U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2009–1159

Land-Cover Change in the Central Irregular Plains, 

1973–2000
Cover photograph. Horse drawn carriage in the northwest region of the Central Irregular Plains (U.S. Geological Survey, 2006).
Land-Cover Change in the Central Irregular 

Plains, 1973–2000 

By Krista A. Karstensen

Open-File Report 2009–1159

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Karstensen, K.A., 2009, Land-Cover Change in the Central Irregular Plains, 1973–2000: U.S. Geological Survey OpenFile Report 2009–1159, 8 p.
iii

Tables

1. Percentage of the Central Irregular Plains that experienced change 

and associated error....................................................................................................................3

2. Raw estimates of percent change in the Central Irregular Plains 

computed for each of the four time periods and associated error 

at an 85-percent confidence level .............................................................................................4

3. Estimated area for each land-cover class in the Central Irregular 

Plains between 1973 and 2000....................................................................................................5

4. Leading land-cover conversions in the Central Irregular Plains during 

each of four time periods ............................................................................................................6

Figures

1. Map showing the Central Irregular Plains ...............................................................................2

2–4. Photographs showing—

2. Wheat field near Jasper, Missouri.....................................................................................3

 3. No-till farming near Hamilton, Missouri ............................................................................7

 4. Conservation Reserve Program land near Graysville, Missouri ...................................7

Contents

Project Background.......................................................................................................................................1

Central Irregular Plains Ecoregion Description........................................................................................1

A Summary of Land-Use Change in the Ecoregion..................................................................................3

Overall Spatial Change ........................................................................................................................3

Number of Changes..............................................................................................................................3

Total Change Per Period ......................................................................................................................3

Land-Cover Composition and Net Change .......................................................................................3

Most Common Land-Cover Conversions ..........................................................................................4

Discussion.......................................................................................................................................................4

Factors Affecting Land-Cover Change in the Ecoregion................................................................4

Economic Climate of the 1970s...........................................................................................................4

Economic Crisis of the 1980s...............................................................................................................4

No-Till Conservation Tillage ................................................................................................................7

The Great Flood of 1993........................................................................................................................7

The Conservation Reserve Program..................................................................................................7

References Cited............................................................................................................................................8
iv

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2

) 0.3861 square mile (mi2)

Conversion Factors

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
Project Background

Spearheaded by the Geographic Analysis and Monitoring 

Program of the U.S. Geological Survey (USGS) in collaboration with the U.S. Environmental Protection Agency (EPA) 

and the National Aeronautics and Space Administration 

(NASA), the Land Cover Trends is a research project focused 

on understanding the rates, trends, causes, and consequences 

of contemporary United States land-use and land-cover 

change. Using the EPA Level III ecoregions as the geographic 

framework, scientists process geospatial data collected 

between 1973 and 2000 to characterize ecosystem responses to 

land-use changes. The 27-year study period was divided into 

five temporal periods: 1973–1980, 1980–1986, 1986–1992, 

1992–2000 and 1973–2000. General land-cover classes for 

these periods were interpreted from Landsat Multispectral 

Scanner, Thematic Mapper, and Enhanced Thematic Mapper 

Plus imagery to categorize land-cover change and evaluate 

using a modified Anderson Land Use Land Cover Classification System for image interpretation.

The rates of land-cover change are estimated using a 

stratified, random sampling of 10-kilometer (km) by 10-km 

blocks allocated within each ecoregion. For each sample 

block, satellite images are used to interpret land-cover change. 

Additionally, historical aerial photographs from similar timeframes and other ancillary data such as census statistics and 

published literature are used. The sample block data are then 

incorporated into statistical analyses to generate an overall 

change matrix for the ecoregion. These change statistics are 

applicable for different levels of scale, including total change 

for the individual sample blocks and change estimates for the 

entire ecoregion. The results illustrate that there is no single 

profile of land-cover change but instead point to geographic 

variability that results from land uses within ecoregions continuously adapting to various factors including environmental, 

technological, and socioeconomic. 

Central Irregular Plains Ecoregion 

Description 

The Central Irregular Plains ecoregion, as defined by 

Omernik (1987), encompasses 122,589 square kilometers 

(km2) across southern Iowa, northern and central Missouri and 

fractions of eastern Kansas and northeastern Oklahoma (fig. 

1). The ecoregion includes the Chariton, Des Moines, Grand, 

Missouri, and Thompson Rivers and their tributaries. 

The Central Irregular Plains tends to be topographically 

more irregular than the Western Corn Belt Plains to the north 

but is less irregular and less forested than the ecoregions to the 

south and east. The topography of the northern sections of the 

Central Irregular Plains found in northern Missouri and southern Iowa ranges from flat to moderately hilly. This portion 

of the ecoregion includes natural wetlands along the Grand 

River. The soils in the ecoregion vary from north to south in 

that glacial tills form the parent material for most of the soil in 

Iowa and the northern half of Missouri while the southern portion of the ecoregion was not glaciated (Chapman and others, 

2002). Additionally, loess deposits generally increase near the 

Missouri River (Chapman and others, 2002). The topographic 

features of the southwestern sections of the ecoregion, in west 

central Missouri, western Kansas, and northern Oklahoma 

generally are smoother than the northern till plains (Chapman, 

and others, 2002). This nonglaciated area is relatively flat and 

can be distinguished by its claypan soils (Chapman and others, 

2002).

The Central Irregular Plains has a variety of land-use 

types. The gently rolling topography and generally fertile soils 

of this ecoregion support a variety of agricultural practices, 

like the contour farming common in Iowa and northern Missouri (Chapman and others, 2002). Agricultural land stretches 

across the entire boundary of the Central Irregular Plains and 

is composed of fields of corn, soybeans, and wheat, as well as 

cattle. Loess deposits near the Missouri River have helped to 

create inherently fertile soils that provide an ideal environment 

for crop production (U.S. Department of Agriculture, 2009a) 

Land-Cover Change in the Central Irregular Plains, 

1973–2000 

By Krista A. Karstensen
2 Land-Cover Change in the Central Irregular Plains, 1973–2000

98° 97° 96° 95° 94° 93° 92° 91°

41°

40°

39°

38°

37°

36°

Central

Great Plains

Flint

Hills

Central

Oklahoma/Texas

Plains

Western

Corn Belt

Plains

Arkansas Valley

Boston

Mountains

Ozark

Highlands

Interior

River

Lowlands

Sample block (10 x 10 kilometers)

Ecoregion boundary

Land-use/land-cover classes

EXPLANATION

Water

Developed

Mechanically disturbed

Mining

Barren

Forest

Grassland/shrubland

Agriculture

Wetland

Nonmechanically disturbed

Ice/snow

0 25 50 MILES

0 25 50 100 KILOMETERS 75

NEBRASKA

IOWA

ILLINOIS

MISSOURI

ARKANSAS

KANSAS

OKLAHOMA

Index map

Base from Environmental Systems Research Institute digital data, 1983

Albers Projection

North American Datum of 1983 (NAD 83)

Land use from National Land Cover Data, 2001

Central Irregular 

Plains Ecoregion

Kansas

Oklahoma

Iowa

Missouri

Figure 1. The Central Irregular Plains.
A Summary of Land-Use Change in the Ecoregion 3

(fig. 2). According to the U.S. Department of Agriculture’s 

National Agricultural Statistics Service (NASS), a majority 

of the Iowa counties in this ecoregion have at least 50 percent of their land in farms as cropland. To the southwest, the 

primary crops during the study period in the Kansas counties 

of the ecoregion were wheat, corn, and sorghum while the 

counties in Oklahoma harvested mostly wheat and soybeans 

(U.S. Department of Agriculture Kansas National Agricultural 

Statistics Service, 2009c and U.S. Department of Agriculture 

Oklahoma National Agricultural Statistics Service, 2009e).

Number of Changes

An estimated 6.5 percent of land cover in the ecoregion 

underwent change once. The percentage of the ecoregion 

that changed more than once during the 30-year study period 

was low; 0.7 percent of the area changed twice, 0.1 percent 

changed three times. According to the statistics, the percent 

of the area that changed twice in this ecoregion is moderately 

consistent with neighboring ecoregions. 

Total Change Per Period

The total amount of change was relatively low during the 

study period. The total change during the 1973 to 1980 time 

period was 1.8 percent (+/- 0.6 percent). During the 1986-

1992 and the 1992–2000 time periods, the total change slightly 

increased to 2.0 percent (+/- 0.6 percent) and 2.2 percent (+/- 

0.8 percent) respectively. (table 2). Overall, these changes are 

moderately higher than values for the neighboring ecoregions. 

All of the change estimates have an associated margin of error 

of less than +/- 0.9 percent. The margin of error varied directly 

with the percent change in that it decreased with the lower 

amount of change from 1986 to 1992 and increased slightly 

between 1992 and 2000.

Land-Cover Composition and Net Change 

Agriculture is the principal land cover in the Central 

Irregular Plains. Though it experienced a slight decline to 

grassland/shrubland, agriculture covered 59.9 percent (+/- 

4.8 percent) of the ecoregion in 2000 (table 3). Forest was 

the second highest land-cover type covering 20.4 percent of 

the ecoregion in 1973 and 20 percent in 2000 (table 3). The 

forested woodlands of the Central Irregular Plains, including 

oak-hickory, are primarily concentrated in the eastern portion 

of the ecoregion. Grassland/shrubland, the third most extensive land-cover type, had a steady gain from 13.5 percent in 

1973 to 15.9 percent in 2000 (table 3). 

Figure 2. Wheat field near Jasper, Missouri (U.S. Geological 

Survey, 2006).

A Summary of Land-Use Change in the 

Ecoregion

Overall Spatial Change 

From 1973 to 2000, 7.2 percent (+/- 2.0 percent) of the 

Central Irregular Plains ecoregion underwent land-cover 

change (table 1). When compared to the statistics calculated 

for the other ecoregions in the Great Plains, the overall spatial 

change in the Central Irregular Plains was moderate. Results 

also indicate that the Central Irregular Plains show a greater 

amount of change than the neighboring ecoregions of the 

Great Plains.

Table 1. Percentage of the Central Irregular Plains that experienced spatial change and associated error.

[+, plus; -, minus; %, percent]

Number of changes Percent of 

ecoregion

Margin of error

(+/- %)

Lower bound

(%)

Upper bound

(%)

Standard error 

(%)

Relative error

(%)

1 6.5 1.7 4.8 8.2 1.2 17.8

2 .7 .3 .3 1 .2 33.3

3 .1 .1 0 .1 0 64

4 0 0 0 0 0 98.8

Overall spatial change 7.2 2 5.3 9.2 1.3 18.4
4 Land-Cover Change in the Central Irregular Plains, 1973–2000

Most Common Land-Cover Conversions

The five leading land-cover conversions from 1973 to 

2000 were: (1) agriculture to grassland/shrubland, (2) grassland/shrubland to agriculture, (3) agriculture to developed, 

(4) forest to agriculture, and (5) grassland/shrubland to forest 

(table 4). 

Overall, the most common type of conversion during 

each study period was the conversion from agriculture to 

grassland/shrubland. Between 1973 and 2000, 5,362 km2 were 

converted from agriculture to grassland/shrubland (table 4). 

However, this conversion did not result in a large net increase 

in grassland/shrubland because during the same time, the second most common conversion was grassland/shrubland being 

converted to agricultural land (2,128 km2).

Discussion

In 2000, agricultural land accounted for the highest 

amount of area in the ecoregion (73,466 km2) despite a net 

decrease of 3.02 percent. Economics play an important role in 

the land-use story of the Central Irregular Plains. 

Factors Affecting Land-Cover Change in the 

Ecoregion

The major factors affecting conversion of agricultural 

land to grassland/shrubland land during the study period were:

• the economic crisis of the 1980’s; 

• the agroeconomics related to advances in conservation 

tillage (no-till);

• the socioeconomic repercussions associated with the 

Great Flood of 1993; and

• the Conservation Reserve Program (CRP). 

Economic Climate of the 1970s

The economic climate of the 1970s encouraged farmers 

to expand production in an effort to benefit from improved export opportunities, strong commodity prices, farm income, and 

farmland values. While abundant credit from various sources 

helped finance the expansion, high rates of inflation and low 

real-estate interest rates further encouraged investment in 

farmland. During this time, a considerable number of farmers 

took on heavy debt loads and became vulnerable to sudden 

shifts in economic forces (Stam and Dixon, 2004).

Economic Crisis of the 1980s

During the economic crisis of the early 1980s, those economic shifts were felt when economic conditions reversed and 

export markets contracted and input prices and interest rates 

rose (Stam and Dixon, 2004). Monetary policies designed 

to reduce inflation prompted interest rates to rise to unprecedented levels in the early 1980s. The financial stress became 

more severe when declines in farm commodity prices, income, 

and land values (the largest asset used to secure debt) made 

it difficult for some farmers to service their debts (Stam and 

Dixon, 2004). While several factors came together to create 

the crisis, the massive increase in farmland prices in the late 

1970s, followed by the sharp decline in land prices between 

1981 and 1992, significantly contributed to the adverse effects 

on farmers and their lenders (Cofer and others, 2009) and may 

Table 2. Raw estimates of percent change in the Central Irregular Plains computed for each of the four time periods and associated 

error at an 85-percent confidence level.

[%, percent; +, plus; -, minus; km2, square kilometers]

Period

Total change

(% of 

ecoregion)

Margin of error

(+/- %)

Lower bound

(%)

Upper bound

(%)

Standard error

(%)

Relative error

(%)

Average rate

(% per year)

1973–1980 1.8 0.6 1.2 2.4 0.4 22.3 0.3

1980–1986 2.2 .8 1.3 3 .6 25.6 .4

1986–1992 2 .6 1.4 2.7 .4 20.8 .3

1992–2000 2.2 .8 1.3 3 .6 25.9 .3

Period

Total change

(km2

 of 

ecoregion)

Margin of error

(+/- km2

)

Lower bound

(km2)

Upper bound

(km2)

Standard error

(km2)

Relative error

(%)

Average rate

(km2 per year)

1973–1980 2,218 734 1,484 2,951 495 22 317

1980–1986 2,663 1,012 1,652 3,675 683 26 444

1986–1992 2,511 774 1,737 3,285 522 21 418

1992–2000 2,644 1,017 1,628 3,661 686 26 331
Discussion

5

Table 3. Estimated area for each land-cover class in the Central Irregular Plains between 1973 and 2000.[%, percent; +, plus; -, minus; km2, square kilometers]

Water Developed Mechanically distrubed Mining Barren Forest Grass/shrub Agriculture Wetlands Nonmechanically disturbed

% +/- % +/- % +/- % +/- % +/- % +/- % +/- % +/- % +/- % +/-

1973 0.7 0.2 1.4 0.4 0 0 0 0 0 0 20.4 3.1 13.5 3.3 62.9 4.4 1.0 0.4 0 0

1980 .7 .2 1.5 .5 0.1 0.1 0 0 0 0 20.1 3.1 13.8 3.4 62.7 4.4 1.0 .4 0 0

1986 .8 .2 1.6 .5 0 0 0 0 0 0 20 3.1 14.3 3.5 62.1 4.5 1.0 .4 0 0

1992 .9 .2 1.8 .7 0 0 0.1 0 0 0 20 3.1 15.2 3.7 60.9 4.6 1.0 .4 0 0

2000 .9 .2 2.1 .8 0 0 .1 0 0 0 20 3.1 15.9 3.8 59.9 4.8 1.0 .4 0 0

Net change .2 .1 .7 .4 0 0 .1 0 0 0 -.3 .2 2.4 1.5 -3.0 1.6 0 0 0 0

Gross change .3 .1 .7 .4 .2 .1 .1 0 0 0 .7 .2 4.2 1.3 4.8 1.4 0 0 0 0

Water Developed Mechanically distrubed Mining Barren Forest Grass/shrub Agriculture Wetlands Nonmechanically disturbed

km2 +/- km2 +/- km2 +/- km2 +/- km2 +/- km2 +/- km2 +/- km2 +/- km2 +/- km2 +/-

1973 821 218 1,722 540 29 35 28 24 28 37 24,956 3,782 16,572 4,055 77,166 5,344 1,266 517 0 0

1980 831 213 1,894 596 88 88 54 30 35 38 24,697 3,751 16,912 4,202 76,813 5,399 1,265 517 0 0

1986 1,011 246 2,022 660 0 0 58 31 30 37 24,564 3,755 17,575 4,321 76,072 5,518 1,257 512 0 0

1992 1,059 247 2,259 798 5 8 73 36 29 37 24,570 3,766 18,695 4,533 74,648 5,694 1,253 510 0 0

2000 1,097 247 2,611 975 8 7 110 57 42 39 24,539 3,741 19,463 4,692 73,466 5,920 1,251 509 0 0

Net change 276 127 889 537 -21 36 82 52 14 13 -418 290 2,890 1,888 -3,700 2,009 -16 20 0 0

Gross change 387 148 892 536 219 177 84 52 29 33 873 254 5,116 1,643 5,907 1,734 40 24 0 0
6 Land-Cover Change in the Central Irregular Plains, 1973–2000

Table 4. Leading land-cover conversions in the Central Irregular Plains during each of four time periods.

[km2, square kilometers; +, plus; -, minus]

Period From class To class

Area 

changed

(km2

)

Margin of 

error

(+/- km2)

Standard 

error

(km2)

Percent of 

ecoregion

Percent of 

all changes

1973–1980 Agriculture Grassland/shrubland 905 381 257 0.7 40.8

Grassland/shrubland Agriculture 585 480 324 0 26.4

Forest Grassland/shrubland 146 108 73 0 6.6

Forest Agriculture 144 65 44 0 6.5

Agriculture Developed 106 116 78 0 4.8

Other Other 331 n/a n/a 0 14.9

2,218 2 100

1980–1986 Agriculture Grassland/shrubland 1,337 607 409 1 50.2

Grassland/shrubland Agriculture 648 450 304 1 24.3

Grassland/shrubland Forest 105 66 44 0 3.9

Forest Grassland/shrubland 104 96 65 0 3.9

Forest Agriculture 85 44 30 0 3.2

Other Other 384 n/a n/a 0 14.4

2,663 2 100

1986–1992 Agriculture Grassland/shrubland 1,663 594 401 1 66.2

Grassland/shrubland Agriculture 391 289 195 0 15.6

Agriculture Developed 136 85 57 0 5.4

Grassland/shrubland Forest 73 39 26 0 2.9

Grassland/shrubland Developed 70 83 56 0 2.8

Other Other 178 n/a n/a 0 7.1

2,511 2 100

1992–2000 Agriculture Grassland/shrubland 1,456 878 592 1 55

Grassland/shrubland Agriculture 505 312 211 0 19.1

Agriculture Developed 206 139 94 0 7.8

Grassland/shrubland Developed 105 107 72 0 4.0

Grassland/shrubland Forest 89 54 36 0 3.4

Other Other 284 n/a n/a 0 10.7

2,644 2 100

Overall

1973–2000 Agriculture Grassland/shrubland 5,362 2,006 1,354 4 53.4

Grassland/shrubland Agriculture 2,128 1,243 839 2 21.2

Agriculture Developed 506 254 171 0 5

Forest Agriculture 323 125 84 0 3.2

Grassland/shrubland Forest 314 125 84 0 3.1

Other Other 1,403 n/a n/a 1 14

10,036 8 100
Discussion 7

have had an affect in the amount of agricultural land in the 

Central Irregular Plains. 

A direct example of the effects of this crisis was found 

in Appanoose County, Iowa. The banking crisis of the early 

1980s was the cause of many land-use changes in southern 

Iowa (D. Clarke, U.S. Department of Agriculture, written 

commun., 2009). The financial institutions needed money 

back from farmers because of the low crop yields (D. Clarke, 

U.S. Department of Agriculture, written commun., 2009). 

Overall, the collapse of the farm banks in the 1980s inflicted 

particular economic hardship on small family-operated farms 

as a number of farm banks failed causing many to foreclose on 

their farms.

No-Till Conservation Tillage

The second economic factor affecting land-use change in 

the Central Irregular Plains is conservation tillage, specifically 

no-till. No-till conservation tillage was not only popular but 

encouraged in many parts of the ecoregion in the 1980s and 

continues to be widely practiced. No-till is a practice where 

the soil is left virtually undisturbed from harvest to planting 

and has increased specifically in southern Iowa and eastern 

Kansas in recent years (D. Clarke, U.S. Department of Agriculture, written commun., 2009; M. Glissman, U.S. Department of Agriculture, written commun., 2009). The overall rate 

of increase in the use of conservation tillage of non-highly 

erodible land has been similar to that on highly erodible land, 

indicating that all producers are motivated by the potential 

of conservation tillage systems to reduce costs, improve efficiency, and increase soil productivity (U.S. Department of 

Agriculture Economic Research Service, 1997). However, the 

use of conservation tillage has leveled off in several regions 

since 1993 due in part to the unusual weather patterns—primarily heavy rainfall and cool planting conditions, which 

create unfavorable planting conditions for conservation tillage 

(U.S. Department of Agriculture Economic Research Service, 

1997). It is important to note that more than 50 percent of the 

scenes used to classify these data were collected from spring 

and late fall months, which may explain that while the land in 

no-till has an agricultural land use, it may spectrally appear as 

grassland/shrubland (fig. 3).

The Great Flood of 1993

The devastation of cropland that was associated with the 

Great Flood of 1993 had an affect on land use in the Central 

Irregular Plains. Specifically, greater than 61 centimeters 

(cm) of rain fell on central and northeastern Kansas, northern 

and central Missouri, most of Iowa, southern Minnesota, and 

southeastern Nebraska, and as much as 97 cm fell in east-central Iowa (Johnson and others, 2004). These amounts were approximately 2003 to 50 percent greater than normal (Johnson 

and others, 2004). From April 1 to August 31, precipitation 

amounts approached 122 cm in east-central Iowa, easily surpassing the area’s normal annual precipitation of 76 to 91 cm 

(Johnson and others, 2004). A substantial amount of cropland 

was lost, which had a particular downward effect on soybean 

and corn yields. While the floodwaters did not have a substantial effect on the entire ecoregion, the extent of the damage 

on agricultural resources was essential to understanding how 

climatic affects on land use may affect the land change. 

The Conservation Reserve Program

The U.S. Department of Agriculture NASS CRP annual cumulative enrollment statistics show that overall, acres 

enrolled in the CRP in the ecoregion declined slightly in the 

later portion of the study period (fig. 4). While that may have 

had a significant affect on the land-change conversion from 

agriculture to grassland/shrubland, other factors such as 

economics and climate also should be considered.

Figure 3. No-till farming near Hamilton, Missouri (U.S. Geological 

Survey, 2006).

Figure 4. Conservation Reserve Program land near Graysville, 

Missouri (U.S. Geological Survey, 2006).
8 Land-Cover Change in the Central Irregular Plains, 1973–2000

References Cited

Chapman, S.S., Omernik, J.M., Griffith, G.E., Schroeder, 

W.A., Nigh, T.A., and Wilton, T.F., 2002, Ecoregions of 

Iowa and Missouri: Reston, Virginia, U.S. Geological Survey, accessed on September 1, 2008, at URL ftp://ftp.epa.

gov/wed/ecoregions/mo_ia/moia_front.pdf

Cofer, R.D., Walser, J.W., and Osborne, T.D., 2009, Do record 

farmland prices portend another steep downturn for agriculture and farm banks: Washington, D.C., Federal Deposit 

Insurance Corporation, accessed on March 18, 2009, at 

URL http://www.fdic.gov/bank/analytical/quarterly/2008_

vol2_4/farmland.html

Johnson, G.P., Holmes, R.R., and Waite, L.A., 2004, The great 

flood of 1993 on the Upper Mississippi River—10 years 

later: U.S. Geological Survey Fact Sheet 2004–3024, 6 p.

Omernik, J.M., 1987, Ecoregions of the conterminous U.S.: 

Annals of the Association of American Geographers, v. 77, 

no. 1, p. 118–125. 

Stam, J.M., and Dixon, B.L., 2004, Farmer bankruptcies and 

farm exits in the United States, 1899–2002: Washington, 

D.C., Economic Research Service, U.S. Department of 

Agriculture, Agriculture Bulletin Number 788, accessed 

on March 18, 2009, at URL http://www.ers.usda.gov/

publications/aib788/aib788.pdf

U.S. Department of Agriculture, Farm Service Agency, 2009a, 

Conservation Programs: CRP contract and summary statistics: Washington, D.C., U.S. Department of Agriculture, 

accessed on March 11, 2009, at URL http://www.fsa.usda.

gov/FSA/webapp?area=home&subject=copr&topic=crp-st

U.S. Department of Agriculture, National Agricultural Statistics Service, 2009b, Iowa statistics: Washington, D.C., U.S. 

Department of Agriculture, accessed on March 11, 2009, at 

URL http://www.nass.usda.gov/Statistics_by_State/Iowa/

index.asp

U.S. Department of Agriculture, National Agricultural Statistics Service, 2009c, Kansas statistics: Washington, D.C., 

U.S. Department of Agriculture, accessed on March 11, 

2009, at URL http://www.nass.usda.gov/Statistics_by_State/

Kansas/index.asp

U.S. Department of Agriculture, National Agricultural Statistics Service, 2009d, Missouri statistics: Washington, D.C., 

U.S. Department of Agriculture, accessed on March 11, 

2009, at URL http://www.nass.usda.gov/Statistics_by_State/

Missouri/index.asp

U.S. Department of Agriculture, National Agricultural Statistics Service, 2009e, Oklahoma statistics: Washington, D.C., 

U.S. Department of Agriculture, accessed on March 11, 

2009, at URL http://www.nass.usda.gov/Statistics_by_State/

Oklahoma/index.asp

U.S. Department of Agriculture, Economic Research Service, 

Natural Resources and Environment Division, 1997, Agricultural Resources and Environmental Indicators, 1996–97: 

Agricultural Handbook No. 712. Washington, DC.

U.S. Geological Survey, 2001, Multi-Resolution Land Characteristics Consortium: National Land Cover Database 

(NLCD 2001) Multi-zone Download Site accessed on June 

4, 2009, at URL http://www.mrlc.gov/nlcd_multizone_map.

phP

Publishing support provided by: 

Rolla Publishing Service Center

For more information concerning this publication, contact:

Director

U.S. Geological Survey

Mid-Continent Geographic Science Center

1400 Independence Road

Rolla, MO 65401

(573) 308–3550

Or visit the Mid-Continent Geographic Science Center website at: 

http://mcgsc.usgs.gov/ 

Karstensen—Land-Cover Change in the Central Irregular Plains, 1973–2000—Open-File Report 2009–1159