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Evaluation method of the ecological benefits of urban green spaces and application conditions

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Evaluation method of the ecological benefits of urban green spaces and application conditions

    Evaluation method of the ecological benefits

    of urban green spaces and application

    conditions

    Evaluationmethodoftheecolo

    andapplicationconditions

    WangWefZhaoLinSCrl

    calbenefitsofurbangreenspaces

    FacultyofLandscapeArchitecture,SouthwestForestryCollege,Kunming650224,ER.China

    AbstractTheimportanceofecologicalbenefitanalysesaboutgreenspacesystemshasbeenwidelydiscussedonthebasisofaper

    ceivedbiastowardsthelandscapingeriectofgreenspacestobebuiltinurbanareasasopposedtotheperceptionofcomprehensive

    ecologicalbenefitsofdesignedplantcommunities.Giventhebasicprincipleofecologicalbenefitanalysesandevaluationmethods

    widelvappliedtoday,themethodologytocalculateecologicalbenefitsand'tomodeltheexpansionofurbangreenspacesbyCITY

    green5.0anditsconditionsforapplicationwereexplored.weproposethataerialimagescanbesubstitutedbyAutoCADgraphicsof

    agreenspacecontainingdetailedinformationofplantdispositionsbydigitizingthekeyfeaturesduringtheworkingprocessinorder

    toevaluatetheecologicalbenefitsquicklyandtoofferproperguidancetotheestablishmentofsmallscalegreenspacesinurban

    areas.Thetheoreticalfoundation,potentialapplicationrangeandprospectsforextensionofthemethodareintroducedbyusingthe

    analysisofecologicalbenefitsofthegreenspacesonthecampusofSouthwestForestryColleg

e,Kunming,asanexample.

    Keywordsurbangreenspaces,ecologicalbenefits,evaluation,CITYgreen5.0,ArcViewGI

    S

    1Introduction

    Urbanecologicalenvironmentshaveseverelydeterio

    ratedalongwiththerapiddevelopmentofurbaniza

    tioninChinaandenvironmentalproblemshavebe

    comelatentfactorsrestrainingfurtherdevelopmentof urbanizationandenhancementofthequalityoflifefor urbanresidents(Cheneta1..1998).Urbangreen spacesplayanimportantroleinimprovingurbanen

    vironmentsandbeautifyingurbanlandscapes(James, 2002).However,themajorityoflandscapearchitec

    turedesignsarebiasedtowardsthelandscapingeffect. especiallyalongrigidlandscapinglineswhilethe ecologicalbenefitsoftheplantstobegrownareUSU. allyignored(Tu,2005).Modemcomputertechnology providesdesignerswithsuperiormeanstoshowtheir intendeddesigns.Theeffectofpictureswithbeautiful colorsandliveimagesarecommonlyconsideredthe mainstandardstojudgethedesignofplantdisposi

    tions(Yangeta1..2002).However,thelandscaping effectshownbythepicturesisusuallydifculttore. alizeandthereisoftenagreatdifferencebetweenthe designedeffectanditsimplementation.Therefore.in thedesigningcoursefortheestablishmentofurban greenspaces,moreattentionshouldbepaidtoplants, includingspecies,amount,plantingstructureandar- rangement,inordertoensurethemaximumecological benefitstobeproducedbygreenspacesandtoimprove

    theurbanecologicalenvironmentasmuchaspossible. Oneofthemostimportantendsinurbanforestry

    Authorforcorrespondence.E-mail:zhaols@public.kmyn.cn researchhasbeenthedevelopmentofquantitative analysisandtheevaluationoffinancialbenefitsofthe urbanforestecosystem.Thismakesitpossibletopre

    sentobjectivelythecomprehensivebenefitsproduced bytheurbanforestecosystem.Thiskindofstudyis opportuneforthecompletionofplanninganddesign ofurbangreenspaces,toensureamorescientificand rationalapproachtotheplantingstructureofurl:Ian greenspaces,tounifyharmoniouslytheecological, socialandeconomicbenefitsandtoacceleratethe establishmentofurbangreenspaces.Itshouldbe beneficialinimprovingtheenvironmental,ecological andeconomicawarenessofthepublicandinpromot

    ingthedecisionmakingcapacityofgovernmentsand

    specificadministrativedepartmentsandtoensurera

    tionaluseofinvestmentsinbuildinggreenspacesand insustainabledevelopmentofecologicallyresponsible environmentalprojectsinurbanareas(ZhaoandGao, 2004).Calculatingcomprehensivebenefitsofgreen spacesclosetothedailylifeoflocalresidentsbyus

    ingquickquantitativeandeconomicanalyseswillbe helpfultoimprovethedesignandbuildinglevelof smallscalegreenspacesandeventuallyimprovethe qualityofentireurbanecosystems.Exploringmethods toevaluatealandscapearchitecturedesigninaquick, reasonable,objectiveandallaroundwayandtofore

    casttheeffectofthelandscapeandecologicalbenefits

    ofthedesigninthenearfuturehasbecomeoneofthe moreurgenttasksofthedecisionmakersforthees. tablishmentofurbangreenspaces.

2l4

    2Eeo-benefitsevaluationandanalytical methods

    Modernurbanforestprojectsandurbanforestrystud

    iesstartedinAmericaandCanada(Lieta1..2003). Researchworkersofurbanforestryabroadhave largelycarriedoutstudiesinthefollowingareasdur

    ingthepasttwodecades:11investigationintothe amountofurbanforestsandrapidestimationofleaf areaindicesofurbanforests(Larseta1..1988;Jaen

    soneta1..1992;Paulaeta1.,2001);thiskindofre

    searchprovidedurbanforesterswithscientificmeth

    odstoobservebasicinformation.includingdistribu

    tion.structureandgrowthstatusofurbanforests;2) analyrsesofconflictsbetweenstreettreesandmunici

    palinfrastructure(VenuandCaula.1994;Peper,1998), inordertounderstandgrowthmodelsofrootsystems. branchesandleavesofdifferenttreespecies,toevalu

    atedamagetosidewalksandsewerpipesbyroot heavingandthecorrespondingrepaircosts;3,analy

    sesofgeneralecologicalbenefits.includingreduction inairpollution,energyconservation,carbonseques

    tration,relevanttendingandadministrationcosts (Klauseta1..1999;McPhersonandJames.1999);de

    tailedquantitativeanalysesofecologicalbenefits producedbyurbanforestshavemadeitpossibleto

    calculatetheexactecologicalbenefitsfromanumber oftreesorevenanindividualstreettreeinmonetary units,suchasmitigationofairpollution(co,S02,03), reductioninstormwaterrunoff,carbonsequestration, energyconservationfromshadingandshieldingoff thewind.

    Atpresent.quantitativeanalysesofecological benefitsofurbanforests,bothabroadandinChina, canbedividedintotwocategories,i...,eanalysesof comprehensiveecologicalbenefitsandanalysesof specificecologicalbenefits.Theformeraimsatana

    lyzingcomprehensiveecologicalbenefitsofforest resourceswithcomparativelygeneralresults;projects inthesecondcategoryaimatanalyzingparticular ecologicalbenefitsofagivengreenspace,suchas carbonsequestration,oxygenrelease,airpurification, noiseabatement,waterconservation,disinfectionand dustretentionwithcomparativelyspecificresults. Sincethesekindsofstudiesareusuallycarriedout overlongperiodsoftimeandrequiresomespecial equipmentandfacilities,oneormoreindicescanbe chosenaccordingtothesiteattributesandresearch conditions.Methodologyofmarketpricesubstitution isgenerallyadoptedintheprocessofmonetaryvalue calculation.Forexample,theSwedishCarbonTax Rateiscommonlyadoptedwhenmeasuringthebene

    fnofcarbonsequestration(Lengeta1..2004). Incontrast,theForestService,USDAhasexplored variousresearchmodelsandtypesofsoftware.CITY

green5.0isafunctionextendedmodelbasedonArc

    View3.xsoftware.ItwasdevelopedbvAMERICAN F0RESTStoconductecologicalbenefitstudies.The ForestryStudiesinChina,Vo1.9,No.3,2007 calculatedbenefitscomprisedfiveaspects,i.e.,air pollutionmitigation,carbonsequestration,stormwater

    mnOffreduction.energyconservationandwildlife habitatconservation.Inthefinalanalysis.thesoftware isabletocalculatethebenefitsintermsofUSdollars. Inaddition.CITYgreen5.0canmodelthefuturede

    velopmentofthegrowthofthestudiedvegetationand evaluatetheexpectedbenefitsoverthenext50years. Studyresultsmaybebeneficialtodecisionmakingfor

    planning.tendingandadministrationofurbanforests. 3BriefintroductiontoCITYgreen5.0

    application

    CITYgreen5.0isamodeldesignedforquickevalua

    tionofecologicalbenefitsofurbanforestsrLiand wang.2004).Atpresent.themodelhasbeenwidely appliedinwesterncountriestoevaluatetheusually expectedbenefitsandtoforecastdynamicallythe growthprocessofurbanforests.Muchrelevantre

    searchhasbeenaccomplished.However,theworking processofCITYgreen5.0demandsaerialphotographs withhighresolutionofthestudyareasinorderto masterquicklvandexactlythestructureofurbanfor

    estsandtodigitizethekeyfeaturesofbuildings, pavements.trees.1awnsandshrubs.Whentheattrib

    utesofthelandcoverobtainedbyfieldinvestigation areenteredintothecomputer,theecologicalbenefits

    producedbytheplantsgrowninthestudiedareascan becalculatedbythemode1.

    Althoughtheaerialphotographsareabletoprovide researcherswithanhistoricalrecordforanarea.photo processing,interpretationandmapproductioncanbe timeconsumingandcostly(MyhreandSilvey,1992). Sincethesedaysphotographsboughtforurbanfor- estrystudiesinChinaaregenerallytakenforurban plannersandengineersconcernedwithurbaninfra

    structure,theyareusuallytakenintheleaf-offseason. whichmakesitquitedifficulttoanalyzeforestcover- ageandtodistinguishtreespecies(Pauleta1.,1995). MuchresearchhasbeencarriedoutintheUnited Statestosearchformorepracticalandeconomical wavsofcollectingdatadescribinglandcoverinurban areas.Forexample.smallaircraftsloadedwithvideo camerashavebeenusedtoassistimagecollecting.It 1sessentialtochoosemorefeasibleandeconomical meanstosubstituteaerialimagesaccordingtolocal conditionswhenanalyticalresearchonecological benefitsofurbanforestsareundertaken.

    4ApplicationofCITYgreen5.0bycondition

    substituti0n

    Smallscalegreenspacesinurbanareas,suchas squares,streetgreenbelts,miniparksandresidential areasaretakenasthemainresearchobjects.Theaerial

WangWeieta1.:Evaluationmethodoftheecologicalbenefitsofurbangreenspacesandapplic

    ationconditions

imagesaretobesubstitutedbyfinalAutoCADgraph

    icsofthegreenspacescontainingdetailedinformation ofplantdispositionwhiledigitizingthekeyfeatures duringtheworkingprocess,ortobesubstitutedby instantlydrawnAutoCADgraphicsofthestudied greenspaceecosystems.

    4.1Theoreticalprinciple

    Aerialphotographsarerequestedforprovidingthe spatialpositionandsizeofeachbuilding,streetand plant(fordigitizingthekeyfeaturesofthestudied area).Duringthisprocess.thedataoftheaerialpho

    tographneedtobeemendedtoeliminatedistortions.A coordinateconversionisalsorequiredaccordingto scaleandaerialphotographsshouldberepeatedlyreg

    istereduntiltheproperprecisionismet(Li.2004). TheAutoCADgraphicofagreenspacecontaining detailedinformationofplantdispositionsisanimpor

    tantcomponentofalandscapearchitecturedesign.It showsdirectlyandclearlydetailedinformationabout buildings,streetsandplants(includingcommonand scientificnamesoftheplantspresent,plantingsites, canopydiameter,DBH,etc.).Generallyspeaking,the finalinspectionandacceptancecheckingofagreening projectare,asarule,strictlybasedondesigngraphics, sotheAutoCADgraphicsarecomparativelyrealistic anddependable.Besides,AutoCADisasoftwarewith user-friendlyinterfaces;itisconvenienttomodifythe originalgraphicsandthegraphicprojectioncanbe donebyactualscalewithoutdistortion.Therefore,itis fasterandmoreconvenienttodigitizethekeyfeatures

    ofthestudiedgreenspacewithAutoCADgraphics thanbytheaerialphotographsandthedigitizingpro

    gressofthestudiedareashouldbeaccomplishedwith higherprecision.

    4.2AutoCADgraphicsacquisition

    TheAutoCADgraphicsofagreenspaceisusually keptbythedepartmentordivisionoflandscapearchi

    tecturedesignandadministrationofthecustomer.Itis possibletoacquirethegraphicsforstudypurposeif appropriateexplanationisgivenandspecificcreden

    rialsareshown.Iftherearenoreadygraphicsofthe studiedurbangreenspacesthatwerebuiltlongago. thegraphicscanbedrawninstantlybysitemeasure

    mentcombinedwithfieldinvestigationintoattributes ofotherrelevantfactors.

    4.3Applicationrange

    Theproposedmethodologyisgenerallydesignedfor benefitanalysesofsmallscalegreenspacesystems andappropriatetoevaluateandmodelecological 215

    benefitsoflandscapingprojectsinurbanareas.Itis necessarytotakeintoconsiderationtheentirerangeof theareatobestudiedwhilereplacingtheaerialpho

    tographsbyAutoCADgraphicsandapropermodefor representation(vectormodeorratermode)shouldbe chosenrationallyfortheinformationdigitizingproc

    ess.Iftheareatobestudiedistoolarge,ortherepre

    sentationmodeisimproperlychosen.itwillbediffi

    cultandcostlytodothefieldsurveyingandtheana

    lyricalresultmaynotbeverygood.

5Acasestudy

    Evaluationoftheecologicalbenefitsofgreenspaces onthecampusofSouthwestForestryCollege,Kun

    ming,southwestChina,wasmadebasedonthetheo

    reticalfoundationandtechnicalprocessdescribed above.First.theAutOCADgraphicsofthegreen spacesonthecampuswasacquiredfromtheCapital ConstructionDepartmentofthecollege.Second,the totalgreenspacesonthecampusweredividedinto fiveparts,i.e.,teachingquarters,studentdormitory quarters,thecentrallawnsection,thecateringsection andtheplaygroundsection.Third,thedataonthe originalAutOCADgraphicwereupdatedbecausethe plantingstatusofvegetationoneachquarterorsection hasbeenchangedconsiderablycomparedwiththe originaldesignmadeyearsago.Forthesections wherethegreenspacesareregularlyallocated,the investigationoftheplanepositionsOfstudiedplants wasdonetogetherwiththespecificdataandattribute investigationoftheplants.Towardsthesectionswhere thegreenspacesarenaturallyallocated,thepositions oftheplantsinthemodelofAutoCADsoftwarewere determinedbyonthespotinvestigationcombined withdigitalphotostakenontheroofofadjacenthigh buildings.Theresultsofthepilotstudyshowedthat theexpectedworkingefficiencyandevaluationpreci

    sionhadbeenconsistentlyachieved.

    6Discussion

    Quickevaluationanddynamicforecastoftheeco

    logicalbenefitsofurbangreenspacesbvCITYgreen

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