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United States Department of Agriculture Forest Service Northeastern Research Station General Technical Report NE-297 Chetan Agarwal Glen M. Green J. Morgan Grove Tom P. Evans Charles M. Schweik A Review and Assessment of Land-Use Change Models: Dynamics of Space, Time, and Human Choice Indiana University Center for the Study of Institutions, Population, and Environmental Change

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United StatesDepartment ofAgriculture

Forest Service

NortheasternResearch Station

General TechnicalReport NE-297

Chetan AgarwalGlen M. GreenJ. Morgan GroveTom P. EvansCharles M. Schweik

A Review and Assessmentof Land-Use Change Models:Dynamics of Space, Time,and Human Choice

Indiana University

Center for theStudy of Institutions,Population, andEnvironmental Change

Abstract

Land-use change models are used by researchers and professionals to explore the dynamicsand drivers of land-use/land-cover change and to inform policies affecting such change. Abroad array of models and modeling methods are available to researchers, and each type hascertain advantages and disadvantages depending on the objective of the research. This reportpresents a review of different types of models as a means of exploring the functionality andability of different approaches. In this review, we try to explicitly incorporate human processes,because of their centrality in land-use/land-cover change. We present a framework tocompare land-use change models in terms of scale (both spatial and temporal) andcomplexity, and how well they incorporate space, time, and human decisionmaking. Initially,we examined a summary set of 250 relevant citations and developed a bibliography of 136papers. From these 136 papers a set of 19 land-use models were reviewed in detail asrepresentative of the broader set of models identified from the more comprehensive review ofliterature. Using a tabular approach, we summarize and discuss the 19 models in terms ofdynamic (temporal) and spatial interactions, as well as human decisionmaking as defined bythe earlier framework. To eliminate the general confusion surrounding the term scale, weevaluate each model with respect to pairs of analogous parameters of spatial, temporal, anddecisionmaking scales: (1) spatial resolution and extent, (2) time step and duration, and (3)decisionmaking agent and domain. Although a wide range of spatial and temporal scales iscovered collectively by the models examined, we find most individual models occupy a muchmore limited spatio-temporal niche. Many raster models we examined mirror the extent andresolution of common remote-sensing data. The broadest-scale models are, in general, notspatially explicit. We also find that models incorporating higher levels of humandecisionmaking are more centrally located with respect to spatial and temporal scales,probably due to the lack of data availability at more extreme scales. Further, we examine thesocial drivers of land-use change and methodological trends exemplified in the models wereviewed. Finally, we conclude with some proposals for future directions in land-use modeling.

The Authors

CHETAN AGARWAL is forest policy analyst with Forest Trends in Washington, D.C.

GLEN M. GREEN is a research fellow with the Center for the Study of Institutions, Population,and Environmental Change at Indiana University–Bloomington.

J. MORGAN GROVE is a research forester and social ecologist with the U.S. Department ofAgriculture Forest Service, Northeastern Research Station in Burlington, Vermont, and co–principal investigator with the Baltimore Ecosystem Study, a Long-Term Ecological ResearchProject of the National Science Foundation.

TOM P. EVANS is an assistant professor with the Department of Geography and associatedirector with the Center for the Study of Institutions, Population, and Environmental Change atIndiana University–Bloomington.

CHARLES M. SCHWEIK is an assistant professor with the Department of Natural ResourceConservation and the Center for Public Policy and Administration at the University ofMassachusetts–Amherst.

Cover Photos

Upper left: Earth, taken during NASA Apollo 17’s return from the moon (Harrison Schmitt, 1972)

Upper right: A young man selling charcoal in southwest Madagascar near the town ofAndranovory (Glen Green, 1987)

Lower left: Secondary forests and pasture with the hills of Brown County State Park, Indiana,in the background (Glen Green, 1999)

Lower right: Fisheye view of a young tree plantation in Monroe County, Indiana (Glen Green,1999)

Contents

Introduction ........................................................................................................................................ 1

Methods ............................................................................................................................................... 2Background ................................................................................................................................... 2Framework for Reviewing Human-Environmental Models .................................................. 2Model Scale ................................................................................................................................... 2Model Complexity ....................................................................................................................... 5Application of the Framework .................................................................................................. 6Identifying the List of Models ................................................................................................... 7

Models .................................................................................................................................................. 8

Discussion .........................................................................................................................................24Trends in Temporal, Spatial, and Human Decisionmaking Complexity .........................24Theoretical Trends ....................................................................................................................26Methodological Trends .............................................................................................................31Data and Data Integration .......................................................................................................32Scale and Multiscale Approaches ...........................................................................................33Future Directions in Land-Use Modeling ..............................................................................34

Conclusion .........................................................................................................................................36

Acknowledgments ............................................................................................................................36

Literature Cited ................................................................................................................................37

Additional References .....................................................................................................................39

Appendix ............................................................................................................................................50

Glossary .............................................................................................................................................62

Figures and Tables

Figure 1.—Three-dimensional framework for reviewing land-use change models. .............. 2

Figure 2.—Hierarchical spatial scales in social-ecological contexts. ........................................ 3

Figure 3.—Spatial representation of a hierarchical approach to modeling urbansystems. ............................................................................................................................ 4

Figure 4.—Three-dimensional framework for reviewing and assessing land-usechange models. ............................................................................................................... 7

Figure 5.—Spatial and temporal characteristics of reviewed models. ...................................24

Figure 6.—Raster and vector characteristics of reviewed models. ........................................25

Figure 7.—Human decisionmaking complexity of reviewed models. ....................................26

Figure 8.—Traditional conceptual framework for ecosystem studies. ..................................26

Figure 9.—Conceptual framework for investigating human ecosystems. ............................27

Figure 10.—Nine-box representation of the interaction between the three dimensionsof space, time, and human decisionmaking with biophysical processes. .......30

Appendix figures: Graphical representations of spatial and temporal scalesunder which the 19 models operate. ........................................................................50

Table 1.—Resolution and extent in the three dimensions of space, time,and human decisionmaking. .......................................................................................... 6

Table 2.—Six levels of human decisionmaking complexity. ...................................................... 6

Table 3.—Summary statistics of model assessment. .................................................................. 9

Table 4.—In-depth overview of models reviewed. .....................................................................10

Table 5.—Spatial characteristics of each model. .......................................................................16

Table 6.—Temporal and human decisionmaking characteristics of each model. ...............19

Table 7.—Summary of model variables that characterize relevant human drivers. ...........29

1

Introduction

Land-use change is a locally pervasive and globallysignificant ecological trend. Vitousek (1994) notes that“three of the well-documented global changes areincreasing concentrations of carbon dioxide in theatmosphere; alterations in the biochemistry of the globalnitrogen cycle; and on-going land-use/land-coverchange.” In the United States, 121,000 km2 of nonfederallands were converted to urban developments between1982 and 1997 (Natural Resources Conservation Service1999). Globally and over a longer period, nearly 1.2million km2 of forest and woodland and 5.6 million km2

of grassland and pasture have been converted to otheruses during the last 3 centuries, according to Ramankuttyand Foley (1999). During this same period, cropland hasincreased by 12 million km2. Humans have transformedsignificant portions of the Earth’s land surface: 10 to 15percent currently is dominated by agricultural rowcrop orurban-industrial areas, and 6 to 8 percent is pasture(Vitousek et al. 1997).

These land-use changes have important implications forfuture changes in the Earth’s climate and, consequently,great implications for subsequent land-use change. Thus,a critical element of the Global Climate Change Programof the U.S. Department of Agriculture’s (USDA’s) ForestService (FSGCRP) is to understand the interactionsbetween human activities and natural resources. Inparticular, FSGCRP has identified three critical actionsfor this program:

1. Identify and assess the likely effects of changes in forestecosystem structure and function on humancommunities and society in response to global climatechange.

2. Identify and evaluate potential policy options for ruraland urban forestry in order to mitigate and adapt tothe effects of global climate change.

3. Identify and evaluate potential rural and urban forestmanagement activities in order to integrate risksassociated with global climate change.

In addition to these action items, attention has focusedon land-use change models. Land-use models need to bebuilt on good science and based on good data. Researchmodels should exhibit a high degree of scientific rigor andcontribute some original theoretical insights or technical

innovations. However, originality is less important inpolicy models, and sometimes it is more desirable for amodel to be considered “tried and true.” Also importantto policy models is whether the model is transparent,flexible, and includes key “policy variables.” This is not tosay that research models might not have significant policyimplications (as is the case with global climate modelsdeveloped during the past decade) nor is it to say thatpolicy models might not make original contributions tothe science of environmental modeling (Couclelis 2002).

Because of its applied mission, the FSGCRP needs tofocus on land-use models that are relevant to policy. Thisdoes not mean that these land-use models are expected tobe “answer machines.” Rather, we expect that land-usechange models will be good enough to be taken seriouslyin the policy process. King and Kraemer (1993) list threeroles a model must play in a policy context: A modelshould clarify the issues in the debate; it must be able toenforce a discipline of analysis and discourse amongstakeholders; and it must provide an interesting form of“advice,” primarily in the form of what not to do — sincea politician is unlikely to do what a model suggests.Further, the necessary properties for a good policy modelhave been known since Lee (1973) wrote his “requiem”for effective models: (1) transparency, (2) robustness, (3)reasonable data needs, (4) appropriate spatio-temporalresolution, and (5) inclusion of enough key policyvariables to allow for likely and significant policyquestions to be explored.

The National Integrated Ecosystem Modeling Project(NIEMP:Eastwide) is a part of the USDA’s GlobalClimate Change Program. Through this project, theForest Service intends to:

1. Inventory existing land-use change models through areview of literature, websites, and professional contacts.

2. Evaluate the theoretical, empirical, and technicallinkages within and among land-use change models.

This report’s goal is to contribute to theNIEMP:Eastwide modeling framework by identifyingappropriate models or proposing new modelingrequirements and directions for estimating spatial andtemporal variations in land-cover (vegetation cover) andforest-management practices (i.e., biomass removal orrevegetation through forestry, agriculture, and fire, andnutrient inputs through fertilizer practices).

2

Methods

Background

Models can be categorized in multiple ways: by thesubject matter of the models, by the modelingtechniques or methods used (from simple regression toadvanced dynamic programming), or by the actual usesof the models. A review of models may focus ontechniques in conjunction with assessments of modelperformance for particular criteria, such as scale (see,for example, the review of deforestation models byLambin 1994). The FSGCRP evaluates models usingthe following criteria:

1. Does the model identify and assess the likely effectsof changes in forest ecosystem structure andfunction on human communities and society?

2. Does the model evaluate potential policy options forrural and urban forestry?

3. Does the model evaluate potential rural and urbanforest management activities?

While this review indirectly covers these topics, wedeveloped an alternative analytical framework. AsVeldkamp and Fresco (1996a) note, land use “isdetermined by the interaction in space and time ofbiophysical factors (constraints) such as soils, climate,topography, etc., and human factors like population,technology, economic conditions, etc.” In this review, weuse all four factors that Veldkamp and Fresco (1996a)identify in the construction of a new analytical frameworkfor categorizing and summarizing models of land-usechange dynamics.

Framework for ReviewingHuman-Environmental Models

To assess land-use change models, we propose aframework based on three critical dimensions tocategorize and summarize models of human-environmental dynamics. Space and time are the first twodimensions and provide a common setting in which allbiophysical and human processes operate. In other words,models of biophysical and/or human processes operate ina temporal context, a spatial context, or both. Whenmodels incorporate human processes, our thirddimension — referred to as the human decisionmaking1

dimension — becomes important as well (Fig. 1). Inreviewing and comparing land-use change models alongthese dimensions, two distinct and important attributesmust be considered: model scale and model complexity.

Model Scale

Social and ecological processes operate at different scales(Allen and Hoekstra 1992; Ehleringer and Field 1993).When we discuss the temporal scale of models, we talk interms of time step and duration. Time step is the smallesttemporal unit of analysis for change to occur for a specificprocess in a model. In a model of forest dynamics, treeheight may change daily. This model would not considerprocesses which act over shorter temporal units. Durationis the length of time that the model is applied. Forinstance, change in tree height might be modeled dailyover the course of its life from seedling to mature tree:300 years. In this case, time step would be one day, andduration would equal 300 years. When the duration of amodel is documented, it can be reported in several ways:109,500 daily time steps, a period of 300 years, or acalendar range from January 1, 1900, to January 1, 2200.

Spatial Resolution and Extent. When we discuss thespatial scale of models, we employ the terms resolutionand extent. Resolution is the smallest geographic unit ofanalysis for the model, such as the size of a cell in a rastergrid system. In a raster environment, grid cells typicallyare square, arranged in a rectilinear grid, and uniformacross the modeled area, while a vector representationtypically has polygons of varying sizes, though thesmallest one may be considered the model’s resolution.Extent describes the total geographic area to which themodel is applied. Consider a model of individual trees ina 50-ha forested area. In this case, an adequate resolutionmight be a 2x2 m cell (each cell is 4 m2), and the modelextent would equal 50 ha.

Scale is a term fraught with confusion because it hasdifferent meanings across disciplines, notably geographyvs. the other social sciences. Geographers define scale as1Words that are in italics are defined in the Glossary on

Page 49.

Time (X)

Space (Y)

HumanDecisionmaking

(Z)

Biophysical Processes Only

Figure 1.—Three-dimensional framework for reviewingland-use change models.

3

the ratio of length of a unit distance (scale bar) on a mapand the length of that same unit distance on the groundin reality (Greenhood 1964). A large-scale map (e.g., amap of a small town or neighborhood at 1:10,000)usually shows more detail but covers less area. Small-scalemaps usually show less detail but cover more area, such asa map of the United States at 1:12,000,000. Other socialscientists give opposite meanings to the terms large scaleand small scale. To them, a large-scale study means itcovers a large extent, and a small-scale study is a detailedstudy covering a small area. By this definition, the word“scale” can generally be dropped completely with nochange in the meaning of the sentence. The term scalealso is complicated by the change in geographictechnology as we move from hard-copy, analog data(maps) to digital products (images and GIS coverages).

To avoid this confusion, we define two other terms, finescale and broad scale, which have more intuitive meaning.Resolution and extent may be used to describe fine- orbroad-scale analyses. Fine-scale models encompassgeographically small areas of analysis (small extents) andsmall cell sizes (and thus are large scale, to use thegeographer’s term), while broad-scale models encompasslarger spatial extents of analysis and cells with larger sizes

(and thus correspond to small-scale maps of geographers).Figure 2 provides an example of analysis moving frombroad scales (A) to increasingly finer scales (E).

We use different terms to characterize temporal andspatial scale. Temporal time step and duration areanalogous to spatial resolution and extent, respectively.Resolution and extent often are used to describe bothtemporal and spatial scales; however, we make thesedistinctions more explicit so that readers will not beconfused by which scale we are referring to in anyparticular discussion, and we think these carefuldistinctions in scale terminology are important for furtherdialog of land-use/land-cover modeling. We propose asimilar approach in describing scale of humandecisionmaking.

Agent and Domain. How does one discuss humandecisionmaking in terms of scale? The social sciences havenot yet described human decisionmaking in terms that areas concise and widely accepted for modeling as time step/duration or resolution/extent. As with space and time, wepropose an analogous approach that can be used toarticulate scales of human decisionmaking in similarterms: “agent” and “domain.”

Figure 2.—Hierarchical spatial scales in social-ecological contexts.

D. Location(LANDSAT image)

X

A. GlobeX

Y

BroadSpatialScale

FineSpatialScale

X

Y

B. Continent

• Watershed or sub-watershed• Village(s), City or cities• Forest(s)• Land adjacent to a river system

E. Field Site

Examples:

Y

X

Y

C. Region

4

Agent refers to the human actor or actors in the modelwho are making decisions. The individual human is thesmallest single decisionmaking agent. However, there aremany land-use change models that capturedecisionmaking processes at broader scales of socialorganization, such as household, neighborhood, county,state or province, or nation. All of these can be consideredagents in models. Domain, on the other hand, refers tothe broadest social organization incorporated in themodel. Figure 2 illustrates agents (villages) and domain(countries of the western hemisphere) for the study ofsocial ecosystems in a hierarchical approach. The agent

captures the concept of who makes decisions, and thedomain describes the specific institutional and geographiccontext in which the agent acts. Representation of thedomain can be facilitated in a geographically explicitmodel through the use of boundary maps or GIS layers(Fig. 3).

For example, in a model of collaborative watershedmanagement by different forest landowners, a multiscaleapproach would incorporate several levels of linkedresolutions and domains. At a broad scale, the domainwould be the collaborative arrangement among owners

Figure 3.—Spatial representation of a hierarchical approach to modeling urban systems.Examples of hierarchically nested patch structure at three scales in the Central Arizona-Phoenix(CAP; upper panels) and Baltimore Ecosystem Study (BES; lower panels) regions. At the broadestscale (A, D), patches in the CAP study area include desert (mustard), agriculture (green), and urban(blue); for the BES, patches are rural (green), urban (yellow), and aquatic (blue). B: The municipalityof Scottsdale, Ariz., showing major areas of urban-residential development (blue, lower portion) andundeveloped open lands (tan, developable; brown, dedicated). C: Enlargement of rectangle in Bshowing additional patch structure at a neighborhood scale (green, golf course/park; mustard,undeveloped desert; red, vacant; pink, xeric residential; purple, mesic residential; yellow, asphalt). E:Gwynns Falls watershed, Maryland, with residential (yellow), commercial/industrial (red), agricultural(light green), institutional (medium green), and forest (dark green) patch types. F: Enlargement ofrectangle in E showing additional patch structure at a neighborhood scale (dark green, pervioussurface/canopy cover; light green, pervious surface/no canopy cover; yellow, impervious surface/canopy cover; red, impervious surface/no canopy cover; blue, neighborhood boundaries; black circles,abandoned lots). Panel A courtesy of CAP Historic Land Use Project (http://caplter.asu.edu/overview/proposal/summary.html); panels D, E, and F courtesy of USDA Forest Service and BES LTER(http://www.ecostudies.org/bes). Source: (Grimm et al. 2000)

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(coincident with the watershed boundaries), the agentwould be the owners and the resolution their associatedparcel boundaries (the agent would be the collaborativeorganization). At a finer scale, the owner would be thedomain, and the resolution would be the managementunits or forest stands within each parcel (the agent beingthe individual). In this example, we also might modelother agents, operating in one of the two domains (e.g.,other parcels), such as neighboring landowners whoseparcel boundaries would also be depicted by the samedomain map. Institutionally, agents may overlap spatially.For example, a landowner might receive financialsubsidies for planting trees in riparian buffer areas froman agent of the Forest Service; receive extension adviceabout wildlife habitat and management from an agent ofthe Fish and Wildlife Service; and have his or her landsinspected for nonpoint-source runoff by an agent fromthe Environmental Protection Agency.

In our watershed example, also consider the role of othertypes of forest landowners. For instance, the watershedmight include a state forester (agent = state) who writesthe forest management plan for the state forest (domain =state boundary) and prescribes how often trees(resolution) in different forest stands (extent) should beharvested (time step) for a specific period (duration)within state-owned property. In this case, the humandecisionmaking component of the model might includethe behavior of the forester within the organizationalcontext of the state-level natural resource agency.

Model Complexity

A second important and distinct attribute of human-environmental models is the approach to address thecomplexity of time, space, and human decisionmakingfound in real-world situations. We propose that thetemporal, spatial, or human-decisionmaking (HDM)complexity of any model can be represented with anindex, where low values signify simple components andhigh values signify more complex behaviors andinteractions. Consider an index for temporal complexity ofmodels: A model that is low in temporal complexity maybe a model that has one or a few time steps and a shortduration. A model with a mid-range value for temporalcomplexity is one which may use many time steps and alonger duration. Models with a high value for temporalcomplexity are ones that may incorporate a large numberof time steps, a long duration, and the capacity to handletime lags or feedback responses among variables, or havedifferent time steps for different submodels.

Temporal Complexity. There are important interactionspossible between temporal complexity and humandecisionmaking. For instance, some human decisions are

made in short time intervals. The decision of which roadto take on the way to work is made daily (even thoughmany individuals do not self-consciously examine thisdecision each day). Other decisions are made over longerperiods, such as once in a single growing season (e.g.,which annual crop to plant). Still other decisions may bemade for several years at a time, such as investments madein tractors or harvesting equipment. When the domain ofa decisionmaker changes, this change may also affect thetemporal dimension of decisions. For example, a forestlandowner might make a decision about cutting trees onhis or her land each year. If this land were transferred to astate or national forest, the foresters may harvest onlyonce every 10 years.

The decisionmaking time horizon perceived by an actorcould also be divided into a short-run decisionmakingperiod, and a long-run time horizon. Again using theforest example, if a certain tree species covering a 100-haarea matures in 100 years, there is a need for a harvestplan that incorporates both the maturity period and theextent of forest land that is available. In other words, atleast one level of actor needs to have an awareness of bothshort and long time horizons and be able to communicatewith other actors operating at shorter time horizons.Institutional memory and culture can often play that role.

Spatial Complexity. Spatial complexity represents theextent to which a model is spatially explicit. There are twobroad types of spatially explicit models: spatiallyrepresentative and spatially interactive. A model that isspatially representative can incorporate, produce, ordisplay data in two or, sometimes, three spatialdimensions, such as northing, easting, and elevation, butcannot model topological relationships and interactionsamong geographic features (cells, points, lines, orpolygons). In these cases, the value of each cell mightchange or remain the same from one point in time toanother, but the logic that makes the change is notdependent on neighboring cells. By contrast, a spatiallyinteractive model is one that explicitly defines spatialrelationships and their interactions (e.g., amongneighboring units) over time. A model with a low valuefor spatial complexity would be one with little or nocapacity to represent data spatially; a model with amedium value for spatial complexity would be able tofully represent data spatially; and a model with a highvalue would be spatially interactive in two or threedimensions.

The human decisionmaking sections of models vary interms of their theoretical precursors and simply may belinked deterministically to a set of socioeconomic orbiological drivers, or they may be based on some gametheoretic or economic models. Table 1 presents the

6

equivalence among the three parameters — space, time,and human decisionmaking — based on the earlierdiscussion about resolution and extent.

Human Decisionmaking Complexity. Given the majorimpact of human actions on land use and land cover, it isessential that models of these processes illuminate factorsthat affect human decisionmaking. Many theoreticaltraditions inform the theories that researchers use whenmodeling decisionmaking. Some researchers areinfluenced by deterministic theories of decisionmakingand do not attempt to understand how external factorsaffect the internal calculation of benefits and costs: the“dos” and “don’ts” that affect how individuals makedecisions. Others, who are drawing on game theoreticalor other theories of reasoning processes, make explicitchoices to model individual (or collective) decisions as theresult of various factors which combine to affect theprocesses and outcomes of human reasoning.

What is an appropriate index to characterize complexityin human decisionmaking? We use the term HDMcomplexity to describe the capacity of a human-environmental model to handle human decisionmakingprocesses. In Table 2, we present a classification schemefor estimating HDM complexity using an index with

values from 1 to 6. A model with a low value (1) forhuman decisionmaking complexity is a model that does notinclude any human decisionmaking. By contrast, a modelwith a high value (5 or 6) includes one or more types ofactors explicitly or can handle multiple agents interactingacross domains, such as those shown in Figures 2 and 3.In essence, Figures 2 and 3 represent a hierarchicalapproach to social systems where lower-level agentsinteract to generate higher-level behaviors and wherehigher-level domains affect the behavior of lower-levelagents (Grimm et al. 2000; Vogt et al. in press; Grove etal. 2002).

Application of the Framework

The three dimensions of land-use change models (space,time, and human decisionmaking) and two distinctattributes for each dimension (scale and complexity)provide the foundation for comparing and reviewingland-use change models. Figure 4 shows the three-dimensional framework with a few general model types,including some that were represented in our review.Modeling approaches vary in their placement along thesethree dimensions of complexity because the location of aland-use change model reflects its technical structure aswell as its sophistication and application.

Table 1.Resolution and extent in the three dimensions of space, time, and human decisionmaking

Space Time Human decisionmaking Resolution or equivalent

Resolution: smallest spatial unit of analysis

Time step: shortest temporal unit of analysis

Agent and decisionmaking time horizon

Extent or equivalent

Extent: total relevant geographical area

Duration: total relevant period of time

Jurisdictional domain and decisionmaking time horizon

Table 2.Six levels of human decisionmaking complexity

Level

1 No human decisionmaking — only biophysical variables in the model 2 Human decisionmaking assumed to be related determinately to population size, change,

or density 3 Human decisionmaking seen as a probability function depending on socioeconomic

and/or biophysical variables beyond population variables without feedback from the environment to the choice function

4 Human decisionmaking seen as a probability function depending on socioeconomic and/or biophysical variables beyond population variables with feedback from the environment to the choice function

5 One type of agent whose decisions are modeled overtly in regard to choices made about variables that affect other processes and outcomes

6 Multiple types of agents whose decisions are modeled overtly in regard to choices made about variables that affect other processes and outcomes; the model might also be able to handle changes in the shape of domains as time steps are processed or interaction between decisionmaking agents at multiple human decisionmaking scales

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The following analysis characterizes existing land-usemodels on each modeling dimension. Models are assigneda level in the human decisionmaking dimension, andtheir spatial and temporal dimensions are estimated aswell. We also document and compare models acrossseveral other factors, including the model type, dependentor explanatory variables, modules, and independentvariables.

Identifying the List of Models

Any project that purports to provide an overview of theliterature needs to provide the reader with someinformation regarding how choices were made regardinginclusion in the set to be reviewed. In our case, weundertook literature and web searches as well asconsultations with experts.

We began our search for appropriate land-use/land-coverchange models by looking at a variety of databases. Keyword searches using “land cover,” “land use,” “change,”“landscape,” “land*,” and “model*,” where * was awildcard, generated a large number of potential articles.

The databases that proved to be most productive wereAcademic Search Elite and Web of Science. Bothdatabases provide abstract and full-text searches. Otherdatabases consulted, but not used as extensively, includeCarl Uncover, Worldcat, and IUCAT (the database forIndiana University’s library collections). We also searchedfor information on various web search engines. Some ofthe appropriate web sites we found includedbibliographies with relevant citations.

These searches yielded 250 articles, which were compiledinto bibliographic lists. The lists then were examined bylooking at titles, key words, and abstracts to identify thearticles that appeared relevant. This preliminaryexamination yielded a master bibliography of 136 articles,chosen because they either assessed land-use modelsdirectly or they discussed approaches and relevance ofmodels for land-use and land-cover change. Articles in themaster bibliography are included in AdditionalReferences. We then checked the bibliographies of thesearticles for other relevant works. Web of Science alsoallowed us to search for articles cited in other articles.

*

Time (X)

Space (Y)

HumanDecisionmaking

(Z)

D

C

E

A

B

F

Key

A-Time series statistical models, STELLAmodels with no human dimension

B- Time-series models with human decision-making explicitly modeled

C- Most traditional GIS situations

D- GIS modeling with an explicit temporalcomponent (e.g., cellular automata)

E- Econometric (regression) and game theoretic models

F- SWARM and SME (spatial modelingenvironment)

The ultimate goal of human-environment dynamic modeling: high in all threedimensions*

Low

High

High

DECISIO

NMAKING

COMPLE

XIY

SPATIAL

COMPLEXITY

TEMPORALCOMPLEXITYHigh

Figure 4.—Three-dimensional framework for reviewing and assessing land-use change models.

8

Twelve models were selected by reading articles identifiedthrough this process, with the selection criteria beingrelevance and representativeness. A model was relevant ifit dealt with land-use issues directly. Models that focusedmainly on water quality, wildlife management, or urbantransportation systems were not reviewed. Seven othermodels were chosen from recommendations receivedfrom colleagues and experts, especially the Forest Service,after also being reviewed for relevance andrepresentativeness.

Our criteria for representativeness included the following:

1. Emphasis on including diverse types of models. Ifseveral models of a particular type had already beenreviewed, other applications of that model type wereexcluded in favor of different model types. Forexample, our search uncovered many spatial simulationmodels, several of which were reviewed.

2. If there were numerous papers on one model (e.g., sixon the NELUP model), only the more representativetwo or three were reviewed.

3. If there were several papers by one author covering twoor more models, a subset that looked most relevant wasreviewed.

Expert opinion helped locate some of the models wereviewed. In addition to our literature and web searches,we consulted with the program managers for the USFSSouthern and Northern Global Climate ChangePrograms to identify other significant land-use changemodels. In addition to the models they identified, theprogram managers also identified science contacts whowere working in or familiar with the field of land-usemodeling. We followed up with these contacts in order to(1) identify any additional relevant models that we hadnot identified through our literature and web searchesand (2) evaluate whether or not our literature and websearches were producing a comprehensive list. Theevaluation was accomplished by comparing our “contacts’lists” with the land-use model list we had developedthrough our literature and web searches. This 3-monthfollow-up activity provided fewer and fewer “newmodels,” so we shifted our efforts to the documentationand analysis of the models already identified.

By the end of the exercise, we had covered a range ofmodel types. They included Markov models, logisticfunction models, regression models, econometric models,dynamic systems models, spatial simulation models, linearplanning models, nonlinear mathematical planningmodels, mechanistic GIS models, and cellular automatamodels. For further discussion, please refer to theDiscussion section.2

Models

Using the framework previously described, we reviewedthe following 19 land-use models for their spatial,temporal, and human decisionmaking characteristics:

1. General Ecosystem Model (GEM) (Fitz et al. 1996)

2. Patuxent Landscape Model (PLM) (Voinov et al.1999)

3. CLUE Model (Conversion of Land Use and ItsEffects) (Veldkamp and Fresco 1996a)

4. CLUE-CR (Conversion of Land Use and Its Effects –Costa Rica) (Veldkamp and Fresco 1996b)

5. Area base model (Hardie and Parks 1997)

6. Univariate spatial models (Mertens and Lambin1997)

7. Econometric (multinomial logit) model (Chomitzand Gray 1996)

8. Spatial dynamic model (Gilruth et al. 1995)

9. Spatial Markov model (Wood et al. 1997)

10. CUF (California Urban Futures) (Landis 1995,Landis et al. 1998)

11. LUCAS (Land Use Change Analysis System) (Berryet al. 1996)

12. Simple log weights (Wear et al. 1998)

13. Logit model (Wear et al. 1999)

14. Dynamic model (Swallow et al. 1997)

15. NELUP (Natural Environment Research Council[NERC]–Economic and Social Research Council[ESRC]: NERC/ESRC Land Use Programme[NELUP]) (O’Callaghan 1995)

2We have tried to be thorough in our search for existingland-use/land-cover change models. However, we would liketo know of any important models we may have missed in thisreview. For this reason, we have posted the model referencesto a web-based database we call the “Open Research System”(at http://www.open-research.org). If you have a reference toa model we missed, we encourage you to visit this site,register with the system, and submit a reference to a modelpublication using the submit publication form.

9

16. NELUP - Extension, (Oglethorpe and O’Callaghan1995)

17. FASOM (Forest and Agriculture Sector OptimizationModel) (Adams et al. 1996)

18. CURBA (California Urban and Biodiversity AnalysisModel) (Landis et al. 1998)

19. Cellular automata model (Clarke et al. 1998,Kirtland et al. 1994)

We summarize key variations in modeling approaches inTable 3. All models were spatially representative. Of the19 models, 15 (79 percent) could be classified as spatiallyinteractive rather than merely representative. The samenumber of models were modular. Models that were notmodular were conceptually simple and/or included few

elements. Interestingly, a majority of the models did notindicate if they were spatially explicit. Anotherobservation was the level of temporal complexity: somemodels include multiple time steps, time lags, andnegative or positive feedback loops.

Tables 4, 5, and 6 provide a summary and assessment ofland-use change models. Table 4 gives basic informationabout each model: type, modules, what the modelexplains (dependent variables), independent variables, andthe strengths and weaknesses of each model. Table 5describes the spatial characteristics of each model: spatialrepresentation or interaction, resolution, and extent. Table6 details the temporal characteristics of each model: timestep and duration as well as the human decisionmakingelement’s complexity, jurisdictional domain, and temporalrange of decisionmaking. Definitions are provided in theGlossary.

Table 3.Summary statistics of model assessment

Review Criteria Number (percentage) of Models

Model Numbers

Spatial interaction 15 (79%) All but 5, 9, 12, 13 Temporal complexity 6 (31%) 1, 2, 3, 4, 15, 16 Human Decisionmaking – Level 1 3 1, 6, 9 Human Decisionmaking – Level 2 2 12, 19 Human Decisionmaking – Level 3 7 5, 7, 10, 11, 13, 17, 18 Human Decisionmaking – Level 4 4 2, 3, 4, 8 Human Decisionmaking – Level 5 2 14, 16 Human Decisionmaking – Level 6 1 15

10

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

Nam

e of

mod

el, i

f an

y, a

nd c

itatio

n T

echn

ical

, de

scri

ptiv

e te

rms

Diff

eren

t mod

els,

or

subm

odel

s or

mod

ules

, tha

t w

ork

toge

ther

D

escr

iptio

n of

oth

er se

ts of

var

iabl

es in

th

e m

odel

1. G

ener

al

Eco

syst

em M

odel

(G

EM

) (F

itz e

t al.

1996

)

Dyn

amic

sy

stem

s mod

el

14 S

ecto

rs (

mod

ules

), e

.g.

hydr

olog

y m

acro

phyt

es

alga

e nu

trie

nts

fire

dead

org

anic

mat

ter

sepa

rate

dat

abas

e fo

r ea

ch

sect

or

Cap

ture

s fe

edba

ck

amon

g ab

ioti

c an

d bi

otic

ec

osys

tem

com

pone

nts

103

inpu

t par

amet

ers,

in a

set

of l

inke

d da

taba

ses,

rep

rese

ntin

g th

e m

odul

es,

e.g.

, hy

drol

ogy

mac

roph

ytes

al

gae

nutr

ient

s fir

e de

ad o

rgan

ic m

atte

r

Spat

ially

dep

ende

nt m

odel

, wit

h fe

edba

ck b

etw

een

unit

s an

d ac

ross

tim

e

Incl

udes

man

y se

ctor

s

Mod

ular

, can

add

or

drop

se

ctor

s

Can

ada

pt r

esol

utio

n, e

xten

t, an

d ti

me

step

to m

atch

the

proc

ess

bein

g m

odel

ed

Lim

ited

hum

an

deci

sion

mak

ing

2. P

atux

ent

Land

scap

e M

odel

(P

LM)

(Voi

nov

et a

l. 19

99)

Dyn

amic

sy

stem

s mod

el

Bas

ed o

n th

e G

EM

mod

el

(1, a

bove

), in

clud

es th

e fo

llow

ing

mod

ules

, wit

h so

me

mod

ifica

tion

: 1)

hyd

rolo

gy

2) n

utri

ents

3)

mac

roph

ytes

4)

eco

nom

ic m

odel

Pred

icts

fund

amen

tal

ecol

ogic

al p

roce

sses

and

la

nd-u

se p

atte

rns

at th

e w

ater

shed

leve

l

In a

ddit

ion

to th

e G

EM

var

iabl

es, i

t -a

dds

dyna

mic

s in

car

bon-

to-n

utri

ent

rati

os

-int

rodu

ces

diff

eren

ces

betw

een

ever

gree

n an

d de

cidu

ous

plan

t co

mm

unit

ies

-int

rodu

ces

impa

ct o

f lan

d m

anag

emen

t thr

ough

fert

ilizi

ng,

plan

ting

, and

har

vest

ing

of c

rops

and

tr

ees

In a

ddit

ion

to th

e st

reng

ths

of

the

GE

M, t

he P

LM in

corp

orat

es

seve

ral o

ther

var

iabl

es th

at a

dd

to it

s ap

plic

abili

ty to

ass

ess

the

impa

cts

of la

nd m

anag

emen

t an

d be

st m

anag

emen

t pra

ctic

es

Lim

ited

con

side

rati

on o

f in

stit

utio

nal f

acto

rs

3. C

LUE

Mod

el

(Con

vers

ion

of

Land

Use

and

Its

E

ffec

ts)

(Vel

dkam

p an

d Fr

esco

199

6a)

Disc

rete

fini

te

state

mod

el

1) R

egio

nal b

ioph

ysic

al

mod

ule

2) R

egio

nal l

and-

use

obje

ctiv

es m

odul

e 3)

Loc

al la

nd-u

se

allo

cati

on m

odul

e

Pred

icts

land

cov

er in

th

e fu

ture

B

ioph

ysic

al d

rive

rs

Land

sui

tabi

lity

for

crop

s T

empe

ratu

re/P

reci

pita

tion

E

ffec

ts o

f pas

t lan

d us

e (m

ay e

xpla

in

both

bio

phys

ical

deg

rada

tion

and

im

prov

emen

t of l

and,

mai

nly

for

crop

s)

Impa

ct o

f pes

ts, w

eeds

, dis

ease

s H

uman

Dri

vers

: Po

pula

tion

siz

e an

d de

nsit

y T

echn

olog

y le

vel

Leve

l of a

fflu

ence

Po

litic

al S

truc

ture

s (t

hrou

gh c

omm

and

and

cont

rol,

or fi

scal

mec

hani

sms)

E

cono

mic

con

diti

ons

Att

itud

es a

nd v

alue

s

Cov

ers

a w

ide

rang

e of

bi

ophy

sica

l and

hum

an d

rive

rs

at d

iffer

ing

tem

pora

l and

spa

tial

sc

ales

Lim

ited

con

side

rati

on o

f in

stit

utio

nal a

nd

econ

omic

var

iabl

es

11

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

4. C

LUE

-CR

(C

onve

rsio

n of

La

nd U

se a

nd I

ts

Eff

ects

– C

osta

R

ica)

(V

eldk

amp

and

Fres

co 1

996b

)

Disc

rete

fini

te

state

mod

el

CLU

E-C

R a

n ap

plic

atio

n of

CLU

E (

3, a

bove

) Sa

me

mod

ules

Sim

ulat

es to

p-do

wn

and

bott

om-u

p ef

fect

s of

la

nd-u

se c

hang

e in

Cos

ta

Ric

a

Sam

e as

CLU

E (

#3, a

bove

) M

ulti

ple

scal

es -

loca

l, re

gion

al,

and

nati

onal

U

ses

the

outc

ome

of a

nes

ted

anal

ysis

, a s

et o

f 6x5

sca

le-

depe

nden

t lan

d-us

e/la

nd-c

over

lin

ear

regr

essi

ons

as m

odel

in

put,

whi

ch is

rep

rodu

cibl

e,

unlik

e a

spec

ific

calib

rati

on

exer

cise

Aut

hors

ack

now

ledg

e lim

ited

con

side

rati

on o

f in

stit

utio

nal a

nd

econ

omic

fact

ors

5. A

rea

base

m

odel

(H

ardi

e an

d Pa

rks

1997

)

Are

a ba

se

mod

el, u

sing

a

mod

ified

m

ulti

nom

ial

logi

t mod

el

Sing

le m

odul

e Pr

edic

ts la

nd-u

se

prop

orti

ons

at c

ount

y le

vel

Land

bas

e -

clas

sifie

d as

farm

land

, fo

rest

, and

urb

an/o

ther

use

s C

ount

y av

erag

e fa

rm r

even

ue

Cro

p co

sts

per

acre

St

andi

ng ti

mbe

r pr

ices

T

imbe

r pr

oduc

tion

cos

ts

Land

qua

lity

(agr

icul

tura

l sui

tabi

lity)

Po

pula

tion

per

acr

e A

vera

ge p

er c

apit

a pe

rson

al in

com

e A

vera

ge a

ge o

f far

m o

wne

rs

Irri

gati

on

Use

s pu

blic

ly a

vaila

ble

data

In

corp

orat

es e

cono

mic

(re

nt),

an

d la

ndow

ner

char

acte

rist

ics

(age

, inc

ome)

and

pop

ulat

ion

dens

ity

Inco

rpor

ates

the

impa

ct o

f lan

d he

tero

gene

ity

Can

acc

ount

for

sam

plin

g er

ror

in th

e co

unty

-lev

el la

nd-u

se

prop

orti

ons

and

for

mea

sure

men

t err

or in

curr

ed b

y th

e us

e of

cou

nty

aver

ages

An

exte

nded

dat

aset

ove

r lo

nger

tim

e pe

riod

s w

ould

impr

ove

the

mod

el's

pred

ictio

ns

Long

-ter

m fo

reca

sts

run

the

risk

of f

acin

g an

in

crea

sing

pro

babi

lity

of s

truc

tura

l cha

nge,

ca

lling

for

revi

sed

proc

edur

es

6. M

erte

ns a

nd

Lam

bin

1997

U

niva

riat

e sp

atia

l mod

els

Mul

tipl

e un

ivar

iate

m

odel

s, b

ased

on

defo

rest

atio

n pa

tter

n in

st

udy

area

1)

tota

l stu

dy a

rea

2) c

orri

dor

patt

ern

3) is

land

pat

tern

4)

diff

use

patt

ern

Eac

h m

odel

run

s w

ith

all

four

inde

pend

ent v

aria

bles

se

para

tely

Freq

uenc

y of

de

fore

stat

ion

All

four

mod

els

run

wit

h al

l fou

r in

depe

nden

t var

iabl

es:

1) r

oad

prox

imity

In a

ll ca

ses,

a s

ingl

e va

riab

le

mod

el e

xpla

ins

mos

t of t

he

vari

abili

ty in

def

ores

tati

on

Doe

s no

t mod

el

inte

ract

ion

betw

een

fact

ors

2) to

wn

prox

imit

y

3) fo

rest

-cov

er fr

agm

enta

tion

4)

pro

xim

ity

to a

fore

st/n

onfo

rest

ed

ge

Pres

ents

a s

trat

egy

for

mod

elin

g de

fore

stat

ion

by p

ropo

sing

a

typo

logy

of d

efor

esta

tion

pa

tter

ns

12

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

7. C

hom

itz

and

Gra

y 19

96

Eco

nom

etri

c (m

ulti

nom

ial

logi

t) m

odel

Sing

le m

odul

e, w

ith

mul

tipl

e eq

uati

ons

Pred

icts

land

use

, ag

greg

ated

in th

ree

clas

ses:

N

atur

al v

eget

atio

n Se

mi-

subs

iste

nce

agri

cultu

re

Com

mer

cial

farm

ing

Soil

nitr

ogen

A

vaila

ble

phos

phor

us

Slop

e

pH

Wet

ness

Fl

ood

haza

rd

Rai

nfal

l N

atio

nal l

and

Fo

rest

res

erve

D

ista

nce

to m

arke

ts, b

ased

on

impe

danc

e le

vels

(re

lati

ve c

osts

of

tran

spor

t)

Soil

fert

ility

Use

d sp

atia

lly d

isag

greg

ated

in

form

atio

n to

cal

cula

te a

n in

tegr

ated

dis

tanc

e m

easu

re

base

d on

terr

ain

and

pres

ence

of

roa

ds

Als

o, s

tron

g th

eore

tica

l un

derp

inni

ng o

f Von

Thü

nen’

s m

odel

Stro

ng a

ssum

ptio

ns th

at

can

be r

elax

ed b

y al

tern

ate

spec

ifica

tion

s D

oes

not e

xplic

itly

in

corp

orat

e pr

ices

8. G

ilrut

h et

al.

1995

Sp

atia

l dyn

amic

m

odel

Se

vera

l sub

rout

ines

for

diff

eren

t tas

ks

Pred

icts

sit

es u

sed

for

shift

ing

culti

vati

on in

te

rms

of to

pogr

aphy

and

pr

oxim

ity

to p

opul

atio

n ce

nter

s

Site

pro

duct

ivity

(no

. of f

allo

w y

ears

)

Eas

e of

cle

arin

g E

rosi

on h

azar

d

Site

pro

xim

ity

Po

pula

tion

, as

func

tion

of v

illag

e si

ze

Rep

licab

le

Tri

es to

mim

ic e

xpan

sion

of

culti

vati

on o

ver

tim

e

Long

gap

bet

wee

n da

ta

colle

ctio

n; d

oes

not

incl

ude

impa

ct o

f lan

d-qu

alit

y an

d so

cioe

cono

mic

var

iabl

es

9. W

ood

et a

l. 19

97

Spat

ial M

arko

v m

odel

T

empo

ral a

nd s

pati

al la

nd-

use

chan

ge M

arko

v m

odel

sLa

nd-u

se c

hang

e M

odel

s un

der

deve

lopm

ent

Inve

stig

atin

g M

arko

v va

riat

ions

, w

hich

rel

ax s

tric

t ass

umpt

ions

as

soci

ated

wit

h th

e M

arko

v ap

proa

ch

Exp

licit

ly c

onsi

ders

bot

h sp

atia

l an

d te

mpo

ral c

hang

e

Not

str

ictly

a w

eakn

ess,

th

is is

a w

ork

in p

rogr

ess

and,

hen

ce, h

as n

ot y

et

incl

uded

HD

M fa

ctor

s

10. C

UF

(Cal

iforn

ia U

rban

Fu

ture

s) (

Land

is

1995

, La

ndis

et a

l. 19

98)

Spat

ial

sim

ulat

ion

Exp

lain

s la

nd u

se in

a

met

ropo

litan

set

ting

, in

term

s of

dem

and

(pop

ulat

ion

grow

th)

and

supp

ly o

f lan

d (u

nder

deve

lope

d la

nd

avai

labl

e fo

r re

deve

lopm

ent)

Popu

lati

on g

row

th, D

LUs,

and

in

term

edia

te m

ap la

yers

wit

h:

Hou

sing

pri

ces

Z

onin

g Sl

ope

Wet

land

s D

ista

nce

to c

ity

cent

er

Dis

tanc

e to

free

way

or

BA

RT

sta

tion

D

ista

nce

to s

pher

e-of

-inf

luen

ce

boun

dari

es

Und

erly

ing

theo

ry o

f par

cel

allo

cati

on b

y po

pula

tion

gr

owth

pro

ject

ions

and

pri

ce,

and

inco

rpor

atio

n of

in

cent

ives

for

inte

rmed

iari

es-

deve

lope

rs, a

gre

at s

tren

gth

Larg

e-sc

ale

GIS

map

laye

rs w

ith

deta

iled

info

rmat

ion

for

each

in

divi

dual

par

cel i

n 14

co

unti

es p

rovi

de h

igh

real

ism

an

d pr

ecis

ion

Com

pres

ses

long

per

iod

(20

year

s) in

a s

ingl

e m

odel

run

H

as n

o fe

edba

ck o

f m

ism

atch

bet

wee

n de

man

d an

d su

pply

on

pric

e of

dev

elop

able

la

nd/h

ousi

ng s

tock

D

oes

not i

ncor

pora

te

impa

ct o

f int

eres

t rat

es,

econ

omic

gro

wth

rat

es,

etc.

Popu

lati

on g

row

th

subm

odel

Sp

atia

l dat

abas

e, v

ario

us

laye

rs m

erge

d to

pro

ject

D

evel

opab

le L

and

Uni

ts

(DLU

s)

Spat

ial a

lloca

tion

su

bmod

el

Ann

exat

ion-

inco

rpor

atio

n su

bmod

el

13

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

11. L

UC

AS

(Lan

d-U

se

Cha

nge

Ana

lysi

s Sy

stem

) (B

erry

et

al. 1

996)

Spat

ial

stoch

astic

mod

el So

cioe

cono

mic

mod

ule

La

ndsc

ape

chan

ge m

odul

e Im

pact

s m

odul

e

Tra

nsit

ion

prob

abili

ty

mat

rix

(TM

P) (

of

chan

ge in

land

cov

er)

Mod

ule

2 si

mul

ates

the

land

scap

e ch

ange

M

odul

e 3

asse

sses

the

impa

ct o

n sp

ecie

s ha

bita

t

Mod

ule

1 va

riab

les:

La

nd c

over

type

(ve

geta

tion

) Sl

ope

Asp

ect

Ele

vati

on

Land

ow

ners

hip

popu

lati

on d

ensi

ty

Dis

tanc

e to

nea

rest

roa

d D

ista

nce

to n

eare

st e

cono

mic

mar

ket

cent

er

Age

of t

rees

M

odul

e 2:

Tra

nsit

ion

mat

rix

and

sam

e as

Mod

ule

1, to

pro

duce

land

-cov

er

map

s M

odul

e 3:

Uti

lizes

land

-cov

er m

aps

Mod

el s

how

s pr

oces

s (t

he

TPM

), o

utpu

t (ne

w la

nd-u

se

map

), a

nd im

pact

(on

spe

cies

ha

bita

t), a

ll in

one

, whi

ch is

ra

re a

nd c

omm

enda

ble

Is m

odul

ar a

nd u

ses

low

-cos

t op

en s

ourc

e G

IS s

oftw

are

(GR

ASS

)

LUC

AS

tend

ed to

fr

agm

ent t

he la

ndsc

ape

for

low

-pro

port

ion

land

us

es, d

ue to

the

pixe

l-ba

sed

inde

pend

ent-

grid

m

etho

d Pa

tch-

base

d si

mul

atio

n w

ould

cau

se le

ss

frag

men

tati

on, b

ut

patc

h de

finit

ion

requ

irem

ents

oft

en le

ad

to th

eir

dege

nera

tion

in

to o

ne-c

ell p

atch

es

12. W

ear

et a

l. 19

98

Sim

ple

log

wei

ghts

Si

ngle

mod

ule

Pred

icts

are

a of

ti

mbe

rlan

d ad

just

ed fo

r po

pula

tion

den

sity

Raw

tim

berl

and

Popu

lati

on d

ensi

ty (

per

coun

ty)

Sim

ple

and

pow

erfu

l ind

icat

or

of fo

rest

sus

tain

abili

ty, o

f the

im

pact

of h

uman

set

tlem

ent

deci

sion

s on

one

fore

st fu

ncti

on

--it

s ro

le a

s ti

mbe

rlan

d

Lim

ited

con

side

rati

on o

f hu

man

dec

isio

nmak

ing

and

othe

r fo

rest

goo

ds

and

serv

ices

13. W

ear

et a

l. 19

99

Logi

t mod

el

Sing

le m

odul

e Pr

edic

ts th

e pr

obab

ility

of

land

bei

ng c

lass

ified

as

pot

enti

al ti

mbe

rlan

d

Popu

lati

on p

er s

quar

e m

ile

Site

inde

x Sl

ope

Tw

o du

mm

y va

riab

les

defin

ing

e

ase

of a

cces

s to

a s

ite

Incl

udes

sev

eral

bio

phys

ical

va

riab

les

Incl

udes

onl

y ba

sic

hum

an c

hoic

e va

riab

les,

e.

g., p

opul

atio

n de

nsit

y

14. S

wal

low

et a

l. 19

97

Dyn

amic

m

odel

T

hree

com

pone

nts:

1)

tim

ber

mod

el

2) fo

rage

pro

duct

ion

func

tion

3)

non

tim

ber

bene

fit

func

tion

Sim

ulat

es a

n op

tim

al

harv

est s

eque

nce

Pres

ent v

alue

s of

alte

rnat

ive

poss

ible

st

ates

of t

he fo

rest

, usi

ng th

e th

ree

mod

el c

ompo

nent

s

The

long

tim

e ho

rizo

n, a

nd th

e an

nual

che

ckin

g of

pre

sent

va

lues

und

er a

ltern

ate

poss

ible

st

ates

of t

he fo

rest

mak

es it

a

usef

ul fo

rest

man

agem

ent t

ool

for

max

imiz

ing

mul

tipl

e-us

e va

lues

Aut

hors

not

e th

at th

e op

tim

al m

anag

emen

t pa

tter

n on

any

indi

vidu

al

stan

d or

set

of s

tand

s re

quir

es s

peci

fic a

naly

sis

rath

er th

an d

epen

denc

e on

rul

es o

f thu

mb

14

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

15. N

ELU

P (O

’Cal

lagh

an

1995

)

Gen

eral

sy

stem

s fr

amew

ork

Eco

nom

ic

com

pone

nt

uses

a

recu

rsiv

e lin

ear

plan

ning

m

odel

Reg

iona

l agr

icul

tura

l ec

onom

ic m

odel

of l

and

use

at c

atch

men

t lev

els

Hyd

rolo

gica

l mod

el

Eco

logi

cal m

odel

Exp

lain

s pa

tter

ns o

f ag

ricu

ltura

l and

fore

stry

la

nd u

se u

nder

diff

eren

t sc

enar

ios

Var

iabl

e ty

pes

incl

ude:

So

il ch

arac

teri

stic

s M

eteo

rolo

gica

l dat

a Pa

rish

cen

sus

data

In

put/

outp

ut fa

rm d

ata

Spec

ies

Land

cov

er

Use

s la

nd c

over

to li

nk m

arke

t fo

rces

, hyd

rolo

gy, a

nd e

colo

gy

in a

bio

phys

ical

mod

el o

f lan

d us

e U

ses

mos

tly p

ublic

ly a

vaila

ble

data

, esp

ecia

lly in

the

econ

omic

mod

el, w

hich

gr

eatly

aid

s tr

ansf

erab

ility

Lim

ited

inst

itutio

nal

vari

able

s

16. N

ELU

P -

Ext

ensi

on

(Ogl

etho

rpe

and

O'C

alla

ghan

19

95)

Line

ar

plan

ning

m

odel

at f

arm

le

vel

Four

sub

mod

els

for

farm

ty

pes

1)

low

land

and

mai

nly

arab

le

2) lo

wla

nd m

ainl

y gr

azin

g liv

esto

ck

3) d

airy

4)

hill

Max

imiz

es in

com

e Pr

ofit

is th

e de

pend

ent

vari

able

Leve

l of f

arm

act

ivit

y G

ross

mar

gin

per

unit

of f

arm

act

ivit

y Fi

xed

reso

urce

s, r

epre

sent

ed a

s ph

ysic

al

cons

trai

nts

Det

aile

d fa

rm-l

evel

mod

el, w

ith

exte

nsiv

e ca

libra

tion

Fa

rmer

s sh

own

as r

atio

nal

prof

it-m

axim

izin

g be

ings

, but

al

so in

clud

es th

e im

pact

of o

ff-

farm

inco

me

Lim

ited

inst

itutio

nal

vari

able

s

17. F

ASO

M

(For

est a

nd

Agr

icul

ture

Sec

tor

Opt

imiz

atio

n M

odel

) (A

dam

s et

al.

1996

)

Dyn

amic

, no

nlin

ear,

pr

ice

endo

geno

us,

mat

hem

atic

al

prog

ram

min

g m

odel

Thr

ee s

ubm

odel

s :

1) fo

rest

sec

tor

- tr

ansi

tion

ti

mbe

r su

pply

mod

el

2) a

gric

ultu

ral s

ecto

r th

at is

op

tim

ized

wit

h th

e fo

rest

se

ctor

sub

mod

el

3) c

arbo

n se

ctor

for

terr

estr

ial c

arbo

n

Allo

cati

on o

f lan

d in

the

fore

st a

nd a

gric

ultu

ral

sect

ors

Obj

ecti

ve fu

nctio

n m

axim

izes

the

disc

ount

ed e

cono

mic

w

elfa

re o

f pro

duce

rs

and

cons

umer

s in

the

U.S

. agr

icul

ture

and

fo

rest

sec

tors

ove

r a

nine

-dec

ade

tim

e ho

rizo

n

Fore

st s

ecto

r va

riab

le g

roup

s:

dem

and

func

tion

s fo

r fo

rest

pro

duct

s ti

mbe

rlan

d ar

ea, a

ge-c

lass

dyn

amic

s

graz

ing

labo

r ag

ricu

ltura

l dem

and

impo

rts/

expo

rts

Car

bon

sect

or v

aria

bles

: tr

ee a

nd e

cosy

stem

car

bon

Add

itio

nal v

aria

bles

: la

nd tr

ansf

er v

aria

bles

Inco

rpor

ates

bot

h ag

ricu

lture

an

d fo

rest

land

use

s Pr

ice

of p

rodu

cts

and

land

is

endo

geno

us

The

mod

el is

dyn

amic

, thu

s ch

ange

s in

one

dec

ade

influ

ence

land

-use

cha

nge

in

the

next

dec

ade

Goo

d fo

r lo

ng-t

erm

pol

icy

impa

cts

Bro

ad s

cale

mea

ns th

at

land

cap

abili

ty v

aria

tion

s w

ithi

n re

gion

s ar

e no

t ta

ken

into

acc

ount

pr

oduc

tion

tech

nolo

gy a

nd c

osts

A

gric

ultu

ral s

ecto

r va

riab

les:

w

ater

15

Tab

le 4

.—In

-dep

th o

verv

iew

of

mod

els

revi

ewed

M

odel

Nam

e/

Cit

atio

n M

odel

Typ

e C

ompo

nent

s/

Mod

ules

Wha

t It

Exp

lain

s /

Dep

ende

nt V

aria

ble

Oth

er V

aria

bles

St

reng

ths

Wea

knes

ses

18. C

UR

BA

(C

alifo

rnia

Urb

an

and

Bio

dive

rsity

A

naly

sis

Mod

el)

(Lan

dis

et a

l. 19

98)

Ove

rlay

of G

IS

laye

rs w

ith

stat

isti

cal

urba

n gr

owth

pr

ojec

tion

s

Stat

isti

cal m

odel

of u

rban

gr

owth

Po

licy

sim

ulat

ion

and

eval

uati

on m

odel

M

ap a

nd d

ata

laye

rs o

f ha

bita

t typ

es,

biod

iver

sity

, and

oth

er

natu

ral f

acto

rs

The

inte

ract

ion

amon

g th

e pr

obab

iliti

es o

f ur

bani

zati

on, i

ts

inte

ract

ion

with

hab

itat

ty

pe a

nd e

xten

t, an

d,

impa

cts

of p

olic

y ch

ange

s on

the

two

Slop

e an

d el

evat

ion

Loca

tion

and

type

s of

roa

ds

Hyd

rogr

aphi

c fe

atur

es

Juri

sdic

tion

al b

ound

arie

s W

etla

nds

and

flood

zon

es

Juri

sdic

tion

al s

pher

es o

f inf

luen

ce

Var

ious

soc

ioec

onom

ic d

ata

Loca

l gro

wth

pol

icie

s Jo

b gr

owth

H

abit

at ty

pe a

nd e

xten

t map

s

Incr

ease

s un

ders

tand

ing

of

fact

ors

behi

nd r

ecen

t ur

bani

zati

on p

atte

rns

Allo

ws

proj

ecti

on o

f fut

ure

urba

n gr

owth

pat

tern

s, a

nd o

f th

e im

pact

of p

roje

cted

urb

an

grow

th o

n ha

bita

t int

egri

ty

and

qual

ity

Hum

an d

ecis

ionm

akin

g no

t exp

licit

ly

cons

ider

ed

Furt

her,

err

ors

are

likel

y fr

om m

iscl

assi

ficat

ion

of d

ata

at g

rid

leve

l or

mis

alig

nmen

t of m

ap

feat

ure

boun

dari

es

Err

ors

also

pos

sibl

e fr

om

limit

atio

ns in

ex

plai

ning

his

tori

cal

urba

n gr

owth

pat

tern

s

19. C

lark

e et

al.

1998

, Kir

tland

et

al. 1

994

Cel

lula

r au

tom

ata

mod

el

Sim

ulat

ion

mod

ule

cons

ists

of c

ompl

ex r

ules

Dig

ital

dat

aset

of

biop

hysi

cal a

nd h

uman

fa

ctor

s

Cha

nge

in u

rban

are

as

over

tim

e

Ext

ent o

f urb

an a

reas

E

leva

tion

Sl

ope

Roa

ds

Allo

ws

each

cel

l to

act

inde

pend

ently

acc

ordi

ng to

ru

les,

ana

logo

us to

cit

y ex

pans

ion

as a

res

ult o

f hu

ndre

ds o

f sm

all d

ecis

ions

Fi

ne-s

cale

dat

a, r

egis

tere

d to

a

30 m

UT

M g

rid

Doe

s no

t unp

ack

hum

an

deci

sion

s th

at le

ad to

sp

read

of b

uilt

area

s D

oes

not y

et in

clud

e bi

olog

ical

fact

ors

16

Tab

le 5

.—Sp

atia

l cha

ract

eris

tics

of

each

mod

el

Spat

ial C

ompl

exit

y Sp

atia

l Sca

le

Mod

el

Rep

rese

ntat

ion

n

Inte

ract

io

Res

olut

ion

Ext

ent

St

atic

. Rep

rese

nts d

ata

on

a m

ap a

nd m

ay p

ortr

ay

vari

atio

n as

wel

l

Dyn

amic

. Inc

lude

s effe

ct o

f var

iatio

n on

pro

cesse

s as w

ell a

s fee

dbac

k be

twee

n ne

ighb

orin

g un

its a

nd lo

catio

n of

pa

rcel

with

in th

e la

rger

scal

e

Ras

ter

or v

ecto

r. T

he a

rea

of th

e ba

sic u

nit o

f an

alys

is. A

gri

d if

raste

r.

Loca

tion

and

tota

l are

a co

vere

d by

mod

el, e

.g.,

grid

are

a x

no. o

f gri

ds

1. G

ener

al E

cosy

stem

m

odel

(G

EM

) (F

itz e

t al.

1996

)

Yes

Yes

Feed

back

bet

wee

n un

its

Ras

ter

Ent

ire

mod

el r

uns

for

each

spa

tial

uni

t T

rial

uni

t of 1

km

can

var

y 2

A tr

ial s

imul

atio

n fo

r th

e Fl

orid

a E

verg

lade

s/

Big

Cyp

ress

are

a A

ppro

x. 1

0,00

0 ac

res

2. P

atux

ent L

ands

cape

M

odel

(PL

M)

(Voi

nov

et a

l. 19

99)

Yes

Yes

Feed

back

bet

wee

n un

its

Ras

ter

Hyd

rolo

gica

l mod

el: 2

00 m

and

1 k

m

5890

5 ce

lls (

200

m)

or 2

352

cells

(1

km2 )

The

Pat

uxen

t wat

ersh

ed (

Mar

ylan

d, U

SA),

co

veri

ng 2

353

km2

3. C

LUE

Mod

el

(Con

vers

ion

of L

and

Use

an

d It

s E

ffec

ts)

(Vel

dkam

p an

d Fr

esco

19

96a)

Yes

Yes

Att

ribu

tes

of o

ne g

rid

unit

aff

ect

land

-use

out

com

es in

ano

ther

uni

t.

Ras

ter

In th

e ge

neri

c C

LUE

mod

el, s

ize

dete

rmin

ed b

y ex

tent

div

ided

by

grid

sca

le n

eutr

al m

atri

x of

23

x23

cells

C

an b

e sc

aled

up

or d

own

See

next

mod

el, C

LUE

-CR

, for

an

appl

icat

ion

4. C

LUE

-CR

(C

onve

rsio

n of

Lan

d U

se

and

Its

Eff

ects

– C

osta

R

ica)

(V

eldk

amp

and

Fres

co

1996

b)

Yes

As

abov

eR

aste

r

R

un a

t loc

al, r

egio

nal,

and

nati

onal

leve

ls

One

gri

d un

it =

0.1

deg

rees

or

6 m

inut

es

(= 7

.5x7

.5 k

m =

56.

25 k

m a

t the

equ

ator

) 2

Mul

tipl

e ex

tent

s th

at c

orre

spon

d to

diff

eren

t m

odul

es

Nat

iona

l: C

osta

Ric

a, 9

33 a

ggre

gate

gri

d un

its

Reg

iona

l: 16

to 3

6 ag

greg

ate

grid

s Lo

cal:

1 gr

id u

nit

5. A

rea

Bas

e M

odel

(H

ardi

e an

d Pa

rks

1997

) Y

es

Rel

ies

on la

nd

hete

roge

neit

y to

exp

lain

th

e co

exis

tenc

e of

se

vera

l lan

d us

es a

nd th

e sh

ift b

etw

een

them

No

Nei

ther

ras

ter

nor

vect

or

Dat

a av

erag

ed a

t cou

nty

leve

l A

vera

ge c

ount

y ar

ea =

315

,497

acr

es

Five

sou

thea

ster

n U

.S. s

tate

s -

Flor

ida,

G

eorg

ia, S

outh

Car

olin

a, N

orth

Car

olin

a,

Vir

gini

a =

147,

423,

760

acre

s

6. M

erte

ns a

nd L

ambi

n 19

97

Yes

Yes

Stat

us o

f pix

el is

dep

ende

nt o

n ot

her

spat

ial f

acto

rs

Ras

ter

80 m

x 8

0 m

(LA

ND

SAT

Pix

el s

ize)

So

uthe

ast C

amer

oon.

Are

a no

t spe

cifie

d, b

ut

is th

e ov

erla

p be

twee

n tw

o LA

ND

SAT

im

ages

17

Tab

le 5

.—Sp

atia

l cha

ract

eris

tics

of

each

mod

el

Spat

ial C

ompl

exit

y Sp

atia

l Sca

le

Mod

el

Rep

rese

ntat

ion

n

Inte

ract

io

Res

olut

ion

Ext

ent

7. C

hom

itz

and

Gra

y 19

96

Yes

Yes

Spat

ial v

aria

tion

in s

ever

al v

aria

bles

, in

fluen

ces

othe

r va

riab

les,

e.g

., w

etne

ss a

nd r

oads

and

slo

pe to

as

sess

impe

danc

e to

mar

kets

Use

s ve

ctor

dat

a on

ly

Cen

tral

and

Sou

th B

eliz

e, a

ppro

x. 2

/3 o

f the

to

tal a

rea

of 2

2,00

0 km

2

8. G

ilrut

h et

al.

1995

Y

es

Dyn

amic

, spa

tial

ly e

xplic

it m

odel

R

aste

r 10

0 m

x 1

00 m

cel

ls, i

n a

60x6

0 ce

ll gr

id,

resa

mpl

ed fr

om 1

20x1

20 g

rid

6 km

2 are

a, r

epre

sent

ativ

e of

a 6

0 km

2 Dia

fore

w

ater

shed

, in

the

Tou

gue

dist

rict

, Gui

nea

9. W

ood

et a

l. 19

97

Yes

N

o R

aste

r C

ell s

ize

of 8

0 m

(x

80m

) O

ne d

epar

tmen

t, V

elin

gara

, in

sout

h-ce

ntra

l Se

nega

l

10. C

UF

(Cal

iforn

ia

Urb

an F

utur

es)

(Lan

dis

1995

, La

ndis

et a

l. 19

98)

Yes

Yes

Vec

tor.

In

divi

dual

sit

es, w

ith

prop

erty

bou

ndar

ies

Mod

el r

un a

t cit

y an

d co

unty

leve

ls

Nin

e co

unti

es o

f the

San

Fra

ncis

co B

ay a

rea

(Ala

med

a, C

ontr

a C

osta

, Mar

in, N

apa,

San

Fr

anci

sco,

San

Mat

eo, S

anta

Cla

ra, S

olan

o,

Sono

ma)

and

five

adj

acen

t one

s, (

Sant

a C

ruz,

Sa

cram

ento

, San

Joa

quin

, Sta

nisl

aus,

Yol

o)

11. L

UC

AS

(Lan

d-U

se

Cha

nge

Ana

lysi

s Sy

stem

)

(Ber

ry e

t al.

1996

)

Yes

T

enta

tive

ly Y

es, i

f the

tran

siti

on

prob

abili

ty fo

r on

e pi

xel,

affe

cted

by

fact

ors

in a

noth

er p

ixel

Ras

ter

Eac

h pi

xel i

n th

is e

xam

ple

repr

esen

ts

90 m

x 9

0 m

, and

has

an

atta

ched

tabl

e w

ith

uniq

ue a

ttri

bute

s

Tw

o w

ater

shed

s, th

e Li

ttle

Ten

ness

ee R

iver

ba

sin

in N

orth

Car

olin

a an

d th

e H

oh R

iver

w

ater

shed

on

the

Oly

mpi

c Pe

nins

ula

in

Was

hing

ton

12. W

ear

et a

l. 19

98

Yes

D

ispl

ays

vari

atio

ns

amon

g co

unti

es

No

Nei

ther

Cou

nty-

leve

l agg

rega

te d

ata

Sout

hern

sta

tes

of th

e U

SA

13. W

ear

et a

l. 19

99

Yes

V

aria

tion

s am

ong

coun

ties

No

V

ecto

r.Fi

ne s

cale

, for

este

d pl

ots

in p

riva

te o

wne

rshi

p

Five

-cou

nty

regi

on a

roun

d C

harl

otte

svill

e,

Vir

gini

a -

Alb

erm

arle

, Flu

vann

a, L

ouis

a,

Gre

ene,

and

Nel

son

14. S

wal

low

et a

l. 19

97

Yes

Y

es

Tak

es in

tera

ctio

ns a

mon

g st

ands

into

ac

coun

t

Still

con

cept

ual,

neit

her

rast

er n

or v

ecto

r M

odel

sim

ulat

es m

ulti

-sta

nd d

ynam

ics

Stan

ds c

an v

ary

in s

ize

Mul

tipl

e st

ands

C

ase

stud

y us

es a

sim

plifi

ed e

cosy

stem

of t

wo

stan

ds.

15. N

ELU

P (O

’Cal

lagh

an 1

995)

Y

es

Inco

rpor

ates

var

iati

on

Yes

V

aria

tion

aff

ects

nei

ghbo

ring

uni

ts

Ras

ter

Eco

logi

cal m

odel

: 1-k

m2 u

nits

T

he m

ain

econ

omic

mod

el tr

eats

the

who

le

catc

hmen

t as

a m

acro

farm

, but

acc

ount

s fo

r la

nd-u

se v

aria

tion

usi

ng th

e la

nd-c

over

dat

a

Riv

er T

yne

catc

hmen

t in

Nor

ther

n E

ngla

nd -

30

00 k

m2

18

Tab

le 5

.—Sp

atia

l cha

ract

eris

tics

of

each

mod

el

Spat

ial C

ompl

exit

y Sp

atia

l Sca

le

Mod

el

Rep

rese

ntat

ion

n

Inte

ract

io

Res

olut

ion

Ext

ent

16. N

ELU

P -

Ext

ensi

on

(Ogl

etho

rpe

and

O'C

alla

ghan

199

5)

Yes

D

evel

oped

four

su

bmod

els

to c

aptu

re

vari

atio

n

Yes

N

ot in

sub

mod

el it

self,

but

in th

e to

tal N

ELU

P m

odel

Nei

ther

Fa

rm le

vel

Mul

tipl

e fa

rms

Tri

al r

uns

for

10 a

nd 1

4 fa

rms,

and

will

cov

er

the

enti

re c

atch

men

t

17. F

ASO

M (

Fore

st a

nd

Agr

icul

ture

Sec

tor

Opt

imiz

atio

n M

odel

) (A

dam

s et

al.

1996

)

Yes

D

ivid

es U

SA in

11

regi

ons

that

may

be

repr

esen

ted

on a

map

Yes

. M

odel

at s

ubco

ntin

enta

l sca

le, a

nd

chan

ges

in in

vent

ory

and

pric

es in

on

e re

gion

aff

ect p

rice

s an

d in

vent

ory

in o

ther

reg

ions

Vec

tor

Dem

and:

one

nat

iona

l reg

ion

Supp

ly: s

ubna

tion

al r

egio

n

The

ent

ire

USA

, exc

ept H

awai

i and

Ala

ska

18. C

UR

BA

(C

alifo

rnia

U

rban

and

Bio

dive

rsit

y A

naly

sis

Mod

el)

(Lan

dis

et a

l. 19

98)

Yes

Y

es, a

s im

pact

of c

hang

es in

one

cel

l -

in te

rms

of h

ighw

ay, g

row

th

polic

ies,

pop

ulat

ion

and

job

grow

th,

influ

ence

s pr

obab

ility

of

urba

niza

tion

of s

urro

undi

ng c

ells

Ras

ter

One

-hec

tare

gri

d ce

ll (1

00x1

00 m

) C

ount

y le

vel i

n C

alifo

rnia

Pi

lot s

tudy

for

Sant

a C

ruz

Cou

nty

Mod

el d

atas

ets

deve

lope

d fo

r ni

ne c

ount

ies

19. C

lark

e et

al.

1998

, K

irtla

nd e

t al.

1994

Yes

Yes

Eac

h ce

ll ac

ts in

depe

nden

tly, b

ut

acco

rdin

g to

rul

es th

at ta

ke s

pati

al

prop

erti

es o

f nei

ghbo

ring

loca

tion

s in

to a

ccou

nt

Ras

ter

Con

vert

ed v

ecto

r da

ta, e

.g.,

road

s to

ras

ter

Bas

e da

ta r

egis

tere

d at

30

m x

30

m

Mod

el r

un a

t 1 k

m le

vel

2

Init

ial r

un fo

r 25

6 km

2 reg

ion

arou

nd S

an

Fran

cisc

o in

cen

tral

Cal

iforn

ia, U

SA

19

Tab

le 6

.—T

emp

oral

an

d h

um

anT

able

6.—

Tem

por

al a

nd

hu

man

dec

isec

isio

nm

akin

g ch

arac

teri

stic

s of

eac

h m

o e

ach

mod

el

Mod

el

Tem

pora

l Sca

le

Hum

an D

ecis

ionm

akin

g

T

ime

Step

D

urat

ion

of M

odel

Run

C

ompl

exit

y

Dom

ain

Tem

pora

lRan

ge

T

ime

peri

od fo

r on

e ite

ratio

n of

th

e m

odel

. Mod

ules

may

hav

e di

ffere

nt ti

me

steps

-a

func

tion

of

the

part

icul

ar p

roce

ss.

Tim

e ste

p x

num

ber

of r

uns

A 6

-poi

nt sc

ale

for

hum

an

deci

sionm

akin

g or

hum

an c

hoic

e (r

ank

and

ratio

nale

)

Juri

sdic

tiona

l dom

ain

Sh

ort-

run

deci

sionm

akin

g pe

riod

an

d lo

nger

-run

dec

ision

mak

ing

hori

zon

1. G

ener

al

Eco

syst

em M

odel

(G

EM

) (F

itz e

t al.

1996

)

Init

ial s

imul

atio

n ru

ns a

t 0.5

-da

y ti

me

step

T

he ti

me

step

can

var

y ac

ross

m

odul

es to

mat

ch th

e dy

nam

ics

of p

arti

cula

r se

ctor

s

Can

mat

ch th

e cy

cle

of p

roce

ss

bein

g m

odel

ed

Leve

l: 1

Not

cov

ered

in c

ore

mod

el

Not

rea

lly c

onsi

dere

d N

ot r

eally

con

side

red,

as

ther

e is

no

exp

licit

soc

ioec

onom

ic

com

pone

nt in

the

basi

c G

EM

m

odel

2. P

atux

ent

Land

scap

e M

odel

(P

LM)

(Voi

nov

et a

l. 19

99)

Hyd

rolo

gica

l mod

ule:

one

-day

ti

me

step

La

nd-u

se m

ap fr

om th

e ec

onom

ic m

odel

impo

rted

at

a on

e-ye

ar in

terv

al

Exp

erim

enta

l run

com

pare

d 19

90 la

nd-u

se p

atte

rns

wit

h co

mpl

ete

fore

st

Leve

l: 4

Inco

rpor

ates

hum

an d

ecis

ions

as

a fu

ncti

on o

f eco

nom

ic

and

ecol

ogic

al s

pati

al

vari

able

s Pr

edic

ts p

roba

bilit

ies

of la

nd-

use

conv

ersi

on a

s fu

ncti

ons

of

pred

icte

d va

lues

in r

esid

enti

al

and

alte

rnat

ive

uses

and

the

cost

s of

con

vers

ion

Max

imiz

es r

ent a

s a

func

tion

of

the

valu

e in

diff

eren

t use

s an

d th

e co

sts

of c

onve

rsio

n, h

ence

ge

nera

lly r

efer

ring

to p

riva

te

deci

sion

mak

ing,

but

agg

rega

ted

at th

e gr

id le

vel

Ann

ual i

tera

tion

to c

aptu

re

vari

atio

ns in

land

use

3. C

LUE

Mod

el

(Con

vers

ion

of L

and

Use

and

Its

Eff

ects

) (V

eldk

amp

and

Fres

co 1

996a

)

One

mon

th to

upd

ate

mod

el

vari

able

s C

hang

es in

land

-use

type

s ho

wev

er, a

re m

ade

on

deci

sion

s fo

r ea

ch y

ear

Set b

y us

er

Exa

mpl

e sc

enar

io is

for

seve

ral

deca

des

Leve

l: 4

It a

pplie

s se

vera

l hum

an

driv

ers.

Inco

rpor

ates

col

lect

ive

deci

sion

mak

ing

leve

ls, f

rom

lo

cal t

o na

tion

al

Con

side

rs th

e te

mpo

ral r

ange

of

deci

sion

mak

ing

expl

icit

ly, i

n de

term

inin

g, fo

r ex

ampl

e th

e ti

me

peri

od fo

r up

dati

ng

chan

ges

in la

nd-u

se ty

pes

as w

ell

as m

inim

um e

cono

mic

age

and

ro

tati

on le

ngth

of t

he 1

0 di

ffer

ent l

and-

use

type

s

4. C

LUE

-CR

(C

onve

rsio

n of

Lan

d U

se a

nd I

ts E

ffec

ts –

C

osta

Ric

a)

(Vel

dkam

p an

d Fr

esco

199

6b)

One

mon

th

One

-mon

th ti

me

step

R

un 2

52 ti

mes

Le

vel:

4 H

uman

dem

ogra

phic

dri

vers

on

ly

As

abov

e, a

pplie

d to

Cos

ta R

ica

As

in C

LUE

, abo

ve

20

Tab

le 6

.—T

emp

oral

an

d h

um

anT

able

6.—

Tem

por

al a

nd

hu

man

dec

isec

isio

nm

akin

g ch

arac

teri

stic

s of

eac

h m

o e

ach

mod

el

Mod

el

Tem

pora

l Sca

le

Hum

an D

ecis

ionm

akin

g

T

ime

Step

Dom

ain

Tem

pora

l Ran

ge

Dur

atio

n of

Mod

el R

un

Com

plex

ity

5. A

rea

Bas

e M

odel

(H

ardi

e an

d Pa

rks

1997

)

No

Cro

ss-s

ecti

onal

stu

dy w

ith

1982

da

ta

At s

econ

d st

age,

5-y

ear

tim

e st

ep a

s po

oled

198

7 da

ta

Mos

tly 1

982

to 1

987

data

Le

vel:

3 La

nd-u

se p

ropo

rtio

ns a

re

mod

eled

as

depe

nden

t on

rent

from

land

as

wel

l as

aver

age

age,

inco

me,

and

po

pula

tion

den

sity

Whi

le d

ecis

ionm

akin

g is

m

ostly

at l

ando

wne

r le

vel,

the

stud

y ex

plan

ator

y va

riab

le,

land

-use

pro

port

ions

, is

cons

iste

nt w

ith

the

coun

ty-l

evel

da

ta

Not

con

side

red

in th

is c

ross

-se

ctio

nal s

tudy

6. M

erte

ns a

nd

Lam

bin

1997

13

yea

rs. S

ingl

e ti

me

step

13

yea

rs, 1

973-

86

Leve

l: 1

Hum

an d

ecis

ionm

akin

g no

t in

clud

ed d

irec

tly

Impl

icit

in th

e in

clus

ion

of

vari

able

like

dis

tanc

e fr

om

road

and

tow

n

Not

con

side

red

Not

con

side

red

7. C

hom

itz

and

Gra

y 19

96

Hum

an d

ecis

ionm

akin

g im

plic

it in

the

incl

usio

n of

va

riab

les

that

impa

ct r

ent,

dist

ance

to m

arke

t, so

il qu

alit

y

Not

con

side

red

Not

con

side

red

C

ross

-sec

tion

al a

naly

sis,

hen

ce

tim

e pe

riod

not

app

licab

le

Mos

t dat

a co

llect

ed

betw

een

1989

and

199

2 Le

vel:

3

8. G

ilrut

h et

al.

1995

T

wo

year

s B

ased

on

the

aver

age

culti

vati

on

peri

od in

the

exte

rior

fiel

ds

1953

to 1

989

Leve

l: 4

T

ries

to p

redi

ct lo

cati

on o

f sh

iftin

g cu

ltiva

tion

dec

isio

ns

on th

e ba

sis

of b

ioph

ysic

al

vari

able

s ov

er ti

me,

wit

h fe

edba

ck

Subw

ater

shed

, wit

h a

smal

l en

ough

sca

le to

cap

ture

larg

e cl

eari

ng

No

atte

mpt

to m

odel

in

divi

dual

fiel

ds

Mod

el ti

me

step

trie

s to

mim

ic

the

esti

mat

ed fa

llow

per

iod

of

two

year

s; h

owev

er, t

oo lo

ng a

pe

riod

bet

wee

n th

e ba

se a

nd

final

yea

r -

36 y

ears

9. W

ood

et a

l. 19

97

Tw

o st

eps:

Fou

r ye

ars

(197

3-78

) an

d 12

yea

rs (

1978

-90)

W

ill a

dd a

thir

d st

ep b

y in

clud

ing

1985

17 y

ears

(19

73-9

0)

Leve

l: 1

Not

incl

uded

M

ostly

at f

arm

and

fiel

d le

vel,

whi

le m

odel

ope

rate

s at

de

part

men

t lev

el

Con

side

red

impl

icit

ly, i

n ch

oice

of

tim

e st

ep, t

o ca

ptur

e ag

ricu

ltura

l lan

d-us

e ch

ange

ove

r lo

nger

tim

e pe

riod

s, r

athe

r th

an

the

deci

sion

mak

ing

asso

ciat

ed

wit

h ea

ch c

rop

cycl

e

21

Tab

le 6

.—T

emp

oral

an

d h

um

anT

able

6.—

Tem

por

al a

nd

hu

man

dec

isec

isio

nm

akin

g ch

arac

teri

stic

s of

eac

h m

o e

ach

mod

el

Mod

el

Tem

pora

l Sca

le

Hum

an D

ecis

ionm

akin

g

T

ime

Step

Dom

ain

Tem

pora

l Ran

ge

Dur

atio

n of

Mod

el R

un

Com

plex

ity

10. C

UF

(Cal

iforn

ia

Urb

an F

utur

es)

(Lan

dis

1995

, La

ndis

et a

l. 19

98)

Sam

e as

dur

atio

n?

Not

cle

ar fr

om r

efer

ence

w

heth

er a

nnua

l dat

a ar

e co

llect

ed

1990

-201

0 M

odel

take

s 19

90 b

ase

data

and

fo

reca

sts

grow

th in

201

0

Leve

l: 3.

H

uman

cho

ice

seen

as

dete

rmin

ed b

y m

arke

t pri

ce

and

othe

r en

viro

nmen

tal a

nd

zoni

ng c

onst

rain

ts

No

feed

back

, exc

essi

ve d

eman

d do

es n

ot le

ad to

incr

ease

in

pric

es in

the

mod

el

Mod

el o

pera

tes

at th

e le

vel o

f in

divi

dual

par

cels

, whi

ch is

the

leve

l at w

hich

dec

isio

ns a

re

usua

lly ta

ken

Not

con

side

red

expl

icit

ly

Mod

el r

un c

ompr

esse

s 20

yea

rs

into

one

run

Su

ch h

ousi

ng d

ecis

ions

are

oft

en

mad

e qu

ickl

y M

odel

use

s ba

se-y

ear

pric

e da

ta

It m

ay in

adeq

uate

ly r

epre

sent

ex

ogen

ous

fact

ors

in la

ter

year

s of

the

mod

el

A s

hort

er ti

me

step

may

be

bett

er

11. L

UC

AS

(Lan

d-us

e C

hang

e A

naly

sis

Syst

em)

(Ber

ry e

t al.

1996

)

Five

Yea

rs

Hum

an c

hoic

e m

odel

ed v

ia a

pr

obab

ility

func

tion

for

land

- co

ver

chan

ge, w

ith

basi

c so

cioe

cono

mic

det

erm

inan

ts

and

no fe

edba

ck

Not

con

side

red

expl

icit

ly

Gri

d do

es n

ot in

clud

e ow

ners

hip,

thou

gh it

is a

t fin

e en

ough

sca

le to

bro

adly

re

flect

pri

vate

dec

isio

nmak

ing

in th

e U

SA

Not

con

side

red

expl

icit

ly

Sing

le ti

me

step

15

yea

rs (

1975

-91)

Le

vel:

3

12. W

ear

et a

l. 19

98

Nin

e ye

ars

18 y

rs -

197

4,19

83,1

992

(tw

o ti

me

step

s or

thre

e ob

serv

atio

ns

in fo

rest

inve

ntor

y ye

ars)

Leve

l: 2

Dem

ogra

phic

dri

vers

det

erm

ine

impa

ct

Not

con

side

red

expl

icit

ly

The

impa

ct o

f ind

ivid

ual

deci

sion

s is

agg

rega

ted

to

coun

ty le

vel

Not

con

side

red

expl

icit

ly

13. W

ear

et a

l. 19

99

No

Cro

ss-s

ecti

onal

, 199

0s d

ata

Sing

le r

un, n

o du

rati

on

Leve

l: 3

Hum

an c

hoic

e in

clud

ed a

t ba

sic

dete

rmin

ant l

evel

(p

opul

atio

n de

nsit

y), a

long

w

ith

the

impa

ct o

f sev

eral

bi

ophy

sica

l fac

tors

, on

the

prob

abili

ty o

f a c

erta

in la

nd

use

Ave

rage

pop

ulat

ion

data

at

aggr

egat

e co

unty

blo

ck le

vel,

corr

elat

ed w

ith

indi

vidu

al p

lots

Cro

ss-s

ecti

onal

stu

dy, h

ence

not

co

nsid

ered

exp

licit

ly

22

Tab

le 6

.—T

emp

oral

an

d h

um

anT

able

6.—

Tem

por

al a

nd

hu

man

dec

isec

isio

nm

akin

g ch

arac

teri

stic

s of

eac

h m

o e

ach

mod

el

Mod

el

Tem

pora

l Sca

le

Hum

an D

ecis

ionm

akin

g

T

ime

Step

Dom

ain

Tem

pora

l Ran

ge

Dur

atio

n of

Mod

el R

un

Com

plex

ity

14. S

wal

low

et a

l. 19

97

One

yea

r R

un o

f 250

yea

rs, s

uffic

ient

ly fa

r in

to th

e fu

ture

that

hea

vy

disc

ount

ing

mak

es a

cha

nge

in

the

tim

e ho

rizo

n in

cons

eque

ntia

l

Leve

l: 5

A la

nd m

anag

emen

t mod

el

The

exp

lana

tory

var

iabl

e,

opti

mal

har

vest

rot

atio

ns,

prov

ides

a d

ecis

ion

supp

ort

tool

Focu

sed

on m

ulti

ple

stan

ds,

whi

ch is

the

leve

l at w

hich

de

cisi

ons

are

usua

lly m

ade,

pa

rtic

ular

ly if

ther

e ar

e m

ulti

ple

owne

rs

Land

man

agem

ent d

ecis

ions

are

us

ually

mad

e an

nual

ly, o

r ev

en

mor

e oc

casi

onal

ly, e

spec

ially

fo

r fo

rest

s.

The

long

tim

e ho

rizo

n, a

nd th

e an

nual

che

ckin

g of

pre

sent

va

lues

und

er a

ltern

ate

poss

ible

st

ates

of t

he fo

rest

mak

es it

a

usef

ul fo

rest

man

agem

ent t

ool

15. N

ELU

P (O

’Cal

lagh

an 1

995)

E

cono

mic

mod

el u

ses

annu

al

data

from

par

ish-

leve

l rec

ords

The

tim

e st

ep o

f the

hyd

rolo

gic

mod

el w

as n

ot a

vaila

ble

Eco

nom

ic s

ubm

odel

test

ed w

ith

annu

al d

ata,

198

1-88

Le

vel:

6

The

mod

el o

vert

ly m

odel

s ch

oice

s of

farm

ers,

whi

le

acti

ons

of o

ther

act

ors

are

incl

uded

in th

e fo

rm o

f te

chno

logy

or

polic

y co

nstr

aint

s

The

mai

n ec

onom

ic m

odel

tr

eats

the

who

le c

atch

men

t as

a m

acro

-far

m, t

hus

perh

aps

over

esti

mat

ing

fact

or m

obili

ty

The

ann

ual t

ime

step

co

rres

pond

s to

tim

e sc

ale

of

broa

d ag

ricu

ltura

l de

cisi

onm

akin

g

16. N

ELU

P -

Ext

ensi

on

(Ogl

etho

rpe

and

O'C

alla

ghan

199

5)

Ann

ual f

inan

cial

and

cos

t dat

a 10

-yea

r pe

riod

, 198

1-82

to 1

991-

92

Leve

l: 5

Thi

s su

bmod

el in

clud

es c

hoic

es

of fa

rmer

s W

hen

com

bine

d w

ith

the

rest

of

the

NE

LUP

mod

el, i

t w

ould

ran

k at

6

Als

o tr

ies

to m

odel

thei

r ri

sk-

aver

se b

ehav

ior

The

mod

el r

esol

utio

n pe

rfec

tly

mat

ches

the

deci

sion

mak

ing

unit

- th

e in

divi

dual

farm

The

ann

ual t

ime

step

co

rres

pond

s to

the

tim

e sc

ale

of

broa

d ag

ricu

ltura

l de

cisi

onm

akin

g

17. F

ASO

M (

Fore

st

and

Agr

icul

ture

Se

ctor

Opt

imiz

atio

n M

odel

) (A

dam

s et

al.

1996

)

Dec

adal

– 1

0 ye

ars

100

year

s, 1

990-

2089

Po

licy

anal

ysis

lim

ited

to 5

0 ye

ars,

199

0-20

39

Dem

and

regi

on: n

atio

n Fa

ctor

dec

isio

nmak

ing

is

mod

eled

at s

ubna

tion

al

regi

onal

leve

l, w

ith

aggr

egat

ion

from

indi

vidu

al

land

owne

r le

velr

athe

r th

an a

t fa

rm le

vel

A d

ecad

al ti

me

step

is c

onsi

sten

t w

ith

the

slow

rat

e of

cha

nges

in

fore

st s

ecto

r, b

ut n

ot th

e an

nual

de

cisi

onm

akin

g cy

cle

in

agri

cultu

re. T

o co

mpe

nsat

e, th

e ag

ricu

ltura

l obj

ecti

ve fu

ncti

on is

w

eigh

ted

by a

fact

or r

efle

ctin

g th

e ha

rves

t of a

gric

ultu

ral

prod

ucts

eac

h ye

ar d

urin

g a

deca

de.

Leve

l: 3

Hum

an c

hoic

e se

en a

s ec

onom

ic r

atio

nal

deci

sion

mak

ing

base

d on

re

turn

s un

der

alte

rnat

ive

uses

w

ith

limit

ed fe

edba

ck fr

om

the

envi

ronm

ent

Acc

ount

s fo

r ch

ange

s in

inte

r-te

mpo

ral a

nd p

rice

co

mpl

exit

y

23

Tab

le 6

.—T

emp

oral

an

d h

um

anT

able

6.—

Tem

por

al a

nd

hu

man

dec

isec

isio

nm

akin

g ch

arac

teri

stic

s of

eac

h m

odel

Mod

el

Tem

pora

l Sca

le

Hum

an D

ecis

ionm

akin

g

T

ime

Step

Dom

ain

Tem

pora

l Ran

ge

Dur

atio

n of

Mod

el R

un

Com

plex

ity

18. C

UR

BA

(C

alifo

rnia

Urb

an

and

Bio

dive

rsity

A

naly

sis

Mod

el)

(Lan

dis

et a

l. 19

98)

Not

app

aren

t 15

yea

rs, 1

995

to 2

010

Proj

ecti

ons

mad

e fo

r th

e la

tter

ye

ar

Leve

l: 3

Long

eno

ugh

mod

el p

erio

d to

ca

ptur

e lo

nger

term

shi

fts

in

urba

niza

tion

and

its

dete

rmin

ants

Hum

an d

ecis

ionm

akin

g in

the

urba

niza

tion

con

text

im

plic

itly

a fu

ncti

on o

f hi

ghw

ay fa

cilit

ies,

nat

ural

co

nstr

aint

s, g

row

th p

olic

ies,

an

d jo

b an

d po

pula

tion

gr

owth

U

sefu

l dep

icti

on o

f zon

ing

polic

ies

Cal

cula

tes

impa

cts

at 1

-ha

grid

le

vel,

a bi

t bro

ader

than

in

divi

dual

dec

isio

nmak

ing

leve

ls in

the

urba

n co

ntex

t A

lso

incl

udes

the

impa

cts

of

scal

e de

cisi

onm

akin

g, i.

e.,

coun

ty o

r su

bcou

nty-

leve

l zo

ning

19. C

lark

e et

al.

1998

, Kir

tland

et a

l. 19

94

Ann

ual

Use

d lin

ear

inte

rpol

atio

n to

es

tim

ate

annu

al c

hang

es

betw

een

data

sets

Use

d ab

out 9

0 ye

ars

of d

ata

for

valid

atio

n to

pro

ject

urb

an

grow

th 1

00 y

ears

from

199

0

Leve

l: 2

Whi

le h

uman

dec

isio

ns n

ot

expl

icit

ly m

odel

ed, t

heir

im

pact

take

n in

to a

ccou

nt

Ope

rate

s at

a b

road

er s

cale

of 1

km

2 , uti

lizin

g th

e ag

greg

ate

impa

ct o

f hun

dred

s of

hum

an

deci

sion

s th

at a

ffec

t ur

bani

zati

on

Ann

ual t

ime

step

app

ropr

iate

to

refle

ct a

ggre

gate

cha

nges

in b

uilt

area

, as

mos

t bui

ldin

gs a

re r

eady

in

less

than

a y

ear

24

Discussion

Trends in Temporal, Spatial,and Human Decisionmaking Complexity

Figure 5 shows the spatial representation and extent andthe temporal time step and duration of the models. Thistype of diagram is constructed by plotting four values:time step and duration on the x-axis and resolution andextent on the y-axis. The plotted area for each modelrepresents the spatial and temporal scales under which themodel operates (colors of models aid the reader indistinguishing them). The 19 models examined in thereport collectively cover a wide range of scales, from lessthan a day to more than 100 years, and from less than 1ha to more than 1 million km2. Yet this range of scales isnot covered by one model. Clearly, models seem to beassociated with a particular spatio-temporal niche.

Temporal Complexity. Many models with separateecological modules operate at fine time steps, e.g., a dayor a month (except certain climate-focused models). Thisfine temporal resolution allows these models to more

accurately represent rapid ecological changes with time incertain biophysical spheres, e.g., hydrology. Models withmultiple time steps (e.g., models 1, 2, 3, 4, 15, 16) canspan both fine and coarse time steps and reflect thetemporal complexity of different socioeconomic andbiophysical sectors more effectively. Some of the morecomplex models (3 and 4) also incorporate time lags andtake into account the time taken for different crops andother land uses to provide economic returns as well asprovide a 2-year buffer against food shortages by carryingover yield surpluses from previous years.

Spatial Complexity. More than half of the modelsprovide for spatial interaction and demonstrate theadvantages of spatially explicit models that move beyondsimple spatial representation. These models include theimpact of variations across space and time of differentbiophysical and socioeconomic factors on land-usechange. Figure 6 depicts the 19 models as in Figure 5, anddisplays which models use a raster, a vector, or neitherapproach. The spatio-temporal footprint of theLANDSAT datasets also is included.

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

ands

cape

Lo

catio

n

Reg

iona

l G

loba

l

Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

SpatialExtentSpatial Resolution

TimeStep

Duration

Cross-Sectional

Cross-Sectional

19

Figure 5.—Spatial and temporal characteristics of reviewed models. The numbers correspond to models listedon pages 8-9.

25

Eleven of 19 models are raster based, four are vectorbased, and four are classified as neither. That may change,for example, if model 14 goes beyond the conceptualstage. The mechanistic vector models (10 and 18) arefocused at city and county levels and provide the finestspatial resolution. Their extent may be limited byavailability of data. Most of the raster models have spatialresolutions that are larger than 30 to 80 m, broadlymirroring the pixel size of common remote-sensing data(e.g., LANDSAT TM and MSS). Likewise, the rastermodels seem to have extents at or less than the areacovered by one LANDSAT scene (170 km x 185 km).

The model with the largest extent (neither a raster nor avector model) was the continental-scale FASOM model(17), with a 100-year time horizon. This model is a goodexample of a dynamic, mathematical programming modelthat predicts allocation of land between agriculture andforestry, and is spatially representative but not spatiallyexplicit.

Human Decisionmaking Complexity. Figure 7 (aspace–time–human-decisionmaking diagram) addshuman decisionmaking complexity to the graphicalrepresentation of temporal and spatial scales. Modelsincorporating higher levelsof human decisionmaking aremore centrally located with respect to spatial and

temporal scales, probably due to the lack of dataavailability at more extreme scales. Each model’s humandecisionmaking level is listed in Table 3. Models at level 3(7 of 19) include significant elements of humandecisionmaking beyond demographic drivers, but aredefined by the lack of feedback; thus, the CUF model(10) allocates land based on cost, but does not factor infeedback on prices. At level 4, models incorporatefeedback, but most do not overtly model a particular kindof actor. Thus, the PLM, CLUE, and CLUE-CR models(2, 3, and 4) have well-developed ecological sectors andextensive human decisionmaking elements as well asfeedback among sectors, but do not explicitly modeldifferent types of actors. Model 8 (a land-use model thatincorporates shifting cultivation decisions) is ranked at 4based on its complexity in portraying humandecisionmaking. Models at levels 5 (models 14 and 16)and 6 (model 15) explicitly model one or more kinds ofactors. Model 14 simulates harvest decisions and includesboth economic and noneconomic criteria (e.g., habitat forwildlife). The NELUP model extension (model 16) is afarm-level model that includes the impact of farmingdecisions on changes in land-use intensity and land cover.The general NELUP model (15) has ecological andeconomic components and farming decisions, and canserve as a decision-support tool to provide feedback onthe impact of collective-level policies (e.g., support prices

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

ands

cape

L

ocat

ion

R

egio

nal

Glo

bal

Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Raster

Neither

Vector

MSSScene

TMScene

TotalLandsat Archive

Cross-Sectional

Cross-Sectional

Vector

Converted to

Raster

19

Figure 6.—Raster and vector characteristics of reviewed models. The numbers correspond to models listed on pages 8-9.

26

or conservation programs). These characteristics positionthe NELUP model among the most detailed in terms ofmodel specification in a variety of sectors affecting land-use change. However, it should be noted that a highlydetailed model is not necessarily more suitable than amodel with less specificity. The utility of a land-usechange model can be measured primarily by its ability todemonstrate emergent patterns in land-use changeprocesses and, secondarily, as a predictive tool.

Theoretical Trends

Social Drivers of Land-Use Change. A generalconsensus has emerged from working groups focusing on

social drivers of global change, particularly as it relates toland-use change. Building on the National ResearchCouncil’s report (Stern et al. 1992:2–3; hereafter referredto as the NRC report) on “Global EnvironmentalChange: Understanding Human Dimensions”, a Long-Term Ecological Research (LTER) Network workinggroup developed a report (Redman et al. 2000; hereafterreferred to as the LTER report) to the National ScienceFoundation (NSF), “Toward a Unified Understanding ofHuman Ecosystems: Integrating Social Science into Long-Term Ecological Research”. The LTER report articulatescore social science areas that need to be studied tounderstand variations in human land-use, production,and consumption patterns.

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

ands

cape

L

ocat

ion

R

egio

nal

Glo

bal

Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

654321

Cross-Sectional

Cross-Sectional

Human Decision-making Level

19

Figure 7.—Human decisionmaking complexity of reviewed models. The numbers correspond to models listed on pages 8-9.

Figure 8.—Traditional conceptual framework for ecosystem studies.

EcosystemDynamics

Biogeophysical Drivers

Human Activities

27

Social Patterns and Processes

• Demography

• Technology

• Economy

• Institutions

• Culture

• Information

Ecological Patterns and Processes

• Primaryproduction

• Populations

• Organic matter

• Nutrients

• Disturbance

Interactions

• Land use

• Land cover

• Production

• Consumption

• Disposal

“Natural” Ecosystems

Human Systems

Political and Economic Conditions

Biogeographical Conditions

Figure 9.—Conceptual framework for investigating human ecosystems.

To further illustrate this need, we examine the simplifiedmodel in Figure 8, which describes a general, traditional,conceptual framework that many ecologists have used tostudy ecosystems. Although this conceptual model ispowerful in its inclusion of both ecological and human-based processes, important interactions and feedbacksinfluencing long-term ecosystem dynamics are absent. Anactivity such as land use, traditionally seen as a driver, alsocan be viewed as the result of more fundamental socialand ecological patterns and processes. Incorporatinggreater contributions from the social sciences withexisting biophysical/ecological models could greatlyenhance our understanding of global change in general,and land-use change in particular.

In contrast to Figure 8, the LTER report proposes a moredynamic framework that explicitly links what is oftendivided into separate “natural” and human systems into amore integrated model (Fig. 9).

Although disciplinary training and traditional modelingoften treat elements of human and ecological systems asdistinct, this framework emphasizes dynamic linkages byfocusing on the interactions at the interface of the humanand ecological components of any human ecosystem. TheLTER report defines the following interactions as thespecific activities that mediate between the human andecological elements of the broader human ecosystem:

• Land-use decisions• Land cover and land-cover changes• Production• Consumption• Disposal

While each activity can be examined independently, thereport acknowledges their strong interdependencies.Though there might be other mediating activities, theLTER report proposes that the activities listed above are agood starting point since they already are identified byboth ecologists and social scientists as prominent andrelevant processes.

The next step is to develop a perspective on whatmotivates these activities. To integrate the social,behavioral, and economic aspects of human ecosystems,the LTER report proposes a list of social patterns andprocesses. We further propose that this list can be used asa practical guide for modeling land-use change. Theseprocesses include the following:

• Demography• Technology• Economy• Political and social institutions• Culturally determined attitudes, beliefs, and behavior• Information and its flow

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Aspects of the last three drivers on the list — institutions,culture, and information will be difficult to integrate withmore familiar biological factors. Certain aspects of thesedrivers (and the first three to a lesser extent) areconstrained by human perception of the driver and how itis already integrated into the established system. In ahuman ecosystem, all choices are not equally available toeveryone; choices are conditioned by human perceptionsand preconceptions as well as physical constraints.

To guide the development of land-use models that aremore inclusive of social patterns and processes, we see aneed for land-use model developers to consider one broadquestion and three subsidiary questions.

How did the social-ecological system develop into itscurrent state, and how might it change in the future?

This question focuses on several critical aspects of thebroader system, such as the nature of feedback linkages,rates of change, important system components, and thespecifics of resource use and production. Three subsidiaryquestions also are important for land-use modeldevelopment:

• How have ecological processes influenced the socialpatterns and processes that have emerged?

• How have social patterns and processes influencedthe use and management of resources?

• How are these interactions changing, and whatimplications do these changes bring to the state ofthe social-ecological system?

These questions can guide the development of anintegrated land-use model as researchers attempt tocharacterize the fundamental aspects of systemcomposition, system trends, and system operation. Suchan integrated approach to modeling land-use changemight necessitate a collaborative venture among scientistsin different disciplines, each expanding from a traditionalviewpoint. For most social scientists, this would mean agreater emphasis on the flow of matter and energy inhuman ecosystems. For ecologists, issues surroundinginformation flow and decisionmaking might take ongreater relevance.

Current Social Drivers in Land-Use Models. Relevanthuman-driver variables from all land-use models reviewedfor this report are summarized in Table 7 and theAppendix. These drivers can be examined in the contextof the social drivers identified by both the NRC andLTER reports. While some aspects of social drivers (suchas demography, markets, institutions, and technology) areincluded in several models, there is no clear and

systematic consideration of each type of driver (and therelationships among them) in any one model. Certainlynot all drivers are equally important over time, space, andat different scales. We propose that, similar to ecologicalmodels of forest growth (that might include the relativeeffects of nitrogen, water, and light availability andchanges in atmospheric carbon on different tree species),there is a comparable need for land-use models that caninclude the relative effects of different social drivers onland-use change in the context of space, time, and scale.This is particularly crucial for assessing alternative futurescenarios and relative impacts of different policy choices.We believe it is crucial for developers of land-use modelsto discuss and adopt a more comprehensive andsystematic approach to including social drivers of land-use change within the context of the NRC and LTERreports and existing social science efforts.

Multidisciplinary Approaches. Land-cover change is acomplex process affected by many social and ecologicalprocesses. The multidisciplinary nature of land-coverchange is widely recognized in both the social and naturalsciences, yet the institutional powers of the disciplinesremain strong and multidisciplinary science is still in itsinfancy. The broad spatial and temporal scales of thehuman dimension of land-cover change (that ourreviewed models cover) demand that models also crossmultiple disciplines. As the dimension becomes broader,more disciplines may need to be incorporated. Any modelof land-cover change is probably limited by the person(s)constructing it, in accordance with their disciplinarylimits in understanding and funding. Some of the modelswe examined incorporated multiple disciplines; GEM,PLM, and NELUP (models 1, 2, and 15) incorporatedmany biophysical disciplines as well as social sciences andfields of modeling methods. Other models, especially thepurely statistical ones, were more limited in scope. Ingeneral, the higher the ability of the model to deal withcomplexity, the more multidisciplinary the model is likelyto be.

Temporal and Spatial Synchrony and Asynchrony.Human decisionmaking does not occur in a vacuum.Rather, it takes place in a particular spatial and temporalcontext, and, since decisionmaking about land use usuallyconcerns some biophysical processes, we must includethese processes in the discussion.

The spatial extent of human problems is sometimessmaller and sometimes larger than key actors. Equivalencebetween the spatial extent of a given biophysical processand the jurisdictional domain of at least onedecisionmaking unit often can help actors make effectivedecisions. A lack of equivalence can present potentialproblems inhibiting the incorporation of all impacts of a

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process in decisionmaking. In the real world, decisions aremade at multiple scales with feedback from one scale toanother. Also, actors at a finer scale may have evolved adecisionmaking system at a broader scale, withoutactually having an actor at that scale.

This problem of scale mismatch occurs when the physicalscale of an ecological system varies substantially from thatof at least one organized decisionmaking system thatregulates human actions related to that system. Forexample, scale mismatch can occur when the physicalsystem is much larger than any human decisionmakingsystem that affects it. Most global ecological problems arecharacterized by this kind of scale mismatch and often arecharacterized as externalities. For example, until aninternational treaty or special regime is created, nation-

states are smaller than the stratosphere, but actions takenwithin all nation-states affect the level of greenhouse gasescontained in the stratosphere. Looking at atmosphericozone as a shield, substantial progress has been made indeveloping a successful international regime to limit thelevel of chlorofluorocarbons that can be emitted, as wellas providing a warning system for when ozone levels aredangerously low (Sandler 1997). While stratosphericozone levels are still falling, measurable progress has beenmade. In regard to global warming, various efforts toachieve an international regime to limit greenhouse gasemissions are under way, but such a regime is still a longway from being realized (Young 1999).

Scale mismatch also can occur when the ecological systemis smaller (or a dramatically different geographic shape)

Table 7.—Summary of model variables that characterize relevant human drivers

Human drivers or social patterns and preferences

Model variables Model Numbersa

Population size 2, 3, 4, 10, 15, 18 Population growth 2, 3, 4, 10, 18

Population density 2, 3, 4, 5, 10, 11, 12, 13, 18

Returns to land use (costs and prices) 2, 5, 10, 14b, 16, 17 Job growth 10, 18 Costs of conversion 2, 10 Rentc 2, 3, 5, 16 Collective rule making Zoning 2, 10, 15, 18 Tenure 7, 11

Relative geographical position to infrastructure:

Distance from road

2, 3, 4, 6, 10, 11, 18, 19

Distance from town/market 6, 7, 10d, 11, 18 Distance from village/settlement 8, 19

Infrastructure/Accessibility

Presence of irrigation 5 Generalized access variable 13 Village size 8e Silviculture 2, 15, 16, 17 Agriculture 2, 15, 16, 17 Technology level 3, 4, 17 Affluence 3, 4, 5 Human attitudes and values 3, 4 Food security 3, 4 Age 5

aModel 1 is not listed because it has no human driver. At the time of the review, model 9 was under construction. bModel 14 includes wealth and substitution effects of harvesting decisions across stands; includes nontimber benefits,

e.g., of providing forage and cover to wildlife. cIt is not clear if economic rent is a variable in model 18. Model 10 measures distance to both downtown San Francisco and the nearest sphere-of-influence boundary (as a proxy for infrastructure costs – water, drainage, electricity, etc.).

d

ePopulation is a proxy of village size in model 8.

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than any relevant decisionmaking regime (e.g.,watershed management). Wilson et al. (1999)analyze scale mismatches that occur in fisherieswhen managers in a large fishery agency perceivetheir task as managing a single large population offish, when, in fact, multiple, small, spatially discretepopulations actually characterize the fishery. If afishery is characterized by “metapopulations” wherelocal populations of fish are relatively discrete andreproduce separately, then management of thespecies at a broad scale may overlook the protectionof specific spawning grounds and allow rapidextinction of local populations (Hanski and Gilpin1997). The extinction of local populations canadversely affect the spawning potential of the entirepopulation. Similarly, if urban areas are governedonly by large units of government, andneighborhoods are not well organized, manyneighborhood-level functions are overlooked,eventually leading to serious problems throughoutan urban area (McGinnis 1999).

At a regional scale, SO2 emissions from midwestern

U.S. coal-burning power plants carry downwind andcause high ozone levels (in the lower atmosphere) inseveral states on the east coast. This has led to regionalinitiatives, like the 34-state Ozone Transport AuthorityGroup trying to resolve the problem.

Furthermore, missing connections might arise ifpotentially effective institutions exist at the appropriatescales but decisionmaking linkages between scales areineffective. Decisions also might be based on informationaggregated at an inappropriate scale, even though it mayexist at the appropriate scale (Cleveland et al. 1996). Anexample of the latter is the biennial national forest coveranalysis prepared by the Forest Survey of India. Whileforest cover is assessed at the level of small local units, it isaggregated and reported at the district level, which is alarger administrative unit, rather than at the watershed-based forest division level, at which forests are managed.

When human decisions relate to processes that changeover time, there might be a temporal mismatch betweenthe time step and duration of biophysical processes andthe decisionmaking time horizons of the human actors.For example, elected officials on 3- to 5-year terms haveshort decisionmaking horizons and make decisions onissues and processes that often have long-term biophysicalconsequences, such as tree species with long rotations ornuclear waste storage. (See earlier discussion ondecisionmaking time horizons.)

Humans usually use some form of discounting tocompare preferences over time. The discount rate may be

implicit or explicit. A farmer choosing between growingan annual crop and planting trees that are harvestable in30 years is comparing the flows of costs and benefits overdifferent periods. Since models do not have the luxury ofimplicit comparisons, they usually use a discount rate tocompare such choices. Most models make suchcomparisons by adjusting the value of money as afunction of time. However, linking biophysical and socialmodels by valuing social, economic, and environmentalsystems with this single parameter involves manyassumptions and has been controversial (Lonergan andPrudham 1994).

Figure 10 represents spatial and temporal interaction ofdecisionmaking and biophysical processes in a nine-boxfigure. The middle edge boxes (a, b, c, and d) representthe four factors whose interaction determines land use —time, space, human decisionmaking, and biophysicalprocesses. The corner boxes represent the results of theinteraction of the two adjacent headings. Thus, box iirepresents the temporal dimension of biophysicalprocesses (i.e., time step and duration), while box iiirepresents the spatial dimension of humandecisionmaking. The center box represents the problemsof mismatches between decisionmaking and biophysicalprocesses in the temporal and spatial dimensions, asdiscussed above. Land-use models and modeling tools or

Resolution and extent

(iv)

Space

(b)

Jurisdictional domain

(iii)

BiophysicalProcesses

(d)

TemporalMismatch

(v)

Spatial mismatch

HumanDecision-making

(c)

Time step andduration

(ii)

Time

(a)

Decisionmakingtime horizon

(i)

Figure 10.—Nine-box representation of the interaction betweenthe three dimensions of space, time, and human decisionmakingwith biophysical processes.

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approaches may be viewed in terms of their sophisticationor technical ability in portraying processes in each of thethree dimensions of space, time, and humandecisionmaking.

Methodological Trends

The reviewed models employ a range of modelingmethods (Table 4). The CUF and CURBA models (10and 18) both use a mechanistic GIS simulation,combining layers of information with growth projections.Both were noted for their detailed vector resolution. Arange of statistical/econometric models (5, 6, 7, 9, 12,and 13) applied either raster or vector approaches (thoughat least two used neither) using aggregated county-leveldata, mostly without spatial complexity. Dynamic systemsmodels include the GEM and its application, the PLM (1and 2). The NELUP model (15) also used a generalsystems framework. Additionally, several other models (3,4, 8, 11, 14, and 17) used dynamic approaches. Model 19applied a cellular automata approach to analyze urbanexpansion.

Systems Approach. Nonlinearities and spatial andtemporal lags are prevalent in many environmentalsystems. When models of environmental systems ignorethe presence of nonlinearities and spatial and temporallags, their ability to produce insights into complexhuman-environmental systems may be significantlyreduced.

Statistical approaches using historical or cross-sectionaldata often are used to quantify the relationships amongthe components of human-environmental systems. In thiscase, rich datasets and elaborate statistical models areoften necessary to deal with multiple feedbacks amongsystem components and spatial and temporal lags. Modelresults often are driven by data availability, theconvenience of estimation techniques, and statisticalcriteria — none of which ensure that the fundamentaldrivers of system change can be satisfactorily identified(Leamer 1983). A statistical model can provide onlyinsight into the empirical relationships over a system’shistory or at a particular point in time, but is of limiteduse for analyses of a system’s future development pathunder alternative management schemes. In many cases,those alternative management schemes may includedecisions that have not been chosen in the past, and theireffects are therefore not captured (represented) in the dataof the system’s history or present state.

Dynamic modeling is distinct from statistical modelingbecause it builds into the representation of a phenomenonthose aspects of a system that we know actually exist (suchas the physical laws of material and energy conservation)and that describe input-output relationships in industrial

and biological processes (Hannon and Ruth 1994, 1997).Therefore, dynamic modeling starts with this advantageover the purely statistical or empirical modeling scheme.It does not rely on historical or cross-sectional data toreveal those relationships. This advantage also allowsdynamic models to be used in more applications thanempirical models. Dynamic models often are moretransferable to new applications because the fundamentalconcepts on which they are built are present in manyother systems.

To model and better understand nonlinear dynamicsystems, we must describe the main system componentsand their interactions. System components can bedescribed by a set of state variables (stocks), such as thecapital stock in an economy or the amount of sedimentaccumulated on a landscape. These state variables areinfluenced by controls (flows), such as the annualinvestment in capital or seasonal sediment fluxes. Thenature of the controls (size of the flows), in turn, maydepend on the stocks themselves and other parameters ofthe system. Using this approach, models are constructedby identifying, choosing, and specifying values andrelationships among stocks, flows, and parameters.

Many land-use change models focus on specific processesaffected by a defined set of variables. An alternativeapproach is to examine land-use change as onecomponent of a socioecological system. In developing thissystems approach, one difficulty lies in deciding how toincorporate model complexity. Researchers from thesocial sciences may tend to add complexity on the socialside while generalizing components on the biophysicalside. Researchers in the natural sciences might do theopposite. A multidisciplinary team must struggle to find acompromise, making the model complex enough tooperate properly and produce reasonable behaviorwithout making any single part of the model overlycomplex. Another difficult task is to incorporate scaleissues into this systems approach. A number of researchershave developed models that provide great insight intovery complex systems (Voinov et al. 1998; Voinov et al.1999). Many of these models operate at a set spatial scale,but there might be important processes or relationshipsthat are not evident at that particular spatial scale.

Once a systems model has been constructed, what-ifscenarios can be explored more easily than with othermodeling approaches that are not systems oriented. Inparticular, a systems approach can examine whatfeedbacks exist in a socioecological system such as theimpact of increases or decreases in agriculturalproductivity on the local market prices of thoseagricultural goods. This scenario-testing ability hasproved valuable both to researchers and to policy experts

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in elucidating important relationships in differentsystems.

Modularity of Models. The multidisciplinary nature ofland-cover change modeling is paralleled by modularity inthe models themselves. Of the 19 models evaluated, allbut four were characterized by modular components.Modularity might help facilitate modeling land-coverchange by assigning a particular disciplinary aspect of themodel to a separate module. We found the majority of themodular models tended to consider multiple disciplines.This was true for models with explicit biophysical andsocial components, such as models 1, 2, 3, 4, and 15, andfor the largely biophysical models, which incorporatemultiple processes in a single model.

The complexity of a model also is related to modelmodularity. Complex models typically involve theinteraction of multiple parameters, and their creation andvalidation can be facilitated by utilizing multiple modularcomponents; for example, modularity allows differentprocesses to run at different time steps, different actorscan be modeled simultaneously in different modules, anddifferences in their decisionmaking horizons can beincorporated by varying the time step of differentmodules.

Data and Data Integration

The recent explosion in data availability has enabled thedevelopment of more rigorous models. More data canenable more accurate calibration and validation ofmodels. Data for independent variables are used tocalibrate model runs and the time frame for dataavailability often determines the time step for particularmodules. After calibration, models often are validated bycomparing outputs of variables being modeled, typicallyland cover, with actual land-cover data. Model calibrationand validation are perhaps the most critical and labor-intensive parts of model development.

Data often are differentiated by source and are eitherprimary or secondary. Primary data collection can betailored to specific requirements. If collected extensivelyat a regional scale, the source is spread out by necessityand the data must be broadly aggregated. If, on the otherhand, detailed information is collected intensively at ahigh concentration, say 100-percent sampling, resourceconsiderations often lead to very localized coverage.Secondary data, by definition, are limited to data alreadyavailable but often cover longer time scales and broaderspatial scales (e.g., U.S. census data are averaged forcensus blocks, large subcity units). At least one reviewedmodel (15) consciously restricted itself to publiclyavailable data so the model could be transferable to otherlocations.

Another issue is data form and availability over time.When data are sought covering the last several centuries,data sources often are limited and highly aggregated.Assessing older land-use changes may involve otherdisciplines (e.g., archaeology) to understand land cover.Thus, the forest transition in the United States, wheredeforestation likely peaked around 1900, and Braziliandeforestation, which shows no signs of peaking yet, arealmost always viewed in a different light primarilybecause of data availability.

Satellite images offer an extensive source of land-coverdata collected remotely at a cost that is significantly lowerthan the cost of manual collection. Several recent datatrends include higher spatial and spectral resolution andhigher frequency of acquisition with time. The number ofsatellites providing imagery has increased dramaticallysince the early use of satellite imagery. In the 1970s, theprimary platform for publicly available imagery was theLANDSAT MSS instrument. Currently there is a varietyof platforms, each with different imaging characteristics,including French SPOT panchromatic and multispectralinstruments, data from the Indian IRS family of satellites,and radar imagery from the Japanese JERS satellite. Dataare available at increasingly finer resolutions as well. Thefirst satellite instrument used for public land-covermapping in the 1970s (LANDSAT MSS) provided imagedata at a spatial resolution of 56 x 79 m. The currentLANDSAT 7 provides much finer resolution at 28.5 x28.5 m. The private IKONOS satellite launched in 1999provides 1-m panchromatic data and 4-m multispectraldata. Also, image data are available over an increasinglywider spectral range, which includes data in optical,thermal, and radar wavelengths.

Along with improved satellite data come complications intheir use for land-use modeling. Satellite imagery isavailable from the early 1970s. Examining land-usechange prior to this period requires the use of otherremotely sensed data, such as aerial photography, orground-collected historical information. A variety ofmethodological issues related to comparing land-use dataderived from different data sources complicate the studyof land-use change processes across long periods. Perhapsmore importantly, many land-use change processes aretime dependent. For example, timber harvests in manyareas of the United States are based on an approximate40-year rotation cycle, while tropical subsistence rotationsmay be much shorter (5 years). These temporal issueshave serious implications for land-use change analysis interms of identifying the relationship of these land-usechanges within the context of varying study durations.

The LANDSAT system provides an excellent source ofland-cover data over a long duration (1972 to the

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present). However, between 1972 and 1982, only imagedata from the LANDSAT MSS instrument was available,but acquisition of MSS images was curtailed in 1992 afterwhich only Thematic Mapper (TM ) images wereavailable. The difference in resolution between the MSSand TM instruments means that the more recent, finerdata will have to be resampled to a broader resolution forcomparison. There also is a question of data availabilityoutside the United States, where several areas have spottyimage availability. For example, from the mid-1980s tothe early 1990s, there is extremely limited availability forWest African LANDSAT TM scenes. This differentialavailability of imagery is due to market-oriented policiesfollowing the privatization of the LANDSAT system inthe mid-1980s.

Finally, we must consider questions of data migration andreading-device obsolescence. Data formats areproliferating, and data stored in older formats need to bemigrated to newer formats as older formats becomeobsolete along with the accompanying hardware andsoftware. The ability to read diverse formats affects dataavailability and might, in the extreme case, renderarchives of little use. For example, the earliest LANDSATsatellites included a higher-resolution instrument, theReturn Beam Vidicon (RBV), which at the time wasthought to be a superior instrument to the MSS.However, these image data are stored on magnetic tapeformat which current data providers no longer use; thismeans the archives currently do not provide access toRBV data.

Despite the above caveats, the LANDSAT TM is a usefulremotely sensed data source. It has global coverage, anexcellent dataset for the United States, and couldpotentially map the entire world at 16-day intervals(except for occurrences of cloud cover). Another broader-scale remote sensing source is the AVHRR with a lowerresolution of 1.1 km, but which provides daily data forthe entire globe. AVHRR applications include a famineearly-warning system (operational in a dozen Africancountries) that maps agricultural production based onland-cover parameters.

Aerial photographs, another form of remotely senseddata, usually have a higher resolution than satellite imagesand can provide detailed information on land cover. Somecounties in Indiana use aerial photos to determine land-use categories at extremely fine scales for property taxassessment. Aerial photographs have been available in theUnited States for more than half a century. However, theyhave both geometric and radiometric distortions, whichmake them not directly comparable with satellite images.Aerial photographs often vary in scale and season ofacquisition. For example, aerial photos in Indiana were

acquired every 5 years alternately in summer and winterand usually require manual interpretation, a skilled andlabor-intensive task with a declining supply ofinterpreters.

Nearly all parameters used in land-cover change modelshave a spatial dimension and much of the data can beorganized effectively using a Geographic InformationSystem (GIS). While some models might use parametersthat are spatial in nature, these parameters may not bespatially explicit. For example, models 5, 12, 14, and 16exhibit parameters neither as raster (grid cells) nor asvector (points, lines, or polygons). In our survey, thesenonspatially explicit models may reflect unavailable dataat finer scales (see Fig. 6).

One of the strengths of GIS and spatial representation isthe ability to integrate data from disparate sources. Forexample, population data collected as point data fromvillages in a rural area can be used to create a surface ofland-use intensity by creating a weighted interpolationsurface modified by other community-level variables suchas the sex ratio, occupation of village residents, andlandholdings. This land-use intensity surface can beintegrated with a land-use map to explore the relationshipbetween land use and past land-use changes and topredict future changes. These data transformations areenabled by a GIS approach through the development of aspatial representation of the factors affecting the land-usesystem. There are varieties of sources of error associatedwith these data transformations and researchers mustevaluate the contribution of these errors to the overallerror in the model. However, even with these errors,spatial representation can allow explorations ofrelationships between social and biophysical factors,which would not be possible with nonspatially explicitmethods of research.

Scale and Multiscale Approaches

We considered scale in three dimensions in thisassessment. We also have demonstrated the broadequivalence of spatial (resolution and extent) andtemporal (time step and duration) scales and their echoesin temporal (decisionmaking horizon) and spatial(jurisdictional domain) attributes of humandecisionmaking. Mertens and Lambin (1997) hint at theimportance of both resolution and extent when theyrecognize the tradeoff between analysis at broad scales(where the high level of aggregation of data may obscurethe variability of geographic situations, thus dilutingcausal relationships) and fine scales (impractical, if therewere no possibility of generalizing over large areas).

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One of the issues in broader-scale decisionmakingmodeling is that developing such a sector-level modelinvolves “huge complexities likely to arise while trying toassess behavioural characteristics at the sector level”(Oglethorpe and O’Callaghan 1995). Certainly, fine-scalemodels have particular benefits. Oglethorpe andO’Callaghan (1995) conclude that the farm-level modelallows them to project land-use patterns and managementpractices arising as a result of agricultural market andpolicy changes while demonstrating the short- and long-term consequences for the environment.

The resolution and extent of a model or its submodulesoften are based on the extent of computing poweravailable and the scale at which certain biophysicalprocesses operate. Increasingly, there is recognition thatdifferent land-use change drivers operate at differentscales and that interscale dynamics should be included inland-use/cover change models (Veldkamp and Fresco1996a).

The importance and challenge of scale and nested,hierarchical approaches cannot be overestimated. Thephysical, biological, and social sciences are struggling withthe issue of scale and these have implications forappropriate frameworks for collecting and analyzing dataat different spatial and temporal scales. This issue infusesmany activities that influence modeling, from datacollection, to data analyses, to interpretation of results. Ina “human” spatial sense, scales of interest range fromindividuals to groups or institutions of increasingly largesize until they encompass global networks.

In a similar fashion, understanding processes acting atvarying temporal scales is important to understand high-frequency processes as well as those operating over longerperiods. The importance of this challenge is morepronounced when modelers consider integrated models.For example, some social and ecological processes may beassociated with a particular scale, while other processesmight occur across multiple scales. Further, ecological andsocial processes may not operate at the same scale andlinkages may have to be developed to connect acrossscales. It is unknown whether theories that explainprocesses at one scale can be used to explain processes atother scales. To date, no land-use model combining socialand ecological processes has completed a multiscaleapproach. Thus, fundamental research and modelingparadigms may need to be rethought (Redman et al.2000).

We will need to develop a number of capabilities formultiscale approaches and models of land-use change.These include the ability to identify the following(Redman et al. 2000):

• Optimal scale(s) and resolution(s) for modelingunderlying social and ecological patterns and processesof land-use change

• Time lags, nonlinear relationships, and defining eventsthat affect the responses among social and ecologicalprocesses of land-use change

• Spatial characteristics of certain phenomena, such asshape, adjacency, and matrix, and how they affect socialand ecological processes of land-use change

• Boundary conditions relative to space and time thatmight affect social and ecological processes of land-usechange

• Broad-scale data to explain fine-scale behavior(ecological inferences) and fine-scale data to explainprocesses at other scales of land-use change

• Data associated with one unit of analysis that can bedis- and reaggregated to another unit (e.g., from censustracts to watersheds) to model land-use change

Future Directions in Land-Use Modeling

Many of the models reviewed in this report have beenunder development for a long time. Models that haveevolved over a long period often have to accommodatechanges in mission and expansion into new substantiveareas important to the system being modeled but notoriginally included in earlier versions of the model. Forexample, the PLM (model 2) was originally designed asan ecologically based model of the Patuxent watershed inthe Eastern United States. Subsequent functionality hasbeen added to the PLM to incorporate various social-based inputs, including population growth, agriculturalpolicy, and land-use management. This new functionalityhas expanded the domain of the model but the social-based inputs might not always be optimallyaccommodated by the modeling framework developed forthe original ecologically based components of the model.

This is not to detract from the considerableaccomplishments of the PLM or the spatial modelingenvironment (SME) framework in which the PLM hasbeen implemented. However, developing models in thisfashion may lead to early design decisions which obstructthe performance of future model components added tothe base model.

In another example, during a model-design workshop insupport of the FLORES model, the initial discussionamong the workshop participants was used to design theoverall framework for the model: the time step, spatialunit of analysis, and how the model components wouldinteract. Certain compromises had to be made by each of

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the workshop groups representing separate components ofthe model.

Constraints. Availability of data for model validationimposes serious constraints in considering variables forinclusion. Models that use significant amounts of primarydata are constrained in extent or duration, or both. Somemodel development approaches deliberately haverestricted themselves to publicly available data for spatialreplicability.

Another issue in the land-use modeling community is theduplication of effort and sharing of models. We haveobserved that several models addressing similar systemsoften are developed independently. This has the advantageof demonstrating unique approaches to the same researchquestions and may produce better models by enactingsome form of competition between models. Thedownside to multiple development is the considerabledocumentation needed to allow model developers tounderstand each other’s code such that supplanted codemay be cannibalized into other models. Issues ofintellectual property rights also need to be addressed.

Opportunities. In accordance with Moore’s Law, we havewitnessed incredible increases in raw computing power.Desktop PCs now run models that would have required aroomful of mainframe computers a decade ago. Thisdevelopment is a great enabler and has contributedimmeasurably to expanding land-use modeling efforts.More computing power gives models the ability toexpand their extents and durations and, at the same time,make resolutions and time steps smaller.

Modeling tools also are getting better: they do more withtime and are more user-friendly. Development ofmodeling tools allows us to build more sophisticatedmodels in all three dimensions. Various modelingframeworks have been developed that provide modeldevelopers with tools suited to address common aspects ofland-use systems. They are easier to learn and use thanwriting code and often have graphical interfaces. Forexample, STELLA (type A in Fig. 4) provides a format fordynamic modeling that has a very intuitive graphic userinterface and can be used to develop simple studentmodels or complex research models. Another example isthe SWARM simulation package (type F in Figure 4),developed at the Santa Fe Institute, which has been usedfor modeling multiagent systems and the interactionsbetween the agents in those systems. A variety of otherdevelopment tools are available to researchers. Many ofthese tools, such as STELLA, are commercially based,while others, such as SWARM, are accessible undervarious public licensing structures. Of course, manymodels we reviewed (5, 13, 14, 15, and 16) still depend

on labor-intensive mathematical programming oreconometrics for their core modeling.

Open-Source Approaches. Models involving time, space,and human decisionmaking can be incredibly complexand depend upon knowledge from many disciplines.Until now, most models have developed in isolation. Thisis related to the fact that modelers have been fundedthrough grants or focused funds from a particularorganization with an interest in human-environmentalmodeling. Even in the context of large interdisciplinaryresearch centers like the NSF networks cited previously,efforts have been constrained by funds, staff, andexpertise.

In contrast to traditional approaches to modeldevelopment, recent advances in worldwide webtechnology have created new opportunities forcollaboration in the development of human-environmental modeling. Recently, “open-source”programming efforts have been used to solve complexcomputing problems (see for example, Kiernan 1999;Learmonth 1997; McHugh 1998; OSI 2001). Open-source programming is based on a collaborative licensingagreement that enables people to freely downloadprogram source code and utilize it on the condition thatthey agree to provide their enhancements to the rest of theprogramming community. There have been severalsuccessful, complex programming endeavors using theopen-source concept, the most prominent being theLinux computer operating system. However, some open-source endeavors have failed, but the Linux model hasshown that extremely complex problems can be tackledthrough collaboration over the Internet and that this kindof collaboration can produce robust results. The stabilityof the Linux software program is due to “Linus’ Law”(Linus Torvalds is the initial developer of Linux): “Givenenough eyeballs, all [problems] are shallow” (Raymond1999). In other words, if we can get enough human eyes(and brains) with various skills and expertise workingtogether, many problems, regardless of their complexity,can be solved because some individual or a team ofindividuals will come up with elegant solutions.

How is an open-source approach to computing connectedto human-environmental modeling? We propose that asimilar approach to the development of human-environmental models provides the basis for focusingenough “eyeballs” on important human-environmentalproblems (Schweik and Grove 2000). A similar argumenthas been made for open source endeavors in other areas ofscientific research (Gezelter 1999). Initiating such anopen-source modeling effort will require severalcomponents: (1) a web site to support modelingcollaboration (e.g., data and interactions among

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individuals, such as bulletin boards and FAQs); (2) theestablishment of one or more modeling “kernels” (corecomponents of models using various technologies) thatare designed in a modular fashion and allow relativelyeasy enhancements from participants; and (3) thedevelopment of mechanisms for sharing modelenhancements that encourage participation and provideincentives that are comparable and as valued as publishingin peer-reviewed journals.

In 2000, we initiated a web site titled “Open ResearchSystem” or ORS (open-research.org). The first step of thiseffort was to develop a web-based metadatabase thatallows the open sharing of geographic and nonspatialdatasets and references to publications and reports. If areader knows of a model not covered in this review or inthe Appendix, he or she could visit this site, register, andsubmit a publication reference to the system database.This would allow other visitors to the site, through thesearch facility, to find the model publication. The nextstep of this project is to move toward extending thedesign to allow the sharing of various types of land-covermodels in an open-source approach.

We recognize that the application of the open-sourceprogramming concept to human-environmental modelingmight appear daunting and even radical. However, theLinux example shows how extremely complex problemscan be solved when enough people work on them. Giventhe complexities involved in modeling time, space, andhuman decisionmaking, the open-source programmingconcept might be a vital modeling approach for creativesolutions to difficult human-environmental modelingproblems.

Conclusion

Land-use/land-cover change is a widespread, accelerating,and significant process. Land-use/land-cover change isdriven by human actions, and, in many cases, it alsodrives changes that impact humans. Modeling thesechanges is critical for formulating effective environmentalpolicies and management strategies. This report detailsour efforts to inventory land-use change models througha review of literature, websites, and professional contacts.We examined in detail 19 of these land-use changemodels and developed a framework that evaluated scaleand complexity in three critical dimensions—time, space,and human choice or decisionmaking—to observe anddescribe multiple models in a single synoptic view.

We advocate the use of the LTER report list of socialpatterns and processes as a practical guide forincorporating social processes in modeling land-usechange. This list includes: demography; technology;

economy; political and social institutions; culturallydetermined attitudes, beliefs, and behavior; andinformation and its flow. We also advocate a morecomprehensive and systematic approach to include socialdrivers of land-use change within the context of the NRCand LTER reports and existing social science efforts.

Finally, open-source modeling offers additional hope forfuture modeling. There have been several very successful,complex programming endeavors using the open-sourceconcept. These methods might spur the development ofland-use/land-cover modeling as well.

We would like to conclude with some thoughts aboutland-use models and policy. Increasingly, the policycommunity is interested in land-use models that arerelevant to their needs. To answer policy questions, policymakers will have to begin to identify the key variables andsectors that interest them, their scales of analysis, and thescenarios they anticipate. At the same time, land-usemodelers should begin discussions with policy makers tounderstand their needs. Given policy makers’ needs, land-use modelers will have to translate those needs withparticular attention to implicit and explicit temporal,spatial, and human decisionmaking scale and complexityand the interactions between scale and complexity.Further, land-use modelers will need to consider therelative significance of different drivers on land-usechange within the context of policy makers’ needs. Issuesof scale mismatch between physical and decisionmakingsystems, missing connections between levels ofdecisionmaking and intertemporal preferences gainadditional importance in this context. There is the needto provide a framework for collaboration and modeldevelopment. We propose a modular open sourceapproach and believe land-use change is a sufficientlyimportant and complex environmental issue that iturgently needs the collective resource provided by such anapproach.

AcknowledgmentsWe appreciate the guidance provided by Elinor Ostromduring the development of this report and thank JohnBranigin, Laura Wisen, and Charlotte Hess at theWorkshop in Political Theory and Policy Analysis Library,Indiana University, who conducted the literature searchfor the project. Personnel at the Indiana UniversityLibrary provided all of the databases, except for the websearch engines. We gratefully acknowledge support fromthe National Science Foundation and the EnvironmentalProtection Agency through their funding to the Centerfor the Study of Institutions, Population, andEnvironmental Change (NSF Grant SBR-9521918) andthe Baltimore Ecosystem Study (NSF Grant DEB-9714835 and EPA Grant R-825792-01-0).

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Zavala, M. A.; Burkey, T. V. 1997. Application ofecological models to landscape planning: the caseof the Mediterranean basin. Landscape and UrbanPlanning. 38: 213–227.

Zheng, D. L.; Alig, R. J. 1999. Changes in thenonfederal land base involving forestry in westernOregon, 1961–94. Res. Pap. PNW-RP-518. Portland,OR: U.S. Department of Agriculture, Forest Service,Pacific Northwest Research Station. 28 p.

50

APPENDIX:Plots of human driver variables represented in the models

across space and time

A graphical representation of the temporal time step and duration and the spatialresolution and extent of the models facilitates several observations. The plotted area foreach model represents the spatial and temporal scales under which the model operates.The 19 models examined in the report (see list on pages 8-9) together cover a range ofscales from less than a day to more than 100 years and from less than 1 ha to more than 1million km2. Yet this range of scales is not covered by any one model. Clearly, modelsseem to be associated with a particular spatio-temporal niche.

SpatialExtent

SpatialResolution

TemporalTime Step

TemporalDuration

51

19

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Population Size

19

14

12

Temporal Scale [days]

Spat

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cale

[m2 ]

Plot

Site

L

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Population Growth

52

19

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

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L

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R

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Glo

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Population Density

19

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

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L

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Returns to Land Use(Costs and Prices)

53

19

14

12

Temporal Scale [days]

Spat

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cale

[m2 ]

Plot

Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Job Growth

19

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

L

ands

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L

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R

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Glo

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Costs of Conversion

54

19

14

12

Temporal Scale [days]

Spat

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cale

[m2 ]

Plot

Site

L

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L

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Glo

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Rent

Not 4

19

14

12

Temporal Scale [days]

Spat

ial S

cale

[m2 ]

Plot

Site

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L

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Collective Rule Making:Zoning

55

19

14

12

Temporal Scale [days]

Spat

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cale

[m2 ]

Plot

Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Collective Rule Making:Tenure

19

14

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Temporal Scale [days]

Spat

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[m2 ]

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Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

5

Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Infrastructure/AccessibilityDistance from Road

56

19

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Temporal Scale [days]

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[m2 ]

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Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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2

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151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Infrastructure/AccessibilityDistance from Town/Market

19

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Temporal Scale [days]

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[m2 ]

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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2

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151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Infrastructure/AccessibilityDistance from Village/Settlement

57

19

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Temporal Scale [days]

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[m2 ]

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

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151

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1615

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Infrastructure/AccessibilityPresence of Irrigation

19

14

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Temporal Scale [days]

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[m2 ]

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Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Infrastructure/AccessibilityGeneralized Access Variable

58

19

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Spat

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[m2 ]

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Village Size

19

14

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Temporal Scale [days]

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[m2 ]

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

13

6

2

11

151

18

1615

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Farm

Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Silviculture andAgriculture

59

19

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12

Temporal Scale [days]

Spat

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[m2 ]

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Site

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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6

2

11

151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Technology Level

19

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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2

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151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Affluence

60

19

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Temporal Scale [days]

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[m2 ]

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Age

19

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Hourly Daily Monthly Yearly Decadal Centennial

3 & 4

8

0.1 1 10 100 1000 10,000 100,000(1 week) (1 month) (1 year) (10 years) (100 years)

1

100

10,000

1,000,000

100,000,000

10,000,000,000

1,000,000,000,000

100,000,000,000,000

(1 km2)

(100 km2)

(10,000 km2)

(100 x 106 km2)

(1 ha)

(1 x 106 km2)

79

106

11

5 States

Pixel / Stand

County/watershed

Landsat scene

Tree

U.S.A

17

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151

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Cross-Sectional

Cross-Sectional

Human Drivers or Social Patterns and Preferences Model Variables

Human Attitudes and Values& Food Security

61

GlossaryArea base model: Allocates proportions of a given landbase to predefined land-use categories.

Complexity: In this paper we refer to three types ofcomplexity—spatial, temporal, and humandecisionmaking—all of which are defined in thisGlossary.

Conceptual model: Theoretical description ofsocioeconomic and physical processes.

Control (or flow) variables: System elements thatrepresent the action or change in a state.

Discrete finite state model: Model that is discrete (spacerepresented as cells or blocks) and finite state (representsan object as being in only a few, finite number of states orconditions).

Duration: The length of time for which the model isapplied. The duration of a model’s results may bereported as the number of time steps used (e.g., 100annual times steps), the period of the model (100 years),or the model dates (January 1, 1900, to January 1, 2000).

Dynamic systems model: Systems models that attemptto capture changes in real or simulated time.

Extent: The total geographic area to which the model isapplied.

Human decisionmaking: How models incorporatehuman elements. Human decisionmaking sections ofmodels vary in terms their theoretical precursors and maybe simply linked deterministically to a set ofsocioeconomic or biological drivers, or may be based onsome game theoretic or economic models. Threeattributes of human decisionmaking that are important toconsider in thinking about diverse models of land-usechange are complexity, jurisdictional domain, andtemporal range.

Human decisionmaking (HDM) complexity: Thespecificity and detailed consideration given in a model tothe decisions that humans make that affect land-usechange. For this exercise, we have developed a scale ofcomplexity that ranges from 1 to 6.

Jurisdictional domain: The spatial scope of humandecisionmaking. If desired, a jurisdictional domain maybe split up to reflect resolution, the decisionmakingdomain for a particular actor, and to reflect spatial extent,in this case the total area over which the actor(s) has(have)influence, or the jurisdictional range.

Linear planning model: Model that optimizes a linearfunction subject to several linear constraints, expressed aslinear inequalities or equalities.

Markov model: A probabilistic modeling method wheremodel state outcomes rely strictly on previous model

states. With this modeling technique, cell conditionalprobabilities are used to change cell states through a seriesof iterative operations.

Resolution: The smallest spatial unit of analysis for themodel. For example, in a raster or grid representation ofthe landscape, each unit or cell area is usually treated as aconstant size.

Spatial complexity: The presence of a spatial componentof a model or information. Spatial complexity may berepresentative or interactive.

Spatial dynamic model: Models that are spatially explicitand dynamic.

Spatial interaction: Models are based on topologicalrelationships. Topology is a mathematical procedure fordefining spatial relationships, usually as lists of features,and using the concepts of connectivity, area definition,and contiguity.

Spatial Markov model: Spatially explicit model thatcarries over memory from one state to the next, butusually from only the last state; e.g., the probability thatthe system will be in a given state (land class) at sometime t

2, is deduced from the knowledge of its state at time

t1.

Spatial representation: Spatially representative modelsare able to display data as maps but do not includetopology and spatial interactions.

Spatial stochastic model: Spatially explicit model that isinteractive and incorporates random changes todetermine transition probabilities from one land cover toanother.

State variables: Elements that make up the system forwhich the model is being developed.

Temporal complexity: A model’s ability to handle a largenumber of time steps, time lags, and feedback responses.

Time step: The smallest temporal unit of analysis of themodel variable.

von Thünen: German landowner Johann Heinrich vonThünen developed a model that relates intensity and typeof land use to transportation costs and land rent. Themodel (published in The Isolated State, 1826) involves ahomogenous plane within which exists an isolated city.Land-use patterns around this city are a function of travelcost to the city. Land uses producing goods with arelatively high transportation cost (e.g., perishable orheavy products) would be produced close to the city, andland uses producing more durable goods (with lowertransportation costs) would be produced farther from thecity. This arrangement results in a series of different land-use zones around the city. Many authors have applied andexpanded upon von Thünen’s initial theory (e.g.,Papageorgiou 1990).

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Agarwal, Chetan; Green, Glen M.; Grove, J. Morgan; Evans, Tom P.; Schweik, Charles M.2002. A review and assessment of land-use change models: dynamics of space,time, and human choice. Gen. Tech. Rep. NE-297. Newtown Square, PA: U.S.Department of Agriculture, Forest Service, Northeastern Research Station. 61 p.

A review of different types of land-use change models incorporating human processes.Presents a framework to compare land-use change models in terms of scale (both spatialand temporal) and complexity, and how well they incorporate space, time, and humandecisionmaking. Examines a summary set of 250 relevant citations and develops abibliography of 136 papers. From these papers, 19 land-use models are reviewed indetail as representative of the broader set of models. Summarizes and discusses the 19models in terms of dynamic (temporal) and spatial interactions, as well as humandecisionmaking. Many raster models examined mirror the extent and resolution ofremote-sensing data. The broadest-scale models generally are not spatially explicit.Models incorporating higher levels of human decisionmaking are more centrally locatedwith respect to spatial and temporal scales, probably due to the lack of data availability atmore extreme scales. Examines the social drivers of land-use change and methodologicaltrends and concludes with some proposals for future directions in land-use modeling.

Keywords: cellular automata, dynamic model, GIS, human decisionmaking, human-environment, land cover, LUCC, model comparison, model modularity, spatial model

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