61Lowmultifunctionalredundancyofsoilfungald

LETTERLowmultifunctionalredundancyofsoilfungaldiversityatmultiplescalesAkiraS.Mori,1*ForestIsbell,2SaoriFujii,1KobayashiMakoto,3ShunsukeMatsuoka4andTakashiOsono41GraduateSchoolofEnvironmentandInformationSciences,Yoko-hamaNationalUniversity,Yoko-hama,Kanagawa240-8501,Japan2DepartmentofEcology,EvolutionandBehavior,UniversityofMinnesota,SaintPaul,MN55108,USA3FieldScienceCenterforNorthernBiosphere,HokkaidoUniversity,Otoineppu438,Otoineppu,Hokkaido098-2501,Japan4CenterforEcologicalResearch,KyotoUniversity,Otsu,Shiga520-2113,Japan*Correspondence:E-mail:[e-mail]sthatbiodiversitymighthelpsustainmultipleecosystemfunctions.Toevaluatepossiblebiodiversity–multifunctionalityrelationshipsinanaturalsetting,weconsidereddifferentspatialscalesofdiversitymetricsforsoilfungiinthenorthernforestsofJapan.Wefoundthatmultifunctionalityincreasedwithincreasinglocalspeciesrichness,suggestingalimiteddegreeofmultifunctionalredundancy.Thisdiversity–multifunctionalityrelationshipwasindependentofthecompositionaluniquenessofeachcommunity.However,westillfoundtheimportanceofcommu-nitycomposition,becausetherewasapositivecorrelationbetweencommunitydissimilarityandmultifunctionaldissimilarityacrossthelandscape.Thisresultsuggeststhatfunctionalredundancycanfurtherdecreasewhenspatialvariationsinidentitiesofbothspeciesandfunctionsaresimulta-neouslyconsideredatlargerspatialscales.Wespeculatethatdifferentscalesofdiversitycouldprovidemultiplelevelsofinsuranceagainstthelossoffunctioningifhigh-levelsoflocalspeciesdiversityandcompositionalvariationacrosslocationsarebothmaintained.Alternatively,makingspeciesassemblagesdepauperatemayresultinthelossofmultifunctionality.KeywordsBelowgroundprocesses,biodiversity-ecosystemfunctioning,compositionalcharacteristics,ecosystemmultifunctionality,forestbiodiversity,functionalredundancy,multifunctionaldissimilarity,scaledependency,speciesimportance.EcologyLetters(2016)19:249–259INTRODUCTIONTherearecurrentlyincreasingconcernsanddemandsforcon-servingbiodiversityworldwide.Theseconcernsprimarilyresultfromsubstantialdeclinesinbiodiversityatvariousspa-tial,temporalandbiologicalscales,whichhavebeengloballyrecognisedforthelastseveraldecades(Butchartetal.2010).Concurrently,thereisagrowingbodyofscientificevidenceindicatingthatbiodiversityisnotmerelyaresponsevariabletoenvironmentalchangesbutalsoapredictorofvariousecosystemfunctionsandservices(Duffy2009;Cardinaleetal.2012;Balvaneraetal.2013),whichareessentialforsustaininghumanwellbeing(MA2005).Notably,therolesofbiodiver-sityformaintainingecosystemfunctioningcanbemorestronglyrealisedwhenmultiplefunctionsareconsideredsimultaneously(Hector&Bagchi2007;Zavaletaetal.2010;Isbelletal.2011;Maestreetal.2012;Byrnesetal.2014;Lef-checketal.2015).Theseinvestigationsof‘ecosystemmulti-functionality’areofpracticalimportancebecausehumansocietydoesnotrelyonasinglefunctionorservice,butrather,inreality,requiresmultiplefunctionsandservicesobtainedfromnature.Animportantissueinconsideringtherolesofspeciesassemblagesforpromotingmultipleecosystemfunctionsisthatof‘lowmultifunctionalredundancy’(Morietal.2013);i.e.speciesthatarefunctionallyredundantwhenasinglefunc-tionisconsideredcannolongerberedundantwhendifferentfunctionsaresimultaneouslyconsidered(Gamfeldtetal.2008;Zavaletaetal.2010;Isbelletal.2011).Suchlowredundancysuggeststhatthefunctionaluniquenessofspecies(speciesidentity)canbeamajordeterminantforoverallfunctionalityofecosystems,inadditiontothefundamentalimportanceofthelevelofspeciesdiversity(e.g.a-diversity).Importantly,thisfunctionalimportanceofindividualspeciestosupportsomefunctionscanbecomeparticularlysignificantforsustainingmultifunctionalitywhenthereisspeciesturnoveracrossspace,timeorecosystemfunctions.Thisisbecausenospeciescanalwayspromoteallfunctionsatdifferentlocationsandtime-points(Zavaletaetal.2010;Isbelletal.2011).Thus,togainabetterpictureofthediversity–multifunctionalityrelation-shipsandtocarefullyassessthepossibleredundancyamongspecies(Gamfeldtetal.2008),itisalsonecessarytoaccountforvariationsinspeciescompositionamongcommunities(compositionalcharacteristics).Suchaperspectivebaseondifferentscalesofdiversitycouldbeespeciallyimportantformaintainingthemultifunctionalityofnaturalsystems,wherecommunitiesoftenshowalargevariationinspeciescompositionacrossspaceandtime.Althougharecentstudyinamodelecosystem(Pasarietal.2013)shedlightontheimportanceofcompositionaldistinct-nessamonglocalcommunities(b-diversity)topromoteecosystemfunctioning,itisstillunknownwhethersuchspatialvariationsincompositionalcharacteristicsaffectmultifunc-tionalityinnaturalsystems.Innature,communitiesthatareformedthroughnaturalassemblyprocessesmightcontaincomplementarysuitesofspeciesthatarebetteradaptedtolocalconditions(Pasarietal.2013).Furthermore,real-worldsituationsarecharacterisedbyaskeweddistribution(i.e.unevenness)ofspeciesabundance(McGilletal.2007),non-randomlossofspecies(Brackenetal.2008;Selmantsetal.©2015JohnWiley&SonsLtd/CNRSEcologyLetters,(2016)19:249–259doi:10.1111/ele.125602012),andhi