Natural Resources
Conservation Service

Ecological site R097XB046IL

Chicago Moist Clayey Flats

Last updated: 1/16/2024
Accessed: 08/14/2026

Home / esd CATALOG / MLRA 097X / ecological site R097XB046IL

USC

Metric

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.

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 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 lower landscape positions and flats, and is somewhat poorly drained to well drained. Vegetation is usually wet-mesic prairie.

Associated sites

F097XB041IN	Chicago Loamy Slopes
R097XB047IL	Chicago Wet Clayey Flats
R097XB052IL	Chicago Dolomite Prairie

F097XB041IN

Chicago Loamy Slopes

R097XB047IL

Chicago Wet Clayey Flats

R097XB052IL

Chicago Dolomite Prairie

Similar sites

F097XA022MI	Moist Loamy Drift Plains
R097XB052IL	Chicago Dolomite Prairie
F097XA018MI	Dry Loamy Drift Plains

F097XA022MI

Moist Loamy Drift Plains

R097XB052IL

Chicago Dolomite Prairie

F097XA018MI

Dry Loamy Drift Plains

Table 1. Dominant plant species

Tree	Not specified
Shrub	Not specified
Herbaceous	(1) Andropogon gerardii (2) Spartina pectinata

Download full description

Physiographic features

Flats on offshore lacustrine deposits.

Table 2. Representative physiographic features

Landforms	(1) Lake plain
Runoff class	Low to high
Ponding duration	Very brief (4 to 48 hours)
Ponding frequency	None to rare
Elevation	581 – 741 ft
Slope	0 – 5 %
Water table depth	10 – 39 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 range

Actual range

Bar

Line

Figure 2. Monthly precipitation range

Characteristic range

Actual range

Bar

Line

Figure 3. Monthly minimum temperature range

Characteristic range

Actual range

Bar

Line

Figure 4. Monthly maximum temperature range

Bar

Line

Figure 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) CHICAGO MIDWAY AP [USW00014819], Chicago, IL
(3) INDIANA DUNES NATL LKS [USC00124244], Chesterton, IN

Soil features

Soils are well drained to somewhat poorly drained fine loams and clays. They are commonly classified as Aeric Epiaqualfs, Aquic Argiudolls, and Udollic Epiaqualfs, and commonly mapped as Blount, Elliott, and Del Rey series.

Table 4. Representative soil features

Parent material	(1) Lacustrine deposits (2) Not specified
Surface texture	(1) Clay (2) Loam
Drainage class	Somewhat poorly drained to well drained
Permeability class	Moderately slow to moderately rapid
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 occurred every 2-5 years limiting the recruitment of tree species. High water table provides moisture and favors a mixture of upland and facultative wetland species. Restricted rooting depth combined with medium to high fertility and frequent fire favored grassland vegetation.

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 text

State 1
Reference State

The Reference State consists of mostly prairies and open woodland.

Dominant plant species

big bluestem (Andropogon gerardii), grass
prairie cordgrass (Spartina pectinata), grass

Community 1.1
Dry-Mesophytic Forest

Community 1.2
Wooded Grassland

Community 1.3
Prairie

Community 1.4
Regenerating Forest

Community 1.5
Mesophytic Forest

Pathway 1.1A
Community 1.1 to 1.2

Blowdown; increased fire/drought.

Conservation practices

Prescribed Burning
Early Successional Habitat Development/Management
Forest Stand Improvement

Pathway 1.1B
Community 1.1 to 1.3

Blowdown/clearcut + Increased fire regime. May be coupled with drought for a time to reduce vigor of resprouting trees. Large herbivores may also increase browse pressure to reduce resprouting success.

Conservation practices

Prescribed Burning
Early Successional Habitat Development/Management
Forest Stand Improvement

Pathway 1.1C
Community 1.1 to 1.4

Blowdown/clearcut

Conservation practices

Forest Stand Improvement

Pathway 1.1D
Community 1.1 to 1.5

Succession; decreased fire/drought

Pathway 1.2A
Community 1.2 to 1.1

Succession

Pathway 1.2B
Community 1.2 to 1.3

Increased fire/drought; Blowdown or tree mortality.

Conservation practices

Prescribed Burning
Early Successional Habitat Development/Management
Forest Stand Improvement

Pathway 1.3A
Community 1.3 to 1.1

Succession; reduced fire frequency.

Pathway 1.3B
Community 1.3 to 1.2

Reduced fire/drought; moderate tree recruitment.

Conservation practices

Tree/Shrub Establishment

Pathway 1.3C
Community 1.3 to 1.5

Succession; decreased fire/drought.

Pathway 1.4A
Community 1.4 to 1.1

Succession.

Pathway 1.4B
Community 1.4 to 1.2

Blowdown; increased fire/drought.

Pathway 1.4C
Community 1.4 to 1.5

Succession; decreased fire/drought.

Pathway 1.5A
Community 1.5 to 1.1

Increased fire/drought with mortality.

Conservation practices

Prescribed Burning
Forest Stand Improvement

Pathway 1.5B
Community 1.5 to 1.3

Blowdown/clearcut; increased fire and drought. Intense browsing or drought needed in combination with frequent fire to induce tree mortality unless fire is every two years or less.

Conservation practices

Prescribed Burning
Early Successional Habitat Development/Management
Forest Stand Improvement

Pathway 1.5C
Community 1.5 to 1.4

Blowdown/clearcut

Conservation practices

Forest Stand Improvement

State 2
Cultural State

[Alternative States to be developed; refer to component communities.]

Community 2.1
Sustainable Crop, Pasture, or Plantation

Community 2.2
Unsustainable Crop, Pasture, or Plantation

Community 2.3
Conservation Feature

Can 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 2.2

Revert to unsustainable cultural practices.

Pathway 2.1B
Community 2.1 to 2.3

Establish conservation feature.

Conservation practices

Conservation Cover
Grassed Waterway

Pathway 2.2A
Community 2.2 to 2.1

Implement sustainable cultural practices.

Conservation practices

Conservation Crop Rotation
Cover Crop
Nutrient Management
Integrated Pest Management (IPM)

Pathway 2.2B
Community 2.2 to 2.3

Establish conservation feature.

Conservation practices

Conservation Cover
Grassed Waterway

Pathway 2.3A
Community 2.3 to 2.1

Implement sustainable cultural practices.

Conservation practices

Conservation Cover
Conservation Crop Rotation
Nutrient Management
Integrated Pest Management (IPM)

Pathway 2.3B
Community 2.3 to 2.2

Revert to unsustainable cultural practices.

State 3
Seminatural State

[Alternative States to be developed; refer to component communities.]

Community 3.1
Ruderal Meadow & Shrubland: Dactylis glomerata - Festuca spp. - Solidago canadensis Ruderal Mesic Meadow Alliance

Community 3.2
Exotic Ruderal Forest: Acer platanoides - Ailanthus altissima - Pinus spp. Exotic Ruderal Forest Alliance

Pathway 3.1A
Community 3.1 to 3.2

Succession.

Pathway 3.2A
Community 3.2 to 3.1

Blowdown/clearcut.

Transition T1A
State 1 to 2

Clear vegetation; cultivate domesticated species

Transition T1B
State 1 to 3

Clear vegetation, invasive species introduced

Restoration pathway R2
State 2 to 1

Remove domesticated species; restore native species.

Conservation practices

Brush Management
Tree/Shrub Site Preparation
Tree/Shrub Establishment
Restoration and Management of Rare and Declining Habitats
Upland Wildlife Habitat Management
Herbaceous Weed Control

Transition T2A
State 2 to 3

Abandoned, succession.

Restoration pathway R3
State 3 to 1

Control invasive species; restore native species

Conservation practices

Brush Management
Tree/Shrub Site Preparation
Tree/Shrub Establishment
Restoration and Management of Rare and Declining Habitats
Upland Wildlife Habitat Management
Herbaceous Weed Control

Restoration pathway T3A
State 3 to 2

Clear vegetation; cultivate domesticated species

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 (%)

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	08/14/2026
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:

Download reference sheet

Natural ResourcesConservation Service

Ecological site R097XB046IL

Chicago Moist Clayey Flats

Last updated: 1/16/2024 Accessed: 08/14/2026

Search

General information

Figure 1. Mapped extent

MLRA notes

Classification relationships

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Natural Resources
Conservation Service

Last updated: 1/16/2024
Accessed: 08/14/2026