Ecological-economic analysis of wetlands: scientific integration for management and policy

Ecological Economics 35 (2000) 7–23

SPECIAL ISSUE

THE VALUES OF WETLANDS: LANDSCAPE AND INSTITUTIONALPERSPECTIVES

Ecological-economic analysis of wetlands: scientificintegration for management and policy

R. Kerry Turner a,b, Jeroen C.J.M. van den Bergh c, Tore Soderqvist d,*,Aat Barendregt e, Jan van der Straaten f, Edward Maltby g,

Ekko C. van Ierland h

a Centre for Social and Economic Research of the Global En6ironment (CSERGE), Uni6ersity of East Anglia, Norwich,NR4 7TJ, UK

b Uni6ersity College London, London, UKc Department of Spatial Economics, Free Uni6ersity, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands

d Beijer International Institute of Ecological Economics, The Royal Swedish Academy of Sciences, Box 50005,SE-10405 Stockholm, Sweden

e Department of En6ironmental Sciences, Uni6ersity of Utrecht, PO Box 80115, 3508 TC Utrecht, The Netherlandsf Department of Leisure Studies, Tilburg Uni6ersity, PO Box 90153, 5000 LE Tilburg, The Netherlands

g Royal Holloway Institute for En6ironmental Research, and Geography Department, Royal Holloway, Uni6ersity of London,Huntersdale, Callow Hill, Virginia Water, Surrey GU25 4LN, UK

h Department of Economics and Management, Wageningen Agricultural Uni6ersity, PO Box 9101,6700 HB Wageningen, The Netherlands

Abstract

Wetlands all over the world have been lost or are threatened in spite of various international agreements andnational policies. This is caused by: (1) the public nature of many wetlands products and services; (2) user externalitiesimposed on other stakeholders; and (3) policy intervention failures that are due to a lack of consistency amonggovernment policies in different areas (economics, environment, nature protection, physical planning, etc.). All threecauses are related to information failures which in turn can be linked to the complexity and ‘invisibility’ of spatialrelationships among groundwater, surface water and wetland vegetation. Integrated wetland research combiningsocial and natural sciences can help in part to solve the information failure to achieve the required consistency acrossvarious government policies. An integrated wetland research framework suggests that a combination of economicvaluation, integrated modelling, stakeholder analysis, and multi-criteria evaluation can provide complementaryinsights into sustainable and welfare-optimising wetland management and policy. Subsequently, each of the various

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R.K. Turner et al. / Ecological Economics 35 (2000) 7–238

components of such integrated wetland research is reviewed and related to wetland management policy. © 2000Elsevier Science B.V. All rights reserved.

Keywords: Cost-benefit analysis; Ecological-economic wetland modelling; Valuation of wetland goods and services; Hydrology;Multi-criteria evaluation; Stakeholders

1. Introduction

Wetlands provide many important services tohuman society, but are at the same time ecologi-cally sensitive and adaptive systems. This explainswhy in recent years much attention has beendirected towards the formulation and operationof sustainable management strategies for wet-lands. Both natural and social sciences can con-tribute to an increased understanding of relevantprocesses and problems associated with suchstrategies. This article examines the potential forsystematic and formalised interdisciplinary re-search on wetlands. Such potential lies in theintegration of insights, methods and data drawnfrom natural and social sciences, as highlighted inprevious integrated modelling and assessmentsurveys (Bingham et al., 1995). The various com-ponents of integrated wetlands research will bereviewed here.

There is some disagreement among scientistson what constitutes a wetland, partly because oftheir highly dynamic character, and partly be-cause of difficulties in defining their boundarieswith any precision (Mitsch and Gosselink, 1993).For example, Dugan (1990) notes that there aremore than 50 definitions in current use. Likewise,there is no universally agreed classification ofwetland types. Classifications vary greatly in bothform and nomenclature between regions; seeCowardin et al. (1979) for one influential classifi-cation system. Some features of wetlands,nonetheless, are clear. It is the predominance ofwater for some significant period of time and thequalitative and quantitative influence of the hy-drological regime that characterise and underliethe development of wetlands. The Ramsar Con-vention definition, widely accepted by govern-ments and NGO’s world-wide, is as follows:‘areas of marsh, fen, peatland or water, whethernatural or artificial, permanent or temporary, withwater that is static or flowing, fresh, brackish or

salt including areas of marine water, the depth ofwhich at low tide does not exceed 6 m ’. Whilelacking scientific exactness, this definition conveysmuch of the essential character of wetlands, aswell as implying the complexity involved. What itdoes not provide, however, is any guidance onthe generic characteristics of wetlands that influ-ence how wetlands actually function. Any inte-grated wetland research approach has somehowto make compatible the very different perceptionsof what exactly is a wetland system, as seen froma range of disciplinary viewpoints (Maltby et al.,1994, 1996). In this article the main characteris-tics of wetland processes and systems are re-viewed in a cross-disciplinary way.

Globally, wetlands are under heavy pressure.Despite the increasing recognition of the need toconserve wetlands, losses have continued. Onemain reason is that wetlands throughout theworld are considered by many to be of little orno value, or even at times to be of negative value.This lack of awareness of the value of conservedwetlands and their subsequent low priority in thedecision-making process has resulted in the de-struction or substantial modification of wetlands,causing an unrecognised social cost.

The paper is organised as follows. Section 2discusses the causes of wetland degradation andloss. Section 3 presents a framework for ecologi-cal-economic analysis of wetlands. Section 4 givesa classification of stakeholders in the context ofwetlands functions and values. Section 5 discussesthe use of valuation techniques and cost-benefitanalysis for wetland analysis. Section 6 considersthe application of multi-criteria evaluation tech-niques for decision-making in the context of wet-land management. Section 7 reviews thepossibilities for integrated ecological-economicmodelling. Section 8 links integrated wetlandanalysis to policy issues ranging from local toglobal levels. A final Section 9 provides conclu-sions and suggestions for further research.

R.K. Turner et al. / Ecological Economics 35 (2000) 7–23 9

2. Causes of wetland degradation and loss

Wetlands perform many functions that are po-tentially very valuable, also in economic terms.Reasonable questions would then be why thesevalues have so often been ignored in the policyprocess, and why wetland losses and/or degrada-tion have been allowed to continue. For example,coastal wetlands have been lost because of portexpansion and urban and industrial sprawl all overthe world (Pinder and Witherick, 1990). Despite anational policy to maintain the deltaic wetland atKoper (Slovenia) because of, for example, its im-portant role for migrating birds, it is still endan-gered by two pressure forces: urban and industrialpollution, and the local governments’ wish toexpand built-up and industrial zones (Hesselink,1996). Another example is the Spanish nationalpark Coto Donana which has been damaged as aconsequence of changes in hydrology (Llamas,1988). Farmers argued that they needed freshwaterfrom the river for their intensive cultivation ofstrawberries. Despite the ecological significance ofthe national park, local and regional governmentsresponded by ‘correcting’ the boundaries of thepark and the river regime was adjusted in accor-dance with the farmers’ request. Furthermore,tourist resort developers succeeded in constructinga tourist village on a site in the heart of the park.Similarly, the government of the Netherlands hasin principle — through concessions — allowedsome drilling for gas exploitation in the WaddenSea on financial grounds, despite the fact that thisarea is an internationally important wetland formigrating birds from Scandinavia. The latter istrue not least since most alternative wetland sitesfor these birds have already been lost throughconversion by agriculture and industry. Other ex-amples include the Aral Sea which suffers fromwater shortages because its river water supply isused upstream for cotton-fields, the Everglades inthe USA which is under stress due to the inflow ofnutrients from reclaimed areas where sugar cane isgrown, Ireland, where extensive peatlands havebeen dug up for fuel, and in South East Asia, wheremangrove forests have been converted to fish andshrimp cultivation ponds (Turner and Jones, 1991;Ruitenbeek, 1994; Tri et al., 1998).

These examples illustrate the conflicting interestsof various stakeholder groups at different geo-graphical scales. It deserves to be emphasised thatsome past conversion might well have been insociety’s best interests, where the returns from thecompeting land use are high. However, wetlandshave frequently been lost to activities resulting inonly limited benefits or, on occasion, even costs tosociety (Bowers, 1983; Turner et al., 1983; Batieand Mabbs-Zeno, 1985). Why is that the case? Abasic cause is the existence of market failures dueto the public nature of several wetland goods andservices. But what about the policies that have infact been introduced to prevent wetlands fromdeterioration? Have there been policy interventionfailures?

Wetlands are the only single group of ecosystemsto have their own international convention. Thecall for wetland protection gained momentum inthe 1960s, primarily because of their importance ashabitat for migratory species. The Ramsar Con-vention, which came into force in 1975, is aninter-governmental conservation treaty, where aframework for international co-operation was pro-vided for the conservation of wetland habitats toensure their conservation and wise use. At present(November, 1999), 116 countries are Ramsar Con-tracting Parties, with 1005 wetland sites included inthe Ramsar List of Wetlands of InternationalImportance (see http://www.ramsar.org/in-dex.html). These sites cover about 71.7 millionhectares, which correspond to about 0.5% of theworld’s land surface. The focus of the conventionon migrating birds was followed up in 1982 by theBonn Convention (Convention on the Conserva-tion of Migratory Species of Wild Animals), whichwas intended to promote international conserva-tion measures for migratory wild animal species.Also typical wetland species are protected due tothe Convention on Biological Diversity (Rio deJaneiro, 1992).

In Europe, the Council of Europe installed theConvention on the Conservation of EuropeanWildlife and Natural Habitats (Bern Convention,1982) in which species were linked with habitats.The EU added the Bird Directive (1979) for theprotection of areas vital to birds. Later came theDirective governing the Conservation of Natural


and Semi-natural Habitats and Wild Flora andFauna (Habitat Directive, 1992). Related measuresare, among others, national inventories of areas tobe protected, a list of areas of EU interest, andunder the heading of Natura 2000, a EuropeanEcological Network of protected areas is to be setup.

On a national level many countries have in-stalled national parks and nature reserves to pre-serve wetlands. Governmental and non-govern-mental listings of threatened species (‘Red Lists’)have added another measure to help protect wet-land species from a changing wetland environment.Most countries have indirectly helped wetlands intheir physical planning at national, regional andlocal government levels. National environmentalpolicies have also constrained the process ofchange in wetlands by encouraging the mainte-nance or restoration of clear water, maintainingthe original hydrology, and fighting the problemsof acid rain or the fragmentation of the ecosystems.

The present set of regulations does not, however,seem to be sufficient. While the integration ofwetlands protection strategies into different na-tional policies has occurred, local economic devel-opment at the expense of wetlands is still quitecommon. Local people have used their right toimprove their own conditions, without often con-sidering the effects on a wider geographical scale.What we typically see here is what Turner andJones (1991) refer to as interrelated market andintervention failures, which derive from a funda-mental failure of information, or lack of under-standing of the multitude of values that may beassociated with wetlands. The information prob-lem results because politicians and the generalpublic insufficiently understand the role and func-tions of wetlands as well as the indirect conse-quences of land use, water management,agricultural pollution, air pollution and infrastruc-ture for the quality and sustainability of wetlands.This is partly related to the complexity and ‘invis-ibility’ of spatial relationships among groundwa-ter, surface water and wetland vegetation.Moreover, existing policies in different areas (envi-ronmental quality, nature protection, physicalplanning, etc.) are inconsistent or contradictory.Many human activities therefore result in external

effects, such as pollution from industry or agricul-ture, that may have an adverse impact on siteselsewhere, but for which, due to a lack of enforce-able rights, no compensation is paid to thoseaffected. Pollution of wetlands, often regarded asnatural sinks for waste, has been an importantfactor in their degradation. Many wetlands andessential features, such as their ability to supplywater, have traditionally been treated as publicgoods and exposed to ‘open access’ pressures, witha lack of enforceable property rights allowingunrestricted depletion of the resource.

In some cases, there is a long history of institu-tional arrangements among direct extensive users,such as common property regimes which made itimpossible for ‘everybody’ to use the resource. Therules aimed to control and regulate the use of thewetland in such a way that the threat of overuseand overexploitation could be neutralised. In mod-ern societies, the use of resources such as wetlandschanged dramatically in a few decades. In Europe,for example, under the influence of the CommonAgricultural Policy which ‘subsidised’ land conver-sion to arable regimes. The historic common prop-erty regime was based, however, on traditionalforms of wetland use, and could not cope with newforms of use, such as the construction of harbours,expansion of tourism resorts, intensification ofagriculture and fishing. This suggests that newproperty rights regimes, adapted to recent eco-nomic uses threatening the wetlands ecosystems,have to be introduced in order to prevent a furtherdegeneration of wetlands. However, even in caseswhen there are well-defined property rights towetlands, many of the functions they performprovide benefits off-site which the resource owneris unable to appropriate. The lack of a market forthese off-site wetland functions limits the incentiveto maintain the wetland, since the private benefitsderived by the owner do not reflect the full benefitsto society.

3. A framework for ecological-economic analysisof wetlands

Wetland characteristics are those properties thatdescribe a wetland area in the simplest and most


objective possible terms. They are a combinationof generic and site-specific features. A generallist would include the biological, chemical andphysical features that describe a wetland suchas, e.g. species present, substrate properties, hy-drology, size and shape; for example, Adamusand Stockwell (1983) give 75 wetland character-istics. Wetland structure may be defined as thebiotic and abiotic webs of which characteristicsare elements, such as vegetation type and soiltype. By contrast, wetland processes refer to thedynamics of transformation of matter or energy.The interactions among wetland hydrology andgeomorphology, saturated soil and vegetationmore or less determine the general characteris-tics and the significance of the processes thatoccur in any given wetland. These processes alsoenable the development and maintenance of thewetland structure which in turn is key to thecontinuing provision of goods and services.Ecosystem functions are the result of interactionsamong characteristics, structure and processes.They include such actions as flood water con-trol, nutrient retention and food web support(Maltby et al., 1996).

These ecological concepts constitute the upperpart of Fig. 1. They allow an ecological charac-terisation of wetlands. But an economic valua-tion of wetlands requires a complementarytypology, since economic values depend on hu-man preferences; what people perceive as theimpact wetlands have on their well-being.1 Ingeneral, the economic value, i.e. the benefits, ofan increased (or a preserved) amount of a goodor service is defined as what individuals are will-ing to forego of some other resources in orderto obtain the increase (or maintain the statusquo). Economic values are thus relative in thesense that they are expressed in terms of some-

thing else that is given up (the opportunitycost), and they are associated with the type ofincremental changes to the status quo that pub-lic policy decisions are often about in practice.

The step from the ecological characterisationto economic valuation is the essential link be-tween wetland ecology or functioning and wet-land economics and values. We label this step asgoing from wetland functioning to wetland uses(see Fig. 1). Economic values will always becontingent upon the wetland performing func-tions that are somehow perceived as valuable bysociety. Functions in themselves are thereforenot necessarily of economic value; such valuederives from the existence of a demand for wet-land goods and wetland ser6ices due to thesefunctions. For example, fertility and nutrientcharacteristics would be crucial in providingforestry and agriculture benefits, but these char-acteristics do not in themselves representbenefits (in the anthropocentric sense). See Fig.1 for examples of wetland goods and services;the latter may be recognised as providers ofbenefits that people gain without necessarilyhaving to come in contact with a wetland.

While the total amount of resources that indi-viduals would be willing to forego for an in-creased (or preserved) amount of a wetlandservice reveals the total economic value (TEV)of this increase (or preservation), different com-ponents of TEV can be identified (see Fig. 1).Use 6alue arises from humans’ direct or indirectutilisation of wetlands through wetland goodsand wetland services, respectively. A value cate-gory usually associated with use value is that ofoption value, in which an individual derivesbenefit from ensuring that a resource will beavailable for use in the future. See, however,Freeman (1993) and Johansson (1993) on optionvalue ambiguity. Another type of value oftenmentioned in the valuation literature is quasi-option value, which is associated with the poten-tial benefits of awaiting improved informationbefore giving up the option to preserve a re-source for future use (Arrow and Fisher, 1974).Quasi-option value cannot be added into theTEV calculation without some double counting;it is best regarded as another dimension of

1 A major stumbling block in valuing wetlands in economicterms has in fact been the lack of a common terminology.Authors use a confusing mix of terms, for example, ‘wetlandfunctions and their social values’ (Marble and Gross, 1984),‘functional values’ (Adamus and Stockwell, 1983), ‘populationvalues’ and ‘ecosystem values’ (Mitsch and Gosselink, 1993),‘attributes’, ‘criteria’ and ‘values’ (Usher, 1986), ‘structure’ and‘function’ (Turner, 1988) and ‘functions’, ‘uses’ and ‘attributes’(Barbier, 1989) (see also Maltby et al., 1996).


ecosystem value. Nonuse value is associated withbenefits derived simply from the knowledge that aresource, such as an individual species or an entirewetland, is maintained. Nonuse value is thus inde-pendent of use, although it is dependent upon theessential structure of the wetland and functions itperforms, such as biodiversity maintenance.

Various components of nonuse value have beensuggested in the literature, including the most

debated component, existence value, which can bederived simply from the satisfaction of knowingthat some feature of the environment continues toexist, whether or not this might also benefit oth-ers. This value notion has been interpreted in anumber of ways and seems to straddle the instru-mental/intrinsic value divide. Some environmen-talists support a pure intrinsic value of natureconcept, which is totally divorced from an-

Fig. 1. Connections among wetland functions, uses and values.


thropocentric values. Acceptance of this leads torights and interests-based arguments on behalf ofnon-human nature. The existence of such philo-sophical views is one reason why the concept ofTEV should not be confused with the ‘total value’of a wetland. Moreover, the social value of anecosystem may not be equivalent to the aggregateprivate TEV of that same system’s components;the system is likely to be more than just theaggregation of its individual parts. See Gren et al.(1994) and Turner et al. (1997) on the existence ofa ‘primary value’ of ecosystems.

The adoption of a functional perspective is thecorrect way to identify wetland goods and ser-vices, but if each of them is identified separately,and then attributed to underlying functions, thereis a likelihood that benefits will be doublecounted. Benefits might therefore have to be allo-cated explicitly between functions. For instance,Barbier (1994) noted that if the nutrient retentionfunction is integral to the maintenance of biodi-versity, then if both functions are valued sepa-rately and aggregated, this would double countthe nutrient retention which is already ‘captured’in the biodiversity value. Some functions mightalso be incompatible, such as water extraction andgroundwater recharge, so that combining thesevalues would overestimate the feasible benefits tobe derived from the wetland. Studies that attemptto value the wetland as a whole based on anaggregation of separate values tend to include acertain number of functions although these stud-ies do not usually claim to encompass all possiblebenefits associated with the wetland. Examplesinclude Thibodeau and Ostro (1981), Bishop et al.(1987), Costanza et al. (1989), Dixon (1989),Hanemann et al. (1991), Hanley and Craig (1991),Loomis et al. (1991), Thomas et al. (1991), White-head and Blomquist (1991), Farber (1992),Ruitenbeek (1992), and de Groot (1994).

4. Stakeholders in wetland functions and values

Integrated ecological-economic analysis in-volves an identification of how particular func-tions might be of use, rather than simply thedegree to which the function is being performed.

The extent of demand for the products or servicesprovided, or the effective ‘market’, also needs tobe assessed if the full extent of economic value isto be assessed. So who are the relevant users, i.e.those who assign economic values to wetlands? Itis possible to identify at least nine more or lessorganised groups of stakeholders:1. Direct extensi6e users directly harvest wetland

goods in a sustainable way, i.e. consistent withrapid ecosystem recovery. They thus possess aparticular form of ecological knowledge en-abled by an institutional setting that may beunder increasing environmental change pres-sure. They harvest the wood for timber or fuel,the reed for roofs, the available wetland plantsand fruits for produce, the waterfowl andmammals for pelts and meat, and fishes andshellfishes for food.

2. Direct intensi6e users have access to new tech-nology that allows more intensive harvesting.In some cases there is a risk that the yield ofthe wetland exceeds its primary production;the wetland system loses resilience and thestocks are depleted. In other cases, such as theharvesting of biomass from fenland and subse-quent fuel or feedstock production, ecosystemsintegrity can be maintained and enhanced.

3. Direct exploiters dredge the sediments in thewetland, or exploit mineral resources, peat,clay and sand without due concern for the‘health’ of the wetlands.

4. Agricultural producers drain and convert wet-lands to agricultural land, since, at least in theshort to medium run, the soil is fertile, nutri-ents are plentiful and water is freely available.

5. Water abstractors use wetlands as sources ofdrinking water, agricultural irrigation, flowaugmentation, etc. These practices may resultin a wetland suffering a fall in its water tableand consequent quality degradation, or in thediversion of ‘polluted’ water into the wetland.

6. Human settlements close to wetlands. Manywetlands are located in the transition zonefrom land to water, and may thus constituteconvenient areas for the expansion of humansettlements and their infrastructure; a paradoxis often evident as the very presence of water isa valuable amenity that needs to besafeguarded.


7. Indirect users benefit from indirect wetlandservices such as storm abatement, flood miti-gation, hydrological stabilisation and waterpurification to individuals and communitiesacross large catchment areas; because of theextensive spatial provision of such servicesmany recipients will be unaware of theirorigin.

8. Nature conser6ation and amenity groups com-bine nature conservation objectives with anenjoyment of the presence of plant and animalspecies. This aesthetic value of wetlands isoften mixed with recreation usage values.

9. Nonusers may, geographical distance notwith-standing, attribute nonuse value to wetlands,possibly due to their recognition of intrinsicvalue in wetlands.

Clearly not all stakeholder interests are mutu-ally compatible and the potential for value confl-ict is high. Policy makers are therefore required toundertake complex trade-off procedures andwould benefit from the provision of integratedeconomic data and analysis.

5. Monetary valuation techniques and cost-benefitanalysis

A range of valuation techniques exists for as-sessing the economic value of goods and servicesprovided by wetlands (Fig. 1). Many wetlandfunctions result in goods and services that are nottraded in markets and therefore remain un-priced.It is then necessary to value these goods or ser-vices using non-market valuation techniques. Fordetails on these techniques, see, e.g. Dixon andHufschmidt (1986), Mitchell and Carson (1989),Braden and Kolstad (1991), Freeman (1993),Hanley and Spash (1993), Turner (1993b), Pearceand Moran (1994), Bromley (1995), Turner andAdger (1996), and Bateman and Willis (1999). Forsurveys of application of various valuation meth-ods to wetlands, see, e.g. Gren and Soderqvist(1994), van Ierland and de Man (1996), and Bar-bier et al. (1997). The potential transfers of esti-mated wetland benefits to settings other thanthose originally studied, known as ‘benefits trans-

fer’, is discussed in Green et al. (1994), Willis andGarrod (1995), and Brouwer et al. (1997).

Quantifying and evaluating wetland conserva-tion benefits in a way that makes them compara-ble with the returns derived from alternative usescan facilitate improved social decision making inwetland protection versus development conflictsituations. Cost-benefit analysis (CBA) based onthe economic efficiency criterion offers onemethod to aid decision-makers in this context. Inorder to be comprehensive, a CBA of a proposedpolicy affecting a wetland should take into ac-count the policy’s impact on the wetland’s provi-sion of goods and services. However, it should beclear from the preceding section that such predic-tions typically require detailed knowledge of howthe policy would affect wetland functioning, i.e.the basis for the provision of goods and services.This knowledge is often imperfect and qualitativein nature. In particular, to predict in detail apolicy’s impact on such wetland functioning as,for example, nutrient and sediment retention, gasexchange, and pollution absorption, for any givensegment of landscape, is in many cases likely topush present ecological knowledge beyond itsbounds. Even wetland structure is incompletelyknown; for example, changes may affect the insectfauna, or soil fungi, and many of these speciesmay never even have been described taxonomi-cally (Westman, 1985). Adaptations of CBA toaddress issues of ecological complexity, notablyrelating to irreversibility and foregone preserva-tion benefits, are useful in performing CBA ofextreme scenarios regarding wetlands context(Krutilla and Fisher, 1975; Porter, 1982; Hanleyand Craig, 1991; Hanley and Spash, 1993).

Two important conclusions follow from theseobservations, and they will be further discussed insubsequent sections. Firstly, in order to makeCBAs of wetland policies more reliable, the eco-nomic valuation of wetland goods and serviceshas to be as comprehensive as possible. This callsfor integrated modelling of the links between wet-land ecology (characteristics, structure, processesand functioning) and wetland economics (the de-mand for the goods and services supplied bywetlands). Secondly, even if improvements inCBAs as a basis for decision-making are desir-


able, it is clear that the outcome of a CBA is noton its own sufficient. The CBA criterion relies ona particular ethical basis, and it may need to becomplemented as policy-makers introduce, or re-spond to, concerns other than economic effi-ciency. Moreover, the lack of detailed,quantitative knowledge of wetland functioning (inpractice) precludes a full economic valuation ofwetlands.

6. Multi-criteria evaluation for wetlandconservation

Multi-criteria decision analysis (MCDA) offersone way to illuminate policy trade-offs and aiddecision making in contexts where a range of,often competing, policy criteria are considered tobe socially and politically relevant (Nijkamp,1989; Janssen, 1992). MCDA typically includesmultiple criteria, such as economic efficiency, eq-uity within and between generations, environmen-tal quality and various interpretations ofsustainability. For example, various versions of‘strong’ and ‘weak’ sustainability have been sug-gested in the literature, see, e.g. Pearce et al.(1989), Ayres (1993) and Turner (1993a). Weightscan reflect the relative importance of each crite-rion considered in a particular decision context. AMCDA may thus illustrate how a particular pol-icy would impact on and influence the variousstakeholder groups introduced in Section 4.

Governments have now formally adopted sus-tainable development as a policy objective, as wellas imposing a range of national conservationmeasures and designations, complementing theRamsar Convention, to protect wetlands. Sustain-ability concerns can be introduced as a series ofconstraints on an otherwise market-oriented andCBA-based decision-making process. For exam-ple, a practical means of dealing with uncertaintyis to introduce a safe minimum standard criterion(Ciriacy-Wantrup, 1952; Bishop, 1978; Crowards,1996). By introducing physical constraints on de-velopment options, opportunities for future well-being can be preserved rather than trying toimpose a structure on future preferences whichmay be difficult to predict and to control. Under

the sustainability principle, there is a requirementfor the sustainable management of environmentalresources, whether in their pristine state orthrough sympathetic utilisation, to ensure thatcurrent activities do not impose an excessive costand loss of options burden on future generations.It has been suggested that it is ‘large-scale com-plex functioning ecologies’ that ought to formpart of the intergenerational transfer of resources(Cumberland, 1991).

Wetlands are complex multi-functional systems,and they are therefore likely to be most beneficialif conserved as integrated ecosystems (within acatchment) rather than in terms of their individualcomponent parts. Sustainability implies a widerand more explicity long-term context and goalthan environmental quality enhancement. In thisrespect, concepts such as ecosystem health orintegrity (determined by properties such as stabil-ity and resilience or creativity), interpretedbroadly, are useful in that it helps focus attentionon the larger systems in nature and away from thespecial interests of individuals and groups. Thefull range of public and private instrumental andnon-instrumental values all depend on protectionof the processes that support the functioning oflarger-scale ecological systems. Thus when a wet-land, for example, is disturbed or degraded, weneed to look at the impacts of the disturbanceacross the larger level of the landscape.

A strength of a MCDA is that it provides bothecological and economic information as a basisfor decision-making. A separate issue is, however,to what extent this information would in fact betaken into account in real policy-making situa-tions. Ecological information may not adequatelyinfluence the final decisions in the socio-economicsystem. For example, short-term commercial in-terests and related financial gains may appear tobe more persuasive than longer-term ecologicalconservation arguments. The economic informa-tion provided by a CBA would perhaps be a morepowerful and pragmatic support for conservationinterests. But there may be a paradox here. Acomprehensive CBA would rely also on a quan-tification of benefits due to non-market wetlandgoods and services, possibly also including nonusevalue, if the benefit estimation involved the use of


contingent valuation techniques. At the first glance,these benefits have the same configuration as ‘nor-mal’ (market-based) economic information; bothtypes of information are measured in monetaryterms. On the other hand, nonuse value is hypothet-ical in the sense that it is not revealed by marketbehaviour. Such information may be a good toolto influence the perception of decision-makers andcitizens regarding the high value of wetlands, butits influence in decision-making is likely to be limitedby its non-market character, and the opportunitiesit raises for opponents to challenge its ‘subjective’basis in formal proceedings or court cases.

7. Integrated ecological-economic modelling ofwetlands

Integrated modelling comes in two forms. Onestrives towards a single model, while the otheremploys a system of heuristically connected sub-models. Coupling wetland ecology and wetlandeconomics within one integrated model inevitablyinvolves compromises and simplifications. In gen-eral, in systems analysis based on models forwetlands a trade-off is needed between generality,precision and realism (cf. Costanza et al., 1993).Interdisciplinary work may involve economists orecologists transferring elements or even theories andmodels from one discipline to another and trans-forming them for their specific purpose. For exam-ple, a simple dynamic model summarising andsimplifying some of the statistical and causal rela-tionships of a spatial hydrological model and astatistical wetland vegetation model can be linkedto the outcomes to a simplified economic model. Anumber of approaches to integrated modelling exist,based on generalised input-output models, nonlin-ear dynamic systems models, optimisation models,land use models linked to geographical informationsystems (GIS), and mixed models. Important ele-ments for integration are connected scenarios,models and indicators, and the arrangement ofconsistency among units, spatial demarcations, andspatial aggregation of information in various sub-models. An overview of integrated modelling ap-proaches and applications is given in van den Bergh(1996).

Considerable effort is devoted to increasing theprecision at the natural science description level inorder to facilitate the linking to the socio-eco-nomic level. The prediction of processes and pro-cess changes in a wetland — both short and longterm — is of utmost importance in the assessmentof wetland functions. Many important functionsare directly related to hydrology. Moreover, wateris the transport medium for nutrients and otherelements, including contaminants. Based on infor-mation and models of hydrological processes, nu-trient fluxes, sedimentation, erosion, and evenflooding can be quantified. The modelling chaincan be continued with chemical modelling and thequantification of nutrient balances. Given thesedata, the likely presence of plant and animalspecies in the ecosystem may be predicted, as wellas the consequent impacts on biodiversity of hy-drological changes.

Different methods and models are available toimprove the science of wetland systems(Jørgensen, 1986; Mitsch et al., 1988; Andersonand Woessner, 1992). Some are focused on asingle dimension (e.g. Janse et al., 1992), whilesystem modelling requires a multidisciplinary ef-fort (e.g. Hopkinson et al., 1988; van der Valk,1989; De Swart et al., 1994). The models areanalytical, numerical or statistical and describe asteady-state or dynamic change. Moreover, aerialphotography and satellite imaging (FGDC, 1992)can be incorporated by way of GIS-systems toadd spatial relations. For an example of how astatistical wetland vegetation model is linked to aregional groundwater flow model of a wetlandarea within a GIS framework, see Barendregt andWassen (1989), Barendregt et al. (1993), andAmesz and Barendregt (1996).

The development of methods for the practicalassessment of wetland functioning has followedthe increase in the intensity of wetland scientificresearch over the last two decades. In particular,this has been the case in North America, where amultitude of biophysical methods has been pro-duced to meet a range of operational require-ments (Lonard and Clairain, 1995). Within theNorth American context the main purpose ofwetland assessment has been to better informdecision makers of the publicly valuable wetland


functions that may be lost or impaired by devel-opment projects (Adamus and Stockwell, 1983;Larson and Mazzarese, 1994). Both regulatoryand policy instruments have driven the need forpractical wetland assessment methods in NorthAmerica, but they have been generally exclusivelybiophysical in approach and until recently havelacked the validation of closely coupled scientificprocess studies. Recent work in both the UnitedStates and Europe has focused on the possibilitiesof predicting wetland ecosystem functioning bytheir hydrogeomorphic characterisation. Effortshave also been made to establish functional clas-sifications of wetlands (Simpson et al., 1998).Brinson (1993) has outlined a hydrogeomorphicclassification for wetlands which underpins amethodology involving comparison of the ‘as-sessed’ wetland with suitable reference sites (Brin-son et al., 1999).

A European research initiative (FunctionalAnalysis of European Wetland Ecosystems,FAEWE) recognises the intrinsic value of thehydrogeomorphic approach, and is based on thecharacterisation of distinctive ecosystem/land-scape entities called hydrogeomorphic units(HGMU) (Maltby et al., 1994, 1996). Work atfield calibration sites has shown that a wetlandmay be comprised of a single HGMU or may becomposed of a mosaic of various units. Empiricalscientific research at Europe-wide calibrationsites, including process studies and simulationmodelling, have been used to assess the validityand robustness of the hydrogeomorphic concept.Clear relationships already have been found toexist between individual HGMUs and specificwetland functions including nutrient removal andretention (Baker and Maltby, 1995), floodwatercontrol (Hooijer, 1996), ecosystem maintenance(Climent et al., 1996) and food web support(Castella and Speight, 1996). Links to economicvaluation of fractions have also been set out(Crowards and Turner, 1996; Maltby, 1998). Seevan den Bergh et al. (1999) for a recent exampleof a wetland study for the Netherlands that em-ploys a system of integrated hydrological, ecologi-cal and economic models. This study adopts aspatial disaggregation into 73 polders and uses amulti-criteria evaluation procedure to aggregate

environmental, economic and spatial equityindicators.

8. Mitigating present failures through institutionsand policies

It was illustrated above that decisions aboutwetlands often are characterised by inconsisten-cies in terms of geographical scale; local versusnational versus international versus global scale.Three important ways to mitigate these inconsis-tencies are: (1) to create awareness of wetlandvalues on all levels; (2) to clarify the division ofresponsibilities between different decision levels inorder to arrive at a consistent hierarchy of deci-sions; and (3) to encourage local institutionalarrangements that are consistent with sustainablewetland use. We discuss these ways in turn below,and it will be evident that they are complementaryin nature.

The creation of a better awareness of wetlandvalues is directly linked to the improved informa-tion that can be obtained from integrated ecologi-cal-economic models. In particular, recentadvances in the development of such models andtheory all seem to stress the importance of theoverall system, as opposed to individual compo-nents of that system. The economy and the envi-ronment are jointly determined systems linked ina process of coevolution, with the scale of eco-nomic activity exerting significant environmentalpressure. The dynamics of the jointly determinedsystem are characterised by discontinuous changearound poorly understood critical threshold val-ues. But under the stress and shock of change, thejoint systems exhibit resilience, i.e. the ability ofthe system to maintain its self-organisation whilesuffering stress and shock. This resilience capacityis, however, related more to overall systemconfiguration and stability properties than it is tothe stability of individual resources.

In order to make progress in the importantwork of building integrated models, natural andsocial science researchers should reach agreementon:� terminology and typology appropriate to

valuation;


� the scale of effects to be analysed and possibleassociated thresholds;

� valuation methodologies;� links between valuation and systems and sce-

nario analysis;� the transferability of information and results in

both the scientific and economic realm;� the focus of the analytical approach, whether

thematic or by site;� consideration of valuation within its context,

i.e. the prevailing political and socialframework.For some of these items, this paper has sug-

gested a basis for agreement, which may serve asa platform for mutual understanding betweenscholars from different disciplines.

While scientific integration and the resultingimproved information is a prerequisite for miti-gating the fundamental failure of information dis-cussed in the preceding section, more is neededfor actually changing policies and stakeholder be-haviour. This brings us to the two other forms ofmitigation. Firstly, in order to arrive at a consis-tent hierarchy of decisions, the following levelsand responsibilities may be defined:� global: to define changes and appropriate pol-

icy responses at the global scale such as CO2

fixation in organic soils to prevent globalwarming and sea level rise (these require inter-national agreements by governments, e.g. Bio-diversity and Climate Change FrameworkConventions, etc.);

� international regions: to define changes in thesequence of wetlands (landscape ecology scale)such as the range of wetlands profitable formigrating birds, with breeding areas for repro-duction, migrating areas with plenty of foodand wintering areas to maintain the population(requiring measures such as regulation at thelevel of the Council of Europe);

� national: to maintain the national biodiversityincluding the defined national functions of wet-land (requiring national instruments and na-tional discussions on the economic andgeographical development of designed areas);

� sub-national regions: to maintain the sequenceof wetlands in a county or province (requiringregulations available on that regional level such

as national park or nature reserves conserva-tion powers);

� local: to maintain the present biodiversity andlocal financial returns, available from the localwetlands (requiring local regulations restrictingusage, but also mandates given to regional/lo-cal authorities to balance the interests of multi-ple stakeholders in wetland are as surroundingcatchment areas, e.g. trade-off navigation,recreation and amenity and nature conserva-tion goals in a wetland area).International cooperation and agreements

within the first three levels would enable an inter-national optimisation of the sequence of wetlandareas. Relevant sequences of wetlands includethose which would facilitate the use by migratingbirds of their complete migrating routes, and aninternational network of wetlands which wouldmaintain all the flora and fauna characteristic towetlands. As many wetlands are of internationalsignificance and in this sense a global heritage,their protection should also be the responsibilityof the international community buttressed by anew Global Ecological Framework to strengthenmeasures such as the Ramsar Convention. Anextension of the Global Environment Facility, forexample, could be made in order to finance wet-land protection schemes.

Many important economic decisions are, how-ever, taken at the local or regional levels, bothaffecting and influenced by the local economy orthe functions provided by the wetlands. Interna-tional and national regulations often fail to ad-dress the local subtleties involved in multiple usewetland areas. The EU’s Habitats Directive, forexample, has at its core a rather static interpreta-tion of conservation. This becomes problematicfor local/regional agencies which have a mandateto balance a range of stakeholder interests and tomanage a rate of change in a dynamic ecologicalsystem. Local interest groups are also difficult toinfluence if the case being made requires an appre-ciation of the ‘wider’ benefits of wetland protec-tion, up to the global scale of significance.

A key to resolving present failures thus seemsto be behavioural change at the local level, thethird form of mitigation mentioned above. In-creased scientific knowledge of wetland ecosys-


tems and their benefits to society has to be gainedhand-in-hand with efforts to increase publicawareness of these benefits. Such a communica-tion is, however, only likely to be successful if dueaccount is taken of the potential difference inworldviews between the scientists and local people(Burgess et al., 2000). Likewise, special attentionshould be paid to existing stakeholder structure,and potentially existing local ecological knowl-edge and local institutional arrangements formaintaining wetlands (cf. Berkes and Folke,1998). Such institutions may constitute a basis forbuilding wetland management institutions thathave already gained social acceptance at the locallevel, in contrast to governmental regulations im-posed in a top-down fashion.

9. Conclusion and prospect

Wetlands all over the world are threatened inspite of various international agreements and na-tional policies. A number of reasons have beenidentified here. Market failures exist due to thepublic good nature (a lack of enforceable propertyrights) of certain wetland goods and services, aswell as to externalities from users (e.g. agriculture,industry, water abstraction) upon other stake-holders, including nonusers. A failure of informa-tion and lack of understanding of the multitude ofvalues associated with wetlands is largely due tothe complexity and ‘invisibility’ of spatial rela-tionships between groundwater, surface water andwetland vegetation. In addition, there have beenpolicy intervention failures, notably a lack ofconsistency among policies in different areas (e.g.economic, agriculture, environment, nature pro-tection, physical planning).

Integrated wetland research combining socialand natural sciences can help to partly solve theinformation problem and to get a grip on therequired consistency among various governmentpolicies. A framework was presented that suggeststhat a combination of economic valuation, sys-tems modelling, stakeholder analysis, and multi-criteria evaluation can provide complementaryinsights into sustainable and welfare-optimisingwetland management and policy. A recent Eu-

ropean study underpins the importance ofcombining the various techniques to arrive at acomprehensive understanding of sustainable solu-tions to wetland degradation and loss (Turner etal., 1999). For example, integrated models canprovide detailed information about the ecohydro-logical consequences, and associated economiccosts and benefits, of land use policies. Valuationstudies can provide insights about the loss ofnonuse values associated with particular policies.Moreover, such values can be used to supporteconomic accounting modules in integrated wet-land models.

In order to make progress, further and inten-sified co-operation is needed between social andnatural scientists. This can be done along at leasttwo different lines. Integrated models can be de-veloped that connect in a systematic and coherentway knowledge and theories of the various sci-ences. Such an approach is ambitious and requiresdetailed description of natural and socio-eco-nomic processes at a spatially disaggregate level.As an alternative, ‘heuristic integration’ can takeplace in which, for instance, scenarios are devel-oped that reflect realistic changes due to (lack of)wetland management. Economic valuation experi-ments based on these scenarios can subsequentlycause integration via individuals’ assessment —through assigning values — of the relative(un)desirability of the changes implied by thescenarios. A combination of the two approacheswould make it possible to refine the presentationof scenarios to individuals. This would involve asequential process: developing an integratedmodel of a wetland system; using this model toinform individuals about the consequences of aproposed scenario of change; and present resultsvia geographical information systems and com-puter visualisation of impacts, for instance, on thelevel of landscapes. Given that the research effortis multidisciplinary enough to allow due attentionto the social context of the scenarios and theconsequences of the institutional arrangementsmore or less explicitly implied by them, such aprocess would imply improved valuationexperiments.


Acknowledgements

We are greatful to Guest Editor William J.Mitsch and six anonymous referees for usefulcomments on earlier versions of this paper.

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Ecological-economic analysis of wetlands: scientific integration for management and policy

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