Structuralandfunctionalvegetationdevelopmentincrea

EcologicalEngineering39(2012)104–112ContentslistsavailableatSciVerseScienceDirectEcologicalEngineeringjournalhomepage:∗,WilliamJ.Mitsch1WilmaH.SchiermeierOlentangyRiverWetlandResearchPark,EnvironmentalScienceGraduateProgramandSchoolofEnvironmentandNaturalResources,TheOhioStateUniversity,352DodridgeStreet,Columbus,OH43202,USAarticleinfoArticlehistory:Received2September2011Receivedinrevisedform28November2011Accepted28November2011Availableonline26December2011Keywords:MitigationbankwetlandsVegetationstructureandfunctionEmergentmacrophytesFloristicqualityassessmentindexWetlandcreationandrestorationOlentangyRiverWetlandResearchParkabstractVegetationsurveysofsevenOhiowetlandsiteswereconductedfrom2008to2010duringpeakbiomass.Thesesevensitesincludedfivecreated/restoredmitigationbankwetlands,acreatedriverineresearchwetland,andanaturalreferencewetland.Allofthecreated/restoredwetlandsrangedinagefrom3to18years.Theobjectiveofthisstudywastoexaminethedevelopmentofvegetationstructureandfunctionofmitigationbankwetlandslessthen20yearsofageandtocomparethesetoreferencewetlands.Vegetationstructureexaminedincludedspeciesrichness,floristicqualityassessmentindex(FQAI),Shannon–Wienerdiversityindex(H),andcommunitydiversityindex(CDI).Functionalattributesincludedabovegroundnetprimaryproductivity(ANPP)andfunctionalgroupcompositionofdominantspecies.Forbothstructureandfunction,thereferencewetlandswerestatisticallydifferentfromthewetlandmitigationbanksites(P0.001,MANOVA).Structurally,thereweresignificantdifferencesofFQAIscore(P0.05)andspeciesrichness(P0.05)withageinthemitigationsites.Functionally,therewasasignificantdifferencebetweenANPP(P0.05)andageinthemitigationsites.Overthedifferenttypesofwetlands,thereferencewetlandshadsignificantlydifferentANPP,FQAIscores,andspeciesrichnessthandidthemitigationsites(P0.001,P0.05,andP0.001,respectively).CDIandHwerenotstatisticallydifferentbetweenmitigationsitesandthereferencewetlands.ANPP,FQAI,andspeciesrichnesstendedtobehigherinthereferencesitesthaninthemitigationsites.Overall,themitigationbankwetlandswerenotstatisticallysimilartothereferencesites.Withinthemitigationbanks,theyoungersiteshadhighervaluesforstructuralattributesthantheoldermitigationsites.©2011ElsevierB.V.Allrightsreserved.1.IntroductionThroughoutmuchofthehumidUnitedStates,therehasbeenasignificantlossofnaturalwetlandssinceEuropeansettlement.MostoftheUpperMidwesternstateshavelostmorethan80%oftheirwetlands,whileOhiohaslostapproximately90%ofitsnat-uralwetlandssincethe18thcentury(Dahl,1990).Onewaytocombatfurtherlosshasbeenthroughwetlandmitigation.UnderSection404oftheU.S.CleanWaterAct,apermitisrequiredtodrain,damage,ordestroyajurisdictionalwetland(legallyrecog-nizedwetlandasdeterminedbytheWetlandDelineationManualpublishedbytheArmyCorpsofEngineers)(MitschandGosselink,2007;SalzmanandThompson,2007).Thepermitholderisthen∗Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddresses:[e-mail](K.C.Stefanik),[e-mail](W.J.Mitsch).1Presentaddress:EvergladesWetlandResearchPark,KapnickCenter,FloridaGulfCoastUniversity,4940BayshoreDrive,Naples,FL34112,USA.requiredtomitigatethelossofthewetlandsthatweredamagedordestroyed,usuallyataratiogreaterthan1:1,i.e.wheremorewetlandareaiscreatedorrestoredthanwaslost.Thepurposeofagreaterthan1:1ratioistoavoidanetlossofwetlandareaandecosystemprocesses.Mitigationcanbedoneonanindividualbasisorbyanorganizationthatspecializesinwetlandcreationandrestoration.Thesecondtypeofmitigation,oftenreferredtoasawetlandmitigationbank,iswhenwetlandsarecreatedorrestoredwithoutregardtoaspecificpermitpriortowetlanddestruction.Wetlandareacreditsfrommitigationbanksarethensoldtopermitholderstofulfilltheirpermitrequirements(MitschandGosselink,2007).Ideally,thedesignofacreatedorrestoredwetlandshouldbemodeledafterthenaturalwetlandthatwasdamagedordestroyedinordertoreplicatethewetlandtypeandecosys-temprocessesofthenaturalsite.Inmanycases,particularlywithmitigationbankwetlands,informationregardingthenat-uralwetlandthatwasdamagedordestroyedcannotbeusedintheplanningofthemitigationwetland.Instead,referencewetlandslocatednearthemitigationsiteareusedasaguidefor0925-8574/$–seefrontmatter©2011ElsevierB.V.Allrightsreserved.doi:10.1016/j.ecoleng.2011.11.016K.C.Stefanik,W.J.Mitsch/EcologicalEngineering39(2012)104–112105mitigationconstructionandmonitoring(LePage,2011).Theuseofhighqualityreferencewetlandscanillustratetheoverallgainorlossofwetlandfunctionduetomitigationandcanaidinbet-terinitialconstructionofthemitigationwetlands(BrinsonandRheinhardt,1996).Monitoringofmitigationwetlandsusuallylastsforthefirstfiveyearsaftercreation/restoration,atwhichpointthesuccessofthewetlandisdetermined(NRC,2001).Thesuccessandqualityofthesecreatedandrestoredwetlandsaredeterminedusinghydrologic,vegetation,andsoilcharacteristics,withemphasisbeingplacedonvegetation(NRC,2001;Spielesetal.,2006).Vegetationpar