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.