Agricultural intensification and environmental degradation ...€¦ · intensification on the...
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Agricultural intensification and environmental degradation in the UK: a system dynamics approach John Dearing, David Armstrong Mackay, James Dyke, Guy Poppy University of Southampton Les Firbank University of Leeds EcoSummit 2016 Montpellier
Transcript of Agricultural intensification and environmental degradation ...€¦ · intensification on the...
AgriculturalintensificationandenvironmentaldegradationintheUK:asystemdynamicsapproach
John Dearing, David Armstrong Mackay, James Dyke, Guy Poppy
University of Southampton
Les Firbank
University of Leeds
EcoSummit 2016
Montpellier
AbstractHere,weadoptacomplexsystems,evolutionaryperspectivetothestudyofmodernagriculturalintensificationandecosystemservicesbasedonanalysesofdiversetimeseriescoveringthepastfewdecades.ThepaperdescribeschangeintwocontrastingagriculturalregionsintheUK,majority-arableEEnglandandmajority-pastoralSWEngland,sincethemiddleofthe20thcentury.
WefindthatsignificantdegradationofregulatingservicesoccurredinEEnglandintheearly1980s,reflectingaperiodofrapidintensificationandescalatingfertiliser usage,butthatregulatingserviceshavebeguntorecoversince2000mainlyasaresultoffertiliserusagedecouplingfromincreasingwheatyield.Soilerosion/suspendedsedimenttransportandatmosphericpollutionhavealsoimproved,butsomebiodiversitymetricscontinuetoworsen.
Overall,regionalGDPgrowthhasbeguntodecouplefromecologicaldeteriorationinrecentyears.WepresentresultsofaprototypedynamicalsystemsmodelofregionalUKagri-environmentsystemsthatseekstoidentifyfutureagriculturaltrajectoriesthatmaintainandimprovecurrenttrendsandtrade-offs:onesthatarebothresilienttosocial,economicandclimateimpacts,andenvironmentallysafe.
Researchquestions
Howtoaddress‘resilience’incontextofnationalagri-ecosystemsandfoodsecurity?
How’resilient’istheUKagroecosystem?
Canevolutionary/systemsapproachesovercomelimitationsofconventionalmodels?
Canwesimulate‘nearfuture’systembehaviour forinputintonational/regionalpolicy?
Researchapproach
Compiletime-seriesdataforUKregions(orUKasawhole)forecosystemservices,fertilizerinputsandsocio-economicvariablessince1950.
Deriveevolutionaryandnonlinearperspectivesonagri-ecosystemchangethroughtime.
Useselectedstatisticalrelationshipstocreatesimpledynamicalsystemsmodelsforexploringfuturescenarios.
Ecosystemservicesandinputs1950-2013
Provisioningservices-wheatandlivestockyields- risinguntil1990s
Regulatingservices–riverinenutrients,sedimenterosion,farmbiodiversity,andatmosphericpollution–mainlyworseninguntillate1990sexceptbiodiversity(birds)
Agriculturalinputs–fertilizer–risinguntilmid-1980sthendeclining
Socio-economicvariables1950-2013
Risingtrendsinpopulationrisesanddecliningagriculturallabourheadcountasagriculturehasintensified.
Foodprices,farmincomeandfarminputcostsvolatilewithdecadalswings.
Foodpriceindexmoreorlesstracksfarminputcosts.
Risingfarmincomessince2000despiteconstantfarmsubsidiessincemid1990s.
AgriculturalKuznetscurves
PhaseplotofprovisioningandregulatingservicedegradationversusUKGDPpercapita.
RegulatingservicedegradationdeclinesafterUKGDPpercapitareaches~£21000.
Wheatyieldremainshighafter~£21000percapita,butlivestockdensitycollapsesafter2001duetothefoot-and-mouthdiseaseoutbreak.
Suggestscurrentlowlandarablesysteminrelativelyresilientstate.
Multivariateanalyses- PCA
PrincipalComponent1(PC1)explains~52%ofthedatavariance– reflectsagriculturalintensification.
PrincipalComponent2(PC2)explainsafurther~17%-reflects???
Variablesarelabelledasintext,andthenumberedpoints(canthesebeadded–usefultoshow??)representsequentialyears(from1980[33]to2013[1]).
Correlationanalysis
Correlationmatrixofbiophysicalandsocioeconomicvariables.
Leftofdiagonal:scatterplotsandloesssmoothing(redlines)
Diagonal:univariateplotsandkerneldensityplotsofeachvariable
Rightofdiagonal:pairwisepearsoncorrelationcoefficientsofvariablepairingwithsignificance(redstars)
Redboxesindicatesignificantrelationshipswehypothesise tobecausalforconstructingmodel.
Dynamicalsystemsmodel
Preliminarycausalloopdynamicalsystemsmodelwithsimulationdrivers/resultsfor1980-2013shownineachvariablebox(italicsforimposeddrivers).Arrowthicknessindicatescorrelationstrength.
Scenariosimulation– businessasusual
Whereis2050onthesegraphs?Scenariomaintainingfarmingpractice/efficienciesat2013levelsshowsnoimprovement?inregulatingservicesandplateauingtodecliningwheatyieldafter2050Ispost-2050shown?.Forbiodiversitytorecoverwhileyieldremainshighrequiresreducedmechanisationandpesticideuse.
Dynamicalsystemsmodelwithsimulationdrivers/resultsfor1980-2050shownineachvariablebox.
SummaryAgriculturalintensificationdroveincreasedenvironmentaldegradationinEnglanduntilthe1980s.Sincethen,UKlowlandagriculturecanbedefinedasareasonablyresilient‘stablestate’withhighyieldsandcontrolledenvironment(exceptforbiodiversity).
Pastpolicies(fieldburning,nitratevulnerablezonesandEUsubsidies)havehadmajorimpactsonimprovingregulatingservices.Climatewarminghashadanegativeeffectonintensification.
Simulationssuggestthatinfaceofglobalwarmingitisdifficulttoincreaseyieldand/orlivestockpopulationwithoutdrivingthesystemintolowerresiliencestateswithfurtherbiodiversitydeclineandthreatenedimprovementsinagriculturalpollution.
A‘resilience’approachthatprioritisesintegratedsystembehaviouroverprecisionofforecastsprovidesastrongbasisfordevelopingpolicy:moredebateisneededwithregards‘trade-offs’betweenyieldsandenvironmentalquality.
Acknowledgements
WegratefullyacknowledgesupportfromtheInstituteofLifeSciencesResearchStimulusFund,UniversityofSouthampton
WegratefullyacknowledgedatabeingmadefreelyavailablebyRothamstedResearch.
• Z-scoreplotillustratingtheimpactofagriculturalintensificationonthebiophysicalparametersoftheEasternEnglandagroecosystem.UKwheatyield(whichiscloselymatchedbyEastEnglandwheatyieldwheredataisavailable)isusedasaproxyforprovisioningservices,fertiliseruseisusedasaproxyforagriculturalinputs,andtheregulatingserviceindexisconstructedfromthemeanoftheproxiesforriverinenutrientcontamination,sedimenterosion(reconstructedfromtherelativedifferencebetweensuspendedsolidsandbiologicaloxygendemandintheRiverGreatOuseatBedford),farmbiodiversity,andatmosphericpollutionbetween1980and2013.
• ZscoreplotillustratingtheimpactofagriculturalintensificationonthebiophysicalparametersoftheSouth-WestEnglandagroecosystem.Livestockdensity(animalnumberperhectare)isusedasaproxyforprovisioningservices,fertiliseruseisusedasaproxyforagriculturalinputs,andtheregulatingserviceindexisconstructedfromthemeanoftheproxiesforriverinenutrientcontamination,sedimenterosion(reconstructedfromtherelativedifferencebetweensuspendedsolidsandbiologicaloxygendemandintheRiverExe),farmbiodiversity,andatmosphericpollutionbetween1980and2013.
• PhaseplotoftheZ-scoresforwheatyield(UK)andfertiliserusage(totalforEnglandandWales)between1965and2013.Fertiliserusageandwheatyieldincreasetogetherbetween1978and1984,butafter1984becamedecoupledasfertiliseruserapidlydeclinedandwheatyieldremainedstable.
