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T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 7122. Environmentalservices

andagriculture

alsoexists:thepotentialforoffsettingorcompensatingforenvironmentaldegradationgeneratedbyothersectorsoftheeconomy.Bioenergyisanothernewlyemergingmarketthatmayalsoleadtomajorshiftsintheecosystemservicesprovidedbyagriculture(seealsoUN-Energy,2007).

Thechangesinecosystemmanagementthatarenecessarydependonlocation,theexistinglevelofeconomicdevelopment,populationdensity,agro-ecologicalconditionsandprimarytechnologiesemployedinagriculture.Allthesefactorsaffectthereturnstolandandlabourinagricultureandthepotentialcostsandbenefitsofchangesinpracticeaimedatgeneratingadditionalenvironmentalservices.

Thischapter,andtheremainderofthereport,focusesprimarilyonthreecategoriesofenvironmentalproblemswhereagriculturehasasignificantroletoplay:climatechange,waterdegradation(pollutionanddepletion)andbiodiversityloss.Thesethreedomainshavealreadyseenanexpansionofpaymentprogrammestoagriculturalproducerstoenhancetheprovisionofenvironmentalservices.Farmersarebeingpaidtosequestercarbontomitigateclimatechange,toimprovewatershedmanagement(andthuswaterqualityandflow)andtoconservebiodiversity.Thesecategoriesalsoappeartohavethemostsignificantpotentialforfuturegrowthinsuchpaymentprogrammes.Thereare,ofcourse,anumberofotherecosystemservicesforwhosemanagementagricultureplaysacrucialrole,suchassoilformationornutrientcycling,whicharecrucialformaintainingsoilfertilityandreversinglanddegradation.

Thischapterprovidesabriefoverviewofthetechnicalrelationshipbetweenagricultureandenvironmentalchanges,howthisrelationshipshapespolicyoptionsandthespecifictypesofactionsfarmersand

Thebenefitsthathumanshaverealizedfromagriculturehavebeenimmense.Today,agriculturefeedsover6billionpeople,andrecentdecadeshaveseensignificantincreasesintheproductivityofagriculturewiththeintroductionofnewvarietiesandproductionmethods(Tilmanet al.,2002).However,thesebenefitshavecomeatacost.OftheecosystemservicesevaluatedintheMillenniumEcosystemAssessment,agricultureiscreditedwithincreasingtheprovisioningservicesoffoodandfibreproductionoverthepasthalfcentury,butattheexpenseofdegradationofmanyotherecosystemservices.TheMillenniumEcosystemAssessment,aswellasreportsarisingfromothermorerecentstudiessuchasWater for food: water for life (ComprehensiveAssessmentofWaterManagementinAgriculture,2007)andLivestock’s long shadow: environmental issues and options(FAO,2006a)recognizethatagriculturecanandshouldbemanagedtoenhanceecosystemservicesbeyondtheprovisionoffoodandothergoods.

Increasedproductionofagriculturalgoodsattheexpenseofotherecosystemserviceshasresultedinglobalandlocalenvironmentalchangesthathavesignificantimpactsonhumanhealthandwell-being(Foleyet al.,2005).Agriculturalproductionpracticescangenerategreenhousegasemissionsandleadtowaterdepletionandpollution,landdegradationandlossofbiodiversity.Agricultureitselfisoneofthemainvictimsofdegradedecosystems,withagriculturalproductivityhamperedbyproblemsofclimatevariability,soildepletion,waterscarcityandquality,andpestanddiseasevulnerability.Changingthebalanceofecosystemservicesprovidedbyagricultureconstitutesasignificantsteptowardsredressingthenegativeconsequencesofcertainformsofagriculturalproduction.Afurthermotivationforsuchachange

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 1�otheragriculturalproducerscanundertaketoincreasethesupplyofthethreecategoriesofenvironmentalservices.

How can agricultural producers generate environmental services?

Beforediscussingthespecificissuesassociatedwitheachofthethreecategories,somegeneralobservationsarecalledfor.Generally,forfarmerstoincreasetheirsupplyofcertainenvironmentalservices,somechangeintheagriculturalproductionsystemisneeded.

Toprovideenhancedlevelsofenvironmentalservices,farmerscanaltertheirproductionpracticesinavarietyofways,including:• changesinproductionsystems,where

landsremaininagriculturebutproductionactivitiesaremodifiedtoachieveenvironmentalobjectives(e.g.reducedtillageorleavingmorecropresiduesonfields);

• land-diversionprogrammes,wherelandsaredivertedfromcropandlivestockproductiontootheruses;

• avoidingachangeinlanduse(e.g.refrainingfromtheconversionfromforesttoagriculture).

These distinctionsareimportantinassessingthedegreetowhichenvironmentalserviceprovisioninvolvesatrade-offwithagriculturalproduction,whichinturnisfundamentalforunderstandingthemotivationsofproducersregardingwhetherornottoimplementachange.Thetypeofchangerequiredcouldalsohavemacro-levelimplications,ifimplementedonalargescale,throughitsimpactsonfood,landandlabouravailability,andonprices(Zilberman,LipperandMcCarthy,forthcoming).

Theconditionsdeterminingthepotentialtochangethemixofecosystemservicesprovidedbyagriculturalproductionsystemshaveseveraldimensions.First,changestoincreasetheoutputofoneecosystemservicearelikelytohaveeffectsonanumberofotherservices.Thesemaybepositiveornegative.Inmanycases,changesinvolveareductioninsomeprovisioningservices–evenifonlytemporary–inordertoenhancethesupplyofothersupporting,regulating

orculturalservices.Trade-offsmayalsoariseamongthevarioustypesofregulatingandsupportingecosystemsservicessupplied.Forexample,establishingaplantationoffast-growingtreespeciestogeneratecarbonsequestrationmayreducebiodiversity.Likewise,increasinghabitatforonespeciescouldhavenegativeimpactsonanother.

Second,agro-ecologicalconditionssuchasclimate,soilquality,topographyandwateravailabilityarekeydeterminantsofthemixofecosystemservicesthatcanbegeneratedfromaparticularsystemofmanagement.Specificagro-ecologicalconditionsmaybehighlyproductiveforoneservicebutnotforanother;forexample,steeptopographycanresultinhighlyproductivewatershedprotection,butbeveryunproductiveforagriculture.

Third,thepotentialforchangingthemixofservicesprovidedbyagro-ecosystemsdependscriticallyonthemanagementsystemscurrentlyinplaceandonthepolicyandeconomicfactorsthatdrivethem.Forexample,wheatcanbeproducedwithinalarge-scale,highlycapital-intensivemechanizedsystem,asinAustraliaorCanada,orthroughsmall-scale,labour-intensivesystemswithfewornochemicalinputs,asinEthiopia.Bothareexamplesofwheatfarmingsystems,buttheproductivityofeach,intermsofwheatyieldandthemixofecosystemservices,isquitedifferent.Changestoincreaseenvironmentalservicesforonesystemmaynotberelevanttotheother.

Afourthandfinalpointtobemadeisthatecosystemservicestakedifferentforms,notallofwhichareequalfromthepointofviewofthebeneficiaries.Amajorreasonforthepastemphasisonprovisioningservicesoverothertypesofecosystemservice,isthefactthatmostprovisioningservicestaketheformofwhat,ineconomists’terms,areconsidered“privategoods”.Incontrast,regulating,supportingandculturalecosystemservicesareoften“publicgoods”(seeBox2).

Thesectionsbelowlookmorecloselyatthetypesofchangethatagriculturalproducerscanmaketoenhancetheprovisionofthespecificservicesofclimatechangemitigation,improvedwatermanagementandbiodiversityconservation.

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 71�

Agriculture and climate change mitigation

Thesummaryforpolicy-makersoftheFourthAssessmentReportoftheIntergovernmentalPanelonClimateChange(IPCC)statesunequivocallythatglobalwarmingisoccurringandthatitisverylikelycausedbygreenhousegasemissionsarisingfromhumanactivities.Itwarnsthat:

Continued greenhouse gas emissions at or

above current rates would cause further

warming and induce many changes in

the global climate system during the 21st

century that would very likely be larger

than those observed during the 20th

century.(IPCC,2007a,p.13)

Climatechangewillgeneratesignificantcoststobothdevelopinganddevelopedcountries.Suchcostswillincludeincreasedfrequencyandintensityofsevereweathereventssuchasfloods,tornadosandhurricanes;increaseddroughtinsomeregions;lossofcoastalareasandwatershortages;andchangesintheincidenceofdisease.Developingcountriesarelikelytobearaheavierburdenowingtotheirgreatervulnerabilityaswellastheseverityofchangestheyarelikelytoexperience.

Climatechangecouldresultinlarge-scalemigrationandconflicts,whichalsocarrysignificantcosts(Stern,2007).

TheIPCCFourthAssessmentReportalsonotestheimportanceofmakingimmediateandsignificantreductionsingreenhousegasemissions.Thereportstatesthatmitigationeffortsoverthenexttwotothreedecadeswilldeterminetoalargeextentthelong-termglobalmeantemperatureincreaseandthecorrespondingclimatechangeimpactsthatcanbeavoided(IPCC,2007b).Essentially,therearetwowaysofmitigatingclimatechange:reducingthesourceoftheemissionorincreasingtheamountofgreenhousegasstorageinterrestrialsystems(e.g.throughcarbonsequestration).Thus,agriculture’sroleinmitigatingclimatechangeistwofold:reducingitsownemissionsandenhancingtheabsorptionofgreenhousegases.

Agricultureisanotablesourceofthethreemajorgreenhousegases:carbondioxide,methaneandnitrousoxide.Carbondioxideismostsignificantinrelationtoglobalwarming,butmethaneandnitrousoxidealsomakesubstantialcontributions.Agriculturalactivitiesandland-usechangescontributeaboutone-thirdofthetotalcarbondioxideemissionsandarethelargestsourcesofmethane(fromlivestockandfloodedriceproduction)andnitrousoxide(primarily

Publicgoodsareaspecialcaseofexternalities(seeBox1).Theyaregoodsorservicesforwhichconsumptioncannotbeconfinedtoaparticularconsumerorgroupofconsumersandwhoseusebyoneconsumerdoesnotaffecttheusebyanother.Forexample,mitigatingtheimpactsofclimatechangeisabenefittoeveryoneintheglobalcommunity,anditisnotpossibletoexcludesomepeoplefromenjoyingthebenefiteveniftheydonotpayfortheservice.Atthesametime,oneperson’senjoymentoftheclimatechangemitigationbenefitdoesnotdetractfromanotherperson’senjoymentofthesamebenefit.Publicgoodscan

rangefromglobal(e.g.climatechangemitigation,biodiversityconservation)tolocal(e.g.floodcontrol).

Itisimportanttonotethat,whileservicessuchasclimatechangemitigationarepublicgoods,theresourcesthatprovidethem(e.g.forestlands)maywellbeprivatelyowned.Indeed,itisthisdistinctionthathelpsmotivatepaymentsforenvironmentalservices.

Source:FAO,2002b.

BOX2Public goods

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 1�

fromapplicationofinorganicnitrogenousfertilizer).

Agriculturealsoplaysanimportantroleasacarbon“sink”throughitscapacitytosequesterandstoregreenhousegases,especiallyascarboninsoilsandinplantsandtrees(seeFigure3).Carbonsequestrationinvolvesincreasingcarbonstorageinterrestrialsystems,eitheraboveorbelowground.Changesinland-andsoil-usepracticescantriggeraprocessofsoilcarbonaccumulationovertime.Eventually,thesystemwillreachanewcarbonstockequilibriumorsaturationpoint,andnonewcarbonwillbeabsorbed.Carbonsequestrationpresentsbothadvantagesanddisadvantagesasameansofmitigatingclimatechange.Themainadvantageisthatitisrelativelylow-costandcanbereadilyimplemented.Moreover,itprovidesmultipleassociatedbenefitsastheresultantincreaseinrootbiomassandsoilorganicmatterenhancewaterandnutrientretention,availabilityandplantuptakeandhence

landproductivity.Amajordisadvantageisthat,unlikeotherformsofclimatechangemitigation,carbonsequestrationisreversible;indeed,changesinagriculturalmanagementpracticescanaccelerateorreversethedegreeofsequestrationinarelativelyshorttimeframe.

Thephysicalpotentialtosequestercarbonvariesconsiderablybyland-usetypeandregion.Table1showsanestimateofcarbonsequestrationpotentialthroughland-usechangeforatotalof48developingcountriesoveraten-yearperiod.Thefiguressuggestthatsignificanttechnicalpotentialexistsforcarbonemissionsmitigationfromagriculture:almost2.3billiontonnes.Realizingthispotentialwouldrequirechangesinlandmanagementonanadditional50millionhectaresofland(Nileset al.,2002).Incomparison,95millionhectaresarecurrentlyfarmedusingconservationagriculturesystems,whichprovidesignificantsoilcarbonsequestration

FIGURE 3Above- and below-ground carbon sequestration

Decomposition

Litter fall

Soil organic matter pools

LeachingLeaching

Mineralization

Nutrient uptakeGaseous loss

BIOMASS AND NUTRIENT STORAGE

CO2

Source: FAO.

ABOVE

GROUND

BELOW

GROUND

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 71�

services(Derpsch,2005).Theeconomicfeasibilityoftherequiredland-usechangesisnotyetclear,althoughthereisgrowingevidencethatchangesinproductionsystemsleadingtocarbonsequestrationcouldalsoprovideothereconomicbenefits.

Potential for carbon sequestration in above-ground biomassAbove-groundsequestrationisachievedbyincreasingtheamountofbiomassabovegroundintheformoftreesandshrubs.Carbonsequestrationratesvarybytreespecies,soiltype,regionalclimate,topographyandmanagementpractice.Theadoptionofagroforestry,rehabilitationofdegradedforestsandestablishmentofforestplantationandsilvopastoralsystemscountamongthemanyland-usechangesthatcangenerateabove-groundcarbonsequestration.

Thecarbonsequestrationpotentialofaland-usesystemisdeterminedbytheaveragecarbonstoredinthatsystemduringarotationperiodrelevanttothetypeofgrowthinquestion.Carbonissequesteredwhenmovingfromsystemswithlowertohighertime-averagedstocks.Palmet al.(2005)estimatedtheannualaverageamountofcarbonstoredover20yearsundervariousland-usesystemsforthreesitesinthehumidtropics.TheyfoundthatachangefrommanagedandloggedforeststoundisturbedforestinIndonesiayieldedanetgainof213tonnesofcarbonperhectareoverthelifeoftheforest.Similarly,changingfromshortfallowtoimprovedfallowinBrazil

increasedcarbonsequesteredperhectareby4.6tonnesovereightyears.

Thehighestaverageamountofcarbonthatcanbesequesteredperhectareperyearisgenerallyobtainedbyexpandingforestareaviaafforestationorreforestation.Annualcropsandpasturesstoreasmallfractionofthatamount.Amountsachievedbyloggedforests,agroforests,treecrops,timberplantationsandsecondaryforestfallowsfallinbetween.Secondaryforestfallowsof20–30years,forexample,storearound75tonnesofcarbonperhectare,withsequestrationoccurringatanannualrateof5tonnesperhectareduringthefirsttenyearsofregrowth(FearnsideandGuimarães,1996).

Anyinterventionthatpreventsconversionfromahighertoalowercarbon-storinglanduse,orthatencouragesconversionfromalowertoahighercarbon-storinglanduse,willcontributetonetcarbonstorage.Thus,awiderangeofotherforestryandagroforestrysystemscanmakeameaningfulcontribution.Forexample,Poffenbergeret al.(2001)estimatedthat,withprotectionandassistedregeneration,dryforestsincentralIndiacoulddoubleperhectareratesofcarbonsequestrationfrom27.3to55.2tonneswithintenyearsinsecondaryforests,andincreasethemfrom18.8to88.7tonnesinoldgrowthforestafter50years,ataverymodestcost.

Potential for carbon sequestration below groundAllsoilscontainsomecarbon,depositedasdeadplantmaterialorinsomeinorganic

TAblE 1Potential carbon mitigation from land-use change, 2003–12

RegionAvoided

deforestation1Sustainable agriculture2

Forestrestoration3 ToTAl

(Million tonnes of carbon)

Africa 167.8 69.7 41.7 279.2

Asia 300.5 227.3 96.2 624.0

LatinAmerica 1097.3 93.1 177.9 1368.3

ToTAl 1 565.6 390.1 315.8 2 271.5

1Calculatedfromthemostrecentestimatesofannualforestlossmultipliedbyweightedcarbonstocks;assumesdeforestationratesremainconstant.2Includessoilcarbonsequestrationfromreducingtillageandincreasingsoilcover,conversionofannualcropstoagroforestsandimprovedgrasslandsmanagement.3Includesreforestingdegradedlandsandagroforestry,notplantations.Excludescarbonsequestrationinsoilsundergoingreforestation.

Source: adaptedfromNileset al.,2002.

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 1�

formsuchascalciumcarbonateorcarbondioxidedissolvedingroundwater.Theextentofadditionalcarbonthatcanbesequestereddependsbothonlocalgeophysicalconditionsandthecroppingsystem.

Map1presentsaglobalviewofareaswithsignificantpotentialtosequesteradditionalcarboninsoils.Thispotential,referredtoasthe“soilcarbongap”,indicateslocationswheresoilcarbonlevelsarecurrentlylowbutmedium-to-hightechnicalpotentialforsequestrationexists,dependingonsoiltype,climatesoilmoistureandlandcoverconditions.Itmustbestressedthatthismap,aswellasothermapspresentedinthisreport,isbasedonglobaldatabasesatacoarsescaleofresolutionandwithvariableaccuracy.Consequently,theresultspresentedcanonlysuggestlocationsthatshowpotentialforthevariousindicatorsconsidered.Country-levelstudiesandmoresophisticatedmodelswouldberequiredtoderivemoreaccurateestimates.

Map2indicatesthelocationofcroplandswithmedium-to-hightechnicalpotentialtosequestercarbon.Thismapprovidesa

preliminaryperspectiveonwherecroppingsystemscouldbechangedtoachievesubstantialsoilcarbonsequestration.Ithighlightstheintersectionoflocationswithmedium-to-highsoilcarbonsequestrationpotential(indicatedinMap1)andcroplands,asidentifiedbytheGlobalLandCover2000Project(GLC2000)database.3

Around30percent(4.7millionkm2)ofthelandcharacterizedbymedium-to-highpotentialforcarbonsequestrationislocatedinareaswhereagriculturalproductionispractised,representing15percentoftotalcroplandsasdefinedbyGLC2000.One-quarterofthisareaislocatedinAsiaandone-quarterinAfrica.

Whichtypesofchangestoagriculturalproductionpracticescouldincreasesoil

3 GLC �000 is a collaboration of partners around the world with the general objective to provide for the year �000 a harmonized land cover database over the whole globe. Croplands are defined by GLC land classes �6 (cultivated and managed areas), �7 (mosaic: cropland/tree cover/other natural vegetation) and �8 (mosaic: cropland/shrub or grass cover). Further details are available at http://www-gvm.jrc.it/glc�000/.

MAP 1Potential to sequester additional carbon in soils

Soil carbon gap

Note: available at http://www.fao.org/geonetwork/srv/en/google.kml?id=31151&layers=potential_sequester_carbonSource: FAO.

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 71�

carbonsequestration?Lasse(2002)providesalistofmanagementtechniqueswiththispotential,includingtheplantingofcovercrops,mulchfarmingcombinedwithzerotillage,andagroforestry.Someofthesepracticeswouldalsoincreaseabove-groundcarbonstocks.Reliableestimatesonhowmuchcarboncouldbesequesteredinsoilsundervariousmanagementpracticesandfarmingpatternsinthedevelopingworldarestillsparse.TheestimatesproposedbyLalet al.(1998)fortropicalareasareabouttwiceashighasthosefordrylands.

Theeffectsoncarbonsequestrationofmodificationstocroppingpracticescandifferdramaticallybypracticeandbylocation.StudiesinselectedlocationsinIndiaandNigeriasimulatingtheimpactofland-usechangesovera50-yearperiodsuggestthatundercurrentpracticessoilcarbonwillcontinuetodeclineataslowpace,butthatchangesinlandusecouldsignificantlyincreasesoilcarboninthelongterm(Figure4)(FAO,2004a).Therangeofsequestrationpotentialforthedifferentpracticesconsideredislarge,fromnegativeforcontinuouscultivationpracticesto

around40tonnesperhectarewiththeretentionofcropresiduesandsubstantialadditionoffarmyardmanure.Forthepracticeswiththehighestsequestrationpotential,carbonsequestrationcontinuesfortheentiredurationofthesimulationandeventhendoesnotreachequilibrium,suggestingthatcarbonsequestrationthroughchangesinagriculturalpracticesrequiresconsiderabletimeforthefullimpacttotakeeffect.

Water quantity and quality

Watershedprotectionservicesarephysicallydelimitedbywatershedboundaries.Incontrastwithcarbonsequestrationandmanybiodiversityconservationservices,therefore,theyareprimarilyofinteresttolocalandregionalusers(Landell-MillsandPorras,2002).

Water quantityWaterusehasgrownrapidlyoverthepastcentury,increasingmorethansevenfoldbetween1900and2000whilethehuman

MAP 2Potential to sequester additional carbon in soils on croplands

Other croplandsCroplands with soil carbon gap Other land with soil carbon gap

Note: available at http://www.fao.org/geonetwork/srv/en/google.kml?id=31152&layers=potential_sequester_carbon_croplandSource: FAO.

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 1�

populationgrewbyaboutafactoroffour(UNDP,2006).Despiteadeclineinpercapitaconsumptionsincethe1980s,globalwaterusecontinuestoincrease(ShiklomanovandRodda,2003).

Table2reportstwoindicatorsrelatedtotheuseoffreshwaterresources.The“watercrowdingindex”measuresthenumberofpeopleservedpermillioncubicmetresperyearofaccessiblerunoff.Therelativewateruseor“waterstressindex”expressestheratioofwaterwithdrawalstosupply.Atthegloballevel,currentwateruserepresentsabout13percentofannualsupply(MillenniumEcosystemAssessment,2005b)withanoverallupwardtrend,indicatingincreasingpressureonfreshwaterresources.

TheMillenniumEcosystemAssessment(2005b)projectsanincreaseof13percentintheglobalwatercrowdingindexby2010.ProjectionsreportedintheHuman Development Report 2006(UNDP,2006)

suggestthat,by2025,over3billionpeoplearelikelytobeexperiencingwaterstressand14additionalcountriesmightbeclassifiedaswater-scarce(i.e.havinglessthan1000cubicmetresperpersonperyear).

Mostwaterforhumanuseisdrawndirectlyfromriversorfromgroundwater.Thelattermayoriginatefromrenewableor“fossil”aquifers.Eachsourcepresentsitsownmanagementissues.Renewablegroundwaterisdirectlylinkedtothecyclingoffreshwaterthroughtheatmosphereandsoilsandisthusreplenishedbyprecipitationandcertainagriculturalpractices.Fossilgroundwaterisfoundindeepundergroundaquiferswithlittlelong-termnetrecharge.Theuseoffossilgroundwaterissimilartotheminingofminerals:onceextracted,it,effectively,cannotbereplacedasreplenishmenttimescanreachthousandsofyears(Margat,1990).

7

Futchimiram, NIGERIA Lingampally village, INDIA

FIGURE 4Changes in soil carbon for different cropping systems

Current practiceCurrent practice

Total soil carbon (tonnes/ha) Total soil carbon (tonnes/ha)

0

1950 1975 2000 2025 2050 1950 1975 2000 2025 2050

10

20

30

40

0

10

20

30

40

50

60

70

YEAR YEAR

Source: FAO, 2004a.

LAND-USE PRACTICES

1 Current practice: extensive agropastoral with slash and burn

2 Continuous cultivation 3 100 kg/ha urea, no grazing residues 4 Five-year fallow, five-year cultivation, two applications

farmyard manure (FYM) 3 tonnes/ha, grazing residues 5 Continuous cultivation, FYM 1.5 tonnes/ha/year,

grazing residues 6 Continuous cultivation, FYM 1.5 tonnes/ha/year,

plant residues 0.5 tonne/ha/year, no grazing

LAND-USE PRACTICES

1 Current practice: rainfed cropping, FYM applied at 3.9 tonnes/ha/year

2 FYM 3 tonnes/ha/year 3 FYM 3 tonnes/ha/year, green manure 500 kg/ha/year,

vermicompost 250 kg/ha/year4 As current practice but incorporating crop residues

into soil 5 FYM 3 tonnes/ha/year, leave plant residues 6 FYM 3 tonnes/ha/year, plant residues, green manure,

vermicompost7 FYM 6 tonnes/ha/year, plant residues, green manure,

vermicompost

43

12

6

5

213

54

6

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 720

Inadditiontodirectextractionfromriversandaquifers,threeothertechnologiesareusedtoincreasefreshwateravailability:damsandotherartificialimpoundments,desalinizationofoceanwaterandlocalizedrainwaterharvesting.Desalinizedwatercurrentlysupplieslessthan1percentofglobalwaterconsumption.Waterharvestingreferstoanumberoftechnologies,traditionalandmodern,thateitherharvestsurfacerunofforincreasewaterinfiltration.Theseincludewaterchannelsanddamstocatchandconveywater,techniquestoincreasesoilmoisturecontent,andreservoirsforirrigationandhouseholduseandtoreducefloodpeaks.

Agricultureaccountsforabout70percentofallwateruseworldwideandupto95percentinmanydevelopingcountriesandthusinfluencesboththequantityandqualityofwateravailableforotherhumanuses(FAO,2007b).Changesinagriculturalpracticescouldcontributetowaterquantitybypromotingtherechargeofgroundwateraquifers,butperhapsthemostimportantcontributionagriculturecouldmaketoimprovingthequantityandqualityofavailablewaterresourcesisthroughmoreefficientuseofthewateritrequires.Afurtherpossibilityisthereuseofwastewaterforagriculturalpurposes;currently,about2millionhectaresareirrigatedusingthismethod(ComprehensiveAssessmentofWaterManagementinAgriculture,2007),andthepotentialexiststoincreasethisareasignificantly.

Prettyet al.(2006)analysed144projectsindevelopingcountrieswhereacombinationofresource-conservingmanagementpractices,suchasintegratedpestandnutrientmanagement,conservationtillageandagroforestry,hadbeenintroduced.Itwasfoundthatthesepracticesalsoprovideanotableimprovementinwaterproductivity,especiallyforrainfedagriculturalsystems.Averageincreasesinwaterproductivityrangedfrom16percentforirrigatedriceand29percentforirrigatedcottonto70percent,102percentand108percentforrainfedcereals,legumes,androotsandtubers,respectively.

Numerousstudieshaveestablishedthepositiveimpactofzerotillageonwaterinfiltrationcapacity,soilmoisturecontent,soilerosionandwater-holdingcapacity.IntheUnitedStatesofAmerica,forexample,no-tillsystemswerefoundtoreducewaterrunoffby31percent;increasewaterinfiltration,dependingonsoiltype,bybetween9percentand100percent;andreducesoilerosionbyupto90percent,whichinturnreducedsedimentloadsinriversandpollutantsinwaterbodies(Hebblethwaite,1993).AlsoGuo,ChoudharyandRahman(1999)reportedimprovedpercolationowingtobettersoilstructureinno-tillsystems,whichresultedindecreasedsoilerosion.InvariousBrazilianlocations,soillosseswerereducedbyupto87percentunderconservationagriculture,whilerunoffwasreducedbyupto66percentunderwheat–soybeanrotations(SaturnioandLanders,1997).

TAblE 2Indicators of freshwater provisioning services, 2010

Geographic region/country groupingWater crowding index Water stress index

(People/million m3/year) (Percentage)

Asia 391 19

LatinAmerica 67 4

NorthAfrica/MiddleEast 2020 133

Sub-SaharanAfrica 213 3

FormerUnionofSovietSocialistRepublics 161 20

OECDcountries 178 20

WoRlD ToTAl 231 13

Note: Thesefiguresarebasedonmeanannualconditions.Thevaluesfortherelativeusestatisticsshownrisewhenthesubregionalspatialandtemporaldistributionsofrenewablewatersupplyanduseareconsidered

Source:FromEcosystems and human well-being: current state and trends bytheMillenniumEcosystemAssessment.Copyright©2005bytheauthor.ReproducedbypermissionofIslandPress,Washington,DC.

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 21Theexactquantificationofaquifer

rechargethroughimprovedwaterinfiltrationrequiresfurtherresearch.Todate,thereismainlyanecdotalevidencethattheintroductionofconservationagricultureandothersoilandwaterconservationpracticesimproveswatershedservices.InthestateofParaná,Brazil,itwasreportedthat,aftertheintroductionofano-tillsystem,apondthathadbeenhabituallydryformostpartsoftheyearhadrefilledandthatthenearbyriverhadbeguntocarrywateralsointhedryseason(FAO,2003b).InIndia,AgarwalandNarain(2000)reportedthattheAvariandRuparelriversbegantocontainwaterallyearroundafterasetofwater-harvestingpracticesandsoilconservationmeasureswereimplementedinthewatersheds.With

respecttolivestockmanagement,rotationalgrazing,improvedlivestockdistributionandincreasedtreecoveronpastureshavebeenfoundtoimprovewaterrecharge(FAO,2006a).Nevertheless,moreresearchisneededontheexactrelationshipsandtimelagsbetweentheintroductionofimprovedagriculturalmanagementforwaterconservationandimprovementsinwaterquantity.

Table3summarizesinqualitativetermsthelikelyimpactsofmajorchangesinlanduseonwateravailability.Unfortunately,thehydrologicalrelationshipsbetweenlanduseandthegenerationofmoreandcleanerwaterarecomplexandsite-specific,andscientificevidenceisoftenlacking(RobertsonandWunder,2005;FAO,2004b).

TAblE 3brief overview of hydrologic consequences associated with major classes of land cover and use change

TyPE oFlAnD-USE CHAnGE

ConSEQUEnCES on FRESHWATERPRovISIonInG SERvICE ConFIDEnCE lEvEl

natural forestto managed forest

Slightdecreaseinavailablefreshwaterflowandadecreaseintemporalreliability(lowerlong-termgroundwaterrecharge)

Likelyinmosttemperateandwarmhumidclimates,buthighlydependentondominanttreespecies

Adequatemanagementpracticesmayreduceimpactstoaminimum

Forest topasture/agriculture

Strongincreaseinamountofsuperficialrunoffwithassociatedincreaseinsedimentandnutrientflux

Decreaseintemporalreliability(floods,lowerlong-termgroundwaterrecharge)

Verylikelyatthegloballevel;impactwilldependonpercentageofcatchmentareacovered

Consequencesarelesssevereifconversionistopastureinsteadofagriculture

Mostcriticalforareaswithhighprecipitationduringconcentratedperiodsoftime(e.g.monsoons)

Forest to urban

Verystrongincreaseinrunoffwiththeassociatedincreaseinpollutionloads

Strongdecreaseintemporalreliability(floods,lowerlong-termgroundwaterrecharge)

Verylikelyatthegloballevelwithimpactdependentonpercentofcatchmentareaconverted

Strongereffectswhenlowerpartofcatchmentistransformed

Mostcriticalforareaswithrecurrentstrongprecipitationevents

Invasion by specieswith higher

evapotranspiration rates

Strongdecreaseinrunoff

Strongdecreaseintemporalreliability(lowlong-termgroundwaterrecharge)

Verylikely,althoughhighlydependentonthecharacteristicsofdominanttreespecies

ScarcelydocumentedexceptforSouthAfrica,AustraliaandtheColoradoRiverintheUnitedStatesofAmerica

Source:FromEcosystems and human well-being: current state and trends bytheMillenniumEcosystemAssessment.Copyright©2005bytheauthor.ReproducedbypermissionofIslandPress,Washington,DC.

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 722Moststudiesinthisareahavefocusedontheimpactsofforestprotectionandreforestationintheproximityofwatersources,buteveninthesestudiestheresultshaveoftenbeenambiguous.Increasingtreecovercanreduce,aswellasincrease,theavailabilityofwater.Becauseatypicalwatershedisaffectedbytheactivitiesofmanyfarmers,improvedagronomicpracticeswouldneedtobeadoptedwidelyinordertohaveameasurableimpact,andthelong-termmonitoringneededtoassessthechangesinlargewatershedscanbecostly.Nevertheless,althoughscientificevidenceontheinfluenceofimprovedmanagementonwaterlevelsandgroundwaterrechargeisscarce,researchhasclearlyestablishedtheopposite–thatsoildegradationanddeforestationcausewatertablestodecline.

Map3(p.23)showscroplandsinSouthAsiaandSoutheastAsiawithhighlevelsofsheeterosion,indicatingpotentialoff-siteimpactsintheformofsiltationandsedimentationinwaterways.ThemapisbasedonthefindingsoftheAssessmentoftheStatusofHuman-InducedSoilDegradationinSouthandSoutheastAsiaconductedbetween1994and1997bytheInternationalSoilReferenceandInformationCentre(ISRIC)andFAO(vanLyndenandOldeman,1997).Notalltheareasshownwillnecessarilyhavethepotentialtoplayastrongroleinprovidingwatershedservicesthroughland-usechange,dependingontheirlocationwithrespecttohydrologicalfunctions,butthosethatdoarestilllikelytorepresentasignificantareaandaconsiderablenumberofagriculturalproducers.

Water qualityTheUnitedNationsEconomicCommissionforEurope(UNECE)definedwaterqualityasthe“physical,chemical,andbiologicalcharacteristicsofwaternecessarytosustaindesiredwateruses”(UNECE,1995,p.5).Mostaquaticspeciesareabletoadapttonaturalchangesinwaterquality,buthumanactivitieshaveaddedpollutantsthatthreatenmanyspeciesandrequiretreatmenttosupplypotablewater.

Mostofthehumanimpactsonwaterqualitygloballyhaveoccurredoverthelast

century(MillenniumEcosystemAssessment,2005b).While,inthepast,themainsourcesofcontaminantscomprisedorganicandfaecalpollutionfromuntreatedwastewater(thiscontinuestobethecaseinmanydevelopingcountries),today,themostprevalentcontaminantscanbetracedtoagriculturalandindustrialproduction.Withinagriculture,contaminationassociatedwithsoilerosion,nutrientrunoffandpesticidespredominate.Livestockproductionisamajorsourceofpollutioninmanycountries,withnutrientcontaminationfromwastesrepresentingagrowingproblem(FAO,2006a).Adistinctionshouldbemadebetweenpointsourcepollution(aspecific,confineddischargeofpollutantsintoawaterbody)andnon-pointsourcepollution(amorediffusedischargeofpollutants).Inmostcases,agricultureisanon-pointsourceofpollution,wheretheexactsourcesarediffuseanddifficulttodetect.Anexceptionislarge,highlyconcentratedlivestockoperationswhereimpactscanbetracedbacktoanidentifiablesource.

Improvingwaterqualitythroughchangesinagriculturalproductionsystemsgenerallyinvolvesreducingsalinizationandharmfulrunofffromagriculturalfieldsintheformofsoilerosion,pesticidesandotheragriculturalchemicalsorlivestockwaste.Onemeansistheimprovementofnutrient-useefficiencybymatchingmorecloselytheapplicationoffertilizerswiththecapacityofplantsfornutrientuptake.Soiltestingandimprovedtimingoffertilizerapplication,aswellastheuseofcovercropsandreducedtillage,areallusefulmeansforthispurpose(Tilmanet al.,2002).Measurestoimprovethemanagementoflivestockwastecanalsocontributetoenhancedwaterquality.Suchmeasuresincludechangesintheproductionprocess(feedmanagement)andthecollection,storage,processingandutilizationofmanure(FAO,2006a).

Asuccessfulexampleofmeasurestoreducenon-pointsourcewaterpollutionfromlivestockproductionisfoundinFrance.TheVittelbottledwatercompanyenteredintoagreementswithfarmers,encouragingthemtomodifytheirland-managementpracticestoreducenitratesinthewatersource(Perrot-Maître,2006).Themodifiedfarmingpracticesincludedtheelimination

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 2�

ofmaizecultivationforanimalfeedandapplicationofagrochemicals,theuseofextensivecattleranchingwithreducedanimalnumbers,andthemodernizationoffarmbuildingstominimizenutrientrunoff.

Asthisexampleillustrates,measurestoreducepollutioncausedbylivestockproductioninvolvechangesbothtocroppingpracticesinfeedproductionandtotechniquesforraisinglivestock.Thepollutantsconcernedincludenutrientexcretionsofexcesslevelsofnitrogen,phosphorusandheavymetals.Livestockwastecanalsoincludeavarietyofmicro-

organismsthatareapotentialhazardtohumanhealth.

biodiversity conservation

TheConventiononBiologicalDiversity(CBD)definesbiologicaldiversityas“thevariabilityamonglivingorganismsfromallsourcesincluding...terrestrial,marineandotheraquaticecosystemsandtheecologicalcomplexesofwhichtheyarepart;thisincludesdiversitywithinspecies,amongspeciesandofecosystems”(CBD,1993,Article2).

MAP 3Croplands with high rates of human-induced erosion

Other lands with high rates of human-induced sheet erosion

Croplands with high rates of human-inducedsheet erosion

Other croplands

Note: available at http://www.fao.org/geonetwork/srv/en/google.kml?id=31153&layers=croplands_humaninduced_erosionSource: FAO.

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 72�Biodiversityiscommonlymeasuredat

thegenetic,speciesandecosystemlevels,althoughitisdifficulttodefine“unitsofbiodiversity”forthepurposeofcarryingouttransactions.Withinanyofthesethreelevels,conservationofbiodiversityinvolvesmaintainingthefollowingdimensions(MillenniumEcosystemAssessment,2005b):• variety, reflectingthenumberof

differenttypes;• quantity and quality, reflectinghow

muchthereisofanyonetype;• distribution, reflectingwherethat

attributeofbiodiversityislocated.TheMillenniumEcosystemAssessment

concludedthathumanactivitieshaveledtoamorerapidlossofbiodiversityonEarthoverthepast50yearsthaneverbeforeinhumanhistory.Itidentifiedfivekeydriversofbiodiversityloss:habitatchange,climatechange,invasivealienspecies,overexploitationandpollution.TheAssessmentarguedthatthelossofspeciesandtheprogressivehomogenizationofmanyecosystemscontinuestobeoneofthemainthreatstothesurvivalofournaturalaswellassocio-economicsystems(MillenniumEcosystemAssessment,2005b).

Thebiodiversityassociatedwithagriculturalecosystemsisknownasagriculturalbiodiversity,andisgenerallyregardedasthemultitudeofplants,animalsandmicro-organismsatgenetic,speciesandecosystemlevels,indispensableinsustainingkeyfunctionsforfoodproductionandfoodsecurity(CBD,2000).Itprovidesthebasisofthefoodsecurityandlivelihoodsofeveryone(FAO,1997).

Agriculturalbiodiversityistheoutcomeoftheinteractionsamongtheenvironment,geneticresourcesandthemanagementsystemsandpracticesusedbyfarmersandistheresultofcarefulselectionandinventivedevelopmentovermillennia.Itincludesgeneticdiversityofcropsandlivestockaswellascrop-associatedbiodiversity(e.g.pest-suppressivebiodiversitypollinators,soilbiodiversity).

Concernshavebeenraisedinrecentyearsoverthelossofagriculturalbiodiversitythroughhomogenizationofagriculturalproductionsystems(FAO,1997).Forcropandlivestockgeneticdiversity,twomajorconcernshavebeenvoiced:increasing

levelsofgeneticvulnerabilityandgeneticerosion(FAO,1997).Geneticvulnerabilityoccurswhereawidelyusedcroporlivestockvarietyissusceptibletoapestorpathogenthatthreatenstocreatewidespreadcroplosses.Geneticerosionisthelossofgeneticresourcesthroughtheextinctionofalivestockvarietyorcrop.Themaincauseofgeneticerosionisthereplacementofindigenousvarietieswithimprovedones.Lossofecosystemservicesusefultofoodsecurityisafurtherconcern.Withoutpropermanagementofagriculturalbiodiversity,somekeyfunctionsoftheagro-ecosystemmaybelost,suchasmaintenanceofnutrientandwatercycles,pestanddiseaseregulation,pollinationandlanderosioncontrol.

Theconservationofcropandlivestockgeneticdiversitymaybeensuredeitherex situorin situ.Ex situmethodsincludeseedandgenebanks,whilein situconservationtakesplaceinfarmers’fields,pondsorforests.Thetwoapproachesarecomplementary;theex situcollectionspreserveastaticsetofgeneticresources,whilein situeffortspreserveadynamicprocessofevolution,asgeneticresourcesadapttochangingpressuresfromnaturalandhumanselection.

Theapproachesusedtoconserveagriculturalbiodiversitylinkconservationtosustainableusebyhumans.Giventhespecificfeaturesofagriculturalbiodiversity,themechanismsandtoolsusedtoguaranteeitssustainablemanagement,includingconservation,areoftenspecificanddifferfromthosetraditionallyusedforwildbiodiversity(suchasprotectedareas).

Howcanagriculturalproducersconservebiodiversity?Thenecessarymeasuresdependnotonlyonthetypeofbiodiversitytobeconservedbutalsoonproductionsystemsandlocation.Thesectionsthatfollowexplorethreemainwaysinwhichagriculturalproducerscancontributetobiodiversityconservation:reducingagriculturalexpansionintobiodiversity-richlands;adoptingagriculturalproductionsystemsthatsupportthejointproductionofbiodiversityconservationandagriculturalproducts;andconservingagriculturalbiodiversity.

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 2�Minimizing agricultural expansion into areas rich in wild biodiversity Agriculturecancontributetowildbiodiversityconservationbyrefrainingfromusinglandandwaterresourcesthatarerichinspeciesdiversity.Thisapproachincludesbothmaintainingareaswithrelativelyundisturbedecosystemsandretiringlandorwaterareascurrentlyinproductionlocatednearspecies-richareas,especiallyiftheyhavelimitedsuitabilityforagriculture.Theseareascanthenbeincorporatedintoprotectedareassuchasnationalparksandreserves,whicharethecornerstonesofwildbiodiversityconservation.Theapproachmayalsoinvolveeliminating,reducingorimprovingagriculturalproductionpracticesandoveralllandmanagementinareasthathavebeenidentifiedasimportant“corridors”forwildlifemigrationandecosystemconnectivity.

Map4isoneofseveralgeneratedbyastudyofland-usechangeintheneotropics(Wassenaaret al.,2007)andprovidesanindicationofareasatriskofconversiontoagricultureinpartsofSouthAmerica.Thestudyidentifiedtheareasathighestriskofconversiontopastureandcroplandsusingamodelthatexplicitlyincorporatesdimensionssuchaslocation,suitabilityandvariousfactorsaffectingtherelativeeconomicvaluesoflanduses.Themapidentifiesdeforestationhotspotareasinred(atriskofconversiontopasture)andorange(atriskofconversiontocropland).ManyoftheecoregionsthatwouldbeaffectedbytheprojecteddeforestationarepartoftheWWF(WorldWideFundforNature)Global200priorityecoregions(acollectionofthemostbiologicallydiverseandrepresentativehabitatsonearth)andothersfallintotheConservationInternationalbiodiversityhotspotzones(Wassenaaret al.,2007;WWF,2007).Theseareareaswherecropandlivestockproducerscouldsupplysignificantbiodiversityconservationservicesbyavoidingtheirconversiontoagriculturaluseorbyfacilitatingconservationinagriculturalareas(e.g.byprovidingwildlifecorridorslinkinghabitatareas).

Conserving wild biodiversity in agricultural ecosystems Agriculturalproducerscanalsoconservebiodiversitywithinagriculturalecosystems.

McNeelyandScherr(2002)outlineasetofpossiblemeasures:

1.enhancewildlifehabitatonfarmsandestablishfarmlandcorridorsthatlinkuncultivatedspaces;

2.mimicnaturalhabitatsbyintegratingproductiveperennialplants;

3.usefarmingsystemsthatreducepollution;

4.modifyresourcemanagementpracticestoenhancehabitatqualityinandaroundfarmlands.

AnexampleofthefirstcaseisfoundinCostaRica,wherewindbreaksformedbyplantingamixofindigenousandexotictreespecieswereestablishedon150hectaresspanning19farmingcommunities.Thewindbreaksservedasbiologicalcorridorsconnectingremnantforestpatchesinthearea,andtheyalsobenefitedfarmersbyreducingwinddamage(McNeelyandScherr,2002).Otherexamplesthatcouldfallintothiscategoryincludetheestablishmentofhedgerowsandagroforestry.Schrothet al.(2004)provideacomprehensivereviewoftheroleofagroforestryforconservingbiodiversitybyprovidingcorridorsandnewhabitatforwildspecies,amongothermeasures.

Shade-growncoffeeisaprominentexampleofthesecondtypeofstrategy.Shade-growncoffeeisproducedundertheshelterofacanopyoftreesofvaryingheights,providinganenvironmentthattendstobeattractivetomigratorybirds.Incontrast,coffeegrownunderconventionalsystemshaslowlevelsofbiodiversity(PagiolaandRuthenberg,2002).

Manyexamplesexistthatcanillustratethethirdcategory,thatofachangeinfarmingpracticestoreducepollution.InVietNam,ricefarmers’overuseofpesticideswasgeneratingoff-farmpollutionthatharmedlocalhabitats.Aneducationcampaignledtoreducedpesticideuse,benefitingthemanyspeciesoffrogsandfishthatinhabitricepaddies.InChina,intensivepesticideusetocontrolthericeblastdiseasewassubstantiallyreducedbyplantingadiversesetofricevarieties.InthePhilippines,soilerosionandsubsequentpollutionofwaterwayswereavoidedbyintroducingnaturalvegetationcontourstrips(McNeelyandScherr,2002).

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 72�

Thereintroductionofshort-term(overonetotwoyears)improvedfallowsystemsintosmallholderagriculturalsystemsinKenyaandZambiaprovidesanexampleofthefourthcategory.Thismeasurenotonlyhelpedtorestoresoilfertilitybutalsoprovidedahabitatforwildspecies(McNeelyandScherr,2002).

Incertainareas,silvopastoralpracticescanofferanalternativetocattleproductionsystemsbasedsolelyonpasture.Such

practicesincludeplantinghighdensitiesoftreesandshrubsinpastures,cut-and-carrysystemswherebylivestockarefedwiththefoliageofspecificallyplantedtreesandshrubsinareaspreviouslyusedforotheragriculturalpractices,andusingfast-growingtreesandshrubsforfencingandwindscreens(Pagiolaet al.,2007).Theon-sitebenefitsofsilvopastoralpracticestolandusersincludeadditionalproductionfromthetreecomponent,suchasfruit,fuelwood,

MAP 4Projected expansion of cropland and pasture, 2000–2010

Pasture expansionCropland and pasture expansion

Grazed pastureCroplandCropland expansion ForestNon-survey area

Note: available at http://www.fao.org/geonetwork/srv/en/google.kml?id=31154&layers=cropland_pasture_expansionSource: Wassenaar et al., 2007.

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 2�

0 2 4 6 8 10

Silv

op

asto

ral s

yste

ms

Number of bird species observed

Natural pasturewithout trees

Improved pasturewithout trees

Natural pasturewith low tree density

Improved pasturewith low tree density

Fodder bankwith woody species

Fruit orchards(multiple species)

Natural pasturewith high tree density

Improved pasturewith high tree density

Source: Pagiola, 2006.

FIGURE 5Biodiversity impact of adopting silvopastoral systems in Esparza, Costa Rica

fodderortimber;maintainingorimprovingpastureproductivitybyincreasingnutrientrecycling;anddiversificationofproduction(DagangandNair,2003).

AsFigure5illustrates,silvopastoralpracticesalsohaveimportantbiodiversitybenefits.Theyhavebeenshowntoplayamajorroleinthesurvivalofwildlifespeciesbyprovidingscarceresourcesandrefuge;tohaveahigherpropagationrateofnativeforestplants;andtoprovideshelterforwildbirds.Theycanalsohelpconnectprotectedareas(Dennis,ShellardandAgnew,1996;HarveyandHaber,1999).Inaddition,silvopastoralpracticescanfixsignificantamountsofcarboninthesoilandinthestandingtreebiomass(Fisheret al.,1994;Pfaffet al.,2000)andhaveabeneficialeffectonwaterservices(Bruijnzeel,2004).

Conserving agricultural biodiversity Awiderangeofmethodsexistforconservingagriculturalbiodiversity,dependingonthespecificcomponentthatisfocusedupon.Methodsdifferintermsofthedegreeofhumaninterventioninthenaturalsystem,rangingfromhighlymanagedex situgeneandseedbankstomaintainingwildrelativesofcultivatedspeciesinwildernessareas.Measuresalsoincludetheon-farmconservationandutilizationofso-called

“landraces”,ortraditionalvarietiesofcropsandlivestock,whichareoftenhighlyadaptedtotheirlocalenvironments.Diversitycanbepromotedbyprovidingincentivestomaintainaheterogenoussetofcropvarietiesinproduction,particularlyrarelandracevarieties,orbymanagingfieldmarginstoencouragepest-suppressingnaturalenemiesandpollinators.Jarvis,PadochandCooper(2007)provideanextensiveoverviewofthetoolsusedbyfarmerstoconserveandfurtherdevelopbiodiversityintheirfields.

Becauseagriculturalbiodiversityisdirectlylinkedtoagriculturalproduction,workingwithinagriculturalmarketchannelstoprovideincentivestofarmerstoconserveagriculturaldiversityisanimportantstrategy.Inrecentyears,theinternationalcommunityhasprovidedsupporttofarmersforconservingagriculturalbiodiversityin situ.Theseprogrammesseektoincreasetheavailabilityandproductivityofdiversityinproductionsystems,orenhancethereturnstomaintainingdiversesystems.Increasingthedemandfordiverseproductsthroughtheestablishmentoflabelling,certificationororiginschemesandnichemarketdevelopmentisonestrategy(BioversityInternational,2006).Increasingthediversityofagriculturalseedsupplysystemsisanother(FAO,2006b).Oneexamplethatinvolves

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 72�directpaymentstofarmersformaintainingdiversecropvarietiesistheGEF-fundedproject“ADynamicFarmer-BasedApproachtotheConservationofAfricanPlantGeneticResources”implementedinEthiopiafrom1992to2000(GEF,2007a).

other environmental services agricultural producers can supplyThesectionsabovehavefocusedonthreedifferent,butveryimportant,environmentalservices.However,itshouldbeunderlinedthat,apartfromthese,agriculturalproducerscananddosupplymanyotherenvironmentalservices.Landscapeaestheticsisoneservicefromwhichsomefarmersarealreadyreceivingsignificanteconomicbenefitsintheformofecotourismandagrotourism(Box3).Otherservicesforwhichsomefarmersarebeingpaidincludepollinationservicesandreductioninthespreadofanimaldiseases,

cropdiseasesandinvasivespecies.Forexample,somefarmersinaffectedareashavereceivedpaymentstocullchickensasameasuretopreventthespreadofavianinfluenza.

Importance of scale, location and coordination in supplying environmental services

Astheabovediscussionhasshown,agriculturalproducerscanimplementnumerouschangestoimprovethebalanceofservicesprovidedbyagriculturalecosystems.Thefocushasbeenonthechangesthatindividualfarmerscanmaketoincreasethesupplyofeachofthreeenvironmentalservices.However,particularlyincasesofwatershedmanagementandbiodiversityconservationservices,bothscaleandlocation

BOX3landscape aesthetics

Managinglandscapeaestheticsisanotherenvironmentalserviceforwhichmarketsaredeveloping,butwhichisnotcoveredindetailinthisreport.Landscapeaesthetics,or“ruralamenities”,involvesthepleasurepeoplegainfromseeing,visitingorevenknowingoftheexistenceofcertainlandscapefeatures.Thepleasurecancomefromnovelty(watchingageysererupt),diversity(ahillsidecultivatedusingavarietyofpractices),naturalbeauty(vistasoftheHimalayas),culture(visitstoasacredplace)orthecontinuedexistenceofanendangeredspeciesinafar-awayplace.

Landscapesthushavedistinctvaluesinthemselvesthatcanbeofdifferenttypes.Peoplemaybeinterestedsimplyinensuringthecontinuingexistenceofcertainlandscapes,habitatsorecosystems,eveniftheyarenotbenefitingfromthemdirectlyinanyotherway.However,landscapescanalsohavemoredirectusevalues,exploitedthroughactivitiessuchasnaturetourism,ecotourismoragritourism.Naturetourismisanyvisittoalocationwiththeprimarygoalofappreciatingsomeelementofnature.Theterm

“ecotourism”,inthiscontext,isusedtodescribevisitstoplaceswithuniquefloraandfauna,suchastheAmazonwatershedortheSerengetiPlains.Agritourism(oragrotourism)involvesvisitstolandscapeswherehumanshavepractisedagricultureinwaysthatresultinattractivesceneryanddistinctiveproductsandcuisine.

Provisionoflandscapeaestheticsservicesoftenhasimportantsynergieswiththeprovisionofotherenvironmentalservices,especiallyconservingbiodiversity.Somedestinationsaresetuptoallowvisitorstoseeuniquecollectionsofdiversespecies.Manyofthesedestinationsareprotected,whichincreasesthelikelihoodthattheywillmaintainspecieslostinsurroundingareasorregulatewaterqualityandquantity.Naturetourismcanenhancetheconservationofbiologicaldiversity,especiallywhenlocalcommunitiesaredirectlyinvolvedwithtourismoperators.Iflocalcommunitiesreceiveincomedirectlyfromatouristenterprise,theyaremorelikelytoprovidegreaterprotectionfor,andconservationof,localresources.

Agriculturecanhavedistinct,butdiffering,rolesinensuringtheprovision

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S 2�arehighlyrelevantfortheeffectivenessofthechanges,whichinturnhasimplicationsforcoordinationrequirements.Indeed,changesonthepartofoneproduceraimedatimprovingahabitatorreducingerosioninawatershedareunlikelytobesufficienttoprovidetheseenvironmentalservices,unlesstheproducercontrolsalargeproportionofthelandandwaterresourcesimportantfortheserviceprovision.Thismeansthatconsideringchangeatalandscapelevelisasimportantasitisatthescaleoftheindividualproductionunit.Italsomeansthattheeffectivenessofanygivenchangemaydependcriticallyoncoordinatingtheactionsofanumberofproducers.

Table4(pp.30–31)summarizesasetofmanagementchangesagriculturalproducerscanimplementtoincreasethesupplyofthethreeenvironmentalservicesunderdiscussion.Itpresentstheminthecontext

alsooftheassociatedlandscape-levelmanagementandthedegreeofcoordinationamongproducersrequiredforeffectivesupply.

Technical versus economic potential to supply environmental services

Theprecedingsectionshavediscussedthetechnicalpotentialforagriculturetoprovideenvironmentalservices.This,essentially,tellsushowmuchofanenvironmentalservicefarmerscould provide,butitisimportanttorecognizethatthisisnotthesameaswhattheyare likely to provideintheabsenceofadditionalincentives.Thedistinctioncorrespondstothedifferencebetweenthetechnicalandeconomicpotentialforsupplyingenvironmentalservices.

oflandscapeaestheticsservices.Theserolesrangefrombringingormaintainingspecificareasorlandscapesunderagriculturalproductiontomanaginglandsunderagriculturalproduction.Farmersmaynotnecessarilytakeintoaccountthattheirlandmayprovideruralamenitieswhenmanaginganddecidinghowtodevelopit.Indeed,inseveraldevelopedcountries,theprovisionofruralamenitiesisoneofthemainmotivationsbehindtheimplementationofvariouspubliclyfundedfarmlandprotectionprogrammes(NickersonandHellerstein,2003).

Thereisanincreasingprivatemarketforlandscapeaestheticsservices.Ecotourismisgrowingrapidly,drivenbyhigherincomesaroundtheworld,increasingeaseandfallingcostoftravelandexpandinginformation.Worldtourismspendingisexpectedtogrowover6percentperyear(UNWTO,1998,asreferencedinHawkinsandLamoureux,2001)andisincreasinglyfocusingonnaturalenvironments.

Theoverallsizeofthemarketforthelandscapeaestheticsandrecreationservicesthatagriculturallandscapesprovideseemslikelytoremainsmaller.

Paymentstofarmingcommunitiesarelikelytobelimitedtothoselivinginoradjacenttoareasofhightouristattraction.Inmanydevelopedcountries,asectorofthetourismindustryhasformedaroundpastoral,agrarianlandscapesandtheaestheticsandactivitiestheyoffer,butacomparableindustryhasnotyetformedindevelopingcountries.

Themostimportantbuyersoflandscapeaestheticsandrecreationalservicesarelikelytobeprivatetouroperatorsandrelatedbusinesses,eitherdirectlyorinaggregategroupsworkinginaparticularareaofhighscenicaesthetics.Privaterecreationalhuntersandfishersandprivateparkvisitorscouldalsobecomebuyersoflandscapeaestheticsandrecreationservices.Therearemanymodelsnowforusingpublicparkvisitorfeestobenefitcommunitygroupswhoprotectlandscapeandrecreationalvalues.Someofthesemodelscouldbecomesignificantinthefuture.

BOX3landscape aesthetics

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 7�0TAblE 4Management options and coordination requirements for three environmental services

EnvIRonMEnTAl SERvICEFARM-lEvEl

MAnAGEMEnT oPTIonSlAnDSCAPE-lEvEl

MAnAGEMEnT oPTIonS

DEGREE oFCooRDInATIon

REQUIRED1

Car

bo

n s

equ

estr

atio

n a

nd

gre

enh

ou

se g

as o

ffse

ts

Carbonsequestrationinsoils Soilorganicmattermanagementandenrichment,reducedfrequencyofcultivation,adoptionofconservationagriculture,soilconservationpractices,improvedgrasslandmanagement

Low

Carbonsequestrationinperennialplants

Increasedarea/useofperennialcrops,farmforestmanagement,agroforestry,naturalregeneration,lengthenedfallowperiods,silvopastoralsystems

Afforestation,naturalregenerationoftreesandforests

Low

Carbonemissionreduction Agriculturalmachineryemissionmanagement,avoideddeforestation

Reducedforestandfallowburning

Low

Methaneemissionreduction Improvedlivestockfeed,peatsoilmanagement

Protectionofpeatareasfromdisturbance

Low

Wat

ersh

ed p

rote

ctio

n

Waterflowregulation Increasedirrigation-useefficiency,protectionofwetlands,farmdrainage,rangemanagement

Well-designedroadandpathconstruction,revegetationofbarelands

Low

Waterqualitymaintenance Reducedagrochemicals,filteringofagriculturalrunoff,improvednutrient-useefficiency

Maintenanceofperennialvegetativefiltersprotectingwaterways

High

Erosionandsedimentationcontrol

Soilconservationandrunoffmanagement,perennialsoilcover,adoptionofconservationagriculture,rangemanagement

Road,pathandsettlementconstruction;revegetationofstreambanks

Moderate

Salinizationandwatertableregulation

Tree-growing Strategictree-growinginthelandscape

Moderate

Aquiferrecharge Plot-andfarm-levelwaterharvesting

Community/subwatershedwaterharvesting

Moderate

Floodcontrol Diversionandstorageponds

Drainagechannelsandstorageponds,maintenanceofnaturalfloods

High

Wild

bio

div

ersi

ty

con

serv

atio

n

Protectionofhabitatforwildterrestrialspecies

Breedingareaprotection,maintenanceofpurewatersources,wildfoodsourcesinandaroundfarmplots,timingofcultivation,increasedcropspecies/varietaldiversity

Naturalareanetworksinandaroundfarms,publicandprivateprotectedareas

Moderate

P A y I n G F A R M E R S F o R E n v I R o n M E n T A l S E R v I C E S �1

Forexample,fromapurelytechnicalperspective,improvedlandmanagementoverthenext50–100yearscouldtheoreticallymakeamajorcontributiontoglobalcarbonsequestration.Thus,Lal(2000)hasestimatedthattheannualincreaseinatmosphericcarbondioxideconcentrationcouldbebalancedoutbytherestorationof2billionhectaresofdegradedlandstoincreasetheiraveragecarboncontentby1.5tonnesperhectareinsoilsandvegetationthroughimprovedsoilmanagementpracticessuchasreducedtillageandfertilization(seealsoRasmussen,AlbrechtandSmiley,1998;Saet al.,2001).However,theactualamountofcarbonsequestrationthatfarmerswillsupplydependsonhowmuchtheywillbepaidforthesoilcarbonandonthecoststheywouldbearinsupplyingit.EconomicstudiesundertakenintheUnitedStatesofAmericashowthat,atcarbonpricesintherangeofUS$50–100pertonne,theeconomicpotentialfallsfarbelowthetechnical

potential(Lewandrowskiet al.,2004;Paustianet al.,2006).

Theeconomicpotentialforsupplyingenvironmentalservicesisacriticalcriterionwhenassessingtheeffectivenessofpaymentsforenvironmentalservicesinincreasingtheeconomicandenvironmentalbenefitsavailablefromagro-ecosystems.Asstatedintheopeningparagraphsofthischapter,thispotentialisafunctionoftheconditionsoftheagriculturaleconomyinquestion.Populationdensity,agro-ecologicalconditions,levelofmarketintegrationandprimarytechnologyemployedinagricultureareallimportantdeterminantsofthecurrentreturnstolandandlabourinagricultureandthepotentialcostsandbenefitsofintroducingchangesthatwouldgenerateadditionalenvironmentalservices.Thesesamefactorsalsoaffectthelevelofeconomicdevelopmentandthusthedemandandwillingnesstopayforenvironmentalservicesatthelocallevel.

EnvIRonMEnTAl SERvICEFARM-lEvEl

MAnAGEMEnT oPTIonSlAnDSCAPE-lEvEl

MAnAGEMEnT oPTIonS

DEGREE oFCooRDInATIon

REQUIRED1

Wild

bio

div

ersi

ty c

on

serv

atio

n

Connectivityformobilespecies

Farmhedgerows,windbreaks,removalofimpenetrablebarriers

Naturalareanetworksinandaroundfarms

Moderateto

high

Protectionofthreatenedecologicalcommunities

Restorationorprotectionoffarmpatchesofnaturalhabitat

Maintenanceofcorridorsconnectingnaturalhabitatfragmentsthroughfarmandotherlands

Moderateto

high

Protectionofwildspecies Eliminationofthreatsfromtoxicchemicals,breedingareaprotection,non-lethalpestcontrolpractices

Barrierstoexcludewildlifefromfarmlands,compensationtofarmersforwildlifedamagetostocksandcrops

Lowto

moderate

Protectionofhabitatforaquaticspecies

Preventionofwaterwaypollutionbycropandlivestockwastesandagrichemicals,protectionorrestorationofon-farmwetlands

Naturalrevegetationalongstreambanks,protectionorrestorationofwetlands

Lowto

moderate

1Reasonsforcoordinatedactionmayincludetheneedforcollectiveinvestments(e.g.toestablishacommunity-widewindbreak),theindivisibilityofinvestment(e.g.torestoreamajorgully),ortheneedforspatialcoordinationtoproducethedesiredoutcome(e.g.there-establishmentofriparianvegetationwouldonlyproducehigherwaterqualityifalllandownersalongthewaterwayparticipate).

Source:adaptedfromFAO,2007c.

TAblE 4 (cont.)

Management options and coordination requirements for three environmental services

T H E S T A T E o F F o o D A n D A G R I C U l T U R E 2 0 0 7�2Conclusions

Agriculturehasthepotentialtoincreasesignificantlytheprovisionofenvironmentalservicessuchasclimatechangemitigation,biodiversityconservation,watershedprotectionandothers,butthiswillrequirechangesinthewayinwhichagro-ecosystemsaremanaged.Howenvironmentalservicescanbegeneratedvariesbytheservice,thetypeofproductionsystemandtheagro-ecologicalcontext.Thetypesofchangeneededtoenhancetheprovisionofecosystemservicesrangefromshiftsinlandorwateruse(e.g.outofcropsorfishingandintolessintensiveusessuchasgrasslandsorforests)tochangeswithinagivenproductionsystem(e.g.theadoptionoffarmingsystemsthatprovidehigherlevelsofenvironmentalservices).

Thebiophysicalprocessesinvolvedindifferentecosystemserviceshavesignificantimplicationsforpolicyresponses.Forexample,therearenogeographiclimitsforcarbonemissionreductionsormitigation;atonneofcarbonsequesteredbyapoorfarmerhundredsofmilesfromanyroadhasexactlythesamevalueasatonnesequesteredbyacommercialplantationnearthecapitalcity.Incontrast,biodiversity

conservationandwatershedprotectionservicesaregenerallylocation-specific,withtheformerprovidingglobalbenefitsandthelatterbeingprimarilyofinteresttolocalandregionalusers.

Synergiesoftenexistbetweentheprovisionofdifferentecosystemservices.Productionpracticesadoptedtoenhanceoneecosystemservicemayenhanceothersatthesametime.Forexample,increasingsoilcarbonsequestrationthroughtheadoptionofconservationagriculturecanhavebeneficialimplicationsnotonlyforclimatechangemitigationandwaterqualitybutalsofortheprovisioningservicesoffoodproduction.However,thereareoftentrade-offsbetweenthedeliveryofdifferentecosystemservices,whichareimportanttounderstand.

Thischapterhasfocusedonthetechnicalpotentialofagriculturetosupplyenhancedlevelsofenvironmentalservices.Whetherthenecessarychangesareeconomicallyfeasibleiscentraltodeterminingiftheycanbeachievedandwhatlevelofpaymentswouldberequiredtorealizethem.Thenextchaptertakesuptheissueofdemandforenvironmentalservices:whowouldpayforenvironmentalservices,whywouldtheypayforthemandhowmuchwouldtheybewillingtopay?