Illinois Natural History Survey - University of Illinois

SOUTHERN TILL PLAIN 

Blck eyed Susans and Cone Flowers in the Southern Till Plain RRA, photo by Mike Jeffords, INHS Today about 2,000 acres of high-quality, relatively undisturbed prairie, or about 0.01% of the original native prairie, exists in Illinois. Many remnants persist along railroad rights-of-way. Twelve Mile Prairie is an example of a dry-mesic prairie along a railroad line. The lack or abandonement of cultivation has helped to maintain the native prairie vegetation.

Map of Site
Land Cover Map of Site
SIZE: 584,788 acres; 914 square miles

 

LOCATION:South-central Illinois; Clay, Clinton, Edwards, Effingham, Fayette, Jasper, Jefferson, Marion, Richland, and Wayne counties.

The Southern Till Plain RRA is the second largest RRA. In presettlement times rolling prairies between broad woodlands following stream corridors characterized the region. The area is now largely agricultural. The soils have a high clay content and are fairly poor. Of the five watersheds that comprise this RRA, four drain to the Little Wabash River and one drains to the Kaskaskia River.

Open areas of agriculture interspersed with grasslands are the preferred habitat for the loggerhead shrike in Illinois. This species has the interesting behavior of impaling its prey - larger insects, small mammals, birds, reptiles, and amphibians - on thorns and fences. The loggerhead shrike is most numerous in the southern third of the state. Populations in north and central Illinois declined steadily and were almost eliminated by 1972 due in part to the loss of hedgerows. The loggerhead shrike is a state-threatened species.

LANDCOVER : The Southern Till Plain RRA is predominantly cropland (58%), followed by grassland (21%). It has the highest acreage of cropland and the second highest acreage of grassland among the RRAs, but due to its large size, the percentages of these landcover types rank eighth and tenth, respectively. Approximately 19% of the site is wooded. There are moderate amounts of upland and bottomland woods. Bottomland woods are concentrated along the lower portion of the Little Wabash River. The acreage and percentage of nonforested wetlands are low.

NATURAL AREAS : Prairie chicken habitat at three separate locations accounts for most of the Natural Area acreage in this site. Notable features at the 15 Natural Areas in this site include grasslands, prairies, aquatic systems, springs, swamps, and forests.

BIOLOGICALLY SIGNIFICANT STREAMS : A single 50-mile stretch of the Little Wabash River is designated as a BSS stream.

HERITAGE SITES : There are 31 Heritage sites within the Southern Till Plain RRA. This is a low number given the size of the site. Six significant community types, two plant species, and five animal species are located here.

STATE AND FEDERAL LAND : A state fish and wildlife area and Carlyle Lake, an impoundment, comprise the public land within this site.

NATURE PRESERVES : Miller Shrub Swamp, a spring-fed wetland, is the only Nature Preserve in this RRA.

NATURAL DIVISIONS : Ninety percent of this site lies in the Southern Till Plain Division and ten percent lies in the Wabash Border Division.

SUMMARY OF SITE CHARACTERISTICS: SIZE, BIOLOGIC RESOURCES, AND PUBLIC LAND

Total Acreage 584,788
Natural Areas

    Acreage

6,903

    Number

15
Biologically Significant Stream Mileage 48.8
Natural Heritage Sites 31
State Land

    State Parks

0

    State Conservation Areas

0

    State Forests

0

    State Fish & Wildlife Areas

1

    Acreage

554

    Percentage of RRA

0.1
Federal Land

    Acreage

682

    Percentage of RRA

0.1

 


 

LANDCOVER

    Acres

    % of RRA

Upland forest 77,292.91 13.22
Bottomland forest 33,609.18 5.75
Wetland- nonforested 981.86 0.17
Grassland 121,895.50 20.84
Cropland 341,724.90 58.44
Urban-Built-up 6,193.05 1.06
Water 3,087.29 0.53
TOTAL 584,784.69 100.01

 


 

ILLINOIS NATURAL AREAS INVENTORY SITES

    Acres

Clay County Prairie Chicken Habitat 2,957
Jasper County Prairie Chicken Habitat 98
Little Wabash River 593
Marion County Prairie Chicken Habitat 3,032
Miller Shrub Swamp 22
Mt. Erie Springs 7
Salem Leckrone Airport Railroad Prairie 3
Sandy Branch Woods 17
Twelve Mile Prairie (Tract No. 1) 12
Twelve Mile Prairie (Tract No. 2) 15
Twelve Mile Prairie (Tract No. 3) 11
Twelve Mile Prairie (Tract No. 4) 28
Twelve Mile Prairie (Tract No. 5) 78
Twelve Mile Prairie (Tract No. 6) 26
Xenia Railroad Prairie 5

 


 

BIOLOGICALLY SIGNIFICANT STREAMS

    Miles

Little Wabash River, Rte 50 to mouth 48.8

 


 

NATURAL HERITAGE CATEGORIES
Communities Occurrences

    Types/Species

    Lake

1 1

    Wetland

2 2

    Forest

1 1

    Prairie

8 2
Threatened and Endangered Animals

    Bird

12 2

    Mammal

1 1

    Mollusk

2 2
Threatened and Endangered Plants

    Plant-Dicot

4 2
Geological Feature
Other

 


 

STATE AND FEDERAL LANDS

    Acres

State Parks 0
State Conservation Areas 0
State Forests 0
State Fish and Wildlife Areas

    Carlyle Reservoir

554
Federal Land

    Carlyle Lake

682

 


 

ILLINOIS NATURE PRESERVES

    Acres

Miller Shrub Swamp 30

 


 

NATURAL DIVISIONS

    Acres

    % of RRA

    % of Natural Division

Southern Till Plain 526,041 90.0 7.4
Wabash Border 58,748 10.0 3.4



Illinois Natural History Survey

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