U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3056

June 2008

A Landscape Indicator Approach to the Identification and 

Articulation of the Ecological Consequences of 

Land Cover Change in the Chesapeake Bay Watershed, 

1970–2000

Printed on recycled paper

Background

The advancement of geographic science in the area of land 

surface status and trends and land cover change is at the core of 

the current geographic scientific research of the U.S. Geological 

Survey (USGS) (McMahon and others, 2005). Perhaps the least 

developed or articulated aspects of USGS land change science 

have been the identification and analysis of the ecological 

consequences of land cover change.

Changes in land use and land cover significantly affect the 

ability of ecosystems to provide essential ecological goods and 

services, which, in turn, affect the economic, public health, and 

social benefits that these ecosystems provide. One of the great 

scientific challenges for geographic science is to understand 

and calibrate the effects of land use and land cover change and 

the complex interaction between human and biotic systems at a 

variety of natural, geographic, and political scales.

Understanding the dynamics of land surface change 

requires an increased understanding of the complex nature of 

human-environmental systems and will require a suite of scientific tools that include traditional geographic data and analysis 

methods, such as remote sensing and geographic information 

systems (GIS), as well as innovative approaches to understanding the dynamics of complex systems. One such approach that 

has gained much recent scientific attention is the landscape 

indicator, or landscape assessment, approach, which has been 

developed with the emergence of the science of landscape 

ecology. 

A Landscape Indicator Approach

Due to the increasing need to monitor ecosystem health 

and because of the traditionally high costs associated with fieldbased monitoring, alternatives to, and adaptations of, the traditional monitoring approach have been developed using highresolution remotely sensed data, standard geographic data, and 

derivative products. Termed the “landscape indicator approach,” 

this alternative applies a combination of concepts from landscape ecology, hydrology, and geography in conjunction with 

remotely sensed and other spatial data and GIS technology to 

the assessment of landscape and ecological conditions (O’Neill 

and others, 1997; Jones and others, 2000; Pitchford and others, 

2000). Figure 1 shows the concept design of a landscape indicator project.

The landscape indicator approach relies on the following:

•	 Geographic analysis of spatially explicit patterns of ecological characteristics (for example, riparian zones near streams) 

to interpret ecological conditions

•	 Concepts from landscape ecology relating changes in landscape patterns to changes in ecological processes

•	 Hierarchy theory that analyzes the consequences of landscape 

change on ecosystems at multiple scales

•	 Spatially explicit digital data and maps of biophysical and 

cultural characteristics and human use to interpret landscape 

patterns relative to ecological conditions

•	 Inclusion of humans as part of the environment

Figure 1. The conceptual components and processing sequence of 

the general landscape indicator model. From Pitchford and others 

(2000).
Typically a landscape indicator project for an area starts 

with the acquisition or development of a series of base geographic data in a GIS format. These data typically include the 

following:

•	 Land use and land cover data in a raster format representing 

one or more time periods 

•	 Stream and hydrology data in a vector format

•	 Road and transportation data in a vector format

•	 Normalized Difference Vegetation Index (NDVI) derived 

from satellite imagery

•	 A digital elevation model

•	 Data from field sampling or a monitoring network, such as 

USGS streamgages

•	 Any other GIS data layers targeted for a specific ecological 

consequence

 These data layers are then used to compute a series 

of landscape metrics and landscape indicators for each of the 

analytical units in the study area, which typically are watersheds. Landscape metrics are defined here as numerical values 

based on a single GIS data layer, such as forest area or total 

road miles. Landscape indicators are numerical values that 

are derived from two or more data layers and some analytical 

operation, such as agriculture on steep slopes or riparian forest 

buffers.

The Chesapeake Bay Watershed

The need to understand ecosystem stresses at the landscape 

level is great in the Chesapeake Bay watershed. The Nation’s 

largest estuary, the Chesapeake Bay has been degraded, in part 

because of the doubling of the human population between 1950 

and 2000; results of the human population increase include 

degradation of water quality, loss of habitat, and declines in 

populations of critical biological communities (Phillips, 2005). 

Rapid changes in land use in the watershed (fig. 2) have affected 

waters flowing into the bay.

Since the mid-1980s, the Chesapeake Bay Program (CBP), 

a multi-agency partnership that includes the U.S. Department 

of the Interior and the U.S. Environmental Protection Agency, 

has worked to restore the bay ecosystem. However, after over 20 

years of restoration activities by the CBP, there is growing concern that ecological conditions in the bay and its watershed have 

not significantly improved. There is an acute need for enhanced 

science to better document the reasons for the lack of significant 

ecosystem improvement and to assess the types and potential 

locations of restoration activities that will provide the greatest 

benefit to achieve ecologically sustainable development in the 

bay watershed (Phillips, 2005).

Jones, Neale, Wade, and others (2001) compared nitrogen 

yields (fig. 3) and bird habitat changes between 1970 and 1990 

in the mid-Atlantic region; the area includes the Chesapeake 

Bay watershed. They demonstrated the usefulness of the landscape indicator approach.

Landscape indicators and landscape metrics represent 

a new analytical approach that could be especially appropriate for the identification and analysis of consequences in the 

Chesapeake Bay Program and in larger USGS land cover 

programs. More robust analytical approaches to the causes and 

consequences of ecosystem decline in the Chesapeake Bay 

watershed are needed in order to develop a more comprehensive 

understanding of the ecological stressors and likely methods for 

successful ecosystem restoration.

1988

2002

Figure 2. Aerial images of the Ashburn area in Loudoun County, 

Va., showing an example of the rapid changes in land use in the 

Chesapeake Bay watershed. The 1988 image is from U.S. Geological 

Survey; the 2002 aerial image (©2002 Commonwealth of Virginia) is 

from The National Map (http://nationalmap.gov).
Objectives and Approach

The objective of the planned USGS research is to develop 

and test a spatial analysis methodology to identify and articulate 

the consequences of land cover change in the Chesapeake Bay 

watershed from 1970 to 2000. To do this, we will use a general 

landscape indicator model framework that utilizes synoptic land 

cover data to compute landscape metrics and landscape indicators as independent variables to explain their spatial relationship 

with a dependent variable representing an ecological consequence (for example, nutrient and sediment loads). We will 

modify the landscape model approach based on work by Jones, 

Neale, Wade, and others (2001) by expanding the historic analysis through the year 2000 and by analyzing high-spatial resolution imagery to articulate the specific land use and land cover 

changes and potential causal factors that relate to the significant 

consequence of the ecological change being evaluated.

By Terrence Slonecker

References Cited

Jones, K.B., Neale, A.C., Wade, T.G., Wickham, J.D., Cross, 

C.L., Edmonds, C.M., Loveland, T.R., Nash, M.S., Riitters, 

K.H., and Smith, E.R., 2001, The consequences of landscape 

change on ecological resources; An assessment of the United 

States Mid-Atlantic region, 1973–1993: Ecosystem Health, v. 

7, no. 4, p. 229–242. 

Jones, K.B., Williams, L.R., Pitchford, A.M., Slonecker, E.T., 

Wickham, J.D., O’Neill, R.V., Garofalo, D., Riitters, K.H., 

Kepner, W.G., and Goodman, I.A., 2000, A national assessment of landscape change and impacts to aquatic resources; 

A 10-year research strategy for the landscape sciences 

program: U.S. Environmental Protection Agency [Report] 

EPA/600/R–00/001, 29 p.

McMahon, Gerard, Benjamin, S.P., Clarke, Keith, Findley, 

J.E., Fisher, R.N., Graf, W.L., Gundersen, L.C., Jones, J.W., 

Loveland, T.R., Roth, K.S., Usery, E.L., and Wood, N.J., 

2005, Geography for a changing world; A science strategy 

for the geographic research of the U.S. Geological Survey, 

2005–2015: U.S. Geological Survey Circular 1281, 54 p. 

(Also available online at http://geography.usgs.gov/documents/USGSGeographySciencePlan.pdf.)

O’Neill, R.V., Hunsaker, C.T., Jones, K.B., Riitters, K.H., Wickham, J.D., Schwartz, P.M., Goodman, I.A., Jackson, B.L., and 

Baillargeon, W.S., 1997, Monitoring environmental quality at 

the landscape scale: Bioscience, v. 47, no. 8, p. 513–519. 

Phillips, S.W., 2005, U.S. Geological Survey Chesapeake Bay 

science plan, 2006–2011: U.S. Geological Survey Open-File 

Report 2005–1440, 52 p. (Also available online at http://

chesapeake.usgs.gov/USGSChesapeakeBayplan.pdf.) 

Pitchford, A.M., Denver, J.M., Olsen, A.R., Ator, S.W., Cormier, S.M., Nash, M.S., and Mehaffey, M.H., 2000, Testing 

landscape indicators for stream condition related to pesticides 

and nutrients; Landscape Indicators for Pesticides Study for 

Mid-Atlantic Coastal Streams (LIPS-MACS): U.S. Environmental Protection Agency [Report] EPA/600/R–00/087, 87 p.

For further information, please contact: 

Terrence Slonecker

Eastern Geographic Science Center

U.S. Geological Survey

521 National Center, 12201 Sunrise Valley Drive

Reston, VA 20192

Telephone: 703–648–4289

E-mail: tslonecker@usgs.gov

Figure 3. Changes in annual nitrogen loading in the Mid-Atlantic 

region from 1970 to 1990 based on a landscape indicator approach. 

From Jones, Neale, Wade, and others (2001). kg/ha/yr, kilograms per 

hectare per year.