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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?