Evaluatingwetlandwithinanurbancontext

EcologicalEngineering15(2000)253–265EvaluatingwetlandswithinanurbancontextJoanG.Ehrenfeld*DepartmentofEcology,E6olution,andNaturalResources,CookCollege,14CollegeFarmRoad,RutgersUni6ersity,NewBrunswick,NJ08901,USAReceived25November1998;accepted10March2000AbstractCoastalregionsareamongthemostrapidlyurbanizingplacesonearth.Thenumerouseffectsofurbanizationonhydrology,geomorphology,andecologymakewetlandsinurbanregionsfunctiondifferentlyfromwetlandsinnon-urbanlands.Furthermore,wetlandsinurbanregionsmaytakeonhuman-relatedvaluesthattheylackinnon-urbanareas,astheyprovidesomecontactwithnature,andsomeopportunitiesforrecreationsthatareotherwiserareintheurbanlandscape.Evaluationsofthesuccessofrestorationsinurbanregionsrequirecriteriafirsttodeterminethekinds,andintensitiesofurbaninfluenceonthesite,andsecondlytoassessfunctionalperformance.Thedevelopmentofsuccesscriteria,atboththelevelsofassessment,dependsontheproperdefinitionofareferencedomain(thesetofwetlandstowhichsuccesscriteriawillapply),andthedocumentationofasetofreferencesiteswithinthedomain;bothmustbebasedwithintheurbancontextappropriatefortheregionofinterest.AnexampleispresentedfromastudyofurbanwetlandsinNewJerseyofaprocedureforestablishingthereferencedomain,thereferencesetofwetlands,andcriteriafortheassessmentofurbaninfluence.©2000ElsevierScienceB.V.Allrightsreserved.Keywords:Cities;Urbanwetlands;Urbanecology;Coastalwetlands;Restoration;Wetlandassessment;Functionalassessment:ecoleng1.IntroductionThegrowthofurban,andsuburbanareashasbeenadominantdemographiccharacteristicofthe20thcentury.Duringthistimeurbanpopula-tionhasincreasedten-fold,andtheproportionofthehumanpopulationlivinginurbanareashasrisenfrom14toover50%(Platt,1994).Muchofthisexpansionofurbanland,andcitizenryhasoccurredalongcoasts,asportcitieshaveex-panded,coalesced,andengulfedneighboringun-developedlands.Between1960and1990,coastalcountiesintheUSincreasedinpopulationby43%,afasterrateofgrowththaninthecountryasawhole.Likewise,between1970and1989,nearlyhalfofallbuildingactivitiestookplacealongthecoasts(Anon.,1994).Asof1981,28%ofmunicipalareaswerecoastal,buttheyac-countedfor55%oftheUSpopulation(Walker,1990).Elsewhereintheworld,thestoryissimilar:ofcitieswithpopulationsover1million,100%ofthoseinSouthAmericaarecoastal,asare75%ofthoseinAsiaandAfrica(Berry,1990).*Tel.:1-732-9321081;fax:1-732-9328746.E-mailaddress:[e-mail](J.G.Ehrenfeld).0925-8574:00:$-seefrontmatter©2000ElsevierScienceB.V.Allrightsreserved.PII:S0925-8574(00)00080-XJ.G.Ehrenfeld:EcologicalEngineering15(2000)253–265254Notsurprisingly,theeffectsofthisburgeoningcoastaldevelopmentonnaturalresourceshavebeenprofound(Walker,1990;Nordstrom,1994).Damagetoandlossofwetlandshavebeenexten-sive(Tiner,1984;DahlandJohnson,1991).ArecentsurveybytheUSDepartmentofAgricul-turefoundthaturbanizationwasimplicatedinwetlandlossinnearlyallsurveyedwatersheds(96%)andmayaccountforasmuchas58%ofthetotalwetlandloss(Anon.,1997;Opheim,1997).Yetwetlandsremainanintegralpartofthedevel-opedlandscape,particularlyalongcoasts,wheresaltmarshessurroundoiltanksandabutsummerhomes,andriparianforestspersistalongstreamsastheymeanderthroughdensedevelopmentandindustrialcampuses(see,forexample,Greiling,1993).Restorationofcoastalwetlandsoftenmusttakeplacewithinurbanregions.Inordertoevaluatethesuccessofsuchrestorations,itisnecessarytoestablishcriteriathatreflectboththeecologicalqualitiesofthewetlandandtherealitiesoftheurbancontext.Below,Idiscussseveralwaysinwhichthecontextofurbanenvironmentsaffectstheprocessofdeterminingsuccesscriteriainrestoration.Thesecommentsarebasedonacon-siderationofthenatureofurbanenvironments,supplementedbytheobservationsofurban:subur-banwetlandsinNewJersey.2.AdaptingsuccesscriteriatocitiesWhilethehumandimensioninrestorationhasbeenstressedrepeatedly,(Jordan,1994),itsim-portanceisbestexpressedinurbanregions.Restorationprojectsnecessarilyaffectmanypeo-pleintheirdailylivesbyalteringtheplacesinwhichtheywalkthedog,commutetowork,doabitoffishing.Suchplacesoftenconstitutetheonly‘natural’habitatsthaturbanresidentsexperi-ence.Themultipleaesthetic,emotional,andprac-ticalvaluesthatpeopleascribetotreeshavebeenablydescribedbyDwyeretal.(1994),manyofthesamevaluesaccruetonaturallandscapes.Sincethecommitmentandinvolvementoflocalcitizensarecriticaltothesuccessofaproject,thesevaluesmustbetakenintoaccountinurbanrestorationmoreexplicitlyandmorefullythaninnon-urbanprojects.Thispointiswellillustratedbyrecentcontro-versiessurroundingecologicalrestorationinChicago(Shore,1997;Gobster,1997).Along-termcollaborativeeffortbymanyagenciesandorganizationssoughttorestoreprairieandoaksavanna.Theeffortprovokedharshpublicoppo-sitionwhensomenewspapersandlocalresidentsrealizedthatre-establishmentoftheseecosystemsinvolvedremovinglargenumbersoftrees.Confl-ictingvalues—theamenitiesprovidedbytreesversusthere-creationofthepre-settlement‘natu-ral’landscape,localdeterminationofthefateoflandversusthescience-basedwisdomofprofes-sionals,theuseofpublicfundsforrestorationversusacquisitionoflandfor