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j ou rn a l h om ep a g e :w w w . e l s e v i e r . c o m / l o c a t e /e c o l i n d
Original
Articles
Ecosystem
services
classification:
A
systems
ecology
perspective
of
the
cascade
framework
Alessandra
La
Notte
a,∗,
Dalia
D’Amato
b,∗,
Hanna
Mäkinen
c,
Maria
Luisa
Paracchini
a,
Camino
Liquete
a,
Benis
Egoh
d,e,
Davide
Geneletti
f,
Neville
D.
Crossman
gaEuropeanCommission-JointResearchCentre,DirectorateD–SustainableResources,ViaEnricoFermi2749,21027Ispra,VA,Italy bUniversityofHelsinki,DepartmentofForestSciences,Latokartanonkaari7,Helsinki,00014,Finland
cLappeenrantaUniversityofTechnology,SchoolofEnergySystems,SustainabilityScience,Saimaankatu11,15140Lahti,Finland dCouncilforScientificandIndustrialResearch,NaturalResourcesandTheEnvironment,POBox320,Stellenbosch7599,SouthAfrica eSchoolofAgricultural,EarthandEnvironmentalSciences,UniversityofKwaZulu-Natal,27PrivateBagX01,Scottsville3209,SouthAfrica fUniversityofTrento,DepartmentofCivil,EnvironmentalandMechanicalEngineering,ViaMesiano77,38123Trento,Italy
gCSIROLandandWater,WaiteCampus,Adelaide,SouthAustralia,5064,Australia
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:Received18April2016 Receivedinrevisedform 17November2016 Accepted18November2016 Availableonline9December2016 Keywords:
Systemsecology Ecosystemfunctioning Cascadeframework Ecologicaltheory
Ecosystemserviceclassification
a
b
s
t
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a
c
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Ecosystemservicesresearchfacesseveralchallengesstemmingfromthepluralityofinterpretationsof classificationsandterminologies.Inthispaperweidentifytwomainchallengeswithcurrentecosystem servicesclassificationsystems:i)theinconsistencyacrossconcepts,terminologyanddefinitions,and;ii) themixupofprocessesandend-statebenefits,orflowsandassets.Althoughdifferentecosystemservice definitionsandinterpretationscanbevaluableforenrichingtheresearchlandscape,itisnecessaryto addresstheexistingambiguitytoimprovecomparabilityamongecosystem-service-basedapproaches. Usingthecascadeframeworkasareference,andSystemsEcologyasatheoreticalunderpinning,we aimtoaddresstheambiguityacrosstypologies.Thecascadeframeworklinksecologicalprocesseswith elementsofhumanwell-beingfollowingapatternsimilartoaproductionchain.SystemsEcologyisa long-establisheddisciplinewhichprovidesinsightintocomplexrelationshipsbetweenpeopleandthe environment.Wepresentarefreshedconceptualizationofecosystemserviceswhichcansupport ecosys-temserviceassessmenttechniquesandmeasurement.Wecombinethenotionsofbiomass,information andinteractionfromsystemecology,withtheecosystemservicesconceptualizationtoimprove defini-tionsandclarifyterminology.Wearguethatecosystemservicesshouldbedefinedastheinteractions(i.e. processes)oftheecosystemthatproduceachangeinhumanwell-being,whileecosystemcomponentsor goods,i.e.countableasbiomassunits,areonlyproxiesintheassessmentofsuchchanges.Furthermore, SystemsEcologycansupportare-interpretationoftheecosystemservicesconceptualizationandrelated appliedresearch,wheremoreemphasisisneededontheunderpinningcomplexityoftheecological system.
©2016TheAuthors.PublishedbyElsevierLtd.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).
1. Introduction
Ecosystem services is now widely used among scientists and policymakers tohighlight the importanceof the environ-ment (including biodiversity) in sustaining human livelihoods (Convention on Biological Diversity, 2010, 1998; Costanza and Kubiszewski,2012;Maesetal.,2016).Animportantmilestoneof ecosystemserviceresearchwastheMillenniumEcosystem
Assess-∗Correspondingauthors.
E-mailaddresses:[email protected](A.LaNotte), dalia.damato@helsinki.fi(D.D’Amato).
ment (MA, 2005)which made prominentthe idea that human well-being depends on ecosystems,and that suchlinkages can betrackedandframedthroughthenotionofecosystemservices. TheMAfoundthatmorethan60%ofecosystemservicesisbeing degradedortransformedendangeringfuturehumanwell-being.
Ecosystemservicesresearchhassinceprogressedatdifferent levels—fromtheoreticalconceptualizationtopracticalapplications (seeBraatanddeGroot,2012;Egohetal.,2012;Seppeltetal.,2011; Potschinetal.,2016forareview).Thisworkhasbeensupportedby severalinternationalinitiativessuchasTheEconomicsof Ecosys-tem and Biodiversity(TEEB, 2010), the UK National Ecosystem Assessment(UKNEA,2011)andseveralEuropeanUnionresearch
http://dx.doi.org/10.1016/j.ecolind.2016.11.030
projects.1Inaddition,someorganizationshavesupportedthis pro-cesswithmodelingtoolssuchastheUSNaturalCapitalProject withtheIntegrated ValuationofEcosystemServicesand Trade-offs(InVEST)tool.Theprivatesectorhavealsoadoptedtheconcept throughinitiativessuchastheNaturalCapitalCoalition(NCC),the WorldBank’sWealthAccountingandtheValuationofEcosystem Services(WAVES),theaccountingsystemdevelopedbytheLondon Group,whichisalsobeingadoptedbytheUnitedNations Environ-mentalProgram(UNEP).
However,therehasbeeninconsistencyindevelopinga frame-work within which such research and policy assessments are carriedout.TheheMA(2005)andsubsequentecosystemservices literature(BoydandBanzhaf,2007; Fisheretal., 2009; Haines-YoungandPotschin,2012;LandersandNahlik,2013;Staubetal., 2011;Wallace,2007)havedevelopedmanydifferentconceptual andempiricalframeworksandassessmentofchangesin ecosys-tems,theirconsequencesforhumans,andactionsforsustainable useof these ecosystems(Albert et al., 2015). The existence of numerousecosystemserviceconceptualizationsandclassification systemshasledtoapluralityintheinterpretationofecosystem servicesandrelatedterminologyanddefinitionswhenitcomesto applications(Boeremaetal.,2016).Largedifferencesin interpreta-tionarefoundinthemeaningofbiophysicalstructure,ecological functions,intermediateservicesandfinalservices(e.g.Landersand Nahlik,2013;Mononenetal.,2016;Spangenbergetal.,2014;UK NEA,2011;TEEB,2010).Theconsequenceofsuchdifferencesisthe ecosystemserviceclassificationsystemshavepoorcorrespondence ofserviceswithbenefitsandblurreddistinctionsbetween interme-diateandfinalservices.Amongthese,theCommonInternational ClassificationforEcosystemServices(CICES),proposedbythe Euro-pean Environment Agency, hasbecome an important frame of referenceforecosystemservicesresearch(Maesetal.,2014).CICES andmostecosystemservicesliteraturearebasedonandinfluenced bythecascadeframeworkproposedbyHaines-Young&Potschin in2010(Haines-YoungandPotschin,2010;Potschinand Haines-Young,2016).Thepurposeofthecascadeframeworkisinfactto showthepathwayofecosystemservicesfromecologicalstructures andprocessestohumanwell-being.
In this context, theneed to develop a framework to assess ecosystemservices isa priorityin ecosystemservices research. Althoughindividualinterpretationsenrichtheresearchlandscape, theambiguitymustbeaddressedsothatamorerigorous frame-workforecosystemservicescanbedevelopedandadopted.Such a framework would improve comparability among ecosystem-service-based approaches and would provide a standardized approachforecosystemassessmentsatglobalandnationalscales. Thefurtherevolutionofecosystemservicesconceptsand frame-workscoulddrawfromthefield ofsystemsecology whichcan provideinsightsintoourunderstandingofthedifferentaspectsof ecosystemfunctioningthatcontributestoecosystemservices.This interdisciplinaryfieldofsystemsecologyadoptsaholisticapproach tothestudyofecologicalandhumansystems.Conceptsfrom eco-logicaltheoryhavebeenalreadydiscussedinpreviousliterature inrelationtoecosystemservices,e.g.ecologicalintegrityand com-plexity,resilience(Kremen,2005;Brand,2008).Ourpaperaims tosystematicallyadoptkeyconceptsfromsystemsecologyto re-defineecosystemservicesandtherelatedcascadeframework.The contributionofourpaperistopresentarefreshed conceptualiza-tionofecosystemservicesthroughthelensofsystemsecology.
1e.g.RUBICODE(RationalizingBiodiversityConservationinDynamic Ecosys-tems),SCALES(SecuringtheConservationofbiodiversityacrossAdministrative Levelsandspatial,temporal,andEcologicalScales),OpenNESS(Operationalization ofNaturalCapitalandEcosystemServices)andESMERALDA(EnhancingecoSysteM sERvicesmAppingforpoLicyandDecisionmAking)
Wefirstlyidentifythemainchallengesassociatedwiththe var-iousinterpretationsofthecascadeframework(Section2.1)andof theexistingclassificationsystemswhosestructureandmeaning doesdependonthechosentheoreticalframework(Section2.2). Secondly,weintroducekeyconceptsfromthedisciplineofsystems ecology(Section3)toaddresstheidentifiedchallenges(Section4). Wefinallyconcludebydiscussingthecontributionofourrefreshed conceptualizationofecosystemservices(Section5).
2. Currentchallengesinecosystemservicesresearch
2.1. Challengeswiththeuseoftheecosystemservicescascade
The cascade framework proposed by Haines-Young and Potschin(2010)linksnaturalsystemstoelementsofhuman well-being, following a pattern similar to a production chain: from ecologicalstructuresandprocessesgeneratedbyecosystems,tothe servicesandbenefitseventuallyderivedbyhumans.Theadvantage ofthisframework istoeffectivelycommunicatesocietal depen-denceonecosystems.
Challenges arise when applying this cascade framework in practice,duetothesimultaneouspresenceintheframeworkof bio-centeredandhuman-centeredspheres.Thismeansthatecosystem servicesassessmentsinclude:
•observationsfroma bio-centredor holisticapproach-i.e. bio-physical structures and processes/functions belonging to the ecologicalsphereandwhichareconsideredasawhole,
•observationsfromareductionist orhuman-centred approach-i.e.ecosystemserviceswhichareprojectedtowardsthehuman end-usesideindividually.
Thischallengeisevidentwhenwetrytomeasureecosystem services,whicharecategorizedandaccountedforindividually.2
Inaddition,differentdefinitionsofecosystemservicesandin particular oftheelements inthe cascadeframework are found intheliterature:biophysicalstructure,process,function,service, benefit.3Asanexample,Table1summarizesthedefinitions pro-videdinrecentecosystemservicesstudies.Forinstance,ecosystem structure is often poorlydistinguishedfrom processes. Wallace (2007,p.237)proposesthat‘animportantdistinction[between thetwo]isthattheformeraregenerallytangibleentitiesdescribed intermsofamount,whilethelatterare[...]generallydescribedin termsofrates’.
Furthermore,thewordfunctionisgenerallyused interchange-ablywithecologicalprocessand/orecosystemservice.According toJax(2005),theterm‘function’isoftenusedtooambiguously. Ecosystemservicesaregenerallydefinedas theecosystem pro-cessesconsideredusefultohumans(MA,2005;TEEB, 2010).In the same light, some studies(ref. Table1) that have assessed, mappedorvaluedecosystemservices,useservicesand benefits assynonyms. Benefitsarein somecasesconsideredastangible naturalresourcesderived fromprovisioningservices(e.g.crops, wood,water),orsomeregulatingservices(e.g.cleanwaterfor mul-tipleusesprovidedbywaterpurification).Benefits,however,can alsobeintangible(e.g.recreationopportunitiesofferedbynature).
2Notethatsomeauthors,e.g.Mononenetal.(2016)havesuggestedtohighlight theprocess-likenatureofecosystemservicesdeliveryassocio-ecologicalsystems, thusmaintainingtheholisticapproachonthefocus.
3Thecascademodeldoesindeedinclude,after‘benefit’,alsothe‘value’stepthat assignstobenefitsaquantificationinmonetaryterms.Theeconomicvaluationof ecosystemservicesisafieldofresearchandapplicationsthatdoesnotaffectthe specificconceptualanalysisproposedinthispaper.Inordertokeepfocusedonthe mainobjectivesofthepaper,wethuschoosenottoincludethe‘value’boxatthis stage.
Table1
Definitionsandexamplesofecosystemservicesterminologyaccordingtoselectedpeer-reviewedliterature. Author&
proposed application
Biophysicalstructure Process Function Ecosystemservices Good Benefit
Batemanetal. (2011)
e.g.animals,birds, plantsandtheir connections,etc.
e.g.nutrientcycling Primaryecological processes Flowofservices (outcomeofstructure andprocesses) providedbyecological assetsinsome assessmentperiod. Anyobjector constructwhich generateshuman wellbeing(physical andnon).
Thechangeinhuman well-beinggeneratedbya good(use-valueandnon). Thesamegoodcan generatedifferentvalues, dependingonthecontext. Boydand
Banzhaf(2007)
Seedefinitionfor ‘process’ Biological,chemical, andphysical interactionsbetween ecosystem components.Functions andprocessesarenot end-products;theyare intermediatetothe productionoffinal ecosystemservices.
Seedefinitionfor ‘process’
Theuseofecological assetoversometime period.
Thingsdirectly enjoyedor consumedby households.
Abenefite.g.recreation, arisesfromthejointuseof finalecosystemservices andconventionalgoods andservices.
Fisheretal. (2009)
Seedefinitionfor ‘ecosystemservices’
Seedefinitionfor ‘ecosystemservices’
Seedefinitionfor ‘ecosystemservices’
Theyareecologicalin nature,inthat aestheticvalues, culturalcontentment andrecreationarenot ecosystemservices. Ecosystemservicesare ecologicalcomponents, functionsand/or processes,aslongas therearehuman beneficiaries.
na Abenefithasanexplicit impactonchangesin humanwellfare,likemore food,betterhiking,less flooding.Forexample, aesthethicvalues,cultural contentmentand recreationarebenefitand notjustafunctionofthe ecosystem,butinclude otherinputslikehuman capital,builtcapital,etc. Maesetal.
(2016)
Thearchitectureofan ecosystemasaresultof theinteraction betweentheabiotic, physicalenvironment andthebiotic communities,in particularvegetation
Anychangeorreaction whichoccurswithin ecosystems,physical, chemicalorbiological. Ecosystemprocesses includedecomposition, production,nutrient cycling,andfluxesof nutrientsandenergy
Subsetofthe interactionsbetween biophysicalstructures, biodiversityand ecosystemprocesses thatunderpinthe capacityofan ecosystemtoprovide ecosystemservices
Thedirectandindirect contributionsof ecosystemstohuman wellbeing(TEEB,2010). Theactuallyused service. Theconcept ’ecosystemgoods andservices’is synonymouswith ecosystemservices. Positivechangein wellbeingfromthe fulfilmentofneedsand wants(TEEB,2010) Müllerand Burkhard (2012) Biophysicalstructures andprocesses (ecosystemproperties) arelinkedinthe cascadecomponentof ecosystemfunctions. Theyareunderstoodas thebasicproducersof ecosystemservices.
Seedefinitionfor ‘biophysicalstrucuture’
Ecologicalintegrity Directandindirect contributionsof ecosystemstructures andfunctions
na intendedassocial, economicandpersonal well-being
Mononenetal. (2016)
Biophysicalstructures thatcreatethebasisfor functioningofthe ecosystem.Spatial perspective. na Functioningof ecosystemthatis neededtoproduce ecosystemservices. Temporalperspective.
na Theusedshareof thepotentialof ecosystemservices. Beneftscanbealso non-material.
Economic,social,health (physicalorspiritual)and intrinsicvalueofthe benefit. Spanenberg etal.(2014) Biophysicalstructure orprocessincludes habitattype
Seedefinitionfor ‘biophysicalstrucuture’
e.g.woodproduction Collectingor harvestingwood(that isthehumanactivityof withdrawingthe naturalasset)
Contributionto aspectsof well-beingsuchas healthandsafety
Willingnesstopayfor morewoodlandor harvestableproducts.
TEEB(2010) Biophysicalstructure orprocess=vegetation coverorNetPrimary Productivity
seeBiophysical structure
Thepotentialthat ecosystemshaveto deliveraservicewhich inturndependson ecologicalstructure andprocesses.
Conceptualizationsof the“usefulthings” ecosystems“do”for people,directlyand indirectly
na Welfaregainsgeneratedby ecosystemservices
Wallace(2007) na Thecomplex interactions(events, recreationsor operations)among bioticandabiotic elementsof
ecosystemsthatleadto adefiniteresult.
Seedefinitionfor ‘process’
Benefitsthatpeople obtainfrom ecosystems;the outcomessought throughecosystem management. na Preferredend-statesof existence,includingthose requiredforhuman survivalandreproductive success,whichtaken togethercircumscribe humanwell-being.These excludeintrinsicvalue.
Haines-YoungandPotschin(2009,p.17)proposea‘pragmaticway forward’,statingthat‘themainissueistoensuretherigorofthe outputsfromouranalysisandnotbecomepreoccupiedwith def-initions,henceeffortsshouldbedirectedto:achievingconsistent valuationandnodoublecounting’.
Moreunifiedandshareddefinitions,however,canbehelpfulin ensuringtherigorofpracticalassessments,andallowadegreeof comparabilityamongstudies.Inparticular,itisimportantto dis-tinguishbetweenservice,process,andbenefit.BraatanddeGroot (2012)arguedthatecosystemservicescontain‘theproduct com-ponent(traditionallycalled“goods”)’,buttheysuggestthat‘inthe nextstageofdevelopmentoftheconcept,thedistinctionbetween goodsandservicesshouldbere-established’.Whenreferringto thecascadeframework,theterminologyincludesbenefitsrather thangoods.Thechallengeofseparatingservicesfromgoodsand/or benefitsisfurtherexploredinthenextsection.
2.2. Challengesinthecurrentecosystemservicesclassifications
Anyapplicationofanecosystemservice-basedapproachstarts withchoosing the servicestobe assessed (and valued)from a listofservices,i.eaclassification system.Classificationsystems areusually based ona theoretical framework whoseprinciples and conceptsare reflected inthemeaning andstructure ofthe itemspresented. It is thusimportant toexplore themain clas-sification systems, in order to highlight the embeddednotions theystate.Forexample, theMillenniumEcosystemAssessment (2005)wasthefirsttoattempttogroupecosystemservicesinto fourcategories:provisioningservices(e.g.food,fibers,fuel,genetic resources);regulatingservices(e.g.,waterpurificationand regula-tion,climateregulation,extremeeventsanddiseasemitigation); supportingservices(e.g.,primaryproductionandnutrientcycling); andculturalservices(e.g.,eco-tourismandrecreation,aesthetic andspiritualvalues).Thiscategorizationprovidedasoundbasisto launchecosystemservicesresearchandapplications,butitdoesnot constituteapropertaxonomy.Inthecascadeframework (Haines-YoungandPotschin,2012),supportingservicesareconsidereda ‘function’ratherthana‘service’.FollowingtheMA,theTEEB clas-sification(2010)alsoexplicitlyreferredtothecascadeframework butrefinedthedistinctionbetweenservicesandbenefits.Theidea ofsupportingservicesinTEEBwasnotfurtherdeveloped.Instead anew‘habitatservices’groupwasintroduced,including ‘mainte-nanceoflifecycles’and‘maintenanceofgeneticdiversity’
Sincesomeecosystemservicecategoriesoverlap,thereisarisk of double countingin valuation,which therefore requiresclear separationbetweenintermediateandfinalservice.TheUS Environ-mentalProtectionAgencyhasproposedadditionalclassifications toavoiddouble counting.Theseinclude FinalEcosystemGoods andServicesClassificationSystem(FEGS-CS)(LandersandNahlik, 2013)andtheNationalEcosystemServicesClassificationSystem (NESCS)(Rhodes,2015).In bothclassificationsystemsthemain focusisonbenefitsandbeneficiaries.Thisisinlinewiththestudy byBoydandBanzhaf(2007)thatsuggesttoaccountfor ‘compo-nentsofnaturedirectlyenjoyed,consumedorusedtoyieldhuman well-being’.FEGS-CSclassificationproposestwocriteriatodefine goodsandservices:i)thepotentialgoodorserviceisvaluedbya beneficiary,and;ii)thepotentialgoodorserviceisconnectedtoat leastthehydrosphereandlithosphere.InFEGS-CSprocessessuchas photosynthesisorcarbonsequestrationarelabeledalltogetheras ‘ecosystemstructuralcomponents’andconsideredasintermediate goodsandservices.Theseareexcludedbecausetheyarenotdirectly usedbyhumans.Similarly,NESCSclassificationrepresentsdistinct pathwaysthroughwhichfinalecosystemservicesenterhuman sys-tems.Thisclassificationapproachfocusesonendcategoriesofuses andusers,andisalignedwiththeNorthAmericanationalaccounts classificationsystem.NESCSemphasizestheconnectionbetween
the‘end-productofnature’andthehuman‘directuses’astangible andintangiblebenefits.
CICESisoneofthemostpopularclassificationscurrentlyand is beingusedbyscientists and policymakersaroundtheglobe but particularlyfromEurope.Similartothe TEEBclassification, CICESdoesnotincludetheMA(2005)‘supportingservices’,but mergestheTEEB(2010)‘habitatservices’withregulatingservices, inacategorycalled‘regulatingandmaintenanceservices’. Com-paredtoFEGS-CSandNESCS,CICESdoespromoteacleardistinction betweenecosystemservicesandecosystembenefits.Inthelatest versionofthecascadeframeworkthatunderpinsCICES(Potschin andHaines-Young,2016),ecosystemservicesareexplicitly indi-catedasfinal services,whilebiophysicalstructure andfunction areindicatedassupportingorintermediateservices.Final ecosys-temservicesarethecontributionsthatecosystemsmaketohuman well-beingasflows.Ecosystemgoodsandbenefitsarecreatedor derivedbypeoplefromfinalecosystemservices.
ThedifferencesbetweenFEGS-CSandCICESaresubtleandare explainedwiththeassistanceofFig.1:a)thecascadeframework thatconstitutesthetheoreticalbackgroundofCICES,and;b)the conceptualframeworkoftheFEGS-CS.FEGS-CSplacesemphasis onthebenefits,beneficiariesandthesocio-economicsystem,while CICESplacesgreateremphasisontheecologicalsystem.Infactwe needtoaddanadditionalbox(i.e.assets/commodities)inthe cas-cadeframeworktohaveamoreconsistentviewofthetwomodels. Inthisadditionalboxthebenefitsenterintoaproductionprocess thatmakesitamarketablegood,aneconomicasset,a commod-ity.Althoughecosystemservicesareidentifiedconsideringhuman needsanddemand,wechooseinFig.1atohavethesocio-economic systemsstartingatthe‘benefit’boxbecauseatthisstagethereal usecantakeplaceandbecausethisistheonlywaytoconsistently comparethetwotheoreticalframeworks.Bycomparingthesetwo classificationstoeach otherand tothe cascadeframework, we observethatFEGS-CSclassificationregardsdifferentbenefitsrather thanecosystemservices.
Themostappropriateclassificationsystemshouldbechosen basedonitsfit-for-purpose(Heinketal.,2015;Spangenbergand Settele,2010),i.e.whethertheecosystemserviceanalysisintends tofocusmoreonecologicalsystems(e.g.consideringimpactson andpressuresfromthesocio-economicside)oronsocio-economic systems(e.g.thebenefitsderivedbysociety).Itishowever impor-tanttobeawareoftheexistinglimitationsofeachclassification system.
3. Thenatureofecosystemservices:asystemsecology perspective
Inthetheoryofsystemsecology,Jørgensen(2012)proposed threefundamentalnotionsasthebasisofecologicalsystems:1) biomass,2)interactionand3)informationinecologicalnetworks. In this section we argue that ecosystem services have in fact beenconceptualizedaseither(bio)mass,informationorinteraction (Fig.2).Weadoptthefollowingdefinitionsofthesekeyconcepts.
Biomass is biological material derived from living or dead organisms.Thequalityaspectofbiomassisalsorelevant,e.g. basedonproteinsynthesisandevolution.
Interactionoccursinanetworkascomponentshaveaneffect upononeanother.Interactionsarethereforetherelationships betweenandamongbioticandabioticcomponents,sometimes characterizedbyatemporalpattern;suchrelationshipscanbe bi-ormulti-directional,asopposedtotheunidirectionalcausal effectofinformation.Inecologicalnetworks,interactionsmight resultinemergentpropertiesofthesystem.Emerging proper-tiesinasystemcannotbepredictedorexplainedbythesum
Fig.1. AcomparisonofCICESandFEGSclassifications.
Fig.2. Aschematicrepresentationofbiomass,information,interaction.
of thecomponents alone, because the latter do not exhibit suchpropertiesthemselves(Edsonetal.,1981;Odum,1977). Social behaviourin animalsisanexample,suchas‘the abil-ityoflargepopulationsofsimple,identicalunits(forexample, spinmagnets)toself-organize,formpatterns,storeinformation, andreach“collectivedecisions”(ParrishandEdelstein-Keshet, 1999).Interactionsinanecologicalnetworkcanalsobedefined asecologicalprocesses.
Informationcanbeconsideredasub-categoryofinteraction; informationis“conveyedorrepresentedbyaparticular arrange-mentorsequenceofthings,includingforexample,genetically transmitted information” (Oxford Dictionary Online, 2014). Information can influence (intentionally or not) the forma-tion ortransformation of other patterns.Organismsinteract withtheirenvironment notjust byexchangingmaterial and energyastraditionallyviewedinEcology,butalsoby
exchang-inginformation (Dusenbery,1992).Theprocess ofacquiring informationinvolvesamechanisticphaseofinformation cap-turebyareceptor,suchasasensoryorgan,andafunctional phaseofinformationde-codification.Thisistheabilityto recog-nizeandprocessthatinformationas‘knowledge’(Guilfordand Dawkins,1991).Consequently,exchangeofinformationoccurs betweentwo(ormore)organismswhenthe‘receiver’ organ-ism(s)is abletocaptureand processtheinformation ofthe ‘sender’.Whileinformationplaysaroleinthegenerationofall ecosystemservices(e.g.geneticinformation),inthisarticlewe specificallydefineinformationastheonehumansreceiveand process.
Anorganismexpressesandconveysbiomass,informationand interactionsviaitsgenotypeand/orphenotype(Fig.2).Werefer heretotheextendedphenotype(Dawkins,1982),whichincludes theappearanceof anorganism(morphology,development,
bio-Fig.3. Thenatureofbiomass,informationandinteractioninSystemsEcology,and thehumanunderstandingandmastershipoftheseconcepts.
chemicalandphysiological processes,etc.)aswellasproperties externaltothebody(phenology,behaviour,productsofbehaviour). Forexample,thesilkproducedbythesilkworm(Bombyxmori)is essentiallybiomass,derivedfromitschrysalisduringthe meta-morphosis.Therefore,theecosystemservice(inthiscasethesilk producedbythesilkworm)isnotadirectproductofitsbodymass, butratheranexpressionofitsphenotype.
Based on the given definitions of biomass, information and interaction,wecanexaminethecurrentclassificationof ecosys-tem services.Most provisioning services are conceptualized as (bio)masse.g.food,fiber,water(deGrootetal.,2002;MA,2005; TEEB, 2010). Genetic resources represent an exception among provisioningservices,sinceweconsiderthemasinformation.In fact,the genotypeor phenotypeofan organismcancontribute to develop drugs or to bioengineering. Regulating services are basedoninteractions amongbiotic andabioticelementsofthe ecosystems:forexamplewaterpurificationderivesfromthe over-allmechanicalandchemicalcapacityofabioticsoil,soilbiotaand vegetationtotrapand‘convert’sediments,nutrients,pollutantsor pathogens.Culturalservicesderivefrominformation.Forexample, we are able toreceive the information from an amenity land-scapegiventhehumanabilitytoperceive(receptor)andappreciate beauty(decodificationandinterpretation).Thisinformationmight influencehumans,forexampletriggeringinspiration,a physiolog-icalrelaxation,asenseoffulfilment,oraspiritualexperience.
Drawingfromthermo-dynamics,Jørgensen(2012,chapter13) proposesthefollowingideas:growthofmatterislimitedbyenergy inputandavailabilityofinorganicelements.Thegrowthof infor-mationandinteractionsinnetworksisdrivenbyevolution(thus linkedtodiversity)andhaspotentialtoexpand(Faithetal.,2010) (Fig.3):informationandinteractionshaveoverallincreasedinthe historyoflivingorganisms.Unlikematterandenergy,information andinteractionscandisappearwithouttracewhenthematerial support(biomass)isdestroyed.4 Thus,biomass,informationand interactionsarecharacterizedbyincreasingcomplexityand oper-ateatdifferenthierarchicallevels.Biodiversityisatthebasisofthis complexity:themorediversity,themoreinformationand interac-tions.TheverydefinitionofBiodiversity(ConventiononBiological Diversity,1992)referstothehierarchicalorganizationofall organ-isms aswellasthefunctional characteristicsof each level.The processesatoneleveloforganizationdeterminetheconditionsin thenextlevel,whilehigherlevelsregulateandcontrollowerlevels byfeedback.Forexample,speciesdiversityinfluencesecosystem propertiesandfunctioning,andviceversa.Ithastobenotedthat
4NotethatgeneticinformationisstoredinDNAandtransmittedacross genera-tions.
thisisanartificialcategorization,sinceinnaturethehierarchyis notclearlydefined,butmorefluid.
4. Refreshingtheconceptualapproachtoecosystem services
4.1. Re-definingthecascadeframeworkbasedonsystemecology
Basedonthedefinitionsabove,weaddressthechallengesin ecosystemservicesresearchidentifiedinsection2.Wecombine thenotionsofbiomass,informationandinteractionwith ecosys-temservicesconceptualizationtoimprovedefinitionsandclarify terminology.WerecallPalmerandFebria(2012)toshowthe link-agesthroughthecascadechain:thecomponentsofanecosystem (thatrepresentthestructure)interactwithdynamicbiophysical processes(thatarefunctions)toproducegoodsandservicesthat peoplerelyon.Weargue thatecosystemservicesshould exclu-sively beconsideredas theinteractions of theecosystemsthat producea changeinhumanwell-being (Table 2).Wetherefore proposethatecosystemservicesarenotindividualecosystem com-ponents or goods.In addition,while allecosystem servicesare derived fromecologicalprocesses(orsocio-ecologicalprocesses Mononenetal.,2016)notallprocessesproduceecosystem ser-vices.Someprocessesmaynotbeofusetohumans,butthisdoes notnegate theirimportance.Ecosystemfunctionandecological processesareconsideredhereassynonyms.
Duetotheutilitarian natureofecosystem services,research and policytend toemphasize end-use benefitsrather than the underpinningecosystemstructuresandprocesses(see‘Traditional understanding of the cascade framework’ in Fig. 4). We pro-poseamodified cascadeframeworktoshiftperspectivetoward ecosystems(see‘systemsecologyre-interpretationofthecascade framework’inFig.4).InFig.4werepresenttheflowfroman eco-logicalperspective.Theelementsofthecascadearenot‘equal’.Itis thusnotenoughtoestablishacausalsequenceamongtheelements ofthecascadebecausetheinherentcomplexityofeachstagemust behighlighted.
Toacknowledgethiscomplexity,thehierarchicalorganization isacrucialconceptinsystemsecology.Hierarchicallevelsinclude atoms,cells,organs,species,populations,ecosystems,landscape, regionsandtheecosphere(Jørgensen,2012).Eachlevelintegrates thefunctionsofthelowerlevel.5Whenweconsiderthehierarchy fromaverticalperspective,eachlevelisconstrainedfromtheupper levelandfromthelowerlevel.However,thereisalsoahorizontal perspective.Thereiscooperationamongthecomponents,which createsnetworks,whereinteractionstakeplace.
Inmanyrepresentationsofthecascadeframeworknatural cap-italisconsideredasexamplesof benefits(reported asassetsor commoditiesdependingonthedegreeofhumaninterventionin theproductionprocess).Naturalcapital,suchasfiberandfood,are biomass.Fromavertical(hierarchical)perspectivethese compo-nentsrepresentalowerlevel,whilepopulationsoforganismsarea higherlevel.Populationsinturnrepresentsalowerlevelcompared totheecosystem.Differentlevelsinteractbetweeneachother verti-cally.Inaddition,interactionsamongbioticandabioticcomponents existalsoathorizontallevel.Verticalandhorizontalinteractions constitutetheservice.
Based on the hierarchicalorganization drawn from systems ecology, it is possibleto highlight the differencebetween
ser-5Forexample:atcelllevelontheonehandtheintegratedcellprocesses deter-minethefunctionalityoftheorgans,ontheotherhandorganscontrolthefinal biochemicalresultsofcells;atthelevelofpopulationsontheonehandthe individ-ualsandtheirinteractionsdeterminethepropertiesofthepopulations,andonthe otherhandpopulationdeterminesthelivingframeworkfortheindividuals.
Table2
Proposeddefinitionsofthecascadeframeworkterminology.
Term Definition Examplesa
Biophysicalstructureb Thesettingforecosystemcomponents(bioticandabiotic).
Thisalsorelatestotheecologicalpattern
Foresttreecover Inlandwaterbodies Processorfunction Anecologicalinteractionamongcomponentsinan
ecosystemovertime.Processesmaygenerateseveral ecosystemservices.
Netprimaryproduction Carboncycling Nutrientcycling Ecosystemservice Aflowgeneratedbytheecosystemincludingecological
interactionsandinformationwhichareusefultohuman beings.Wethereforeproposethatecosystemservicesdo notincludeecosystemcomponentsorgoods,i.e.countable as(bio)massunit.Inaddition,ecosystemservices sometimesrequirehumaninput,whichdoesnot necessarilymeanhuman-madeconstructslikelabour, industrialprocessing,benchesorfishingroads.a
Generationofmaterialfromplants Carbonsequestration
Waterpurification
Aestheticbeautyoflandscape
Good Countableasa(bio)massunit,itisavehicleforecosystem serviceenjoyment.
Woodbiomass
AmountofCO2retainedfromtheatmosphere Amountofpollutantsretainedfromwaterbodies Peopleenjoyingoutdoorrecreationactivities Benefit Whatisgeneratedbytheserviceandleadstoachangein
humanwell-being.
Availabilityofwoodformultipleuses
Healthierairtobreath/climatechangemitigation Availabilityofcleanerwater(insteadofwaterpollutedby economicactivities)
aExampleofhumaninputincludesexistenceofahumanbeingwithhis/hersensoryandperceptionalexperiences.
b Existingliteratureoftenusesthetermecologicalstructureasasynonymforbiophysicalstructure.Wehoweverpreferthelaterterm,becauseitalsoincludesnon-vegetated structures,suchasdunes,aquifersorRockyMountains.
viceandbenefits.Aserviceisaprocessandisdeterminedbythe horizontalandverticalnetworkingactivity.Benefitsare individ-ualcomponents,countableas abiomass unit,and a vehiclefor ecosystemserviceenjoyment(Matthiesetal.,2016).Inthecurrent cascadeframework,greatemphasisisconvergingonthebenefit, becausethis ismostrelevanttohumans.Itisnotourintention todownplaytheimportanceofbenefits(andthusthe‘humans’ roleinco-producingecosystemservices).We,however,arguefor ashiftofperspectivefroma‘twodimensional’toa‘telescopic’ cas-cadeframeworkwhichemphasizestheecologicaldimensionsand complexreality.
Theimplicationsofahierarchicalorganizationareinlinewith the understanding of ecosystems at the basis of the cascade framework:upperlevelschangemoreslowlythanlowerlevels. Variationsanddisturbancesofupperlevelsmayaffectthelower levels;theotherwayround, however, isless frequent,because lowerleveldisturbancesaremitigatedatupperlevel(Jørgensen, 2012).6Forexample,assuminganinitialhealthystateofthe ecosys-tem,whenasinglecomponentofthepopulationisremoved(e.g. atreefromaforestoroneanimalfromapopulation),the regen-erationcapacityisnotaffected,thefunctioningoftheecosystem ismaintainedatahealthystate.Whenaclear-cuttakesplaceor thespeciesbecomerareorextinct,thentheentirehabitatwillbe affected(e.g.theforestwillnotbethereanymoreandthefoodchain willchange).
Anyassessmentandvaluationintendedtoprovideasustainable policyforthemediumandlongtermcannotignorethe ecologi-calsystemsideofthecascade.Theexistenceofthesocialsystem isguaranteedbytheproperfunctioningoftheecologicalsystem. Thevalueoftheecologicalsystemisintrinsic,andtheapproachis holistic,bio-centricandpositivist.Theecosystemservices narra-tiveispartofthehumansystemwhosevalueisutilitarian,andits approachreductionistandhuman-centered.
6 Amalfunctionofonelevelcanbeeliminatedbyreplacingafewcomponentson thelowerlevel.e.gcells,organsandspeciescanbereplacedtobetterfitthenew emergentconditions.Thus,thehigherthelevelis,thelessvulnerableitbecomes.
4.2. Comparingthereneweddefinitionofecosystemservicesto CICESclassification
Weproceedbycomparingtheconceptsintroducedfromsystem ecologytotheCICESclassificationandthecascadeframework.In Table3welistthecorrespondencebetweenCICESclassesandour terminology.Thisanalysisdoesnotintendtoaddanewlevelof complicationtotheecosystemservicesconceptualization.Rather itaimsatclarifyingthedifferencebetweenecosystemservicesand benefitsandtoimproveconsistencyintheclassificationof ecosys-temservices.
AmongthelistofecosystemservicesproposedbyCICES,someof themdonotmeettherequirementsforourdefinitionofecosystem services(i.e.processes)(Table3).For example, allCICES provi-sioningservicesarebenefits(i.e.biomass).Provisioningservices includeforexamplecultivatedcrops.However,theecosystem ser-viceisinfacttheprocesstogeneratecropsandplants,ratherthan thecropsandplantsthemselves.Theuseofthebenefitasaproxy fortheserviceisacommonpractice,butitmightresultindouble counting.Thus,theresultingbenefitfrome.g.regulatingservices shouldbearticulatedclearly,sothatoverlapswithprovisioning servicesare known.Forexample,benefitsfrompollinationmay overlapwithcultivatedcrops;waterflowmaintenancemay over-lapwithwatersupplied;ormaintainingnurserypopulationsand habitatsmayoverlapwithfood(fish)provisioning(Liqueteetal., 2016a).Whenperformingthetrade-offassessment,wedonot sug-gestignoringregulatingservices,butrathertocarefullyconsider betweenprovisioningandregulatingservices.
In CICES the list of services (in particular regulating ser-vices)sometimesincludesfunctionsandbiophysicalstructures.For instance,‘chemicalcondition’isapropertyorcomponentofthe sys-temandnotaprocess.Itisthuspartofthebiophysicalstructure. Theecologicalinteractionsamongcomponents,suchas ‘hydrologi-calcycle’and‘ventilationandtranspiration’areprocessesthattake placewithintheecosystem,andnottheflowofanindividual ser-vicethatproducesadirectchangeinhumanwell-being.Differently frombenefits,thebiophysicalstructurecannotbeaproxyforthe
Table3
Classificationofecosystemservices(CICES)includingthenatureofecosystemservices,thecascadeframeworkstep,theSystemsEcologycategory,themostlogic/common assessmenttechniqueandtheirdegreeofcomplexity.
ListofecosystemservicesaccordingtoCICES Cascade frameworkstep
SystemsEcology category
Assessmenttechnique
Provisioning Cultivatedcrops Benefit Biomass Statisticaldatasets
Wildplants,algaeandtheiroutputs Benefit Biomass Statisticaldatasets
Wildanimalsandtheiroutputs Benefit Biomass Statisticaldatasets
Plantsandalgaefromin-situaquaculture Benefit Biomass Statisticaldatasets
Animalsfromin-situaquaculture Benefit Biomass Statisticaldatasets
Materialsfromplants,algaeandanimalsfor agriculturaluse
Benefit Biomass Statisticaldatasets
Geneticmaterialsfromallbiota Benefit Biomass/information Statisticaldatasets
Rearedanimalsandtheiroutputs Benefit Biomass Statisticaldatasets
Surfacewaterfordrinking Benefit Biomass Statisticaldatasets
Groundwaterfordrinking Benefit Biomass Statisticaldatasets
Fibersandothermaterialsfromplants,algae andanimalsfordirectuseorprocessing
Benefit Biomass Statisticaldatasets
Surfacewaterfornon-drinkingpurposes Benefit Mass Mainlystatisticaldatasets
Groundwaterfornon-drinkingpurposes Benefit Mass Mainlystatisticaldatasets
Plant-basedresources Benefit Biomass Statisticaldatasets
Animal-basedresources Benefit Biomass Mainlystatisticaldatasets
Animal-basedenergy Benefit Biomass Mainlystatisticaldatasets
Regulatingand maintenance
Bio-remediationbymicro-organisms,algae, plants,andanimals
Service Interaction Biophysicalmodelsand/or
measures Filtration/sequestration/storage/accumulation
bymicro-organisms,algae,plants,andanimals
Service Interaction Biophysicalmodelsand/or
measures Filtration/sequestration/storage/accumulation
byecosystems
Service Interaction Biophysicalmodelsand/or
measures
Mediationofsmell/noise/visualimpacts Service Interaction Biophysicalmodelsand/or
measures Dilutionbyatmosphere,freshwaterand
marineecosystems
Function
Hydrologicalcycle Function
Waterflowmaintenance Service Interaction Biophysicalmodels
Massstabilizationandcontroloferosionrates Service Interaction Biophysicalmodels
Globalclimateregulationbyreductionof greenhousegasconcentrations
Service Interaction Biophysicalmodels
Microandregionalclimateregulation Service Interaction Biophysicalmodels
Bufferingandattenuationofmassflows Service Interaction Biophysicalmodelsand/or
measures;Geospatialmodels
Floodprotection Service Interaction Biophysicalmodelsand/or
measures;Geospatialmodels
Stormprotection Service Interaction Biophysicalmodelsand/or
measures;Geospatialmodels
Pollinationandseeddispersal Service Interaction Biophysicalmodelsand/or
measures;Geospatialmodels
Maintainingnurserypopulationsandhabitats Service Interaction Biophysicalmodelsand/or
measures;Complexindicators integratedwithgeospatialmodels
Pestanddiseasecontrol Service Interaction Biophysicalmodelsand/or
measures;Geospatialmodels
Ventilationandtranspiration Function
Weatheringprocesses Function
Decompositionandfixingprocesses Function
Chemicalconditionoffreshwaters Biophysicalstructure Chemicalconditionofsaltwaters Biophysicalstructure Cultural Experientialuseofplants,animalsand
land-/seascapesindifferentenvironmental settings
Service Information Geospatialmodels/complex
indicators Physicaluseofland-/seascapesindifferent
environmentalsettings
Service Information Geospatialmodels/complex
indicators
Aesthetic Service Information Geospatialmodels/complex
indicators
Education Service Information Complexindicators
Heritage,cultural Service Information Complexindicators
Entertainment Service Information Complexindicators
Scientific Service Information Complexindicators
Symbolic Service Information Complexindicators
Sacredand/orreligious Service Information Complexindicators
Existence Value
Bequest Value
Theattemptistodevelopthesameexamplesthroughoutthe‘terminologychain’toshowthattheyareindeeddifferentstageofthesameprocess.E.g.todifferentiatethe carboncyclingasfunctionfromcarbonsequestrationasservicefromCO2tonswill(ifever)bethetaskofthebiophysicalmodel,i.e.onlyoneofthosestageswillbemapped andassessed,itwilldependonthetechniqueusedtoassess(modelorindicatororstatistics).
Fig.4. Froma2Dtoatelescopiccascadeframework(a)Traditionalunderstandingofthecascadeframeworkwithemphasisonend-usebenefits;(b)SystemsEcology re-interpretationofthecascadeframework,withemphasisontheunderpinningcomplexityoftheecologicalsystem.
service7:theyarewhatallowstheserviceflowtobegenerated(cf.
Mononenetal.,2016).InCICESexistenceandbequestvaluesare listedasservices:whenattemptingamonetaryvaluation,existence andbequestnon-usevaluesareconceptsthatfacilitatethechoice ofthevaluationtechniquetobeadopted,buttheyarenot them-selvesecosystemservices.Systemsecologytheorycanthusprovide guidancefor ecosystemserviceassessments: Table3 presentsa newclassificationapproachfor ecosystemservicesassessments. InTable3weattempttotrackcorrespondencewiththedifferent typologiesofmodelingtechniques.Byreferringtothesystems ecol-ogycategoriesofbiomass,interactionandinformationwecould statehowcomplexthelevelofmodelingshouldbe.
Whenecosystemservicesareidentifiedasbiomass, measure-mentwillrequirethecollectionofenvironmentalstatistics and inventories.Thisisthecaseformanyprovisioningservices,where
7 ThisisthereasonwhyinTable3whatcorrespondsto‘Biophysicalstructure’and ‘Function’isnotclassifiedintermsofSystemsEcologycategory,andAssessment techniquearethusreportedasgreycells.
data is usually extracted fromagriculture and forestry statisti-caldatabasesandinventories,orfrommarkettransactions,rather thanbiophysicalprocesses.Simpleandavailableindicatorscanbe used,suchasland-useandland-coverdata,biodiversity monitor-ingmaps,ornationalforestinventories.Inthiscase,ratherthan assessingtheservice itself,thebenefit is usedasproxy forthe ecosystemservice.Thisismostrelevanttoprovisioningservices andthecurrentpracticeofassessment.
Whenecosystemservicesareidentifiedasinteraction,then eco-logicalmodelingormonitoringisneeded.Tocorrectlyassessthe service,thenatureoftheprocessshouldbeunderstood,described analyticallyandmeasured.Thisisthecaseforsomeregulating ser-vices(i.e.allthoseservicesthatdirectlyinvolvebiogeochemical cycles)whereprocess-basedmodeling wouldbetterfitthe pur-pose,becausethemodelshouldbeabletorepresent/replicatethe ecosystemfunctioning(e.g.Liqueteetal.,2016b).Thereare, how-ever,casesinwhichspatialmodelingandstatisticalmodelingcould servetheassessmentpurpose.Inspatialmodelingalgorithmsbased onspatialfeaturesareusedand/ordifferentindicatorsarelinked withlandusedatatoderivemorecomplexindicators(seefor
exam-pleZulianetal.,2013).Instatisticalmodelsecosystemservicesare estimatedbasedonknownexplanatoryvariablessuchassoils, cli-mate,etc.,usingastatisticalrelation.Thiscanbethecaseforthose servicesin whichthemorphologicalfeatures doplayan impor-tantrole(e.g.stormandfloodprotection,soilerosionprotection) orthepresenceofspeciesdeterminesthe‘amount’oftheservice (e.g.maintainingnurserypopulationsandhabitats).
When theecosystem services are identified as information, theassessment techniquemight requirecalculationof spatially explicit, complex indicators. Information does not require bio-physicalmodeling,butspatialmodelingcouldbeused.Allcultural services involve information, and they are generally assessed throughquestionnairesandmentalmodels.Insomecases(e.g. out-doorrecreation)thespatialcomponentcouldplayanimportant roleintermsofdistance;inothercasesitmayjustbeamatterof linkingdifferentindicatorstomakethemspatiallyexplicit.
5. Discussionandconclusion:advantagesofapplyingthe revisedconceptualframework
Thetiminginclarifyingandoperationalizeecosystemservices classificationandmeasurementshasneverbeenmorecritical.As ecosystemservicesbecomeintegratedintopolicyinstruments,the needtostandardizedefinitionsisessentialformonitoringand com-paringpolicyoutcomesfollowingdifferentscalesofinvestment (Bennett etal.,2015;Guerryet al.,2015).Our intentionin this articleistoprovidesomeclaritytoaddressissuesrelatedto ecosys-temservicesdefinitionandconceptualizationhighlightedbyothers (Boyd and Banzaf,2007; Fisherand Turner,2008; Fisheret al., 2009;Wallace,2007).Drawingfromsystemsecology,weadopt thekeyconceptsofbiomass,interactionandinformation,including theideaofdifferentlevelsofcomplexityamongthese(Jørgensen, 2012).Inthisstudy,wehaveusedourunderstandingfromsystems ecologytoapplyittotheecosystemservicesconceptualization.We believethattheconceptsfromsystemecologycansupportamore consistentdefinitionofecosystemservicesandotherelementsof thecascadeframeworkdevelopedbyHaines-YoungandPotschin (2010).
Thecascadeframeworkandrelatedecosystemservices defini-tionisoftenapproachedwithanemphasisonservicesandbenefits. Severalauthors have identified the need todelineate between directandindirectecosystemservices(intermediateandfinal)for thesake of economic valuation and natural capital accounting, where only benefitsfromfinal services canbe aggregated(e.g. Fisheret al.,2009; Heinket al.,2015).Thisapproach mitigates therisk ofdoublecounting,butitmightbeoverlyreductionist. Furthermore,distinctionsbetweenecosystemcapacityandactual supplyoruseoftheecosystemserviceshasbeenproposed(Albert etal.,2015;Burkhardetal.,2014;Villamagnaetal.,2013).By con-sideringcomplexity andtheverticalandhorizontalhierarchical organizationofecosystems,weproposearevisitedinterpretation ofthecascade frameworkasthree-dimensional.Moreemphasis isattributedtothecorrectfunctioningofthecomplexsystemthat generatesindividualecosystemservicesandassociatedbenefitsfor humans.
Tofurtherdeveloptheconceptofecosystemserviceswe pro-posethatecosystem servicesarenot thebenefits,butgenerate benefitsasanoutput,oftenexpressedintermsofbiomass.Aservice impliesthatthereisexchangeofinformationand/orinteraction. Goods are thus interpreted as material vehicles for ecosystem service enjoyment. We also propose that ecosystem functions arenot services,but ecologicalprocessesthat act atecosystem leveland generateflowsofservices.Functionsshouldbe main-tained toensure a sustainable flow of services. It is important toacknowledgethatfunctionsshouldbeconceivedwithamore
holisticandbio-centricapproachcomparedtoecosystemservices, which canbe individuallyidentified and assessed.We also call forgreaterattentiontowardecosystemsciencesforunderstanding long-termecosystemintegrityandecosystemfunctioning,andthus theresilienceofanecosystemagainsthumandrivendisturbances, inordertosecurethevitalecosystemservicesandsustainableuse ofnaturalresources(Currie,2011;Mülleretal.,2010).Theconcepts ofresiliencescience(resilience,adaptabilityandvulnerability)in relationtoecosystemservicesrepresentanimportantareafor fur-therstudies(Brand,2008;Mülleretal.,2010).Forsuchpurposes, ourclarificationcouldbeadvantageous.
Adoptingamorecomprehensiveviewonthedefinitionsinthe cascadeframeworkgivesincreasedrigortocriticalecosystem ser-vicesissuessuchasthetechniquestomap andassess services. For example,EUmember statesneedconsistentdefinitionsand measurementsforeasycomparisonofecosystemservicesstatus, gainorlossacrosscountries.Followingtheadoptionofthe analyt-icalframework,includingaconceptualmodelandtwotypologies, fortheEU,Maesetal.(2016)presentedafirsttestofthe frame-workandanassessmentofexistingindicatorstomap(orquantify) ecosystemservicesatthenationalscale(seealsoMaesetal.,2014). Theserecentstudies,aswellasthatbyEgohetal.(2012),showthat nationalstatisticspresentthebestdataoptionsformapping pro-visioningecosystemservicessuchasagriculturalproduction.This approach,wherebenefitsgenerated(biomass)areusedasaproxy oftheservice,ishighlysimplified.Theunitofassessmentisthe benefitandnottheservice.Choosingaproxysuchasbiomassas representativeofacertainserviceiscommonpractice,whereasa modelthatsimulatesthegenerationofthegood/resource,which involvestheinteractionfunctioning,isoftenleftout.Wesuggest thatthisapproachisnotfullyconsistentwiththetheoretical frame-work.However,it isacceptablein thiscase becausebiomassis conditionedbyecologicalstructureandfunctioning.
Wehopetheinsightintosystemsecologyprovidedinthisarticle willoffersomegroundforreflection,fuelingfurtheradvancement oftheclassification,conceptualization andoperationalizationof ecosystem services.Considering thegrowinginterest innatural capitalaccounting,8itisimportanttoestablishaconsistent con-ceptualgroundtohighlightthedifferencebetweenintermediate functioningwithintheecosystem(function),finalflows(services) and assets(benefits)and theirrespectivedegreeofcomplexity. Giventheneedforeconomicvaluationofecosystemservices,it isimportanttochoosetheappropriatevaluationtechniqueswhich explicitlytargettherealobjectofvaluationandthusavoidto con-sider thesingle,simple assetbeingequal tothemorecomplex servicethatgeneratesthatasset.
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