Natural Resources
Conservation Service
Ecological site R097XB047IL
Chicago Wet Clayey Flats
Last updated: 1/16/2024
Accessed: 06/28/2026
-
Search
Major Land Resource Area or ecological site by name and/or ID.
PreviousSectionsNextGeneral 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.
Click to explore map
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 097X–Southwestern Michigan Fruit and Vegetable Crop Belt
Physiography consists of sandy lake plains and dunes along the western side adjacent to Lake Michigan, and moderately sloping fine-loamy moraine from the Lake Michigan lobe of the Wisconsin Ice Sheet.
Vegetation is mostly mesophytic forests of central and northern hardwood and conifer species with prairie and oak savanna to the south. Compared to inland locations, cold sensitive hardwood species extend further north due to milder winters, and conifers extend further south due to cooler summers, heavier snowfall, and sandier soils. Lake effect snow and delayed spring warm up dampen the fire frequency relative to similar inland sites, except along the south side of Lake Michigan. The northern extent is defined by a major floristic boundary where several central hardwoods species drop out. The southern boundary is defined by fine-loamy moraines with predominantly prairie vegetation.
The ecological site inference area for MLRA 97 is subdivided along a floristic/climatic break roughly from New Buffalo, Michigan to Portage, Indiana. This corresponds to the heaviest lake effect snow belt (>160 cm) south and east of this line and is associated lower historic fire frequencies. The snow belt portion “A”, has more frequent conifer and beech, while the less snowy portion “B” has more prairie and savanna elements. Although differing in precise boundary location, both USFS and EPA ecoregions support a climatic/floristic break at the next higher rank in their respective hierarchies.Classification relationships
Among the USFS ecoregional framework (Cleland et al., 2007), most of MLRA 97 is represented by the Humid Temperate Domain (200), Hot Continental Division (220), Midwest Broadleaf Forest Province (222), South Central Great Lakes Section (222J), subsections 222Ja and 222Jb. MLRA 97 was recently extended northward to be more consistent with the limits of the USFS ecoregions subsections 222Ja and 222Jb, because it is more consistent with vegetation patterns and species distributions. A former portion of MLRA 97 that extended westward from the southern end of Lake Michigan (including most of the city of Chicago) was recently removed from the MLRA due to its predominantly non-sandy deposits and reduced lake effect climate, and would have overlapped USFS ecoregion 222K.
Among the EPA ecoregional framework (Omernik and Griffith, 2014), most of MLRA 97 falls within Eastern Temperate Forests (Level I: 8), Mixed Wood Plains (Level II: 8.1), Southern Michigan/Northern Indiana Drift Plains (Level III: 56), and Level IV: 56d and 56f. Ecoregion 56f continues north beyond MLRA 97. Former portions of MLRA 97 that encompassed the city of Chicago included Level III ecoregion 54, Central Corn Belt Plains, before the last revision of MRLA boundaries.Ecological site concept
The central concept of the Wet Clayey Flats is fine-loamy to clayey wave worked till or lacustrine deposits with a horizon of very low saturated hydraulic conductivity within 100 cm of the surface. Site is generally found in poorly to very poorly drained flats, and is frequently episaturated with a perched water table. Due to very low saturated conductivity, depressional locations are subject to ponding from local rainfall events, but with little groundwater input. Due to the high fire frequency of the surrounding landscape, reference vegetation is wet prairie rather than swamp.
Associated sites
R097XB046IL Chicago Moist Clayey Flats
Similar sites
F097XA023MI Wet Loamy Depression
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous (1) Spartina pectinata
(2) Calamagrostis canadensisPhysiographic features
Depressions on offshore lacustrine deposits.
Table 2. Representative physiographic features
Landforms (1) Lake plain
Runoff class Negligible to low Ponding duration Very brief (4 to 48 hours) to long (7 to 30 days) Ponding frequency Rare to occasional Elevation 581 – 741 ft Water table depth 0 – 10 in Aspect Aspect is not a significant factor Climatic features
The southern Lake Michigan lake plain has a humid warm continental climate with cold winters and warm summers. Almost two thirds of the precipitation is distributed during the warmer half of the year with a significant portion of the precipitation occurring as heavy downpours during thunderstorms. Thunderstorm activity is enhanced inland by lake breeze fronts, while it is diminished near the lakeshore by the stabilizing effect of the cooler lake waters. Occasionally, thunderstorm microbursts cause localized high winds which open single tree gaps in forest canopies, or more rarely, tornados and derechos (severe straight-line winds) open larger gaps. Fall storms bring more frequent strong winds, but with impacts moderated by the lack of leaves (wind resistance) in the canopy. During July, average precipitation lags potential evapotranspiration, resulting in droughty conditions in the upper soil horizons of upland sites. During dry years, this droughty period is extended into August and September, resulting in dry fuels and potential for wildfire over oak and pine dominated areas.
Winter precipitation light with annual snowfall of 0.7 to 1.0 m (28-40 inches), which is only occasionally enhanced by lake effect during instances of cold north or northeast winds. The combination of lower snowfall, and more limited lake amelioration of warm southwesterly winds, contribute to higher fire frequencies relative to similar sites to the north and east.
The area falls within USDA Hardiness zones (-22 to -24 C) 5b and 6a (slightly colder than areas to the north and east) and has limited lake protection from premature spring warm up prior to the last killing frosts, limiting the potential for fruit crops relative to other portions of MLRA 97.Table 3 Representative climatic features
Frost-free period (characteristic range) 150-180 days Freeze-free period (characteristic range) 200-200 days Precipitation total (characteristic range) 40-40 in Frost-free period (actual range) 150-180 days Freeze-free period (actual range) 200-200 days Precipitation total (actual range) 40-40 in Frost-free period (average) 170 days Freeze-free period (average) 200 days Precipitation total (average) 40 in Characteristic rangeActual rangeBarLineFigure 2. Monthly precipitation range
Characteristic rangeActual rangeBarLineFigure 3. Monthly minimum temperature range
Characteristic rangeActual rangeBarLineFigure 4. Monthly maximum temperature range
BarLineFigure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7 Annual average temperature pattern
Climate stations used
-
(1) CHICAGO UNIV [USW00014892], Chicago, IL
-
(2) INDIANA DUNES NATL LKS [USC00124244], Chesterton, IN
-
(3) CHICAGO MIDWAY AP [USW00014819], Chicago, IL
">Influencing water features
Perched water table within 25 cm and hydric, but sometimes seasonally dry.
Soil features
Soils are poorly drained to very poorly drained fine loams and clays. They are commonly classified as Typic Endoaquolls, Typic Argiaquolls, and Cumulic Vertic Endoaquolls, and commonly mapped as Pewamo, Milford, and Ashkum series.
Table 4. Representative soil features
Parent material (1) Glaciolacustrine deposits
(2) Till
Surface texture (1) Clay
(2) Loam
Drainage class Very poorly drained to poorly drained Permeability class Slow to moderately slow Soil depth 79 – 0 in Surface fragment cover <=3" 0 – 5 % Surface fragment cover >3" 0 – 1 % Available water capacity
(0-39.4in)5.12 – 8.66 in Soil reaction (1:1 water)
(0-19.7in)5.5 – 7 Subsurface fragment volume <=3"
(0-59.1in)0 – 35 % Subsurface fragment volume >3"
(0-59.1in)0 – 15 % Ecological dynamics
Fire was locally important adjacent to other fire prone ecological sites. Wet anoxic soils favor facultative and obligate wetland species. The combination of prolonged wetness alternating with frequent fire may inhibit establishment of forest vegetation. Tree species that are fire tolerant tend to be somewhat less flood tolerant, and require elevated tip-up mounds for establishment, which are precluded by the lack of preexisting forest vegetation. Wet prairie communities tend to develop with a species composition reflecting moderate to high nutrient conditions.
State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textState 1 submodel, plant communities
Communities 2 and 5 (additional pathways)
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 1
Reference StateThe Reference State consists of wet prairies, shrub swamps, and marshes.
Dominant plant species
-
prairie cordgrass (Spartina pectinata), grass
-
bluejoint (Calamagrostis canadensis), grass
Community 1.1
Swamp ForestCommunity 1.2
Wet PrairieCommunity 1.3
Shrub-ThicketCommunity 1.4
Emergent MarshCommunity 1.5
Inundated Shrub SwampPathway 1.1A
Community 1.1 to 1.2Temporary prolonged inundation or other factor that induces tree mortality; followed by a frequent fire interval.
Conservation practices
Prescribed Burning Early Successional Habitat Development/Management Forest Stand Improvement Pathway 1.1B
Community 1.1 to 1.3Clearcut/Blowdown.
Conservation practices
Early Successional Habitat Development/Management Forest Stand Improvement Pathway 1.2A
Community 1.2 to 1.1Succession; lack of fire.
Conservation practices
Tree/Shrub Site Preparation Tree/Shrub Establishment Pathway 1.2B
Community 1.2 to 1.3Succession from reduced fire frequency. Shrub establishment.
Conservation practices
Tree/Shrub Site Preparation Tree/Shrub Establishment Pathway 1.2D
Community 1.2 to 1.4Permanent inundation.
Pathway 1.2E
Community 1.2 to 1.5Shrub establishment; permanent inundation.
Conservation practices
Tree/Shrub Establishment Pathway 1.3A
Community 1.3 to 1.1Succession.
Conservation practices
Tree/Shrub Site Preparation Tree/Shrub Establishment Pathway 1.3B
Community 1.3 to 1.2Temporary prolonged inundation or other factors leading to shrub mortality followed by increased fire frequency.
Conservation practices
Brush Management Prescribed Burning Pathway 1.3C
Community 1.3 to 1.4Permanent inundation.
Pathway 1.3C
Community 1.3 to 1.5Permanent inundation.
Pathway 1.4A
Community 1.4 to 1.2Drop in water table; increased fire frequency.
Conservation practices
Prescribed Burning Pathway 1.4C
Community 1.4 to 1.5Temporary drop water table; shrub establishment.
Pathway 1.5A
Community 1.5 to 1.2Drop water table; increased fire frequency with shrub mortality.
Conservation practices
Brush Management Prescribed Burning Pathway 1.5C
Community 1.5 to 1.4Temporary drought; shrub mortality.
State 2
Cultural State[Alternative States to be developed; refer to component communities.]
Community 2.1
Sustainable Crop, Pasture, or PlantationCommunity 2.2
Unsustainable Cultural PhaseCommunity 2.3
Conservation FeatureCan be a grassed waterway, conservation reserve, a small patch pollinator garden, or other land taken out of its primary cultural production to mitigate or reduce impacts of adjacent land use, and is not by itself a permanent restoration of a complete native biological community and associated ecosystem services.
Pathway 2.1A
Community 2.1 to 2.2Revert to unsustainable cultural practices.
Pathway 2.1B
Community 2.1 to 2.3Establish conservation feature.
Conservation practices
Conservation Cover Grassed Waterway Pathway 2.2A
Community 2.2 to 2.1Implement sustainable cultural practices.
Conservation practices
Conservation Crop Rotation Cover Crop Nutrient Management Integrated Pest Management (IPM) Pathway 2.2B
Community 2.2 to 2.3Establish conservation feature.
Conservation practices
Conservation Cover Grassed Waterway Pathway 2.3A
Community 2.3 to 2.1Implement sustainable cultural practices.
Conservation practices
Conservation Crop Rotation Cover Crop Nutrient Management Integrated Pest Management (IPM) Pathway 2.3B
Community 2.3 to 2.2Revert to unsustainable cultural practices.
State 3
Seminatural Drained State[Alternative States to be developed; refer to component communities.]
Community 3.1
Ruderal Drained Meadow & ShrubCommunity 3.2
Exotic Ruderal Drained ForestPathway 3.1A
Community 3.1 to 3.2Succession
Pathway 3.2A
Community 3.2 to 3.1Blowdown/clearcut.
Conservation practices
Early Successional Habitat Development/Management Forest Stand Improvement State 4
Seminatural State[Alternative States to be developed; refer to component communities.]
Community 4.1
Ruderal Wet Meadow & Shrub SwampCommunity 4.2
Exotic Ruderal Swamp ForestPathway 4.1A
Community 4.1 to 4.2Succession.
Pathway 4.2A
Community 4.2 to 4.1Blowdown/clearcut.
Conservation practices
Early Successional Habitat Development/Management Forest Stand Improvement Transition T1A
State 1 to 2Drain; clear vegetation; cultivate domesticated species.
Transition T1B
State 1 to 3Drain; clear vegetation, invasive species introduced.
Transition T1C
State 1 to 4Clear vegetation, invasive species introduced.
Restoration pathway R2
State 2 to 1Restore hydrology; remove domesticated species; restore native species.
Conservation practices
Brush Management Restoration and Management of Rare and Declining Habitats Wetland Wildlife Habitat Management Wetland Restoration Herbaceous Weed Control Transition T2A
State 2 to 3Abandon, succession.
Transition T2B
State 2 to 4Restore hydrology; abandon; succession.
Conservation practices
Wetland Restoration Restoration pathway R3
State 3 to 1Restore hydrology; control invasive species; restore native species
Conservation practices
Brush Management Restoration and Management of Rare and Declining Habitats Wetland Wildlife Habitat Management Wetland Restoration Herbaceous Weed Control Transition T3A
State 3 to 2Clear vegetation; cultivate domesticated species.
Transition T3B
State 3 to 4Restore hydrology.
Conservation practices
Wetland Restoration Restoration pathway R4
State 4 to 1Control invasive species; restore native species.
Conservation practices
Brush Management Restoration and Management of Rare and Declining Habitats Wetland Wildlife Habitat Management Herbaceous Weed Control Transition T4A
State 4 to 2Drain; clear vegetation; cultivate domesticated species.
Transition T4B
State 4 to 3Drain.
Additional community tables
Table 5. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 6. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 1.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 1.4 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 1.5 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 11. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 2.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 13. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 14. Community 3.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 15. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 16. Community 4.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Inventory data references
Site Development and Testing Plan Future work is needed, as described in a future project plan, to validate the information presented in this provisional ecological site description. Future work includes field sampling, data collection and analysis by qualified vegetation ecologists and soil scientists. As warranted, annual reviews of the project plan can be conducted by the Ecological Site Technical Team. A final field review, peer review, quality control, and quality assurance reviews of the ESD are necessary to approve a final document.
Other references
Albert, D. A. et al., 1995. Vegetation circa 1800 of Michigan. Michigan's native landscape as interpreted from the General Land Office Surveys 1816-1856 (digital map), Lansing: Michigan Natural Features Inventory.
Barnes, B. V. and Wagner, W. H., 2004. Michigan trees: a guide to the trees of the Great Lakes region. Ann Arbor (Michigan): University of Michigan Press.
Burger, T. L. and Kotar, J., 2003. A Guide to Forest Communities and Habitat Types of Michigan. Madison, Wisconsin: Department of Forest Ecology and Management, University of Wisconsin.
Cleland, D. T. et al., 1994. Field guide: Ecological classification and inventory system of the Huron-Manistee National Forests, s.l.: USDA Forest Service, North Central Forest Experiment Station.
Cleland, D.T., J.A. Freeouf, J.E. Keys, G.J. Nowacki, C. Carpenter, and W.H. McNab. 2007. Ecological Subregions: Sections and Subsections of the Coterminous United States. USDA Forest Service, General Technical Report WO-76. Washington, DC. 1–92.
Jacquart, E., Homoya, M. and Casebere, L., 2002. Natural Communities of Indiana (Working Draft), Indianapolis: Indiana Department of Natural Resources, Division of Nature Preserves.
Kost, M. A. et al., 2010. Natural Communities of Michigan: Classification and Description, Lansing, MI: Michigan Natural Features Inventory.
Moran, R. C., 1981. Prairie fens in northeastern Illinois: floristic composition and disturbance. Ohio Biol Surv Biol Notes, 15, 164-168.
Omernik, J.M. and G.E. Griffith. 2014. Ecoregions of the Conterminous United States: Evolution of a Hierarchical Spatial Framework. Environmental Management 54:1249–1266.
Swink, F. and Wilhelm, G., 1994. Plants of the Chicago Region. Indianapolis(Indiana): Indiana Academy of Science.
U.S. Department of the Interior, Geological Survey, 2008. LANDFIRE: LANDFIRE 1.1.0 Vegetation Dynamics Models. Accessed August 28, 2012 http://landfire.cr.usgs.gov/viewer/.
U.S. Department of the Interior, Geological Survey, 2011. LANDFIRE: LANDFIRE 1.1.0 Existing Vegetation Type layer. http://landfire.cr.usgs.gov/viewer/Contributors
Greg J. Schmidt
Approval
Nels Barrett, 1/16/2024
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 06/28/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
-
Number and extent of rills:
-
Presence of water flow patterns:
-
Number and height of erosional pedestals or terracettes:
-
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
-
Number of gullies and erosion associated with gullies:
-
Extent of wind scoured, blowouts and/or depositional areas:
-
Amount of litter movement (describe size and distance expected to travel):
-
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
-
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
-
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
-
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
-
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
-
Average percent litter cover (%) and depth ( in):
-
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
-
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
-
Perennial plant reproductive capability:
Print Options
Sections
Font
AAAAOther
PrintThe Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
Accessibility statement
