Article
Reference
Assessing water ecosystem services for water resource management
GRIZZETTI, Bruna, et al.
Abstract
Ecosystem service concepts can offer a valuable approach for linking human and nature, and arguments for the conservation and restoration of natural ecosystems. Despite an increasing interest in the topic, the application of these concepts for water resource management has been hampered by the lack of practical definitions and methodologies. In this study we review and analyse the current literature and propose an approach for assessing and valuing ecosystem services in the context of water management. In particular, to study the link between multiple pressures, ecological status and delivery of ecosystem services in aquatic ecosystems under different scenarios of measures or future changes. This is of interest for the development of River Basin Management Plans under the EU Water Framework Directive.
We provide a list of proxies/indicators of natural capacity, actual flow and social benefit for the biophysical assessment of the ecosystem services. We advocate the use of indicators of sustainability, combining information on capacity and flow of services. We also suggest methods for economic valuation of aquatic ecosystem [...]
GRIZZETTI, Bruna, et al . Assessing water ecosystem services for water resource management.
Environmental Science & Policy , 2016, vol. 61, p. 194-203
DOI : 10.1016/j.envsci.2016.04.008
Available at:
http://archive-ouverte.unige.ch/unige:97002
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Assessing water ecosystem services for water resource management
B. Grizzetti*, D. Lanzanova, C. Liquete, A. Reynaud, A.C. Cardoso
EuropeanCommissionJointResearchCentre(JRC),I-21027(VA),Italy
ARTICLE INFO Articlehistory:
Received22December2015 Receivedinrevisedform1April2016 Accepted10April2016
Availableonlinexxx Keywords:
Waterecosystemservices Ecosystemservicesindicators Ecosystemservicesvaluation WaterFrameworkDirective
ABSTRACT
Ecosystemserviceconceptscanofferavaluableapproachforlinkinghumanandnature,andarguments fortheconservationandrestorationofnaturalecosystems.Despiteanincreasinginterestinthetopic,the applicationoftheseconceptsforwaterresourcemanagementhasbeenhamperedbythelackofpractical definitionsandmethodologies.Inthisstudywereviewandanalysethecurrentliteratureandproposean approachforassessingandvaluingecosystemservicesinthecontextofwatermanagement.Inparticular, tostudythelinkbetweenmultiplepressures,ecologicalstatusanddeliveryofecosystemservicesin aquaticecosystemsunderdifferentscenariosofmeasuresorfuturechanges.Thisisofinterestforthe developmentofRiverBasinManagementPlansundertheEUWaterFrameworkDirective.Weprovidea listofproxies/indicatorsofnaturalcapacity,actualflowandsocialbenefitforthebiophysicalassessment oftheecosystemservices.Weadvocatetheuseofindicatorsofsustainability,combininginformationon capacityandflowofservices.Wealsosuggestmethodsforeconomicvaluationofaquaticecosystemfor eachservice andspatial scaleof application. Wearguethat biophysicalassessmentand economic valuationshouldbeconductedjointlytoaccountforthedifferentvaluesofecosystemservices(ecologic, socialandeconomic)andtostrengthentherecognitionofhumandependencyonnature.Theproposed approachcanbeusedforassessingthebenefitsofconservationandrestorationofaquaticecosystemsin theimplementationoftheEUwaterpolicy.
ã2016PublishedbyElsevierLtd.
1.Introduction
Ecosystem services are defined as the benefits that people obtainfromecosystems(MEA,2005a),andthedirectandindirect contributionsof ecosystems tohumanwell-being(TEEB, 2010).
The concept of ecosystem services is relevant for connecting people to nature. It makes visible the key role of ecosystem functioning and biodiversity to support multiple benefits to humans. Understanding the linkages between the natural and socio-economicsystemscanleadtoimprovedandmoresustain- ablemanagementofecosystems(Guerryetal.,2015).
In 2010theparties oftheConventionof BiologicalDiversity adoptedarevisedStrategicPlanforBiodiversityincludingtheAichi BiodiversityTargets(CBD,2010),areinforcedactiontohalttheloss ofbiodiversityandensureecosystemsareresilientandcontinueto provideessential services.In linewiththisinternationalframe- work,in2011theEuropeanUnion (EU)presentedtheEuropean BiodiversityStrategyto2020(EuropeanCommission,2011)that putemphasisontheprotectionandvalueofecosystemservices,
settingaspecifictargetonmaintainingandrestoringecosystems andtheirservices(Target2).
Aquaticecosystems(rivers,lakes,groundwatercoastalwaters, seas)supportthedeliveryofcrucialecosystemservices,suchas fishproduction,waterprovisioningandrecreation.Keyecosystem servicesarealsoconnectedtothehydrologicalcycleintheriver basin,forexamplewaterpurification,waterretentionandclimate regulation.Mostofthesewaterrelatedecosystemservicescanbe directlyappreciatedbypeopleandquantified,butsome,especially regulatingandmaintenanceservices,arelessevident.Though,all ecosystemserviceshavetobeconsideredforthesustainableuse andmanagementofwaterresources.
InEurope,thedevelopmentofRiverBasinManagementPlans (RBMP)undertheEUWaterFrameworkDirective(WFD,Directive 2000/60/EC)isanactualsituationwhereterritorialplanningfor watermanagementisneeded,andwheretheconceptofecosystem servicescouldbeadoptedtorecognisethemulti-functionalityof thewatersystemsandaccountforthebenefitspeoplereceivefrom nature, justifying the costs of protection and restoration. The Blueprint to safeguard Europe’s water resources (European Commission,2012)indicatedthatnaturalwaterretentionmeas- urescan greatly contributeto reduce theeffects of floods and droughts ensuring the provisioning of ecosystem services, and
*Correspondingauthor.
E-mailaddress:[email protected](B. Grizzetti).
http://dx.doi.org/10.1016/j.envsci.2016.04.008 1462-9011/ã2016PublishedbyElsevierLtd.
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thesemeasuresshouldbeincludedintheRBMPsandintheFlood RiskManagementPlans.In linewiththeBlueprint,somerecent studieshave been reflecting onthe potential of theecosystem serviceapproachintheimplementationoftheWFD,emphasising theopportunityofholisticsystemthinkingtounderstandtheco- benefits ofmeasuresand tointegrate differentsectoralpolicies (Vlachopoulouetal.,2014;COWI,2014;ESAWADI,2010).
However,thelackofagreeddefinitionsofecosystemservices andapproachesfortheirquantificationandvaluationhaslimited the uptake by practitioners and policy makers (Polasky et al., 2015).The MAES Working Group (Mappingand Assessment of Ecosystems and their Services), established to support the implementation of the EU Biodiversity Strategy, hassuggested ananalyticalframeworkfortheimplementationoftheecosystem service approach in the EU, and tested it in a pilot study on freshwaterand marineecosystems(Maesetal.,2016).Two FP7 projects, OpenNESS (2015) and OPERA (2015), are currently workingonthegeneraldefinitionofconceptsandmethodologies for assessing and valuing ecosystem services, and on the operationalizationoftheconceptsthroughrealcasestudies.More specifically onwaterpolicy, the FP7projectsMARS (2015) and Globaqua(2015)aimtounderstandandquantifytheimpactsof pressuresontheecologicalstatusofEUwatersandtheconsequent effectsonthedeliveryofecosystemservices.
Understanding therelationship between multiple pressures, conditionsandservicesofaquaticecosystemswouldhelpdesign measurestoachievethetargetofgoodecologicalstatusofwater systems, foreseen by the WFD, by considering the benefits of investinginnatureconservationandrestoration.Butthelackof cleardefinitionsandpracticalmethodstoassessthewaterrelated ecosystemservicescouldhampertheadoption oftheapproach (Kulletal.,2015;Crossmanetal.,2013).Also,whilemappingof ecosystem services directly linked to land occupation is quite straightforward, for fresh water ecosystems the assessment is more complex, as the hydrological cycle and the land-water interactionshavetobetakenintoconsideration.
The objective of this study was to develop a practical methodology for assessing and valuing ecosystem services relevantfor water resource management, consideringthe links betweenpressures,ecologicalstatusandecosystemservices.The work is based on literature review and scientific partners’ consultation. It started from the experience of the MAES freshwaterpilot and was developed withinthe EU FP7project MARS.
Thepaperisstructuredasfollows.Thefirstpartdescribesthe methodologicalapproachadoptedinthestudy.Thesecondpart presents the results of our analysis in the form of a practical approachforassessingandvaluingecosystemservicesrelevantfor water resource management. The third part discusses the challengesinvaluingecosystemservicesandintegratingbiophys- icalandeconomicassessments.
2.Method
Weanalyseddefinitionsandmethodsforassessingandvaluing ecosystem services to synthesize the current knowledge and propose a practical and flexible approach relevant for water resourcemanagement.Theusecontextoftheapproachisthestudy oftherelationshipbetweenmultiplepressures,ecologicalstatus and delivery of ecosystem servicesin water systems, with the overallgoaltosupporttheEUwaterpolicy(WFD).1Theanalysis
wasbasedonliteraturereviewandconsultationofthescientific partnersoftheprojectMARS,from24researchinstitutesacross Europe.
Thefocusof theanalysisisoninlandwatersandthespatial scaleofinterestrangesfromthewaterbodytothecatchment/river basin andtheEuropeanscale.While forwaterbodies themain focusisonspecificecosystemfunctionsthatsupportecosystem services, and their alteration under different stressors, the catchment is the appropriate scale to observe and quantify processesrelatedtothewatercycle,andtoimplementmonitoring andmanagementplanstoreducemultiple-pressures.Theassess- mentandvaluationofecosystemservicesattheEuropeanscale allows us to address regional trends, identifyhot spots in the delivery or degradation of services, test the effectiveness of regional policies (such as EU Directives) and conduct scenario analysisatthelargescale.Inthedevelopmentofthemethodology weconsideredthesedifferentspatialscales.
Theapproachthatwedevelopedisorganisedinfourbuilding steps: 1) definitions and scoping (Section 3.1); 2) framework (relations betweenpressures, ecological status and delivery of ecosystem services) (Section3.2); 3)biophysical assessment of ecosystem services (Section 3.3); 4) economic valuation of ecosystem services (Section 3.4). In the following part of the paperwedescribetheresultsofourstudyproposingguidelineson howtodevelopthesecomponents.
3.Results:approachforassessingandvaluingwaterecosystem services
3.1.(Step1)Scoping Waterrelatedecosystemservices
Alargevarietyofecosystemserviceshavebeenaddressedby assessments suchas Millennium Ecosystem Assessment (MEA, 2005a), the Economics of Ecosystems and Biodiversity (TEEB, 2010), MAES (Maes etal.,2016), and nationalassessments(e.g.
Pereiraetal.,2006;UKNEA,2011).Inthisstudyweareinterested in ecosystemservices relatedtowaterand aquaticecosystems.
MAESanalysedtheecosystemservicespertypologyofecosystem, consideringtheservicesdelivered byrivers,lakes, groundwater andwetlandsinthefreshwaterpilotstudy,andthoseprovidedby transitionalwaters,coastalwaters,shelfwatersandopenoceanic waterinthemarinepilotstudy.Withaslightlydifferentapproach, Brauman et al. (2007) discussed the ‘hydrologic ecosystem services’,definedastheecosystemservicesthat“encompassthe benefitstopeople producedby terrestrialecosystemeffects on freshwater”,eachhydrologicalservicebeingcharacterisedbythe hydrologicalattributes ofquantity,quality, locationand timing.
Keeler et al. (2012) described in detail water-quality related ecosystemservices.Recently,Guswaetal.(2014)haveaddressed moregenerallythe‘waterrelatedecosystemservices’,discussing the link between hydrological modelling and the ecosystem servicesrelevantforriverbasinmanagement.Fromthesestudies wecanobservetwoapproachesintheorganisationoftheanalysis, oneperecosystemtypology(Maesetal.,2016)andtheotherper hydrological relevant services (Brauman et al., 2007). Both approaches considertheintegrationofalltheservices,thefirst byaccountingforalltheecosystemsintheanalysis,thesecondby integratingtheprocessesintheriverbasin.Theecosystemservices ofrelevanceforthewatermanagement(andtheWFD)arethose relatedtotheaquaticecosystemsandtotheinteractionofwater andlandindifferentecosystems,suchasforests,agriculturallands, riparian areas, wetlands, and water bodies. In this study we indicatealltheseservicesas‘waterecosystemservices’.
Fortheassessment,theidentificationoftherelevantecosystem servicesisthefirststep.Weproposeasimplifiedclassificationof ecosystem services based on the Common International
1 IntheFP7projectMARSthisanalysiswillbeconductedattheEuropeanscale andin16catchments,representingagreatvariabilityofpressuresandecosystem servicesacrossEurope.
Classification of Ecosystem Services Version 4.3 (CICES, 2015), whichistheframeworkadoptedbythecommonimplementation oftheecosystemassessmentapproachintheEU(Supplementary materialS1,wealsolinkedtheclassificationoftheTEEB,2010).The idea is to offer a coherent terminology relevant for scientists, sufficientlysimpleforstakeholders,andmeaningfulforriverbasin managers. The services (S1) can be related to the following ecosystems: lakes, rivers, transitional waters, coastal waters, groundwater, freshwater wetlands, coastal wetlands, riparian areas, floodplains. Providing a list of ecosystem services can supportthepracticalimplementationofthemethodology,butof coursethelistisnottobeconsideredexhaustiveandmoreservices canbeincluded,especiallyhydrologicalservicesrelevantforriver basinplanninganddecisionmaking.
3.2.(Step2)Framework Linkingpressures,ecologicalstatusand ecosystemservicesforwatermanagement
Understandingtherelationshipbetweenanthropogenicpres- suresand ecologicalstatus isthebasisof theRBMP,inorderto devisecost-effectivemeasurestoachieveagoodecologicalstatus forallwaterbodies.Inparticular,forplanningsoundrestoration actions,it is necessary to considerthe complex links between pressurescombinations and the ecological response of aquatic systems(Teichertetal.,2016;Brownetal.,2013;Halpernetal., 2008), as multiple pressures may have additive, synergetic or antagonisticeffects(Nõgesetal.,2015).TheresearchprojectMARS studies the complex relationships between multiple stressors, statusofaquaticecosystemsandthedeliveryofecosystemservices (seeHeringetal.,2015fortheMARSconceptualmodel).
In the EU, water pollution, over-abstractions and hydro- morphological alterations have been indicated as the major significantpressures for the Europeanwater bodies (European Commission,2015).Atthesametime,concernovertheincreaseof alienspeciesexists(Butchartetal.,2010;RegulationEUNo1143/
2014).Overall,themainpressuresaffectingtheaquaticecosystems canbesummarisedasalterationsofwaterquantityandquality, andchangesinthephysicalhabitatandthebiologicalcomponents, asshowninTable1.
Humanactivitiesarethemajordriversforgeneratingmultiple pressures(Fig.1).Pressuresaffectthebiodiversityandthestatusof the aquatic ecosystem, which can result in a change in the ecosystem services and their economic value. The excessive exploitation of ecosystemservices canturn intoa pressurefor an ecosystem. For this reason is important to consider the resilience of the system and to introduce the notion of sustainabilitywhenassessingthedeliveryofecosystemservices (Fig.1).The interestof RBMPistoquantify thechangesin the components of this system under remediation measures and scenariosofpressures.
To support the analysis of these linkages, we developed a conceptual framework for the integrated assessment of water relatedservices(presentedinFig.2).Intheframework,weidentify the main pressures affecting aquatic ecosystems (according to Table1)andthepossiblelinkstothealterationoffourecosystem/
hydrologicattributes:1)waterquantity(includingseasonality);2) water quality;3) biological qualityelements; 4)hydromorpho- logical&physicalstructure.Theattributesaredifferentfromthose proposedbyBraumanetal.(2007),toincludeintheanalysisthe biologicalandhydromorphologicalaspectsandtomakethelinkto theWFDelementsexplicit(sothattherelationshiptoecological status shouldbeinprinciplemore easy).Foreach attribute we selectedanumberofrepresentativeindicators(asexamples)and identifiedsomepossiblerelationshipswiththeecosystemservices suggestedinthisstudy(S1).
Thepurposeofthisframework(Fig.2)istosupporttheusersin describing the relationships between pressures and ecosystem servicesand designaconceptualschemeoftheassessmentand scenarioanalysis.Thearrowsareexamples.Eachusercanselect the relationships under analysis and complete and adapt the frameworktothespecificcaseunderstudy.Theideaistothink about the links between the selected services and specific stressors.Fig. 3, which presents expectedqualitative effects of stressors/pressuresondifferentecosystemservices,couldinspire thisreflection.
3.3.(Step3)Biophysicalassessment 3.3.1.Tools
Severalapproachestoassessandmapecosystemservicesare availableintheliterature,fromlandcovermapscombinedwith scoringfactors(Burkhardetal.,2009)tospecificecosystemservice models based on ecological production functions (Sharp et al., 2015),anddecisionsupporttools(Bagstadetal.,2013reviewed 17toolsforassessingandvaluingecosystemservices).Thesetools Table1
Stressorsandpressuresonwatersystems.
Alterationof:
Waterquantity
Flowmodifications(hydrologicalalterations):
Quantityandfrequency(dams,waterabstractions,irrigation,transfers) Groundwaterabstractions
Changesinprecipitationandtemperature Changesinrunoff
Waterquality
Diffuseandpointpollution:
Nutrients
Chemicals(pesticides,endocrinedisruptingcompounds,nanoparticles,etc.) Metals
Pathogens Litter
Groundwatersalinization
Sediments,increasedturbidityandbrownification
Habitat
Hydromorphologicalalterations(physicalalterationofchannels,bed disruption,dams)
Biotaandbiologicalcommunities
Alienspecies,otherchangesinbiologicalcommunities
Fig.1.Schematic representation of the system under analysis. Relationships betweenhumansandaquatic ecosystems underpresentandfuture scenarios (explanationinthetext).
usuallycombineecologyand economics,consideringthespatial dimension.TheEUFP7projectOpenNESSisstudyingmethodolo- gies for mapping and modelling the biophysical control of ecosystemservicesandapproachesforthevaluationofecosystem services,forapplicationin 27realcase studies.Thebiophysical methods include spreadsheet/GIS approaches (Burkhard et al., 2012;Vihervaaraetal.,2012);Quickscan(2015);BayesianBelief Networks (Smith et al., 2014); State and Transition Models (Bestelmeyeretal.,2011);ESTIMAP(Zulianetal.,2013);InVEST (2015). These methods apply to all ecosystem services, not specifically to waterecosystem services. Most of them rely on thespatialmappingoftheecosystemsandlanduse.
The water quantity and quality, and the water related ecosystemservices,are affectedbythecomplex interactionsof climate,topographyandgeology,landcoverandmanagement,and otheranthropogenicmodificationofthelandscape.Incorporating waterrelatedecosystemservicesinthedecisionmakingprocess requiresthecapacitytopredicttheeffectsoflanduseandclimate changes on the water resources, which can be offered by the hydrological models (Guswa et al., 2014). Hydrological and biogeochemical catchment models are appropriate tools for dealing with water related ecosystem services (Guswa et al., 2014;VigerstolandAukema,2011;Braumanetal.,2007).Theycan represent the dynamic of the river basin (resilience) and the temporal(lagtime)andspatialdistancebetweenbeneficiariesand
impacts, and they can beused in scenarioanalysis of multiple stressors. They also allow describing physical relationships between stressors, status and services as presented in the integratedassessmentframework(Fig.2).
3.3.2.Indicators
Followingthislineandconsideringthewealthofknowledgein hydrological modelling, we propose to base the biophysical assessment of ecosystem services on ‘indicators’ rather than
‘tools’.SimilartoMaeset al.(2014)andLaykeetal.(2012),we suggest the selection of somesuitable indicators or proxies of ecosystemservicesthataredirectlyrelatedtowaterbodiesorto water-landinteractioninthewatershed,asaflexibleandhandy approachtomeasureecosystemservices.
Tosupportthecorrect understandingandappropriateuseof the indicators for ecosystem services, and more generally to structuretheassessment,wehavetoanalysewhichdimensionof theecosystemserviceiscapturedbytheindicators.Tothispurpose weproposeasimplifiedconceptualframeworkforstructuringthe analysisand the classification of indicators ofwater ecosystem services.Theframework,presentedinFig.4,includesthecapacity of theecosystem to deliver theservice, theactual flow of the service, and thebenefits. Capacityreferstothepotential of the ecosystemtoprovideecosystemservices,whileflowistheactual useoftheecosystemservices.Thecapacityreliesonbiophysical Fig.2.Integratedassessmentframeworkforanalysingthelinksbetweenpressures,ecosystemstatusandecosystemservices.Thelistofpressuresandthearrowsdescribing therelationshipsarenotexhaustive;theusersareinvitedtodevelopthespecificrelationshipsatstakeintheircasestudy.
data,whileflowrequirestheacquisitionofsocio-economicdata.
Benefits are associated with human well-being and the value system(forstudiesdiscussingtheconceptsofcapacityandflow andcascademodelofecosystemservicesseeHaines-Youngand Potschin,2010;Laykeetal.,2012;Villamagnaetal.,2013;Maes etal.,2014;Schröteretal.,2014).Servicesareoftenassociatedwith highexploitationoftheecosystem;theriskisanunsustainableuse of nature. For this reason we are interested in looking at the sustainableflowofservices.Thisisconsideredintheconceptual frameworkbyincludingindicatorsinformingaboutthesustain- ability,i.e. indicatorscombining capacity andflow(anexample could be the Water Exploitation Index). In many cases, the informationoncapacityandflowislacking,orthefullcapacityof theecosystemisunknownorunaccountable.Inthesecaseswecan trytocollectindicatorsabouttheefficiencyoftheprocesses(for exampletheremovalrateofapollutantperunitofinput).
Inthisstudywecompiledalistofpotentialproxies/indicators forwaterecosystemservicesbasedontheliteraturereview(the indicators are provided in Supplementary Material S2). We classified them according to the categories of the conceptual framework:capacity,flowandbenefit(thecategoryof‘sustain- ability’and‘efficiency’werenotexplicitlyusedintheclassifica- tion).Ourcompilationincludesatotalof206proxiesandisbased onMaesetal.(2014),Egohetal.(2012),Laykeetal.(2012),Russi etal.(2013)andLiqueteetal.(2013)(minormodificationsfromthe originalauthorslikere-phrasingorre-allocationwererequiredto avoid duplications and to respect our conceptual framework).
Table11ofMaesetal.(2014)comprisesalltheindicatorsproposed in the deliberative process of implementation of the EU BiodiversityStrategyaroundthefreshwaterpilot.AppendixAof Egohetal.(2012)summarisesanextensiveliteraturereview.The Ecosystem Service Indicators Database of the World Resources Institute(www.esindicators.orgaccessedinDecember2015,Layke et al., 2012) compiles metrics and indicators from numerous sourcesthathavebeenidentifiedandappliedbyindividualsfrom variedorganizations.Russietal.(2013)highlightstherelevanceof waterandwetlandsandlinksittodecision-making,providinga fewexamplesofindicatorsforfreshwaterecosystemservices.We reviewedalsoLiqueteetal.(2013),whichincludesa systematic compilation of 476 marine and coastal ecosystem services’ indicators,inordertocoveradditionalaspectsspecificallyrelated totransitionalandcoastalwaters.Intheliteraturereview,other studies were also considered (although some of them do not providedirectly indicators forecosystem services):the specific studies of the Millennium Ecosystem Assessment dealing with freshwater systems (MEA, 2005b,c); UNEP (2009), UNEP-WCM (2011),Feldetal.(2009,2010),TEEB(2010),VigerstolandAukema (2011)andClericietal.(2014)
InFig.4weprovidesomeexamplesofindicatorsofecosystem services for water provisioning and water purification, with references to studies that have used these indicators at the Europeanscale. Otherexamples of application of theproposed conceptualframeworkfor indicatorscan befoundinKarabulut etal.(2016)forwaterprovisioning,Rankinenetal.(submitted)for Fig.3.Expectedqualitativeeffectofstressors/pressuresondifferentecosystemservices.
waterpurification,Vigiaketal.(submitted)forerosionprevention, andLiqueteetal.(submitted)forseveralecosystemservices.
3.4.(Step4)Economicvaluation
Several methods are available in the literature to estimate economicvaluesoffreshwaterecosystemservices(seeforinstance Koundouri et al., 2015). Overall, there are three categories of approaches:cost-based,revealedpreferencesand statedprefer- encesapproaches.Cost-basedapproachesconsiderthecoststhat ariseinrelationtotheprovisionofservices.Revealedpreferences approaches refer to techniques that use actual data regarding individual’s preferences for a marketable good which includes environmentalattributes.Statedpreferencesapproachesreferto methods based on structured surveys to elicit individuals’
preferencesfornon-marketenvironmentalgoods.Anotherpracti- calwaytovalueecosystemservicesundernon-availabilityofsite- specific data or funding constraints is the benefit transfer approach. This approach consists of using economic estimates frompreviousstudiestovalueservicesprovidedbytheecosystem ofinterest(NavrudandReady,2007).Themethodsforeconomic valuation available in the literaturearesummarised in Supple- mentaryMaterialS3.
For the economic assessment, the first step consists of identifyingthebenefitsprovidedbytheecosystemservicetobe valued.Fisheretal.(2009),FisherandTurner(2008)arguedthatit is theeasiestwaytoperformavaluation exerciseavoidingany doublecounting.Followingthis approach,onlytheservicesthat haveadirectimpactonwelfarearevalued.Thespatialscaleofthe assessmentisalsorelevantfortheselectionofthemethod.
Fig.4.Conceptualframeworktoclassifyindicatorsofwaterecosystemservices.Someexamplesofindicatorsfortheecosystemservicesof1)waterprovisioningand2)water purificationarereported.ForstudiesusingtheseindicatorsattheEuropeanscalesee1)DeRooetal.,2012forwaterprovisioning,and2)Clericietal.,2013(capacity),Grizzetti etal.,2012(flow),LaNotteetal.,2015(benefit),Liqueteetal.,2015(sustainability)forwaterretention(nitrogenpurification).
Table2
Freshwaterecosystemservices,typeofvalueandappliedvaluationmethods.Theclassificationofecosystemserviceshasbeendevelopedforfreshandtransitionalwater (ReynaudandLanzanova,2015).
Ecosystemservices Categorya Valuetype Valuationmethodb Examplesofeconomicgoodprovided
1-Fisheriesandaquaculture Provisioning Direct MP,RC fishcatch
2-Waterfordrinking Provisioning Direct MP,CV waterfordomesticuses
3-Raw(biotic)materials Provisioning Direct MP,RC algaeasfertilizers
4-Waterfornon-drinkingpurposes Provisioning Direct MP,PF waterforindustrialoragriculturaluses
5-Rawmaterialsforenergy Provisioning Direct RC woodfromriparianzones
6-Waterpurification Regulation Indirect RC,CV excessnitrogenremovalbymicroorganisms
7-Airqualityregulation Regulation Indirect RC depositionofNOxonvegetalleaves
8-Erosionprevention Regulation Indirect RC vegetationcontrollingsoilerosion
9-Floodprotection Regulation Indirect RC,CV vegetationactingasbarrierforthewaterflow
10-Maintainingpopulationsandhabitats Regulation Indirect RC habitatsuseasanursery
11-Pestanddiseasecontrol Regulation Indirect RC,CV naturalpredationofdiseasesandparasites
12-Soilformationandcomposition Regulation Indirect RC richsoilformationinfloodplains
13-Carbonsequestration Regulation Indirect RC,MP carbonaccumulationinsediments
14-Localclimateregulation Regulation Indirect RC,MP maintenanceofhumiditypatterns
15-Recreation Cultural Direct CV,TC,DC,HP swimming,recreationalfishing,sightseeing
16-Intellectualandaestheticappreciation Cultural Non-use CV,DC matterforresearch,artisticrepresentations 17-Spiritualandsymbolicappreciation Cultural Non-use CV,TC,DC existenceofemblematicspecies
18-Rawabioticmaterials Extraabiotic Direct PF,MP extractionofsandgravel
19-Abioticenergysources Extraabiotic Direct PF,MP hydropowergeneration
aProvisioning,Regulationandmaintenance,Cultural,Extraabioticservices.
b Contingentvaluation(CV),Hedonicprice(HP),Marketprice(MP),productionfunction(PF),Replacementcost(RC),travelcosts(TC).
3.4.1.Economicvaluationatthewaterbody/catchmentscale Thechoiceof theprimaryvaluationmethoddepends onthe ecosystemservicetobevaluedandonthebeneficiarypopulation.
Table2reportsvaluationmethodsperecosystemservicebasedon theliteraturereview.
One of themain difficultiesin the economic valuation is to decideon thesize of the benefiting population(beneficiaries).
Aggregatebenefitsdependonestimatesofbothindividualbenefits and of the number of beneficiaries (Hanley et al., 2003). As a generalrule,thebeneficiariesshouldbethehouseholds/persons aggregatedattherelevantgeographic scale,andshouldinclude both users and non-users impacted by the ecosystem service considered (except for services of only local importance). In addition,for someservices (for examplerecreational services), when spatially aggregating individual benefits, it is usually consideredthatthewillingnesstopay(WTP)decreaseswiththe distancefromwater body providing ecosystemservices, asthe opportunitiesoftheecosystemserviceprovisionareexpectedto decrease with the distance, and concurrently the existence of possiblesubstitutesisassumedtoincrease(BatemanandLangford, 1997;Georgiouet al.,2000;Jørgensenet al.,2013).Generallya distance decay function is adopted to take into account the decreaseofthewillingnesstopaywiththedistancefromthewater bodyprovidingtheecosystemservices(Batemanetal.,2006).This distancedeterminestheboundariesofthegeographicalarea,orso- called economic jurisdiction, over which the individual WTP- valuescanbeaggregatedoverthepopulationofbeneficiariesto calculate the total economic value of a proposed scenario of environmental change (Schaafsma et al., 2012). However, the specification of the distance decay relations has been highly debatedamongeconomists.Anumberofstudieshaveexaminedin particularhowthedistancedecayrelationdiffersbetweenusers and non-users of the ecosystem service (Hanley et al., 2003;
Batemanetal.,2006).
3.4.2.Economicvaluationatthelarge/continentalscale
At the large/continental scale, such as the European scale, methodologiesupscalingvaluesofprimarystudies(valuetransfer) andaccounting forthespatial heterogeneityof biophysicaland socio-economic characteristics are more appropriate. This ap- proachconsistsofameta-analysisusingtheresultsof available paststudiesonecosystemservicesvaluationinwaterbodies to estimateafunctionthatrepresentstherelationshipbetweenthe featuresofwaterecosystemsandthevalueof theservicesthey provided(see Branderet al.,2006, 2007for examples ofmeta- analysisforthevaluationofecosystemservices).
The first step of a meta-analysis consists of searching and selectingstudiesvaluingservicesprovidedbyecosystemssimilar to the one of interest (the policy site), most often through systematicsearches. Allrelevantdatafromprimary studiesare collectedandorganisedinameta-database,includinginformation on methods applied, ecosystem services valued, biophysical characteristicsof theecosystem, and thecharacteristics of the beneficiariesof theecosystemservices.Toenablea comparison across studies, the economic values reported using different metrics (i.e.WTP, marginal values, capitalized value) are stan- dardized. However, this is a difficult and controversial task (Ghermandi et al., 2010). Purchasing power parity indexes are applied to the original values to account for differences in purchasing power among countries, and appropriate price deflators are used to deal with the difference in the years of observation (Ghermandi and Nunes, 2013). In addition, values issuedbydifferentmethodsarenormalized.Forexamplevalues areexpressedinmonetaryunitsperareaand time(Ghermandi etal.,2010;Branderetal.,2012);orpervisitandtime(Brander etal.,2007)orperhousehold/respondentandtime(Brouweretal.,
1999; Johnston et al., 2005). The following step of the meta- analysisistheestimationofthemeta-valuestransferfunction.A regression technique allows accounting for the biophysical or socio-economicaldifferencesbetweentheprimarystudysitesand thepolicysite.Therearetwopopularpanel-datamodelswhichcan beusedforestimatingthemeta-regressionmodel,e.g.thefixed- effect modeland therandom-effect model. Therandom-effects modelallowsthetrueeffectsizetodifferfromstudytostudyand this is the approach usually recommended. The values of ecosystemservicesthatareestimatedbytheregressionanalysis arethentransferredandaggregatedatthelargergeographicareas through a scaling-up procedure. The most appropriate transfer functionamongthedifferentmeta-regressionspecificationshasto beselectedbasedontheexplanatorypowerofthemodel,signand significance of the coefficients estimated. In addition, the appropriate geographic scale for transferring values has to be defined(GhermandiandNunes,2013).
4.Discussion
Considering the current and impellent challenge of the implementation, i.e. being able to translate the concepts of ecosystem services into practice (European Commission, 2011, 2012;Guerryetal.,2015),theneedtobeoperationalconstituted one of the leading criteria in the development of the present reviewandproposedapproach.Weconsideredthisresearchasa learningprocess.Theapplicationoftheapproachison-goinginthe projectMARSatthecatchmentandtheEuropeanscale.Thiswill provide the necessary feedback to improve and refine the approach.
Herewediscusssomeaspectsthatweconsiderimportantwhen assessingandvaluingecosystemservicetosupporttheWFDand RBMP,andhowtheproposedapproachcouldaddressthem.
4.1.Thevaluationofecosystemservices
TheWFDreferstoeconomicvaluationindecision-makingto support the RBMP in the identification and selection of cost- effective Programmes of Measures (PoM, WFD Article 11).
Quantifyingthebenefits(ecosystemservices)thatnatureprovides topeoplewouldhelpjustifytheinvestmentsinconservationand restorationofaquaticecosystems.Inaddition,thedevelopmentof the PoM can be improved integrating all relevant ecosystem services,byconsideringtheco-benefitsofdifferentmeasuresand nature-basedsolutions ondifferentecosystemservices(Liquete etal.,submitted).Thebenefitsofecosystemservicescouldalsobe included in the cost-benefit analysis to implement the cost- recovery principle in the water supply system (WFDArticle 9) (Vlachopoulouetal.,2014;COWI,2014).
Yet the valuation of ecosystem services also involves some importantrisks,i.e.creatingeconomicmarketsforprovisioning, regulatingandculturalservices.Wehavetoreflectonthenotionof
‘valuation’.Anydecisioninvolvingtrade-offsofecosystemservice impliesvaluation(Costanzaetal.,2014).Therearedifferentvalues in therelationshipofhumanand non-humannature,including inherent, fundamental, eudaimonistic and instrumental values (Jaxetal.,2013).Thevaluesthatarecapturedbytheecosystem serviceconceptdependonhowtheconceptisoperationalisedand implemented (approaches and methodologies used). Different stakeholders have different value systems and perspectives.
Thereforeinvolvingallthestakeholdersinthevaluationprocess isnecessarytoconsiderthepluralityofvalues,whileneglecting somevalueswouldexcludethepeoplewhoembracethesevalues (Jaxetal.,2013).
The notion of value should not be restricted to the mere monetaryvaluebutembracealargerrangeofvalues.Ifrestricting
thevalueofecosystemservicestoeconomicvalue,weriskfalse accounting of all valuedimensions and environmental compo- nents(trade-offs)of policydecision(Keeleret al.,2012).‘Value pluralism’ refers to the idea that there are multiple values, including economic (monetary), sociocultural and ecological values.Anintegratedvaluationshouldendorsethevaluepluralism (Gómez-Baggethun et al.,2014). The valuation techniques vary withthetypologyof valuestobeelicited andthescopeof the valuationexercise,thegeographicalscale,spatialresolution,and reliabilityandaccuracyrequired.Thepurposeofthevaluationcan range from awareness raising, to accounting, priority setting, instrumentdesignandlitigation(Gómez-BaggethunandBarton, 2013).
Intheproposedapproach,wethinkitisimportanttointerpret theeconomicvaluationinmonetarytermssensuCostanzaetal.
(2014), i.e. for awarenessraising aboutrelative changes over a periodintime.Thisexcludestheintentoftreatingallecosystem servicesassubstitutable.Weareinterestedmainlyinthechangeof valueastheresultoftheeffectsofmultiplestressorschangesorthe implementationofmeasures.
4.2.Strengthentheconnectionhuman-nature
RBMPsarebasedontheprinciplesofIntegratedWaterResource Management(IWRM),“aprocesswhichpromotesthecoordinated development and management of water, land and related resources,inordertomaximizetheresultanteconomicandsocial welfare in an equitable manner without compromising the sustainability of vital ecosystems” (GWP, 2000). Before the ecosystem service approach, IWRM already stressed the need forconnectingenvironmentandhumanwell-beingandproposed the integration of multi-disciplinary knowledge from different sectorsandstakeholdersinthewatermanagement.Theecosystem servicesapproachhassignificantsimilaritieswithIWRM.Cookand Spray(2012) arguethat thetwo conceptsare ‘nearlyidentical’. Bothaimatamanagementofnaturalresourcesthatoptimisesthe economic and social welfare and contemporary insures the ecological sustainability, integrating the knowledge of stake- holdersandmultipledisciplinaryperspectives.Ecosystemservices and IWRM both share the goal of negotiating the trade-offs betweendifferenthumanandecosystemneeds,whilesupporting sustainability, and require the involvementof stakeholders for making explicit the wholerange of values (notonly economic values).Theecosystemservice approachoffersaframeworkfor analysingthetrade-offsamongdifferentservicesandthelinksto beneficiaries(Braumanetal.,2007).Learningfromthecriticisms to IWRM would help improve the adoption of the ecosystem service approach. These criticisms are related to the lack of consistent definitions, the difficulty of developing a holistic approach, the risk of opposite interpretations of the concepts, and thefailure toincorporate theprinciplesin the governance (CookandSpray,2012).The‘implementationgap’isanimportant challengefortheecosystemserviceapproachandthisstudyaims tocontributetothisendeavour.
Toaddresscurrentsustainabilitychallengestherecognitionof the dependency of human well-being on natural capital is necessary(Guerryet al.,2015). Integrativeframeworkssuchas the ecosystem service approach allow incorporation of natural componentsinthesystemanalysis(Liuetal.,2015).Theconceptof ahuman-ecologicalsystem advocatedbytheecosystemservice approachispowerfulinlinkingbiophysicalprocessesandhuman benefits, and allows ecosystem services to be valued and integratedintheriverbasindecision makingprocess.However, economic models tovalue ecosystemservices related towater qualityareoftenpoorlyintegratedwiththebiophysicalmodels describingtheunderpinningnaturalprocesses(Keeleretal.,2012).
In this studywe consideredboth dimensions of biophysical assessment andeconomic valuationand wesuggesttoperform them in collaboration. This is a crucial but evasive step of ecosystem service analyses, and remains one of the main challenges in this field research (Polasky et al., 2015). The integrationalsodependsonthemethodusedfortheassessment.
In the case of freshwater systems, many biophysical results (comingfrommodelsormeasures)canbeusedasaninputfor economic valuations. Someexamples arethe improvements of juvenilefishtoestimatetheeconomicenhancementofcommer- cial fish by seagrass (Blandon and zu Ermgassen, 2014), the nitrogenretentionefficiencyusedtoestimatethereplacementcost ofwaterpurification(LaNotteetal.,2015),theforecastedtrendof fishbiomassusedtoestimatefutureemploymentinthefishing sector,theerosionrateorlevel ofdegradationlinkedtolossin property values, or theclimate records and forecasts linkedto economicdamagescausedbyfloods.
5.Conclusions
Themethodproposedinthispapertoassessandvaluewater ecosystem services provides some knowledge basis for the enrichment of water management; in particular it proposes a moreholisticviewtotheimplementationoftheEUWFDlinking multiple pressures,ecological status and delivery of ecosystem services.Underthisperspective,theanalysisofcost-effectiveand remediation measures can be improved including all hidden benefitsandbeneficiariesfromwaterecosystemservices.
The first part of the analysis should at least identify the ecosystem services of interest and frame the major effects of multipledriversandpressuresontheecologicalstatusofwater bodies.Then,theapproachsuggestsabiophysicalquantificationof the natural capacity, actual flow and social benefit of water ecosystemservices.Weproposetouseselectedproxies/indicators basedmainlyonhydrologicalmodelsordataforthispartofthe assessment.Oneimportantandnovelpointinthisapproachisto assessalsosomesustainability(orefficiency)indexthatestimates theflowofservicethatcanbesustainedwithacertaincapacity.
This could avoid the overexploitation of certain services. The proposedmethodincludesalsotheeconomicvaluationofaquatic ecosystem, providing a listof techniques for each service and spatialscale ofapplication.There isa largevarietyofvaluation methods that have to be carefully selected. Valuing water ecosystem services could highlight hidden benefits for society andcouldraiseawarenessamongusersandstakeholders.Evenif monetaryvaluesareprobablythemostappealingargumentsfor watermanagement,wealsoadvocateanddescribetheadvantages ofusingapluralityofvalues.Overall,theproposedapproachcanbe usedforassessingthebenefitsofconservationandrestorationof aquaticecosystemsintheimplementationoftheEUwaterpolicy.
There are opportunitiesby adopting theecosystem services approach to capture and integrate all the effects (economic, environmentaland social)associatedwithnewwaterplansand investments. Performing biophysical assessment and economic valuationcollaborativelycouldboostawarenessandinclusionof the interdependence of nature and people for a sustainable management of water resources.Theintegration of biophysical and economic approaches and data remains one of the main challengesandkeyaspectsofthisapproach.
Acknowledgements
This study has been funded by the EU FP7 project MARS (Managing Aquatic ecosystems and water Resources under multiples Stress; project number 603378). The authors would
