U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2008–1088

Interior River Lowland Ecoregion 

Summary Report
Cover. Map showing the Interior River Lowlands Ecoregion
Interior River Lowland Ecoregion Summary 

Report

By Krista A. Karstensen 

Open-File Report 2008–1088

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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Suggested citation:

Karstensen, K.A., 2008, Interior River Lowland Ecoregion Summary Report: U.S. Geological Survey Open-File Report 

2008–1088, 5 p.
iii

Tables

1. The estimated overall spatial change in the Interior River Lowland Ecoregion between 

1973 and 2000.................................................................................................................................1

2. The total and annual rates of land-cover change for each time interval ...........................1

3. The estimated land-cover area for each land-use and land-cover class between 1973 

and 2000..........................................................................................................................................2

4. The leading land-cover conversions for the four time intervals of the Interior River 

Lowland Ecoregion from 1973–2000 ..........................................................................................3

Contents

Ecoregion Description...................................................................................................................................1

Contemporary Land-Cover Change (1973–2000).......................................................................................1

Summary and Conclusion.............................................................................................................................2

References .....................................................................................................................................................2

Figures

1. Map showing the Interior River Lowlands Ecoregion............................................................4

2. Bar chart showing net land-cover changes in the Interior River Lowlands during each 

time interval ...................................................................................................................................5

Ecoregion Description

The Interior River Lowlands ecoregion encompasses 

93,200 square kilometers (km2) across southern and western 

Illinois, southwest Indiana, east-central Missouri, and fractions 

of northwest Kentucky and southeast Iowa (fig 1). The ecoregion includes the confluence areas of the Mississippi, Missouri, Ohio, Illinois, and Wabash Rivers, and their tributaries. 

This ecoregion was formed in non-resident, non-calcareous sedimentary rock (U.S. Environmental Protection Agency, 

2006). The unstratified soil deposits present north of the White 

River in Indiana are evidence that pre-Wisconsinan ice once 

covered much of the Interior River Lowlands. The geomorphic characteristics of this area also include terraced valleys 

filled with alluvium as well as outwash, acolian, and lacustrine 

deposits. 

Historically, agricultural land use has been a vital 

economic resource for this region. The drained alluvial soils 

are farmed for feed grains and soybeans, whereas the valley 

uplands also are used for forage crops, pasture, woodlots, 

mixed farming, and livestock (USEPA, 2006). This ecoregion 

provides a key component of national energy resources as it 

contains the second largest coal reserve in the United States, 

and the largest reserve of bituminous coal (Varanka and 

Shaver, 2007). One of the primary reasons for change in the 

ecoregion is urbanization. 

Contemporary Land-Cover Change 

(1973–2000)

From 1973–2000, 5.60 percent of the total study area 

land cover changed at least once. This change in the ecoregion is known as the footprint. An estimated 5 percent of the 

ecoregion underwent change once (table 1). The percentage of 

the ecoregion that underwent multiple changes was low; 0.60 

percent of the area changed twice, 0.10 percent changed three 

times.

Annual rates of change peaked from 1973 to 1980 with 

1.84 percent change and slowly declined until a slight peak 

from 1992 to 2000, with a 1.75 percent change (table 2). All of 

the change estimates have an associated margin of error of less 

than plus or minus 0.80 percent. The margin of error varied 

directly with the percent change in that it decreased with the 

lower amount of change from 1980 to 1986 and 1986 to1992, 

and increased slightly between 1992 and 2000. When normalized to the annual rate of change, the land-cover change again 

declined after 1980 before increasing again between 1992 to 

2000. During the study period, the conversions from forest 

land to agricultural land and agricultural land to developed 

land dominated the land-cover change. 

Table 2. The total and annual rates of land-cover change for 

each time interval.

[+/-; plus or minus]

Period

1973–1980 1980–1986 1986–1992 1992-2000

Total change (percent of 

ecoregion)

1.84 1.37 1.17 1.75

Margin of error (85 

percent confidence 

level)

+/-0.706 +/-0.389 +/-0.378 +/-0.688

Average annual rate of 

change (percent/year)

0.48 0.27 0.26 0.47

The overall spatial land-cover change in percent of 

regional area between land-use categories during the study 

period is significant. Although agriculture is the primary land 

cover in this ecoregion, the analysis indicated that cropland 

use is intense, and urbanization is expanding, based on several 

economic sectors and industries (Varanka and Shaver, 2007). 

Agriculture is the primary land use; it comprised 65.0 percent 

of the ecoregion but declined marginally to 64.7 percent in 

2000 (table 3). Forest was the next highest land cover-type, 

22.7 percent in 1973, and 20.4 percent in 2000 (table 3). 

Developed land had a small, but steady gain, from 5.37 percent in 1973 to 6.98 percent in 2000. 

Developed land expanded the most, with an increase of 

1.61 percent between 1973 and 2000 (table 3). The largest net 

loss occurred in forest land cover, with net declines of 2.27 

percent. Development generally decelerated during the study 

period (fig. 2), before peaking with the greatest rate of expanInterior River Lowland Ecoregion Summary Report

By Krista A. Karstensen 

Table 1. The estimated overall spatial change in the Interior River 

Lowland Ecoregion between 1973 and 2000.

Overall spatial 

change Number of changes

1 2 3 4

Percent of ecoregion 5.6 5.0 0.6 0.1 0.0
2 Interior River Lowland Ecoregion Summary Report

sion between 1992 and 2000, which is also the period with the 

second highest overall rate of ecoregion change (1.75 percent). 

The five most common land cover conversions are illustrated in table 4. Overall, the greatest change during the study 

period was the conversion from forest to agriculture. Between 

1973 and 2000, the most common conversion (2,110 km2) was 

from forest cover to agriculture (table 4); however, this conversion did not result in a net increase in agriculture because during the same time, agricultural lands were being converted to 

developed land. Conversion from agriculture to developed land 

was the second most common change (1,190 km2). The loss 

of agricultural land cover was masked by a low net amount of 

change (0.66 percent). 

Summary and Conclusion

The study categorized the Interior River Lowland as a 

rich natural environment with a low to moderate demand for 

competing land uses, despite a relatively low population, that 

maintains the stability and growth of the region (Varanka and 

Shaver, 2007). Because of the lack of any statistical analysis of 

neighboring ecoregions, it is recommended that a comparative 

analysis to adjoining ecoregions be conducted at a later date. 

References 

Environmental Systems Research Institute, Inc. data and 

maps– 2006: Environmental Systems Research Institute, 

Inc., scale 1:100,000.

United States Environmental Protection Agency, 2006, Ecoregions of Indiana and Ohio: accessed July 31, 2007, http://

www.epa.gov/wed/pages/ecoregions/ohin_eco.htm

Varanka, Dalia E., and Shaver, David K., 2007, Land-use 

change trends in the Interior River Lowlands Ecoregion: 

U.S. Geological Survey Scientific Investigations Report 

2007–5145, 12 p.

Table 3. The estimated land-cover area for each land-use and land-cover class between 1973 and 2000.

[km2, square kilometers; -, negative]

1973 1980 1986 1992 2000

Net Change 

1973–2000

Land-use class km2 Percent km2 Percent km2 Percent km2 Percent km2 Percent km2 Percent

Water 2,460 2.64 2,520 2.70 2,520 2.70 2,560 2.75 2,620 2.80 160 0.16

Developed 5,010 5.37 5,400 5.79 5,580 5.98 5,790 6.24 6,510 6.98 1,500 1.61

Mechanically disturbed 103 0.11 80.9 0.09 30.4 0.03 20.5 0.02 14.9 0.02 -88.0 -0.09

Mining 118 0.13 91.6 0.10 128 0.14 222 0.24 99.8 0.11 -18.5 -0.02

Natural Bare 15.4 0.02 15.4 0.02 15.4 0.02 17.0 0.02 22.2 0.02 6.80 0.00

Forest 21,200 22.7 20,300 21.8 19,700 21.2 19,300 20.7 19,100 20.4 -2,100 -2.27

Grass/Shrub 470 0.50 414 0.44 396 0.42 417 0.45 408 0.44 -61.6 -0.06

Agriculture 59,700 64.0 60,200 64.60 60,700 65.0 60,700 65.1 60,300 64.7 600 0.66

Wetland 4,250 4.55 4,240 4.54 4,210 4.51 4,210 4.52 4,250 4.56 0.30 0.01

Non-mechanically 

disturbed

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
References 3

Table 4. The leading land cover conversions for the four time intervals of the Interior River Lowland Ecoregion from 1973–2000.

[km2, square kilometers]

Period From Class To Class Area changed (km2) Percent of all changes

1973–1980 Forest Agriculture 856 54.0

Agriculture Developed 304 19.0

Forest Mechanically Disturbed 59.0 4.00

Grassland/Shrubland Forest 58.0 4.00

Agriculture Forest 57.0 4.00

Other Classes Other Classes 244 15.0

Total 1,580 100

1980–1986 Forest Agriculture 603 52.0

Agriculture Developed 138 12.0

Wetland Agriculture 103 9.00

Grassland/Shrubland Forest 65.0 5.00

Agriculture Wetland 48.0 4.00

Other Classes Other Classes 205 18.0

Total 1,160 100

1986–1992 Forest Agriculture 409 42.0

Agriculture Developed 170 14.0

Agriculture Mining 143 15.0

Mining Agriculture 43.0 4.00

Forest Developed 42.0 4.00

Other Classes Other Classes 175 18.0

Total 982 100

1992–2000 Agriculture Developed 574 37.0

Forest Agriculture 245 16.0

Mining Agriculture 139 9.00

Forest Developed 120 8.00

Agriculture Forest 119 8.00

Other Classes Other Classes 336 22.0

Total 1,530 100

1973–2000 Forest Agriculture 2,110 42.0

Agriculture Developed 1,190 24.0

Forest Developed 243 5.00

Agriculture Forest 236 5.00

Agriculture Mining 210 4.00

Other Classes Other Classes 980 20.0

Total 4,970 100
4 Interior River Lowland Ecoregion Summary Report

Figure 1. The Interior River Lowlands Ecoregion.
References 5 Figure 2. Net land-cover changes in the Interior River Lowlands during each time interval.
6 Interior River Lowland Ecoregion Summary Report

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