General Ecology | Landscape Ecology 2103

The natural succession of grassland to woodland ecosystemis slow and may take up to 50 years. It is generally acceptedthat intervention of ecosystem reconstruction followed bynatural succession is the best practicable option for land-fills. If closed landfills were reclaimed properly, they couldprovide an attractive source of land for nature conserva-tion, forestry, and recreation. However, the success ofreclamation depends much upon the growth of plants andthe efficient cycling of nutrients in the cover material. Anintegrated approach which includes gas control, soil man-agement, and directed succession can accelerate thedevelopment of a sustainable ecosystem in terms of struc-ture and function on closed landfills.

See also: Biological Wastewater Treatment Systems.

Further Reading

Chan YSG, Wong MH, and Whitton BA (1996) Effects of landfill factorson tree cover: A field survey at 13 landfill sites in Hong Kong. LandContamination and Reclamation 2: 115–128.

Chan YSG, Chu LM, and Wong MH (1997) Influence of landfill factors onplants and soil fauna: An ecological perspective. EnvironmentalPollution 97: 39–44.

Dobson MC and Moffat AJ (1993) The Potential for WoodlandEstablishment on Landfill Sites, 88pp. London: Department of theEnvironment, HMSO.

Dobson MC and Moffat AJ (1995) A re-evaluation of objections to treeplanting on containment landfills. Waste Management and Research13: 579–600.

Ecoscope (2000) Wildlife Management and Habitat Creation on LandfillSites: A Manual of Best Practice. Muker, UK: Ecoscope AppliedEcologists.

Ettala MO, Yrjonen KM, and Rossi EJ (1988) Vegetation coverage atsanitary landfills in Finland. Waste Management and Research6: 281–289.

Flower FB, Leone IA, Gilman EF, and Arthur JJ (1978) A Study ofVegetation Problems Associated with Refuse Landfills, EPA-600/2-78-094, 130pp. Cincinnati: USEPA.

Handel SN, Robinson GR, Parsons WFJ, and Mattei JH (1997)Restoration of woody plants to capped landfills: Root dynamics in anengineered soil. Restoration Ecology 5: 178–186.

Moffat AJ and Houston TJ (1991) Tree establishment and growth atPitsea landfill site, Essex, U.K. Waste Management and Research9: 35–46.

Neumann U and Christensen TH (1996) Effects of landfill gason vegetation. In: Christensen TH, Cossu R, and Stegmann R(eds.) Landfilling of Waste: Biogas, pp. 155–162. London:E & FN Spon.

Robinson GR and Handel SN (1993) Forest restoration on a closedlandfill: Rapid addition of new species by bird dispersal.Conservation Biology 7: 271–278.

Simmons E (1999) Restoration of landfill sites for ecological diversity.Waste Management and Research 17: 511–519.

Wong MH (1988) Soil and plant characteristics of landfill sitesnear Merseyside, England. Environmental Management12: 491–499.

Wong MH (1995) Growing trees on landfills. In: Moo-Young M,Anderson WA, and Chakrabarty AM (eds.) EnvironmentalBiotechnology: Principles and Applications, pp. 63–77. Amsterdam:Kluwer Academic.

Landscape EcologyJ Wu, Arizona State University, Tempe, AZ, USA

ª 2008 Elsevier B.V. All rights reserved.

What Is Landscape Ecology?

Evolving Perspectives in Landscape Ecology

Some Key Topics in Landscape Ecology

Concluding Remarks

Further Reading

What Is Landscape Ecology?

Landscape ecology has been defined in various ways

partly because the word ‘landscape’ means quite different

things to people with different scientific and cultural

backgrounds. Landscapes are spatial mosaics of interact-

ing biophysical and socioeconomic components

(Figure 1). Just as in other ecological disciplines, a spec-

trum of views exists as to the relative salience or

prominence of the two aspects of landscapes. The diver-

sity of perspectives can often be related to the

philosophical underpinnings of reductionism versus hol-

ism. Nevertheless, few would disagree that landscapes are

compositionally diverse and spatially heterogeneous.

A general definition of landscape ecology may be the

science and art of studying and improving the relationship

between spatial pattern and ecological processes on a

multitude of scales and organizational levels. Landscape

ecology is not only a field of study, but also represents a

new scientific perspective or paradigm that is relevant to a

range of ecological, geophysical, and social sciences.Heterogeneity, scale, pattern–process relationships,

hierarchy, disturbance, coupled ecological–social dynamics,

and sustainability are among the key concepts in landscape

ecology. Typical research questions include: How can spa-

tial heterogeneity be quantified so that it can be related to

relevant ecological processes? What are the processes and

mechanisms responsible for existing landscape patterns?

(a) (c)

(b) (d)

Figure 1 Different kinds of landscapes as spatial mosaics of various patches on a range of scales. (a) A forested landscape from North

America, (b) an agricultural landscape in Europe, (c) a metropolitan landscape in the Sonoran Desert, USA, and (d) a grassland

landscape on the Mongolia Plateau, China. Photo by (a) Tom Spies; (b) Almo Farina; (c, d) Jianguo Wu.

2104 General Ecology | Landscape Ecology

How does spatial heterogeneity influence the flows of

organisms, material, and energy? How does landscape pat-

tern affect the spread of disturbances such as pest outbreaks,

diseases, fires, and invasive species? How do patterns and

processes on different scales relate to each other? How can

ecological information be translated from fine to broad

scales and vice versa? How can the knowledge of spatial

heterogeneity help improve biodiversity conservation,

planning, and management? How can sustainable land-

scapes be developed and maintained?Studies in landscape ecology usually involve the

extensive use of spatial information from field survey,

aerial photography, and satellite remote sensing, as well

as pattern indices, spatial statistics, and computer simula-

tion modeling. The intellectual thrust of this highly

interdisciplinary enterprise is to understand the causes,

mechanisms, and consequences of spatial heterogeneity,

while its ultimate goal is to provide a scientific basis and

practical guidelines for developing and maintaining

ecologically, economically, and socially sustainable land-

scapes (Figure 2).

Evolving Perspectives in LandscapeEcology

Contemporary landscape ecology is characterized by a

flux of concepts and perspectives that reflect the differ-

ences in the origins of ideas and the ways of thinking, both

of which are shaped by physical and cultural landscapes.

The term ‘landscape ecology’ was coined in 1939 by the

German geographer, Carl Troll, who was inspired by the

spatial patterning of landscapes revealed in aerial photo-

graphs and the ecosystem concept developed in 1935 by

the British ecologist, Arthur Tansley. Troll saw the need

for combining the more structurally oriented geographi-

cal approach with the more functionally centered

ecosystem approach, in order to allow for geography to

acquire ecological knowledge of land units and for ecol-

ogy to expand its analysis from local sites to larger

regions. Thus, he defined landscape ecology as the study

of the relationship between biological communities and

their environment in a landscape mosaic on various spa-

tial scales. At the same time, Troll also emphasized the

Nature–society

interactions inlandscapes

Pat

tern

, pro

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, sca

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inte

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ion C

onservation, managem

ent, planning, and design

Integration betweeninterdisciplinary research and

participation from stakeholders

Integration betweennatural and social sciences

Integration among natural sciences

Landscape structure, function, and dynamics

Landscape ecology

Transdisciplinaryresearch

Interdisciplinaryresearch

Multidisciplinary research

Disciplinary research

Figure 2 A hierarchical and pluralistic view of landscape ecology. ‘Hierarchical’ refers to the multiplicity of organizational levels,

spatiotemporal scales, and degrees of cross-disciplinarity in landscape ecological research. ‘Pluralistic’ indicates the necessity to

recognize the values of different perspectives and methods in landscape ecology dictated by its diverse origins and goals. Reproduced

from Landscape Ecology, 21, 2006, 1–6, Cross-disciplinarity, landscape ecology, and sustainability science, Wu J, with kind permissionof Springer Science and Business Media.

General Ecology | Landscape Ecology 2105

holistic totality of the landscape which was perceived assomething of a gestalt (an integrated system organized insuch a way that the whole cannot be described merely asthe sum of its parts). This holistic and humanistic land-scape perspective, focusing on landscape mapping,evaluation, conservation, planning, design, and manage-ment, was embraced and further developed primarily inEurope, and has become a hallmark of landscape ecology.

The concept of landscape ecology was introducedfrom Europe to North America in the early 1980s, andsubsequently stimulated the rapid development of astream of new ideas, theories, methods, and applications.As a result, the field of landscape ecology quickly

flourished in North America, and became a widely recog-nized scientific discipline by the mid-1990s around theworld. Some of the early publications in North Americadefined a landscape as a kilometers-wide land area withrepeated patterns of local ecosystems. However, mostlandscape ecologists now consider such definition toonarrow and rigid. Instead, the most widely accepted defi-nition of landscape is simply a spatially heterogeneousarea whose spatial extent varies according to researchquestions and processes of interest. This multiple-scaleconcept of landscape is more appropriate as it facilitatesthe theoretical and methodological developments of thisinterdisciplinary field by promoting micro-, meso-, and

2106 General Ecology | Landscape Ecology

macroscale approaches. Despite their variations in details,the definitions of landscape ecology in North America allhinge on the idea of spatial heterogeneity. In particular,the North American landscape ecology focuses on therelationship between spatial pattern and ecological pro-cesses on multiple scales ranging from tens and hundredsof square meters to thousands of square kilometers inspace and from a particular point to a period of severaldecades in time. Its primary goal is to understand thecauses, mechanisms, and ecological consequences of spa-tial heterogeneity.

More specifically, North American landscape ecologyhas had a distinct emphasis on the effects of spatial patternon biodiversity, population dynamics, and ecosystem pro-cesses in a heterogeneous area. This research emphasis ispractically motivated by the fact that previously contig-uous landscapes have rapidly been replaced by apatchwork of diverse land uses (landscape fragmentation),and conceptually linked to the theory of island biogeo-graphy developed in the 1960s and the perspective ofpatch dynamics that began to take shape in the 1970s.Island biogeographic theory relates the equilibrium-statespecies diversity of islands to their size (area effect onspecies extinction rate) and distance to the mainland(distance effect on species immigration rate). The heur-istic value of the theory is apparent for understanding theecology of habitat patches submerged in a sea of humanland uses. The patch dynamics perspective, on the otherhand, treats ecological systems as mosaics of interactingpatches of different size, shape, kinds, and history, empha-sizing the transient dynamics and cross-scale linkages ofsuch patchy systems. In this view, a forest is no more thana dynamic mosaic of tree gaps of various age, speciescomposition, and biophysical properties; thus thedynamics of the forest can be adequately predicted byaggregating the behavior of individual tree gaps. Theperspective of patch dynamics has been evident in theconceptual development of landscape ecology in therecent decades.

In summary, the European approach is more humanis-tic and holistic in that it emphasizes a society-centeredview that promotes place-based and solution-drivenresearch. In contrast, the North American approach ismore biophysical and analytical in that it has been domi-nated by a biological ecology-centered view that is drivenprimarily by scientific questions. Here the author hastensto point out that this dichotomy most definitely over-simplifies the reality because such geographic divisionconceals the diverse and continuously evolving perspec-tives within each region. In fact, many ecologists in NorthAmerica have recognized the importance of humans inshaping landscapes for several decades (especially sincethe Dust Bowl in the 1930s). Although humans and theiractivities have been treated only as one of many factorsinteracting with spatial heterogeneity, more integrative

studies have been emerging rapidly in the past few dec-ades with the surging interest in urban ecology andsustainability science in North America. On the otherhand, the perspective of spatial heterogeneity has increas-ingly been recognized by landscape ecologists in Europeand the rest of the world. Thus, the current developmentof landscape ecology around the world seems to suggest atransition from a stage of diversification to one of con-solidation (if not unification) of key ideas and approaches.

In fact, both the European and North Americanapproaches can be traced back to the original definitionof landscape ecology. Carl Troll’s proposal to integratethe geographical and structural approach with the ecolo-gical and functional approach is best reflected in thepattern–process–scale perspective, which enhances thescientific rigor of landscape ecology. The holistic andhumanistic perspective, on the other hand, epitomizesthe idea of landscape as a nature–society coupled systemembraced by Troll and others. This perspective isentailed by any attempt to tackle practical problems inreal landscapes on broad scales. Both the European andNorth American perspectives are essential to the devel-opment of landscape ecology as a truly interdisciplinaryscience.

Some Key Topics in Landscape Ecology

Landscape ecology, as a relatively young scientific enter-prise, is quite comprehensive and dynamic in its scope. Aswith other interdisciplinary fields, it is impossible todefine precisely the domain of landscape ecological stud-ies. To get a sense of what the scientific core of landscapeecology is, a series of key research topics based on thecollective view of leading landscape ecologists andrecent publications in the flagship journal of the field,Landscape Ecology (http://www.springeronline.com), arediscussed here. Five key topics are highlighted in thissection.

1. Ecological flows in heterogeneous landscapes.Understanding how organisms, matter, and energy affect,and are affected by, the spatial pattern of landscapemosaics is a fundamental problem in landscape ecology.Much progress has been made in unraveling the effect ofspatial heterogeneity on the spread of disturbances (e.g.,fires and diseases) and the influence of landscape frag-mentation on population dynamics, particularly throughstudies of metapopulations (structurally discrete andfunctionally connected population ensembles). Researchinto the effects of landscape pattern on ecosystem pro-cesses, while still in its infancy, is currently a rapidlydeveloping area. Important areas for future research alsoinclude the spread of invasive species, the effects of land-scape structure on population genetics (known as

General Ecology | Landscape Ecology 2107

landscape genetics), and the effects of socioeconomicprocesses on ecological flows in landscape mosaics.

2. Mechanisms and consequences of land-use and land-cover

change. Land-use and land-cover change, driven primarilyby socioeconomic processes, exerts the most pervasiveand profound influences on the structure and functioningof landscapes. Thus, quantifying the spatiotemporal pat-tern of landscape change and understanding itsunderlying driving forces are essential. More effort isneeded to couple biophysical with socioeconomicapproaches and to integrate ecological with historicalmethods in the study of land change.

3. Scaling. Spatial pattern and ecological and socioeco-nomic processes in heterogeneous landscapes operate onmultiple scales, and thus understanding the totality oflandscapes requires relating different phenomena acrossdomains in space and time. The process of translatinginformation from one scale or organizational level toanother is referred to as scaling. Landscape ecologistsare leading the way in developing the theory and methodsof scaling, which is essential to all natural and socialsciences. However, many challenges still remain, includ-ing establishing scaling relations for a variety of landscapepatterns and processes as well as integrating ecologicaland socioeconomic dimensions in a coherent scalingframework.

4. Coupling landscape pattern analysis with ecological pro-

cesses. Quantifying spatial heterogeneity is the necessaryfirst step to understanding the effects of landscape patternon ecological processes. Various effects of the composi-tional diversity and spatial configuration of landscapeelements have been well documented, and a great numberof landscape metrics (synoptic measures of landscapepattern) and spatial analysis methods have been devel-oped in the past two decades. The greatest challenge,however, is to relate the measures of spatial patterndirectly to the processes and properties of biodiversityand ecosystem functioning. To address these challenges,well-designed field-based observational and experimentalstudies are indispensable, and remote sensing techniques,geographic information systems (GIS), spatial statistics,and simulation modeling are also necessary.

5. Landscape conservation and sustainability. Because ofthe emphasis on broad- and multiscale patterns and pro-cesses with interdisciplinary approaches, landscapeecology is uniquely positioned to provide a comprehen-sive theoretical basis and pragmatic guidelines forbiodiversity conservation, ecosystem management, andsustainable development. These real-world problemscannot be adequately addressed by species-centered orindividual ecosystem-based approaches. How do spatialprocesses occurring in landscapes (e.g., urbanization, agri-culture, flooding, fires, biological invasion) affect thebiodiversity and ecological functioning of landscapes?How does landscape heterogeneity affect the relationship

between biodiversity and ecosystem functioning? How doecological, economic, and social processes interact todetermine the resilience and vulnerability of landscapes?What are the design principles for sustainable landscapes?These are only a few of many challenging questions land-scape ecology will continue to address in decades tocome.

Concluding Remarks

Emphasis on heterogeneity begs questions of the rela-tionship between pattern and process. Simply put,heterogeneity is about structural and functional patternsthat deviate from uniform and random arrangements.It is this pervasively common nonhomogeneous charac-teristic that makes spatial patterns ecologicallyimportant as it suggests nontrivial relationship to under-lying processes. Thus, studying pattern without gettingto process is superficial, and understanding processwithout reference to pattern is incomplete. Emphasison heterogeneity also makes scale a critically importantissue because heterogeneity, as well as the relationshipbetween pattern and process, may vary as the scale ofobservation or analysis is changed. Thus, wheneverheterogeneity is emphasized, spatial structures, under-lying processes, and scale inevitably become essentialobjects of study. From this perspective, landscapeecology is a science of heterogeneity and scale. On theother hand, with increasing human dominance in thebiosphere, emphasis on broad spatial scales makes itinevitable to deal with humans and their activities. As aconsequence, humanistic and holistic perspectives havebeen and will continue to be central in landscape ecolo-gical research.

The above arguments also, in part, explain the twoseemingly disparate views that have become known as theEuropean and North American perspectives in landscapeecology. The world is already too fragmented ecologi-cally, economically, and socially, and we certainly do notneed a landscape ecology for each continent! As discussedearlier, the two perspectives should be viewed as beingcomplementary rather than contradictory. To increasethe synergies between the two approaches, not only dowe need to appreciate the values of each, but also todevelop an appropriate framework by which differentperspectives and methods can be integrated. This requiresa pluralistic and multiscale perspective (Figure 2).Landscapes out there are messy and are increasinglybeing messed up. Landscape ecology not only is expectedto provide scientific understanding of the structure andfunctioning of various landscapes, but also pragmaticguidelines and tools with which order and sustainabilitycan be created and maintained for the everchanginglandscapes.

2108 Ecological Models | Landscape Modeling

See also: Fitness Landscapes; Habitat; Landscape

Modeling; Landscape Planning; Land-Use Modeling;

Metapopulation Models; Scale; Spatial Distribution;

Spatial Distribution Models; Sustainable Development.

Further Reading

Forman RTT (1995) Land Mosaics: The Ecology of Landscapes andRegions. Cambridge: Cambridge University Press.

Gutzwiller KJ (ed.) (2002) Applying Landscape Ecology in BiologicalConservation. New York: Springer.

Naveh Z and Lieberman AS (1994) Landscape Ecology: Theory andApplication. New York: Springer.

Pickett STA and Cadenasso ML (1995) Landscapeecology: Spatial heterogeneity in ecological systems. Science269: 331–334.

Turner MG (2005) Landscape ecology: What is the state of the science?Annual Review of Ecology and Systematics 36: 319–344.

Turner MG, Gardner RH, and O’Neill RV (2001) Landscape Ecology inTheory and Practice: Pattern and Process. New York: Springer.

Wiens J and Moss M (eds.) (2005) Issues andPerspectives in Landscape Ecology. Cambridge: CambridgeUniversity Press.

Wu J (2006) Cross-disciplinarity, landscape ecology, andsustainability science. Landscape Ecology 21: 1–4.

Wu J and Hobbs R (eds.) (2007) Key Topics in Landscape Ecology.Cambridge: Cambridge University Press.

Relevant Websites

http://www.landscape-ecology.org – International Association

of Landscape Ecology

http://www.springer.com – Landscape ecology, the flagship

journal of the field of landscape ecology and sustainability,

Springer.

Landscape ModelingT R Lookingbill and R H Gardner, University of Maryland Center for Environmental Science, Frostburg, MD, USA

L A Wainger, University of Maryland Center for Environmental Science, Solomons, MD, USA

C L Tague, University of California, Santa Barbara, Santa Barbara, CA, USA

ª 2008 Elsevier B.V. All rights reserved.

Introduction

Maps as Models

Models of the Influence of Pattern on Process

Models of the Spatial Consequences of Landscape

Change

Issues of Landscape Modeling

Further Reading

Introduction

The goal of landscape ecology is to understand the relation-

ships between landscape pattern and ecological process; the

role of human impacts and other forces of landscape change

on these pattern–process relationships; and the principles

required to make informed decisions in natural resource

management. Landscapes are large areas (usually 10’s to

100’s of kilometers on a side) uniquely structured by

local variation in landforms, soils, rivers, and climate.

Understanding the ecological consequences of these biophy-

sical patterns is a sufficient challenge in itself (Ecosystem

pattern and process), yet landscape ecology must also

address the rapid transformations in land use and land

cover that have become a global threat to species diversity

and ecosystem health. It comes as no surprise that models

are playing an essential role in this interdisciplinary science.The interdisciplinary nature of the science of landscape

ecology has produced a diverse set of models varying in

purpose, methods, and complexity. For instance, geogra-

phers may construct models that locate landscape resources

(e.g., spatial distribution models), ecologists may study spe-cies dynamics in fragmented landscapes (e.g.,

Metapopulation models), while economists might focus onthe properties of landscapes that define the potential for

development and commerce (e.g., land use modeling). Inspite of this diversity, landscape models have a number of

similar attributes that we have used to organize this discus-

sion (Table 1). Specifically, landscape models have threemain components: (1) they are spatially explicit formulations

or are based on spatially explicit data (i.e., maps) and considerone or more attributes of landscape heterogeneity; (2) they

address the constraints of pattern on ecological processes by

extrapolating fine-grained measurements across a significantspectrum of temporal and spatial scales; and (3) they define

the potential spatial consequences of change, including theexistence of critical thresholds (regions in state space where

small changes produce disproportionably large effects).