德國土地利用考察后感想課件

科目：專題討論2-1指導教授：林俐玲教授；鄭皆達教授；陳鴻烈教授；林德貴教授報告人：翁志成98年12月4日Howtocalculateandinterpretecologicalfootprintsforlongperiodsoftime:thecaseofAustria1926–1995HelmutHaberl,Karl-HeinzErb,FridolinKrausmann,2001,ecologicalEconomics38OutlineAbstractIntroductionMethodsResultsDiscussionConclusionsInthispaperwepresentcalculationsoftheecologicalfootprint(EF)forAustria1926–1995,baseduponthreedifferentmethodologicalapproaches.InmostEFcalculationspublishedthusfar,materialandenergyflowsareconvertedtoarea(hectares)usingglobalyieldsoftherespectiveyear.Incontrast,weanalyzetheeffectdifferentassumptionsonyieldshaveontheresultsofEFcalculationsbyassuming:(1)constantglobalyieldsasof1995;(2)variableglobalyields;(3)variablelocalyieldsfordomesticextractionandvariableglobalyieldsforimportedbiomass.Abstract

AccordingtoourresultsdifferentassumptionsonyieldscaninfluencetheresultofEFcalculationsbyafactorof2,atleast.WeconcludethatfurtherresearchisnecessarywithrespecttobiomassyieldsassumedinEFcalculations.ThepurposeforwhichEFcalculationsaremade,andtheinterpretationoftheirresults,willdeterminefuturedevelopmentoftheEFmethodology.Keywords:Ecologicalfootprint(EF);Socioeconomicmetabolism;Biologicalproductivity;Biomassyield;Overshoot;Sustainabilityindicators

AnyEFcalculationtriestoassess

howmuchbiologicallyproductiveareaisneeded

toproducetheyearlyresourceflowsconsumedby

thepopulationofaregion(acity,acountry,or

theworld),toabsorbwastesoremissions(especially

CO2),andtohostthebuiltinfrastructurein

thisregion.TheEFincludes:(1)actuallyused

landas,forinstance,croplandandpastures

neededtoproducegoodsandservicesderived

fromthesekindsoflanduseandbuiltupland;(2)theareaofforeststhatwouldbenecessaryto

producetheamountofwoodusedinasustainable

manner;and(3)areathatwouldbenecessary

inordertoabsorbthecarbonreleasedbyburning

fossilfuels.1.Introduction

‘Biocapacity’(BC).IftheEFisbiggerthantheavailableBC,thisisofteninterpretedas‘overshoot,’thisbeingasituationinwhichhumanconsumptionexceedsecologicallimits.Inthispaperwewillpresentcalculationsof

Austria’sEFfor1926–1995.Thisperiodoftime

coversalargepartofAustria’sindustrialization,

includingasurgeoffossil-fueluseandtheindustrialization

ofagricultureaftertheSecondWorld

War.Wearenotawareofanypublishedcalculation

ofEFtimeseriescoveringsuchalongspan

oftime.2.MethodsIncalculatingtheEFintimeseriesthequestionariseswhichyield(productivityperunitarea)shouldbeassumedforconvertingbiomassflowsintofootprintareas.Inordertobeabletocomparetheconsumptionpatternsofdifferentcountries,thecustomaryEFmethodologyusesglobalproductivityaveragestocalculatetheEFofanyspecificresourceused.actualproductivityofcountryAcanbehigherorlowerthantheglobalaverage.Inatimeseriescalculationthisspatialandtemporalvariabilityofyieldsposesaproblem:whichyieldshouldbeusedforconvertingconsumption[kg]intoarea[ha]?WehavechosentocalculatetheEFinAustria1926–1995withthreedifferentmethod(GlobalYield1995、VariableGlobalYield、VariableLocalYield),eachofwhichreflectsaconsistentsetofassumptions(seeFig.1)3.ResultsFig.2showstheresultsofourfootprintcalculations.3700002210001890002倍2210001190002630002.2倍Fig.3presentstheresultsofourcalculationoflocalBCinAustriain1926accordingtothethreemethods.Fig.4comparesAustria’sfootprintwiththelocallyandgloballyavailableBiocapacity,bothinabsolutevaluesandaspercapitafigures.4.DiscussionTable1comparesourresultsfor1995withMathisWackernagel’s(pers.comm.,2000)mostrecentfootprintcalculationsforAustria.5%17%EF-BC=10%EF-BC=23%Analyzingthe

periodfrom1926to1995wefindtwomain

trends:1.Importsofagriculturalbiomass,aboveall

grains,meatandlivinganimals,arehighinthe

earlydecades,butwithagriculturalyields

growingquicklyafter1950,Austriabecomesa

netexporterofagriculturalproduceinthe

1970s.However,whenwealsoconsiderforest

products,Austriaiseitherself-containedora

smallnetexporterofbiomass-energyoverthe

wholeperiod.2.Fossil-fuelconsumptionrisesbyafactorof

about4overthewholeperiod(seeFig.7below).

1650以前出口以木材為主1926-1935進口肉類是明顯的EFcalculationsdependonassumptions

onbiomassyieldswhicharehighly

variableinspaceandtime.Yieldarehighest

oncropland,mediuminforestsandloweston

grassland.Thisisnotonlyafunctionofthenet

primaryproductivity(NPP)oftheseland-use

classes,butdependsalsoonthefollowingfactors:Thelandharvested.CroplandproductsandallforestproductsareconsideredinEFcalculationsonthelevelofprimaryproduce(plantproducts).Sinceabout85–90%ofbiomass-energyislostinthetransformationprocess,grasslandyields—asusedinEFcalculations—aremuchlowerthancroplandorforestyields.Table2showstheyieldsweusedinourEFcalculationsinAustriain1926and1995,andtheglobalyieldin1995asbiomass-energyperunitareaandthecorrespondingEFcomponentperenergycontentofbiomassproducts.5.ConclusionWestill

believethatarea-basedindicatorssuchastheEF

shouldbeamongthefewselectedaggregated‘headline

indicators’thatcanbeusedtodescribethe

‘physicaleconomy’ondifferentspatiallevelsand

intime-seriesanalyses.Wealsofeelthatareause

isanimportantprocesswithrespecttosustainable

developmentthatshouldbemonitored.Ourstudysuggeststhat,althoughitisfeasibletocalculatethefootprintofnationsinalongtime-series,itisnotstraightforwardtointerprettheresults.Currentlyusedmethods