Payments for ecosystem services in the tropics: a closer look at effectiveness and equity

Payments

for

ecosystem

services

in

the

tropics:

a

closer

look

at

effectiveness

and

equity

L

Calvet-Mir

,

E

Corbera

,

A

Martin

,

J

Fisher

and

N

Gross-Camp

Weundertakeareviewofacademicliteraturethatexaminesthe effectivenessandequity-relatedperformanceofPESinitiatives targetingbiodiversityconservationintropicalandsub-tropical countries.Weinvestigatethekeyfeaturesofsuchanalysesas regardstheiranalyticalandmethodologicalapproachandwe identifyemerginglessonsfromPESpractice,leadingtoanew suggestedresearchagenda.Ourresultsindicatethatanalyses ofPESeffectivenesshavetodatefocusedoneitherecosystem serviceprovisionorhabitatproxies,withonlyhalfofthem makingexplicitassessmentofadditionalityandmost describingthatpaymentshavebeenbeneficialforlandcover andbiodiversity.StudiesevaluatingtheimpactofPESon livelihoodssuggestmorenegativeoutcomes,withanuneven treatmentoftheproceduralanddistributiveconsiderationsof schemedesignandpaymentdistribution,andalarge heterogeneityofevaluativeframeworks.Weproposean agendaforfuturePESresearchbasedontheemerginginterest inassessingenvironmentaloutcomesmorerigorouslyand documentingsocialimpactsinamorecomparativeand contextuallysituatedform.

Addresses

1_{InstituteofEnvironmentalScienceandTechnology(ICTA),Universitat} Auto`nomadeBarcelona,08193Bellaterra,Spain

2

InternetInterdisciplinaryInstitute(IN3),UniversitatObertade Catalunya,Spain

3_{DepartmentofEconomics&EconomicHistory,UniversitatAuto`noma} deBarcelona,08193Bellaterra,Spain

4

SchoolofInternationalDevelopment,UniversityofEastAnglia,NR47TJ Norwich,UK

5_{SchoolofGeosciences,UniversityofEdinburgh,EH89XPEdinburgh,} UK

Correspondingauthor:Corbera,E([email protected])

CurrentOpinioninEnvironmentalSustainability2015,14:150–162 ThisreviewcomesfromathemedissueonOpenissue

EditedbyEduardoSBrondizio,RikLeemansandWilliamDSolecki

Received17December2014;Revised26May2015;Accepted 01June2015

http://dx.doi.org/10.1016/j.cosust.2015.06.001

1877-3435/#2015ElsevierB.V.Allrightsreserved.

Introduction

Payments for Environmental or Ecosystem Services

(PES) have become a means to promote biodiversity

conservationandruraldevelopment,particularlyin

tropi-calandsub-tropicalregions[1].NationalorregionalPES

programs are currently implemented in countries like

Costa Rica, Mexico, Ecuador, Vietnam, China, South

Africa or theUnited States, whilesmaller regional

pro-grams have been tested in European countries like

Germanyand theUK[2].Small-scalePESprojects

pro-moted by non-governmental organizations to enhance

watershed protection and biodiversity conservation, as

wellasto protectcarbon reservoirsandsinks underthe

umbrellaoftheUnitedNationsFrameworkConvention

on Climate Change—as carbon offset and REDD+

projects—have also been developed worldwide [3].

Theseprograms andprojects haveusually becomepart

ofaconservationpolicy mix,in whichthedirect

incen-tives provided by PES co-exist with more traditional

regulatoryconservationapproaches[4].

ResearchexaminingtheperformanceofPESschemeshas

increasedexponentially overthepastdecade.Academic

PESreviewstodatehavefocusedonafewprogramsand

projects [5], have had a single topical or geographical

focus[6–11],or have reliedmostly onqualitative

infor-mation provided byproject managers and conservation

organizations[12].Theseanalyses havesought todistill

lessonsonwhatPESschemeshaveachievedin

environ-mental and livelihood terms, to explainthese

achieve-ments, and to analyze what could be done to improve

designandperformance.

Ourreviewaimsatabetterunderstandingofconservation

interventionsbutisdistinctivefromexistingreviewsinat

leastthree ways. First,we focus onlyon peer-reviewed

publicationsanalyzingongoing—notplannedor

poten-tial—PES initiativesimplementedin tropicaland

sub-tropicalcountriesacross Asia,Africa andLatinAmerica.

Theseregionscontainthehighestconcentrationsof

bio-diversityontheplanetandareexperiencingrapidchange

thatisleadingtotheloss of biodiversity[13,14].These

regions also contain deep, multifaceted poverty [15]

wheretheburdenofecosystemprotectionisoftenborne

by those least able to afford it [16]. Second, we are

principally interested in understanding if researchers

have considered PES schemes to be effective both in

achieving their biodiversity and environment-related

goals,thatis,iftheyhaveachieved thegoalsset bythe

correspondentPESprogramorproject,andtobeefficient

in their use of financial resources,given thatPES have

often been praised as cost-effective alternatives

com-pared to more conventional conservation instruments

[17,18]. Finally, we are interested in highlighting if

researchershaveconsideredPESschemestobeequitable,

thatis,iftheyhaveinvolvedpoorpeopleintheirdesign

and implementationand if they have benefited

partici-pants equally. Therefore our objective is not to judge

by ourselves if the PES cases reviewed are effective,

efficient and equitable but instead to annotate what

thereviewedarticle authorsconsidersuchcases tobe.

We alsoacknowledge that theequityjudgments of the

authors in the reviewed articles can be considered less

‘objective’ than effectiveness results, since such

judg-ments may depend on the scholars’ approach to the

conceptandthepotentialforconflictbetweenherviews

andthoseoflocalpeople.However,wethinkthatsome

aspectsofequity,forexamplethedistributionofjobsor

incomederivedfromPESimplementation,canindeedbe

measurableandthuspresentedwithobjectivedata,while

other equity-related criteria might be more prone to

subjectivity,suchastheexistenceofconflictsor

partici-pationlevelsinPES designandimplementation.

Nonetheless,we believethatallaspectsdeserve

atten-tion given that PES is part of a broader international

environmentalgovernanceagendathataimstotransform

thedistributionofrightsandresponsibilitiesinresource

management across the world, and particularly in the

global South[19].An equityfocusis thusimportantto

understandifPEScouldserveasameansof

redistribut-ing thecosts andbenefitsofconservationinawaythat

alleviatespovertyandminimizessocialconflict[20,21].

Finally, throughout our analysis, we investigate the

methods employedby scholars todraw conclusionson

economic andecological effectiveness and equity and

examine if methods and the outcomes described are

relatedtoeachother.

Overall,thefindingsandtheresultingdiscussion

contrib-utetowardestablishinganagendaforfuturePESresearch

by identifyingdataand analyticalgaps, and pointingto

theopportunitiesandchallengeslyingaheadtodevelop

more robust research approaches. The results are also

relevant for PESpractitioners totheextentwe offeran

overview of existing PES schemes in sub-tropical and

tropicalcountries,and wecallfor partnershipsto better

design andmonitorPESworldwide.

Methods

We compiled adatabase of peer-reviewed literature in

Scopus for articles published betweenJanuary 2003—

theyearofthepublicationofthefirstMillennium

Eco-system Assessment Report—and December 2013,

searching for the terms ‘payment for environmental

services’ or‘paymentforecosystemservices’ and

‘con-servation’ anywhere in title, abstract orkeywords, and

the term ‘tropical’ anywhere in the text. The results

returned 213 (‘environmental’) and 200 (‘ecosystem’)

articles,ofwhichover80%hadbeenpublishedbetween

2009and2013,indicatingthegrowingpopularityofthe

subjectandtheincreaseinscholarlyattentiontoPES.

Wetargetedjournalcontributionsthat(i)analyzedoneor

more implemented PES initiatives in tropical or

sub-tropical countries,excludingAustraliaforbeingahighly

developed countryand Chinabecause half thecountry

falls outside the sub-tropics; (ii) focused on initiatives

with direct or indirect biodiversity conservation

objec-tives,thatis,theytargetedtheconservationorrestoration

of an ecosystem, or theprovision of related ecosystem

service(s), and (iii)examined PES effectiveness and/or

equityconsiderations,suchasthedegreetowhich

envi-ronmentalobjectiveshavebeenachieved,people’saccess

to project activities, participation in design and

imple-mentation,andtheimpactanddistributionofincentives.

Weexcludedarticlesdevelopingaconceptualframework,

argumentormodelrelatedtoPEStheory,practiceorthe

targeting of payments [4,22–30]; focusing on analytical

issues unrelated to effectiveness and equity, such as

motivationstoparticipateinPES[31–33];andthosethat

didnotincludeapurposiveanalysisofcasestudies,such

as summary articles in special issues, the above

men-tionedPESreviews,andarticleswithanecdotalevidence

onPESimplementationtoillustratearelatedargument

[34–37].

Our final database includes 34 articles focused on

29 PES programs and projects (Table 1). The World

Bank’ssponsoredRISEMPprojecthasbeen

implemen-tedindifferentcountriesandwehaveconsideredeach

countryschemeasaseparatecasestudy.Thirtyarticles

examine only one PES initiative [38–47,48,49–54,

55,56,57,58–66,67],onepaperfocusesontwocases

[68], and three analyze three or more schemes in the

samearticle[69–71].Fromeachofthesecontributions,

weextractedthefollowinginformationtoprovidesome

background on the location and typology of the PES

schemes analyzed: location of the researched PES

scheme (continent, country), scheme reach (national,

local),typeofservicebeing paidfor(well-defined

eco-systemservice,proxy),andtypeoflandtenurewhereit

hasbeenimplemented(private,public,communal).We

alsorecordedeacharticle’sauthors,yearofpublication,

the PES scheme analyzed, the locationof the scheme

thearticleisfocusingon,theauthor(s)’analytical

objec-tive(s), methods, the characterization of effectiveness

and/or equity by the author(s), and PES outcomes

reported. For the latter, and to reduce potential bias

inarticleassessment,we extractedthe relevanttext in

which the authors explicitly referred to effectiveness,

Table1

SomekeycharacteristicsofthereviewedPESschemes.

Region Country PESscheme PESscale PES developer

Activitiespaidforandlinkwith desiredservices—(Director

Proxy)* Typeof tenure Article(s) #in reference list Asia Cambodia Eco-tourism

payments scheme

Local NGO Villagersmaynothuntkey speciesandmustabidebya landuseplan.Revenuereceived fromtouristvisitsusedtosupport planoverseeingand

enforcement—(Pfor biodiversityconservation)

Private [71]

Asia Cambodia Agri-environment payments scheme

Local NGO Offerspreferentialpricestorice farmers(wildlifefriendly certification)inexchangefor abidingbytheland-useplanand no-huntingrules—(Pfor biodiversityconservation)

Undefined [71]

Asia Cambodia Nest conservation directpayments scheme

Local NGO Farmerspaiddirectlyagainst numberofnestsprotectedfrom poaching—(Dforbird biodiversityprotection)

Communal [71]

Asia Cambodia NGO-driven community-basedpayments scheme

Local NGO Communitiesareexante incentivizedtodeveloplocal institutions(committeesand land-useplans)tostop deforestationinthebufferzoneof aprotectedarea(Pfor biodiversityconservation)

Communal [65]

Central America

Mexico Nationalprogram ofpaymentsfor hydrological services

National Federal government

Farmersandcommunities receivepaymentstoconserve foreststhroughthedevelopment ofmonitoringandpatrolling activities—(Pforwatershed regulation) Communal, Private [54,63,67_] Central America

Mexico PEScarbon forestrynational programscheme

National Federal government

Farmersandcommunitiesare paidforforestconservationor reforestationactivities—(Dfor carbonsequestration) Communal, Private [46] Central America Mexico Fondo Bioclimatico carbonproject scheme

Local NGO Farmersandcommunitiesare paidforforestconservationor reforestationactivities—(Dfor carbonsequestration) Communal, Private [62,69] Central America Mexico Coatepec watershed payments sub-nationalscheme Local Sub-national government (state, municipality)

Farmersarepaidforforest conservationorreforestation activities—(Pforwatershed regulation)

Private [53]

Central America

Mexico MonarchButterfly Fundpayments scheme

Local NGO Farmersandcommunitiesare paidforforestconservation, includingmonitoringand enforcementactivities—(Pfor biodiversityconservation) Communal, Private [47,48] Central America

CostaRica PESnational programscheme

National Federal government

Farmersarepaidforforest conservation—(Pforwatershed regulationandbiodiversity conservation)

Private [39,43,44, 55,61]

Central America

CostaRica RISEMPproject scheme

Local Multilateral organization (WorldBank)

Farmersarepaidtodevelop agro-forestrysustainable practices—(Pforbiodiversity conservationandcarbon sequestration)

Private [38,41,56]

Central America

CostaRica Heredia watershed payments scheme Local Sub-national government (state, municipality)

Farmersarepaidtoconvert agriculturallandintoforests— (Pforwatershedregulation)

Table1 (Continued)

Region Country PESscheme PESscale PES developer

Activitiespaidforandlinkwith desiredservices—(Director

Proxy)* Typeof tenure Article(s) #in reference list Central America

Nicaragua RISEMPproject scheme

Local Multilateral organization (WorldBank)

Farmersarepaidtodevelop silvopastoralmanagement practices—(Pforbiodiversity conservationandcarbon sequestration)

Private [38,40,49]

Central America

Nicaragua SanPedrodel Nortewatershed payments scheme Local Sub-national government (state, municipality)

Farmersarepaidtoconvert agriculturallandintoforests— (Pforwatershedregulation)

Private [70]

Central America

Guatemala LasEscobas watershed payments scheme

Local NGO Enforcedconservationand adoptionofSFMandsustainable agriculturalpracticesby protectedareainhabitants— (Pforbiodiversityconservation andwatershedregulation)

Public(heldin trustbyNGO)

[69]

Central America

Belize RioBravocarbon projectscheme

Local NGO Forestconservationagainsta deforestationanddegradation baselinescenario—(Dfor carbonemissionsavoided)

Public(heldin trustbyNGO)

[69]

Central America

Honduras JesusdeOtoro watershed payments scheme Local Sub-national government (state, municipality)

Farmersarepaidtoconvert agriculturallandsintoforestsand developorganicagriculture— (Pforwaterregulation)

Private [70]

South America

Bolivia LosNegros watershed payments scheme

Local NGO Farmersarepaidforavoiding forestconversioninto agriculture—(Pforwater regulationandbiodiversity conservation)

Private [42]

South America

Bolivia NoelKempff climateaction projectscheme

Local NGO Forestconservationagainsta deforestationanddegradation baselinescenario—(Dfor carbonemissionsavoided)

Undefined [68]

South America

Colombia RISEMPproject scheme

Local Multilateral organization (WorldBank)

Farmersarepaidtodevelop silvopastoralmanagement practices—(Pforbiodiversity conservationandcarbon sequestration)

Private [38]

South America

Colombia Oakbiological corridor payments scheme

Local NGO Farmersarepaidperhectareto promoteforestconservationby switchingtomoresustainable silvopastoralpasture managementpracticesthat wouldincreasemilkproduction andmaintaintheremaining forests—(Pforbiodiversity conservation)

Private [58]

South America

Brazil BolsaFloresta payments programscheme Sub-national Sub-national government (state, municipality)

Householdsarepaidamonthly fee(regardlessofenvironmental additionalitylevel)toreduce conversionofprimaryforestson theirlands,withadditional supportprovidedfor income-generatingactivitiesthatdonot relyondeforestation—(Pfor biodiversityconservation) Communal, Private [60,68] South America

Ecuador SocioBosque payments programscheme

National Federal government

Farmersorcommunitiesarepaid abiannualfeerelatedtothesize oftheirforeststobeprotected. Theycommittoavoidland-use change,huntingforcommercial purposesandtoreportthird partyinvasions—(Pfor biodiversityconservationand watershedregulation)

Communal, Private

whichpaymentsresultinenvironmentaloutcomesthat

wouldnothaveoccurredotherwise-,cost-effectiveness,

equity,existenceofconflictsandperceivedlegitimacy.

Such text was then summarized for explanatory

pur-poses—appearingas‘Outcomeexplained’datain

Sup-plementaryTables1 and2.

PES

for

biodiversity

conservation

in

tropical

and

sub-tropical

regions

LocationandtypologyofPESschemes

Table1showsthatthe29PESschemesexaminedarenot

evenlydistributedacrosstropicalandsub-tropicalregions

butconcentratedinCentralandSouthAmerica,andless

insub-SaharanAfrica.Mexico,CambodiaandCostaRica

have the highest number of PES schemes, with all

schemespresentinCambodiabeingdesignedbyNGOs

and developed at local scales. The Costa Rican PES

nationalprogramisanalyzedin seven articles,Mexico’s

nationalwatershedpaymentsprograminfourarticlesand

theWorldBank’ssilvopastoralRISEMPprojectinthree.

Consistentwithotherreviews[8,11],mostPESschemes

havebeendesignedandpromotedbyNGOsthat,inmost

cases,havereceivedseedfinancialsupportfrom

interna-tionaldonors.National(6) orsub-nationalgovernments,

including states and municipalities (5), have promoted

elevenofthe29PESschemesinourdatabase.Logically,

nationalgovernmentshavesupportedschemesof

nation-alreach,whilesub-nationalandlocalgovernmentshave

promotedschemes affectingareaswithintheir

adminis-trative boundaries, for example, the Bolsa Floresta

schemepromoted bytheBrazilianAmazonasstate

gov-ernment[60,68]orthewatershedpaymentschemeinthe

MexicanmunicipalityofCoatepec[53].

Most analyses report that schemes reward landowners

againsttheprovisionofland-useactivitiesthatconstitute

aproxyofthedesiredecosystemservices.Theexception

areproject schemeslinkedtovoluntary carbonmarkets

Table1 (Continued)

Region Country PESscheme PESscale PES developer

Activitiespaidforandlinkwith desiredservices—(Director

Proxy)* Typeof tenure Article(s) #in reference list Central Africa

Rwanda Nyungwenational parkpayments scheme

Local NGO Householdsarepaidtorefrain fromillicitlycollectingforest products—(Pforbiodiversity conservation)

Undefined [57]

Southern Africa

Madagascar MantandiaPES projectscheme

Local NGO Farmersarepaidtoreduce land-usechangeandtodevelop forestationactivities—(Pfor biodiversityconservationand carbonsequestration) Public [50] Southern Africa Tanzania Uluguru mountains watershed payments scheme

Local NGO Farmersarepaidtoimplement andmaintainasetofspecified soilconservationmeasures,such asagro-forestry,reforestation, grassstripplantingandterrace development—(Pforwatershed regulation)

Private [59]

Southern Africa

SouthAfrica WorkingforWater payments program

National Federal government

Externalcontractorsemploying farmersandcommunitiesare paidtoremovealienvegetation speciestoreducethepresence ofinvasiveplantsoncountry’s scarcewaterresources—(Pfor watershedregulationand biodiversityconservation) Undefined [45] Southern Africa Namibia Community-basedNRM payments program National Federal government

Farmersandcommunities receiveashareofbenefitsfrom photographicsafarisandtrophy hunting,aswellastheyare incentivizedforprotectingwildlife andothernaturalresources— (Pforwildlifeconservation)

Communal [52]

Southern Africa

Mozambique Nhambitacarbon projectscheme

Local NGO Farmersarepaidtoplanttreeson thefarm(boundariesorinmixed rowsalongwithcrops)—(Dfor carbonsequestrationlevelsby plantedspecies)

Undefined [51]

*

Weindicateheretheactivityforwhichtargetedlandownersarepaidfor,andwenoteifpaymentsaredirectlyrelatedtothemeasurementofthe desiredecosystemservices.

(e.g.Belize,Mexico),whichneedtomonitorand

accurate-ly quantify carbon to participate in such markets

[46,51,62,68,69],or niche-basedinitiativesconcentrating

on very particular services, suchas bird nest protection

againstpoaching[71].Tenureconditionsunderlyingeach

PESschemedifferacrosscountriesandaccordingtolocal

realities. In Mexico, for example, national and local

schemes supporting forest conservation and

manage-ment—toprovidecarbonandwatershedservices—

tar-getlands undercommunalandprivateproperty asmost

forestsareadministeredbycommunitieswhoholdthesein

commonorhavedivideduptheirlandsacrosshouseholds.

Thisisalsothecaseofprogramswiththe sameor

com-plementaryobjectives(biodiversityconservation)inBrazil

and Ecuador. This contrasts withthe Costa Rican case,

whereforestsaregenerallyownedprivatelyandpayments

strictlychanneledtoindividuallandowners.

PESschemeswithastrongfocusonsustainable

agricul-turalpracticesoragro-forestryasaproxyforbiodiversity

conservation or watershed regulation target private,

household-managedlandsinordertolinkpractices,

out-comes and payments more directly [38,40,42,51,58,

59,62,70].WhenPES schemesare developedonpublic

lands, NGOsmanage targeted lands in trust or operate

jointlywiththegovernmentinthedesignand

implemen-tationofthescheme[69].Inthisregard,payment

recip-ients can include communities and households living

withinaprotectedarea(e.g. thecasesof Cambodiaand

Guatemala)ortheNGOalone(e.g.thecaseofBelize).It

isworthhighlightingthatsixarticlesinourdatabasedid

notspecifytheunderlyingtenureconditionsofthePES

schemeandwewereonlyabletoinferthoseinoneofthe

six cases becausethe correspondent scheme (i.e. Costa

Rica’sPESnationalprogram)hadbeendescribed

exten-sivelyinother contributions.

Effectiveness

Figure1(seeSupplementaryTable1forextended

infor-mation)includes26articlesanalyzingtheeffectivenessof

24 different PES schemes. However, the figure has

30analyticalobservations(#bulletpoints)becausesome

articlesexamine morethan onePES scheme.The

vari-able chosen to infer effectiveness and themethods for

datacollectionvaryacross casestudies.Scholarsanalyze

PESeffectivenessintermsof(i)changesinthelevelof

ecosystemserviceprovision,thatis,iftheservicetargeted

increasesordecreases;(ii)changesinland-useorhabitat

provision,thatis,ifpaymentsmaintainorexpandthetype

ofland-useorhabitatthatisusedasaproxyofecosystem

servicedelivery;or(iii)thecombinationofbothvariables.

Studies focusedon serviceprovision levelsrely on

per-ceptionsofPESactorsand/orsecondarydataprovidedby

projectmanagers,ongoingfieldmonitoringofbiodiversity

and ecosystem servicesin PES areasover time [52,71],

and the spatial overlap of PES areas with landscapes

providingcriticalecosystemservices[50]toinfer

effec-tiveness. Authors concerned with changes in land use

Figure1 INEFFECTIVE EFFECTIVE Effectiveness assessment Equity assessment NO DATA INEQUITABLE NO DATA EQUITABLE

Current Opinion in Environmental Sustainability

rely on GIS data, including ground-truthing [45] and

econometricmodeling,such asmatchingor

difference-in-difference regressions [39,41,47,48,53,55], actor

perceptions and behavioral change [43,57], and

sec-ondaryproject data [44]. Authorsconcernedwith both

dimensions draw on indices to monitor changes in

service provision and habitat quality across different

types of land uses [40,49,71,72,42], as well as on GIS

andbiophysicalmonitoring ofservicedelivery[59].

Within the PES schemes that have been judged as

effective,therearebothgovernment-ledprograms

imple-mentedatnational scale[39,43,45,52,54,55,60,70] and

small-scaleinitiatives,drivenbyNGOsandotherdonors

[40,46,47,48,49–51,53,56,57,58,69,71,72,42]. Cases

describedasnon-effectivealsoincludeavarietyof

typol-ogies and implementation scales [41,44,59,60,70]. Only

seven studies have used control groups of non-PES

targeted areas or non-participants to account for

con-founding factors, such as biophysical, socio-economic,

political or institutionalfactorsthat maybe influencing

PESperformance[39,41,47,48,51,53,54,55].

CostaRica’snationalPESschemehasbeendescribedby

some as effective[39,55] and byothers as ineffective

[41],dependingontheselectedgeographicalregionand

the methods employed. The success of PES cases in

environmentaltermshasbeenrelatedtoecological

con-ditions, for example, a strong linkage between PES

activities and ecosystem service delivery [45,42], but

mostly to scheme design and its interplay with the

socio-ecologicalcontext.ThelatterincludePESactivities

thatdidnotinducealossofincome,butinsteadworkedas

an upfront incentive for participants to do what PES

activities required (independently if they had planned

to do such activities anyway) [39,40,43,45,51,71];

part-neredwithlocaland/orexternalorganizationstoprovide

technical support and reduce transaction costs [43,71];

inducedlocalbehavioralchangeandledtopracticesthat

diminished resource use, or halted land-use change

[57,71]; and did not involve a major departure from

existing land-use management and cultural practices

[40,53]. Somescholars highlight theimportanceof

pro-vidinglong-term and periodicallyadjusted payments to

balance participants’ changing opportunity and

transac-tioncosts over time [40,49],as wellas preventing PES

implementationinareaswithuncleartenuresituationsor

weaklyenforcedpropertyrights[47,48,53].

Notallarticlesconcernedwitheffectivenessrefer

explic-itlytoadditionalityandthosereferringtoitincludeboth

effectiveandnon-effectivePESschemes.PESschemes

havebeenjudgedadditionalwhenithasbeenconsidered

that the desired land-use management activities or

expected service deliverywould not have been

imple-mented or achieved without PES incentives

[48,50,52,54,58]. PES schemes have been judged as

non-additionalbythecorrespondent authors whenPES

activitieshaveconcentratedonland-useareaswithlowor

zero risk of deforestation [39,41,72], and two of these

cases have been also—and counter-intuitively—

con-sidered effective on the grounds that payments have

contributedtomaintainforestcover(despitealowlevel

ofadditionality)[37,71].Someauthorshighlightthe

dif-ficulty of assessing PES additionality based on project

designandexistingdata[53]orofattributingchangesin

landuseorserviceflowstoPESincentives[59].Onlytwo

ofthearticlesincludedin oursampleconsiderthePES

caseefficient,understoodasareductionovertimeofthe

totalcostsperunitofservicedeliveryorhabitatprovision

ofthegivenPESinitiative[55,71].Fourarticlesreferto

efficiency only vaguely, considering the PES program

inefficient if non-additional [39,41], or indicating how

thePESinitiativecouldreduceadministrativeexpenses

or increase funding levelsin thefuture to become less

costlyperunitofPESserviceor targetedarea[50,61].

Equity

Figure1above(seeSupplementaryTable2forextended

information) includes 24 articles examining the equity

outcomesof24differentPESschemes,with32analytical

observations(#bulletpoints).Weclassifiedtheauthor(s)’

analytical approach to equity following a three-tiered

framework:(a)equityinaccess, iftheauthor(s) examined

localpeople’sabilityto participatein thePESprogram;

(b) equity in decision-making, if the author(s) analyzed

participants’perceivedfairness inproject

decision-mak-ingprocedures;and (c)equity inoutcome,if theauthor(s)

focused on the impact and distribution of project

out-comes,includingincome,across participants[62,69].

Asnotedintheintroduction,werecognizethattheequity

dimensionsofPESdesignandimplementationareprone

to subjectiveanalysis, since they relyon thescholar(s)’

own interpretation of who is legitimately entitled to

participate in a given scheme and who has been left

out, or throughlocal people’s own perspective of what

is fair. But some equity aspects can also be analyzed

objectively, for example measuring changes in relative

income, or participation rates and voting procedures in

meetings. For this reason it is important to be precise

aboutthemethods,dataandtheindicatorsusedtoinfer

thedirectionofsuchoutcomesand,forthispurpose,we

havedistinguishedbetweenstudiesrelyingon

quantita-tivedata(e.g.minutesofPESmeetings,participationand

incomedatafromhouseholdsurveys)fromstudiesbased

onqualitative interviewsandpersonalobservations.

Authors looking exclusively at equity in access mostly

rely on informal interviews [39], program and project

secondarydata [40,63], andonly oneon household and

village surveys [51]. Those concerned with equity in

outcome use interviews, focus groups and/or secondary

programandprojectsecondarydata[44,71].Analysesthat

combinethesetwodimensionsand/oralsolookatequityin

decision-makingrelyonqualitativeresearchmethodsand/

or secondary data [45,46,52,59,62,65,69,71,42], surveys,

regressions and/or inequality indices [60,61, 67,66].

Onecanobservethatthereareonlyfivestudiesthatrely

on quantitativedata fromsurveysto draw lessonsabout

access, decision-makingandoutcome. Thisdoesnot

in-validate the findings of the majority of equity-related

studiesbutsuggeststhatthereisamplescopefor

develop-ingmorequantitativeapproachestoprovide

complemen-tary‘measures’ofequityoutcomes.Seemingly,onlysixof

the articles focused on equity aspects pay attention to

decision-making during the design and implementation

phaseofPESschemesandexplainwhohasbeenincluded

and/orexcludedinsuchprocesses.Amongthese,onlytwo

drawattentiontounequalbargainingpowerinPESdesign

[46,62], while none finds evidence of rent seeking by

powerfulactors,incontrasttoliteratureexpectations[73].

PES schemes considered equitable as well as

environ-mentally effective encompass national PES programs

[45,52,64], and donor or NGO-driven schemes

[40,57,71]. PES schemes considered unfair in one or

more equitydimensions canbeconsideredeither

effec-tive [39,43,46,49,51,69–71,42] or ineffective [44,59,70],

but many have not been judged in this regard [61–

63,67,68,69,66]. Social conflict has been reported in

nine PES schemes [43,46,62,67,68–70,66]. Some PES

activities are reported to have encouraged and ensured

theparticipationofpoorandnon-poorhouseholdsintheir

design andimplementation[40];pursuedgenderequity

[45,52];empoweredlocalcommunitiesthroughdevolved

rightsinresourcemanagement[52];andhaveledtoafair

distribution of material and/or non-material outcomes

across communitiesandindividuals[52,57,71].

By contrast,otherPES schemeshavewidenedthelocal

incomewealthgap,oftenunintentionallyandasaresult

of unfavorable local tenure and political conditions

[44,62,69],suchasinMexico’sPESprogramwhereformal

land right-holdershavecontrolledaccesstopaymentsat

village leveland have tendedto distribute less to

non-right-holders[46,67],orinTanzaniawherethepoorest

householdsdonothaveenoughlandtodedicatetoPES

activities [59]. Asalready noted above, both ‘poor’ and

‘rich’households’participationinPESschemeshastodo

with actual or perceived costs of enrolment, cultural

suitability of practices and the latter’s fit with local

environmentaldiscourses[49,62,67].Someofthe

scho-lars’ proposals to address PES schemes’

underperfor-mance in procedural and distributional terms include

further incentivizing poor landowners or the landless,

whooftenexperiencehigheropportunityandtransaction

costs, and providingthem with additionalexternal

sup-port[43];supportingtransparentandwidebenefitsharing

bycommunity-basedinstitutions[67,71],guaranteeing

tenure security for the landless and non-formal

right-holders; andimprovingthevaluechains ofrelated

mar-kets, particularlysustainably harvested timber, so as to

increase livelihoodgains [43].

Renewing

the

PES

research

agenda

Our review confirms that PES implementation in the

(sub-)tropics encompass distinct implementation

approaches that diverge in conservation goals, scale of

implementation and funding approaches. Related

re-search capturesthe heterogeneityof PES schemes that

has been widelynoted and referredto in existing

liter-atureandreviews[5,74,75].Thesizeofourdatabasedid

notallowforanyrelevantstatisticalinferencetotestany

likely relationshipbetween thetypes of PES analyzed,

thescaleofimplementation,thetargetedtenuresystem

and the scheme’s performance in environmental and

equity terms. However, we can conclude that scholars

report, on average, more positive environmental

out-comes in PES schemes than they report positive

out-comes in terms of equity. Spatial and/or econometric

assessments related to effectiveness are more able to

provide insights on the relative level of environmental

additionality of PES schemes, that is, being able to

compare PES participants’ and non-PES participants’

environmental performancecontrolling forindependent

variablesandconfoundingfactors[47,48,51,53,55].By

contrast,qualitativeresearchseemsmoreabletoprovide

insights on equity, with a majority of schemes being

judgedunfair atprocedural and/ordistributivelevels.

Positivereportingonequityismostlybasedonsecondary

and project management data—columns 7 and 8 of

SupplementaryTable2—(exceptforRef.[57]),while

negative reporting oftenrelies onmore extensive

field-work and primary data collection (except for Refs.

[39,44,63,71,42]).Thesizeofourdatabasedoesnotallow

us to categorically affirm that more independent and

lengthy engagement in the field reveals equity-related

challenges more effectively. However, it enables us to

confirm that equity-related evidence is better captured

throughqualitativeanalysesderivedfrominterviewsand

focus groups; very few scholars are able to quantify

aspects of equity, suchas theimpact of PES payments

onincomeinequality.

Wehavenotedaboveasetofcontext-dependent

(includ-inglocalecologies)andschemedesignand

implementa-tion conditions that are conducive to, or impede the

realization of positive effectiveness and equity effects.

Regarding the first set of conditions, effectiveness and

equity are more likely to be realized when PES land

management activities fit with locally known

manage-ment practicesand resource use culture and if they fit

withthemandateoflocalresourcemanagement

institu-tions,particularlyifPESinvolvessocialcollectives(e.g.a

tenure relations, mediated by local governance

institu-tions,andtheextenttowhichthelatterdeterminewho

cangetinvolvedinthePESscheme,andwhocanbenefit

and byhow much. Additionally,local opportunitycosts

determinetheextenttowhichthepaymentisattractive

tolandusers—leadingto increasedeffectivenesswhen

paymentsexceedsuchvalue-,aswellasthetimehorizon

during which payments are delivered—with

effective-nessandequityincreasingthelongerpayments are

dis-bursed. As for scheme design, key aspects to foster

performanceacrossthetwodimensionsincludelong-term

involvementof PES promoters with local recipients, in

ordertoprovidethenecessaryknowledgeandexpertise,

aswellas promoters’abilityto adaptthePESprojectas

tenurerelationsandlandmanagementcostschangeover

time.

Ourreviewalsodemonstratesthatanalysesof

effective-ness and equity in PES schemes of tropical and

sub-tropicalregionshavenotpaidattentiontoeconomiccosts

data,suchastheopportunitycostofalternativelanduse

activities, orthe transaction costs of program

manage-mentandmonitoring[5].This issurprisinggiven that

effectiveness would need to be related to actual land

managementcostsinordertofindoutthelevelof

cost-effectivenessandtodrawinsightsonPESefficiencyover

time.ThelackofstudiesonPEScost-effectivenesshas

been explained by the fact that most schemes in the

globalSouthlackclearmetricstoquantifytheecosystem

services being delivered, and thus the corresponding

associatedcosts. Thoseschemesfocusedoncarbon are

themostnotableexception[76].However,wearguethat,

whilecostconstraintsareimportant,lackofreflectionas

regardscost-effectivenessisalso relatedtoinsufficient

attention to the issue and the common inability of

researchers to access data on opportunity costs, and

projectstart-up,transactionandrunningcosts.

Thefact thatthemethodologicalapproacheschosenby

scholars to investigate PES performance in terms of

environmental effectiveness and social equity differ

broadly, responds to the variety of research budgets

availableand the scientificschoolsinterested in

under-standingthis conservation tool, whichrange from

land-use scientiststo economists,anthropologists andcritical

geographers.However,wethinkthatfuturePESresearch

would benefitfrom some level of analytical integration

andcoordinatedresearchefforttoholisticallyunderstand

theenvironmental and social outcomes thatPES could

generate if well targeted and fairly implemented by

practitioners. In doing so, scientific research could be

more helpful in providing sound and more coherent

evidence to PES implementing actors, governments

andbothdonorsandservice ‘buyers’.

The relationship between effectiveness and equity in

PEShasalreadybeentheorized[21,77]butourreview

suggeststhatthereis stillaweak linkbetweenthetwo

dimensionsinempiricalstudies. Thisisreflectedinthe

central vertical column and horizontal row of Figure 1

whichrefertoseveralarticlesthatdonotreflectonPES

effectivenessor equityoutcomes.AfuturePESstrategy

(Box1)canconcentrateonanumberofelements.First,

scholarscancontinuetopursuethedevelopmentofglobal

reviews,followingsystematicreviewprotocols, and

ide-allydevelopacomparabledatabaseofPEScases

world-widethatcanhelp identifyingchallengesandtrends in

PES design and implementation, looking at both

effec-tiveness and equity. Those interested particularly in

equitycould also consider the challenge of developing

synthesesofexistingnarrativesonPESinawaythatcan

becomplementarytootherreviewsbased onlargerdata

andmoresystematicsyntheses.

Second,thereshouldbeafocusonlargerresearch

pro-jectsthatcouldfollowPESimplementationinmultiple

locations,focusingononeorvariousPEStypologies,and

based on a shared research framework—drawing, for

example, on similar experiences in common-pool

re-source management and rural livelihoods research

[78,79].Theseprojectsshouldbedevelopedin

partner-shipwithPESpractitioners,notonlytoaccesssitesover

time for research purposes but to develop

locally-in-formed‘theoriesofchange’thatcouldbetestedduring

and/orafter PES implementation. As it has been

sug-gested elsewhere [80,81], coming up with

context-specific hypotheses related to environmental and

socio-economic outcomes is fundamental to rule out

alternative explanations of positive or negative

change—thatcouldbewronglyattributedtoPES

activ-ities-, and to provide more accuratelessons for

practi-tionersand donors.

Box1ElementsofafuturePESresearchstrategy—Activity(A) andGoal(G)

Practitioner-informedmeta-analysisofPES

-(A)todevelopaglobalcomparativeanalysisofcasestudieswith inputsprovidedbyPESmanagersandknowledgeableresearchers -(G)todrawrelevantandsharedinsightsonPESdesignand

implementation

Largerandmorecooperativeresearchprojects

-(A)togenerateanalysesofPESimplementationinformedbypanel data,incooperationwithpractitionersandbasedonlong-term fundingandcooperation

-(G)toidentifyPESimpactsonenvironmentalandsocialconditions, controllingforconfoundingfactors;andtoinvestigateinteractions betweenincentives,individualandcollectivebehavior,wellbeing andlocalinstitutions

Multiplemethods,data&outcomevariables

-(A)todeploymulti-method,andmulti-disciplinaryevaluative frameworks

-(G)tocombineinsightsfromdifferentresearchtechniquestodrawa completeunderstandingofPESeffectsonlocalandregional ecologies,aswellasonsocio-economicandinstitutionalconditions

Third, PES research should rely on robust data and

methods. Spatial land use data from remote sensing,

complemented with on-the-ground monitoring

trans-ects, have beenmostly applied to understandchanges

inthecorrespondentecologicaloutcomevariables,such

asforestcoverorplantdiversity.Asregardsequity

out-comes,surveysandinterviewshavebeenusedtoreflect

on PES procedural and distributional effects, such as

presence of conflict, changes in resource governance,

impact on relative income, and benefit sharing. The

use of coupled ecological and socio-economic data in

econometric matching techniques with

difference-in-differenceregressionmodelscanbehelpfultocompare

performancebetweenPESandnon-PESsitesofselected

variables.

Precisely, involving control groups that act as

counter-factuals and panel datasetsof ecologicaland

socio-eco-nomic data in PES assessment frameworks would be

consistent with an increasingly common approach in

impact assessments of development and conservation

policy [82–84]. We recognize that such an approach

involves aset of challengesrelated to thepossibilityof

selectingvalidland-usepolygons,villageandhousehold

controls,particularlyin contextsof poorsocio-economic

and governance data availability, as well as the more

recurrentproblemsinpaneldataresearch,includingdata

gathering costs, data consistency and changing

circum-stancesin bothprojectandcontrolgroups,for example,

due to migration processes. Connecting well-grounded

‘theories ofchange’ withmeasuresof effectmeansthat

many studies of PES initiativeswill benefitfrom

com-biningresearch methods,and qualitativeworkwill

con-tinuetobecriticaltounderstandhowpeoplesubjectively

thinkandfeelaboutanyobservedecologicalandequity

effects derivedfromPES.

In conclusion, this article set out to review scholarship

literature on PES implementation in tropical and

sub-tropicalregions.Ourdatabaserenderedalimitednumber

of(case)studies,whichsuggeststhatfirst-handempirical

evidenceonongoingschemesmightbescarcerthanone

might think given the popularity of thepolicy

mecha-nism. Seemingly, we have demonstrated that PES

schemes appear to bemore effective in environmental

termsthansociallyequitable.Thisisprobablyourmost

worryingfindinggiven currentgroundedcallsfor

incor-poratingequitycriteriainPESdesign.Wehaveidentified

criticalmethodological gapsrelatedtodevelopingpanel

dataandcontrol-basedassessmentsofPESdistributional

outcomes, particularlyin relation topaymenteffects on

household or collective incomes.In light of these

find-ings,wehaveadvocatedforamoremulti-disciplinaryand

integrated wave of empirical research that, on the one

hand, builds onand supportsthe evolvingand growing

literatureonconservationpolicyimpactassessmentand,

on the other, relies on practitioners as key research

partnersandonPESandresearchdonorsaskeyfunding

supporters.

Acknowledgements

LauraCalvet-MirandEsteveCorberaacknowledgefinancialsupportofthe BiodiversaFrameworkProjectINVALUABLE:Values,Markets,and PoliciesforBiodiversityandEcosystemServices (PRI-PIMBDV-2011-1072).EsteveCorberaisalsofundedbytheSpanishResearch, DevelopmentandInnovationSecretariatthrougha‘Ramo´nyCajal’ researchfellowship(RYC-2010-07183).AdrianMartinandNicole Gross-CampacknowledgefinancialsupportfromtheEconomicandSocial ResearchCouncil(Conservation,MarketsandJustice,ES/K005812/1).We aregratefultoDrissEzzinedeBlas,SvenWunder,JakubKronenberg, Ge´raldineFroger,andananonymousfortheirconstructivecommentson earlierversionsofthismanuscript.

Appendix

A.

Supplementary

data

Supplementary material related to this article can be

found, in the online version, at http://dx.doi.org/10.

1016/j.cosust.2015.06.001.

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