Developinganindexofwetlandconditionfromecologicald

Developinganindexofwetlandconditionfromecologicaldata:AnexampleusingHGMfunctionalvariablesfromtheNanticokewatershed,USAAmyDellerJacobsa,*,MaryE.Kentulab,AlanT.HerlihycaDelawareDepartmentofNaturalResourcesandEnvironmentalControl,DivisionofWaterResources,820SilverLakeBlvd.,Suite220,Dover,DE19904,USAbU.S.EnvironmentalProtectionAgency,NationalHealthandEnvironmentalEffectsLaboratory—WesternEcologyDivision,200SW35thStreet,Corvallis,OR97333,USAcDepartmentofFisheriesandWildlife,OregonStateUniversity,Corvallis,OR97331,USA1.IntroductionThereisanincreasingdemandforinformationthatcanbeusedtounderstandtheecologicalqualityofthewetlandresourceinadditiontostatusandtrendsinthequantityofwetlands(i.e.,area)thatismostcommonlyreported(e.g.,Fennessyetal.,2007).Dataontheecologicalconditionofwetlandscanbeusedtoreportontheambientconditionoftheresource,targetrestorationandprotec-tionefforts,evaluatetheeffectsofmitigationandrestorationpractices,supportregulatorydecisions,andtracktheimpactoflandusedecisions(Fennessyetal.,2007;Wardropetal.,2007a,b;Whighametal.,2007).Whighametal.(2007)andWardropetal.(2007a)havedemonstratedtheuseofhydrogeomorphic(HGM)assessmentstoreportontheconditionofwetlandsonthewatershedscalebyevaluatingtheperformanceofvariousecologicalfunctions(hydrology,biogeochemistry,plantcommunity,habitat,andlandscape).Thisapproachusesmultipleindicestoevaluateconditionbyidentifyinghowspecificfunctionsareperforminginrelationtoreferencestandardsiteswhicharedefinedastheleastdisturbedsitesinthewatershed.Additionally,analysisoftheHGMfunctionscorescandeterminespecificwetlandfeaturesthathavebeenimpacted,thusprovidingguidanceforrestoration.Forexample,intheNanticokeRiverwatershed,thehydrologyfunctioninriverinewetlandswasperformingatalowerlevelthaneitherthewildlifehabitatorplantcommunityfunction(Whighametal.,2007).Thehydrologyfunctionwasusuallylowbecauseofalterationstothestreamchannelthatchangedthehydrologyoftheassociatedwetland.ThissuggestedthattoimprovetheconditionofriverinewetlandsintheNanticokewatershed,restorationeffortsshouldfocusonrestoringalteredstreamchannelsadjacenttoriverinewetlands.RegionalHGMmodelshavebeencompletedforawidediversityofwetlandtypesacrossthecountryincludingbothtidalandnon-EcologicalIndicators10(2010)703–712ARTICLEINFOArticlehistory:Received6August2009Receivedinrevisedform19November2009Accepted23November2009Keywords:WetlandassessmentHGMNanticokewatershedWetlandconditionWetlandfunctionABSTRACTDemandfordataontheecologicalconditionofwetlandsisincreasingasstateandfederalmanagementprogramsrecognizeitsvalueinreportingontheambientconditionoftheresource,targetingrestorationandprotectionefforts,evaluatingtheeffectsofmitigationandrestorationpractices,supportingregulatorydecisions,andtrackingtheimpactoflandusedecisions.Wedevelopedanapproachforgeneratingasinglemeasureofwetlandconditionfromecologicalvariablesusedinhydrogeomorphic(HGM)assessment.AnIndexofWetlandCondition(IWC)wasdevelopedfromHGMfielddatacollectedtoassessfreshwater,non-tidalflat,riverine,anddepressionwetlandsintheNanticokeRiverwatershed.TheHGMvariableswerescreenedandscoredbasedonarangecheck,responsiveness,andmetricredundancy,employingamethodusedtodevelopindicesofbioticintegrity.Weightsoftheindividualvariableswereadjustedtoreflectourunderstandingofwetlandecologyandtoincludevariablesthatrepresentedthevegetation,hydrology,andbufferofawetland.ThefinalIWCscorediscriminatedhigh,medium,andlowsitedisturbanceclassesinflatandriverinewetlandsandhighandlowdisturbanceclassesindepressions,one-wayANOVAF-valuesrangedfrom44.5to79.1(allp0.0001).ThecombinationoftheIWCandHGMassessmentsprovidesacomprehensiveevaluationofthewetlandresource.HGMproducesinformationonspecificwetlandfunctions.TheIWCconciselyconveystheecologicalconditionoftheresourceandmaximizestheutilityofthedatacollectedinanHGMassessment.2009ElsevierLtd.Allrightsreserved.*Correspondingauthor.Tel.:[phone];fax:[phone].E-mailaddresses:[e-mail](A.D.Jacobs),[e-mail](M.E.Kentula),[e-mail](A.T.Herlihy).ContentslistsavailableatScienceDirectEcologicalIndicatorsjournalhomepage:–seefrontmatter2009ElsevierLtd.Allrightsreserved.doi:10.1016/j.ecolind.2009.11.011tidalwetlands()(Adamus,2006;Klimasetal.,2008;Wardropetal.,2007a;Whighametal.,2007).Eachofthesemodelsisreference-basedandscaledtodatacollectedonsitesthatspantherangeofhumandisturbanceandecologicalvariation.Thewealthofdatausedtodevelopthesemodelscharacterizesecological,physical,andlandscapeprocesses,bioticcommunities,andstructureforeachwetlandtypeassessed.HGMandotherfunctionalassessmentmethodsproducescoresforindividualwetlandfunctions;however,thistypeofinformationisnotapplicabletoallsituations.Forexample,whenreportingontheconditionofwetlands,onescoreisoftendesiredbecauseitprovidesameasureofoverallecologicalintegrityofthewetlandortheentireresource,iseasiertoexplaintomanagersandthepublic,andcanbeusedtodetermineifwetlandsaremeetingwat