Simulationofthespatialstressduetourbanexpansionont

LandscapeandUrbanPlanning101(2011)269–277ContentslistsavailableatScienceDirectLandscapeandUrbanPlanningjournalhomepage:∗,JieTianc,PeijunShia,DanHudaStateKeyLaboratoryofEarthSurfaceProcessesandResourceEcology,BeijingNormalUniversity,Beijing100875,ChinabCollegeofResourcesScience&Technology,BeijingNormalUniversity,Beijing100875,ChinacDepartmentofGeologyandGeography,GeorgiaSouthernUniversity,Statesboro,GA30460,USAdStateKeyLabofUrban&RegionalEcology,ResearchCenterforEco-EnvironmentalSciences,ChineseAcademyofSciences,Beijing100085,ChinaarticleinfoArticlehistory:Received4September2010Receivedinrevisedform14February2011Accepted19February2011Availableonline21March2011Keywords:UrbanexpansionWetlandSpatialstressBeijingChinaabstractBasedontheexistingUrbanExpansionDynamic(UED)model,thispaperdevelopsageographicinfor-mationsystem(GIS)-basedmodelthatcanbeusedtoassessthecurrentandpotentialspatialstressonaregionalwetlandecosystemduetourbanexpansion.SyntheticallyutilizingthesimulationcapabilityoftheUEDmodelandthespatialanalysispowerofaGIS,thisnewmodeltakesintoaccountthepresentdisturbancebyongoingurbanexpansion,thepotentialdisturbancebyfutureurbanexpansion,theacces-sibilityviathetransportationnetwork,andtheneighborhoodstability.ThemodelisusedinparticulartosimulatethespatialstressonthemajorwetlandsinBeijingfrom1991to2004.Thesimulationresultsarefoundtobeconsistentwiththeactualremotesensingobservations:arelativelyhighspatialstressnormallyleadstoaneventualconversionintourbanuse.WiththefutureurbanlandspredictedbytheUEDmodel,thismodelisusedtofurtherassessthepotentialspatialstressofurbanexpansiononthemajorwetlandsinBeijingby2015.Moreover,thespatiallystressedwetlandfringeareasinBeijingareidentifiedbasedonthetotalspatialstresscombiningthecurrentandthepotential.TheseareasarefoundtobemainlydistributedindowntownBeijingandtheplainsareasthathaverelativelyeasyaccessibilityviathetransportationnetwork.EffectivemeasuresshouldbetakentoprotectsuchareasfrombeingfurtherdisturbedinordertoachievethegoalofamoreeffectiveconservationofthewetlandecosystemsinBeijing.©2011ElsevierB.V.Allrightsreserved.1.IntroductionUrbanizationisanimportantsignofadvancesinscienceandtechnologyandhuman’sgreaterabilitytoreformthenaturalenvi-ronment.Itisalsooneofthenecessarystagesinacountry’sjourneytowardmodernization(Zhengetal.,2008).Chinahasbeenonthetrackofrapidurbanizationintherecentdecades.From1978to2000,thenumberofsmalltownsinChinagrewfrom2176to20,312,andthenumberofcitieshadreached663from190(Yaoetal.,2008).ItisanticipatedthattheChinesepopulationwillgrowfrom1.2billionto1.6billionduringthiscentury,andtheproportionofurbanpopulationwillincreasefrom20%asof1990to29%in2010and47%bythe2050s(WangandGuang,2001).Oneofthegreat-estchallengesduringurbanizationistounderstandtheimpactof∗Correspondingauthorat:CollegeofResourcesScience&Technology,BeijingNormalUniversity,Beijing100875,China.Tel.:[phone];fax:[phone].E-mailaddresses:[e-mail](C.He),[e-mail](J.Tian),[e-mail](P.Shi),[e-mail](D.Hu).urbanexpansionastheoutcomeoftheinteractionbetweensocioe-conomicdevelopmentandecologicalprocesses(Chenetal.,2010).Wetlandreferstothetransitionalareabetweenanaquaticecosystemandaterrestrialecosystem.Ithasimportantecologi-calfunctionssuchasbalancingwatervolume,holdingbackfloods,regulatinglocalclimate,removingpollutants,providingahabitatforwildlife,andmaintainingaregionalecologicalbalance,aswellassocioeconomicfunctionssuchasbeingusedforentertainmentortourism(Keddy,2000).However,awetlandecosystemisoftenspatiallystressedduringurbanizationbecausemanywetlandshavebeenconvertedintoothertypesoflanduse(e.g.,residentialorcom-merciallands)asaresultofurbanexpansion(Bendor,2009).Suchalossofwetlandscanresultinthedegradationofthelocalecosys-temandstronglyimpactthehydrologicalandclimaticprocessesthere(Wangetal.,2008).DuringthecourseofurbanexpansioninChina,thegreatdemandoflandsforurbanconstructionhasposedtremendousspatialstresstovariouswetlands,whichhavethereforebeenexperiencingarapiddecreaseinsize,aconsider-abledecayoffunction,alossofbiodiversity,andmorefrequentfloodhazards(ChenandLu,2003).Accuratelyassessingthespatialstressonwetlandsduetourbanexpansionandfindinganeffective0169-2046/$–seefrontmatter©2011ElsevierB.V.Allrightsreserved.doi:10.1016/j.landurbplan.2011.02.032270C.Heetal./LandscapeandUrbanPlanning101(2011)269–277meanstoprotectthemduringurbanizationhasthereforebecomeaseriousissuethatneedstobeaddressedinChina(Clarkeetal.,1997;Wangetal.,2008).Thepresentmethodsusedtoassessthespatialstressofurbanexpansiononaregionalwetlandecosystemcanbesummarizedintotwocategories:directmethodsandindirectmethods(OdeandFry,2006).Theformeronesdirectlymeasureoranalyzethechar-acteristicsofaregionalwetlandecosystem(e.g.,area,structure,function,well-being)andtheirchangeinresponsetourbanexpan-sion(Wangetal.,2008).Incontrast,thelatteronesmainlyanalyzean