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.
