on narrow flood plains, natural levees, and floodplain steps. |
F113XY921IL |
Wet Loamy Floodplain Forest This ecological site is located in the floodplain in coarse-loamy water sediments with a high water table. |
Similar sites
F113XY922IL |
Loamy Floodplain Forest This ecological site is located stream river courses and is better drained. Species composition is similar but oak species are more common. |
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Table 1. Dominant plant species
Tree |
(1) Platanus occidentalis |
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Shrub |
(1) Ulmus rubra |
Herbaceous |
(1) Boehmeria cylindrica |
Click on box and path labels to scroll to the respective text.
T1A | - | Lack of natural disturbance events >20 years; repeated timber harvests |
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T1B | - | Woody removal; vegetative seeding; grassland management |
T1C | - | Woody removal; tillage; conservation cropping system; water management |
R2A | - | Forest stand improvement |
T2A | - | Woody removal; vegetative seeding; grassland management |
T2B | - | Woody removal; tillage; conservation cropping system; water management |
T3A | - | Tillage; conservation cropping system; water management |
T4A | - | Vegetative seeding; grassland management |
State 1 submodel, plant communities
1.1A | - | No disturbance events for over 10 years |
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1.2A | - | Natural disturbance 1-3 years |