Do the impacts of alien invasive plants differ from expansive native ones? : an experimental study on arbuscular mycorrhizal fungi communities

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BiologyandFertilityofSoils(2018)54:631–

643https://doi.org/10.1007/s00374-018-1283-8 ORIGINALPAPER

Dotheimpactsofalieninvasiveplantsdifferfromexpansivenative ones?

Anexperimentalstudyonarbuscularmycorrhizalfungic ommuniti es

MartaL.M ajewska¹^&KajaR ola¹^&A nnaM . S tefanowicz²^&M arcinN obis¹^&JanuszBłaszkowski³^&SzymonZ ubek¹

Received:5January2018/Revised:26March2018/Accepted:24April2018/Publishedonline:7May2018

#TheAuthor(s)2018

Abstract

Nostudieshavecomparedsofartheeffectsofalieninvasiveandexpansivenative(widespread,mono-

dominant)plantsonarbuscularmycorrhizalfungi(AMF).FourglobalorEuropeanmostsuccessfulinvaders(Impatiensglandulifer a,Reynoutriajaponica,Rudbeckialaciniata,Solidagogigantea)andtwoexpansiveplantsnativetoEurope(Artemisiavulgaris,P halarisarundinacea)weregrowninpotstoelucidatethemagnitudeanddirectionofchangesinAMFabundance,speciesrichness,ands peciescompositioninsoilsfromundermultispeciesnativevegetation.Inasecondstage,theeffectsofthesechangesonanativeplant,Pl antagolanceolata,wereassessed.PlantspeciesidentityhadlargerimpactonAMFabundance,speciesrichness,andspeciescomposi tionaswellasonP.lanceolatathanoriginofthespecies(alienvs.native).ThiscouldbeduetothecharacterofAMFrelationshipswiththe plants,i.e.,theirmycorrhizalstatusanddependencyonAMF.However,thealterationsinducedbytheplantspeciesinsoilchemicalpr opertiesratherthaninAMFcommunitywerethemajordriversofdifferencesinshootmassandphotosyntheticperformanceofP.la nceolata.Wedeterminedthattheplantsproducedspecies-specificeffectsonsoilpropertiesthat,inturn,resultedinspecies- specificsoilfeedbacksonthenativeplant.Theseeffectswerenotconsistentwithingroupsofinvadersornatives.

KeywordsArbuscularmycorrhizalfungi(AMF).Arbuscularmycorrhiza(AM).Invasiveplants.Expansivenativeplants.Plantspe ciesspecificity.Soilfeedback

Introduction

Plantinvasionsareoneofthemostimportantthreatstobiodi- versityandsignificantdriversofenvironmentaldegradationan dchangeonaglobalscale.However,inmanycases,wedo

ElectronicsupplementarymaterialTheonlineversionofthisarticle(http s://doi.org/10.1007/s00374-018-1283-

8)containssupplementarymaterial,whichisavailabletoauthorizedusers .

*SzymonZubekszymon.zu bek@uj.edu.pl

1 InstituteofBotany,FacultyofBiology,JagiellonianUniversity,G ronostajowa3,30-387Kraków,Poland

2 W.SzaferInstituteofBotany,PolishAcademyofSciences,Lubicz46, 31-512Kraków,Poland

3 DepartmentofEcology,ProtectionandShapingofEnvironment,W estPomeranianUniversityofTechnology,Słowackiego17, 71-434Szczecin,Poland

notknowthedirectionandmagnitudeofinvasiveplantim- pactsontheenvironment,andwearealsounabletoelucidatewhic hfactorsinfluenceinvasionprocesses.Oneofthemech- anismsleadingtothesuccessofinvasiveplantspeciesisthatinva derschangethecomponentsofsoilenvironmentdueto,e.g.,ther eleaseofsecondarymetabolitesasrootexudatesandthroughdep ositionoflitterofvariousqualityandquantityanddifferentuptak eorimmobilizationofnutrients,aswellasdifferentialC prov isiontosymbioticfungi(WolfeandKlironomos2005;Stins onetal.2006;Cantoretal.2011;PerkinsandNowak2012;

TannerandGange2013).Thesecanmodifythechemicaland microbiologicalpropertiesofsoils(Battenetal.2006;Shahetal .2009;Stefanowiczetal.2016,2017,2018),includingthealterat ionsintheabundanceandspeciesdiversityofthemostwidespre adandimportantplantsymbionts—

arbuscularmycorrhizalfungi(AMF)

(Sanonetal.2012;TannerandGan ge2013;Zubeketal.2016 ).Thesefungiinhabittherootsofagreatmajorityofterrestria lplantspeciesandplayanimportantroleintheir

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632 BiolFertilSoils(2018)54:631–643

mineralnutrition,protectionagainstbioticandabioticstresses, andshapingplantcommunitybydifferentlyinfluencingplantsp eciesperformance(SmithandRead2008).Thedisturbanceinth estableAMFcommunitiesasaresultofinvaders’colo-

nizationcandecreasenativeandincreasealienplantperfor- mance,thusfacilitatingplantinvasions(Stinsonetal.2006;Sha hetal.2009;Xiaoetal.2014).

Theinvestigationsconductedsofarhaverevealedspecies- specificeffectsofplantinvasionsonAMFabundance,speciesri chness,andspeciescomposition.Forexample,thestudiesbyLi angetal.(2004)onSolidagocanadensisandChenetal.

(2015)onChromolaenaodorata,Ageratinaadenophora,andFl averiabidentisshowedthatthedominanceoftheseplantsincrea sedAMFspeciesrichness.Itwasalsofoundthattheinvasionof A.adenophoraincreasedAMFabundance(Niuetal.2007).Le kbergetal.

(2013)showedthatinvasionsofCentaureastoebeandEuphorb iaesula,butnotBromustectorum,supportedhigherabundance andspeciesrichnessofAMFthanmultispeciesnativeplantco mmunities.Incontrast,thesurveyperformedbyTannerandGa nge(2013)andZubeketal.

(2016)demonstratedthatReynoutriajaponicareducedAMF abundanceandspeciesrichness.Moreover,twootheralienspe ciesexaminedbyZubeketal.

(2016),namelyRudbeckialaciniataandSolidagogigantea,de creasedthenumberofAMFspecies.ThechangesinAMFabund ance,speciesrichness,andspeciescompositionshouldthusbec onsideredasanimportantmechanismbywhichin-

vasiveplantsoutcompetenativespecies(Hawkesetal.2006;Zh angetal.2010;TannerandGange2013).

Theaforementionedinvestigationsfocusedontheimpactofali enplantsonAMFinthefield.However,undercontrolledconditio ns,nostudieshavesurveyedtheinfluenceofinvadersandcompar edtheireffectswiththeimpactofnativeplants,whichalsocanbe successfulcolonizers,formingfrequentlymonospecificpatche sintheareasoftheirexpansion.Itisim-

portanttonotethatnativeplantscaninfluencesoilmicrobialcomm unitiesusingthesamemechanismsasinvasiveones,buttheimpact ofinvadersmaybemorepronounced,e.g.,duetoconsiderablediff erencesinplanttraitsbetweeninvadersandnatives,oranoveltyo faparticularmechanismtoanativecommunity(WolfeandKlir onomos2005).Therefore,wecon-

ductedanextensiveoutdoorpotexperimentfortwoconsecu- tivegrowingseasons,whichaimedatassessingtheimpactoffoura lieninvasiveplantsversustwocommonnativeplantspecieso nAMFabundance,speciesrichness,andspeciescom-

positionintwosoiltypes.Moreover,theperformanceofamod el,nativeplantgrownsubsequentlyinthesesoils,wasevaluate dinthesoilfeedbackpotexperimentcarriedoutunderlaboratoryc onditions.Understandingtheinteractionsbetweeninvasiveandn ativeplantsandAMFcommunitiesisfundamen-

taltorecognizethecourseandmechanismsofinvasionandtoyield keyplant-

AMFinteractionsnecessaryfortherestorationofinvadedareas(Bu sbyetal.2013).

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BiolFertilSoils(2018)54:631–643 3 Thealienplantsusedinourstudy,namelyImpatiensgland

uliferaRoyle(Balsaminaceae),Reynoutriaj a p onicaHoutt.

(Polygonaceae),RudbeckialaciniataL.,andSolidagogigantea Aiton(Asteraceae),areincludedintheworld’s(Loweetal.2000) and/orEuropean(Tokarska-

Guziketal.2012;Pyšeketal.2012)listsofthehigh- impactinvasiveplants—thetrans-

formers,whichchangethecharacter,condition,form,ornatureo fecosystems(Richardsonetal.2000).I.glanduliferaand R. japonicaarebothofAsianorigin,whileR.laciniataand S. giganteaarenativetoNorthAmerica.Thesespecieswereintr oducedtoEuropeasornamentalplantsandescapedfromcultivat ionintothewild.Theyinvadenatural,semi-

natural,andanthropogenichabitats(Tokarska-

Guziketal.2012).Thetwonativespecies,ArtemisiavulgarisL.

(Asteraceae)andPhalarisarundinaceaL.

(Poaceae),areexpansiveplantsthatfrequentlyco-

occurwiththeinvadersindifferenthabitatsandaretheirmostco mmoncompetitors.Moreover,theyalsohavebecomesuccess- fulinvadersaftertheirintroductiontoNorthAmerica(Westoneta l.2005;Nelsonetal.2014).I.glandulifera,R.laciniata,and S.giganteaandbothnativespeciesformarbuscularmycorrhiza(

AM),whereasR.japonicaisnon-

mycorrhizal(Majewskaetal.2015,2017;Zubeketal.2016).The plantsweregrowninsoilsrepresentingtwohabitats,namelyun managedmeadowandtallherbvegetation,locatedoutsideandw ithinrivervalley,respec-

tively,whicharefrequentlycolonizedbythesespecies.Wecol- lectedthesesoilsfromundermultispeciesnativeplantcommu- nitiestomimicthesituationthatbothinvadersandexpansivenativ eplantsencroachnewarea.Forthelaboratorysoilfeedbackpote xperiment,weusedoneofthenativespeciesthatwerepresentint heplantc ommunitiesonbothsoils,P lantagolanceolataL.

(Plantaginaceae).Thismodel,mycorrhizalspecieswasplantedi nthesoilsconditionedbybothinvadersandnatives.Wehypothe sizedthat(1)bothinvasiveandnativeplantssignif-

icantlyimpactAMFcommunityastheyformmonospecificpa tchesinthecolonizedsites;

(2)duetotheirnovelpresenceintheenvironment,theinvadersco nditionsoilsdifferentlyandex-hibitdifferentplant-

soilfeedbacktypesonP.lanceolataperfor-

mance(mycorrhizalcolonization,biomass,photosyntheticin- dex)thanthenativespecies;

(3)thedirectionofthechangescausedbytheinvadersandnatives isalsoshapedbyspeciesidentityasspeciesdifferintheirmycorr hizalstatusordependen-

cyonAMsymbiosis;and(4)theeffectsoftheinvasiveandnative plantsarealsodeterminedbythesoiltype.

Materialsandmethods

Soi

ls

Thesoilsfortheexperimentwerecollectedfromtwolocations:Kra ków(49°59′49.5″N/19°52′13.6″E)andZator(49°59′59″N/19°

26′40.5″E),situatedinsouthernPoland,whichrepresenttwodiffer enthabitats—unmanagedmeadowoutsiderivervalley

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(thereafterBfallow^soil)andtallherbvegetationwithinrivervalle y(Bvalley^soil),respectively.Wechosethesehabitatsac- cordingtotheobservationsconductedbyKostrakiewicz- GierałtandZając(2014),Majewskaetal.

(2015),Stefanowiczetal.(2016,2017),andZubeketal.

(2016)thatthetestedinvasiveandnativeplantscommonlycoloni zethem.Bothsoilswerecollectedfromundermultispeciesplantc ommunitythatwasdevoidofalienplants.Forbothsoiltypes,onl ythetopca.30cmofsoilwascollected.Thesoilswereclassifiedasl oamysand(Stefanowiczetal.2018).Thephysicochemicalpropert ies,namelypH;organicC(CORG)content;total(T)contentsofCT, NT,CaT,KT,andPT;andexchangeable/available(EX)contentsof

seedswerehomogenouslyscatteredonthesoilsurfaceandcoat- edwith0.5cmofsoillayer(Čudaetal.2015).InthecaseofannualI.

glandulifera,wealsosowed30seedsperpotinthesecondyear.Th efollowingtreatmentconfigurationswereestablished:

(1)withoutplants(allplantsthatemergedfromthesoilseedbankw ereconsequentlythinnedout),(2)A.vulgaris,

(3)P.a r undinacea,(4)A . v ulgaris+ P.a rundinacea,( 5) I.glandulifera,(6)R.j a p onica,(7)R . laciniata,and(8) S.gigantea.AsweobservedthatA.vulgarisand

P.arundinaceaalsoformmixedpatchesinnaturalstands,weestabl ishedadualtreatmentofthesespecies.Foreachtreatment,wehads ixreplicates,96potsintotal(2soiltreatments×8plant

− +

CaEX,KEX,N(N-NO3,N-NH4),andPEX,oftheinitialsoils wereexaminedpriortoourexperiment.Moreover,weconductedt hesameanalysesattheendoftheexperimenttodeterminepotentia linvasive/nativeplant-

inducedchangesinsoilproperties(Stefanowiczetal.2018).

Plants

Intheoutdoorexperiment,weusedfourinvasive(I.glandulifera, R.j a ponica,R . l a ciniata,a n d S . g i gantea)a n d t w o n a tive(

A.vulgarisandP.arundinacea)plants.Theseedsoffivestudiedspe ciesandt herhizom esof R . japoni cawere gathered i n October2013andinApril2014,respectively.Weusedtherhi- zomesofR.japonicainthestudyduetotherarityorabsenceofseed productionofthisspeciesinsouthernPolandandtheveg- etativewayofspreading(Beerlingetal.1994).Plantmaterialwasc ollectedatthesameareaassoil.Forthelaboratorysoilfeedbackexp eriment,weselectedP.lanceolataasarepresenta-

tiveofresidentplantspeciesonbothsoils.Thismycorrhizalplantis commonlyusedinstudiesevaluatingtheimpactofinvasiveplants onnativeplantperformance(Lorenzoetal.2013;TannerandGang e2013;Guisande-

Collazoetal.2016;Zubeketal.2016).TheseedsofP.lanceolata wereobtainedfromHerbadorco.(Poznań,Poland).

Theoutdoorexperiment

SetupandmaintenanceTheexperimentwascarriedoutfortwogr owingseasons,from12April2014to25August2015,intheJagiell onianUniversityBotanicalGardeninKraków(50°3′57.83″N,19

°57′19.05″E).Thegardenissituatedinthetem-

perateclimatezone,wherethemeanannualtemperatureis8.2°Can dthemeanannualprecipitationis678mm.Thesoilsfromtwohabit atsweresievedthroughgardensieves(meshsize1.5cm)toremove stones,coarseroots,andotherparticles;then,eachsoilwashomoge nized.Sixsamplesofeachsoiltypewerecollected(initialsoils).The n,thesoilswereputinto10-

lplasticroundpots(25cmwide×30cmhigh)withdrainageholesa ndsaucertray,onetypeofsoilperpot.Theseedsoffivesurveyedsp eciesweresownseparatelyorinpairs,ca.30seedsperpot.Inthecas eof

R.japonica,onerhizomewastransferredintoeachpot.The

treatments×6replicates).Thepotswerearrangedinacomplete- lyrandommannerwithca.50-

cmdistancebetweenthemandkeptinopenspaceundernaturalsun lightconditions.Theplantswerewateredinthespringandsummer using 1 lofwaterperpot,accordingtoneed.Ifanyundesirablepla ntspeciesappearedinthepots,itwasimmediatelyremoved.Durin gthewinter(fromOctober2014toMarch2015),theplantswerepro tectedfromcoldusingbubblewrap(thesidesofeverysinglepotwe recov-

eredto10cmaboveapot)thenrandomlygroupedintoblocksandw rappedupbynonwovenfabric.After6months,thecoverwasremo ved,andpotswereagainrandomized.After17months,wefinished theexperiment.Allpotsweretransportedtothelaboratory.

MaterialharvestingTheshootsofbulkedplantswereharvest- edandtopsoillayer(upto3cmofthepotdepth)wasalsoremove d.Theremainingsoilwasremovedfromthepotbytappingtheri mofthepotfirmlyagainstahardsurfaceandthenthematerialw asputintoaplasticbag.Fromeachpot,weremoved3cmofsoilla yerfromthesidesandbottom.Therootswereexcavatedandgen tlycleanedfromsoilresidues.Theshootsandrootswerewashed separatelyintapwater.Thedryweightofabovegroundpartsofpl antswasmeasured(Stefanowiczetal.2018).Belowgroundpart sofplantsweretakenforstaininginordertodeterminethepresen ceofAMF.Thesoilfromeachpotwashomogenizedandthendi videdintoportions:(1)ca.100gforAMFsporeisolation, (2)ca.500gforestablishingthesoilfeedbackexperiment, (3)ca.100gforPLFAanalyses(seebelow),and(4)ca.1000gfor physicochemicalanalyses(Stefanowiczetal.2018).

AssessmentofAMFrootcolonizationPhillipsandHayman(19 70)methodwithminormodifications(Majewskaetal.2015)w asusedforstainingofinvasiveandnativeplantroots.Theobser vationofAMFstructureswasconductedusingalightmicrosc ope(NikonEclipse80iwithNomarskiinterferencecontrast ).Arbuscularmycorrhizalfungicolonizationwasdetermin edasreportedbyTrouvelotetal.

(1986)andtheparametersanalyzedweremycorrhizalfreque ncy(F),relativemycorrhizalrootlength(M),andrelativearb uscularrichness(A).

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Arbuscularmycorrhizalfungisporeisolationandidentifica- tionThesporesofAMFwereisolateddirectlyfromtheinitialsoil s,attheexperimentsetupin2014.Atharvest(2015),weextracte dsporesfromallpots,whichrepresenteighttreat-

ments.Theprocedureofsporeextractionranasfollows:ca.100 gofsoilsamplewascollectedfromhomogenizedsoilofeachpot, thenputintoplasticzipbagandstoredinarefriger-

atorforafewdaysuntilanalyzed.Thesporeswereisolatedfrom 50gofsoilbycentrifugation(1389×gfor1min)inasucrosesoluti on(Brundrettetal.1996),rinsedinwateronasieveof50- μmmeshsize,countedin aPetridish,andmountedonslidesin a dropofpolyvinylalcohol/lacticacid/glycerol(PVLG)and inamixtureofPVLG/Melzer’sreagent(1:1,v/v)

(Omaretal.1979).Thetaxonomicalclassi-

ficationofAMFsporeswascarriedoutusinganOlympusBXligh tmicroscopeasreportedbyBłaszkowski(2012).

Phospholipidfattyacid16:1ω5analysisPhospholipidfattyaci d(PLFA)16:1ω5wasusedasamarkertoevaluatetheAMFa bundanceinsoils(Olsson1999).Theanalysiswasperfo rmedaccordingtoPalojärvi(2006),excludingthelipidextracti ondoneasreportedbyMacnaughtonetal.

(1997).Theproceduresandequipmentusedinthepresentstud ywerethosebyZubeketal.(2016).

Thelaboratorysoilfeedbackexperiment

SetupandmaintenanceFortheestimationoftheperformanceoft henativeplantinthetestedsoils,weconductedtheexper- imentunderlaboratoryconditions.Weplaced450goftheiniti alsoilsandthesoilsfromeverysinglepotofeachtreat-

EvaluationofP.lanceolataphotosyntheticperformanceChl orophylla fluorescencetransientsOJIPofintactandfullyexpandedlea vesweremeasuredusingaHandyPEAfluorimeter(producedbyHans atechInstrumentsLtd.,King’sLynn,Norfolk,UK).Thestudiedmater ialwassimultaneouslydark-

adaptedfor30minbeforemeasuringusingleafclips.Wecarriedoutth emeasurementsonsixleavesofrandomlychosenplantsofeachpot.T hedatafromeachindividualpotwereaveraged.Themea-

surementswereconductedasreportedbyStrasseretal.

(2004)andTsimilli-

MichaelandStrasser(2008).Foreachpot(sample),theaverageOJIP fluorescencetransientswerecalculatedaccord-

ingtotheJIPtest(Strasseretal.2004),withBBiolyzer^software(La boratoryofBioenergetics,UniversityofGeneva,Switzerland).

Theperformanceindex(PIABS),whichevaluatestheoverallphotosynt heticperformance,waschosenforpresen-

tation.ThedescriptionofthisparameterwasgivenbyTsimilli- MichaelandStrasser(2008).

Statisticala nalysis Two-

wayanalysisofvariance(plant×soiltype)followedbyTukey’s(

HSD)testwasperformedtorevealsignificantdiffer-

encesinthemycorrhizalparameters(F,M,A),photosyntheticpa rameter(PIABS),shootmass,AMFsporeandAMFspeciesnumb ers,and16:1ω5PLFAconcentrationsinthesoilsacrossalltreat ments.Priortotheanalysis,thedistributionnormalitywasverifi edusingtheLillieforstest.Levene’stestwasper-

formedtoassesstheequalityofvariances.

Thearbuscularmycorrhizalcommunityattributes(i.e.,AM Fsporenumber,thenumberofAMFspecies,theconcen- trationof16:1ω5PLFA)andsoilchemicalparameters(i.e.,₋ ₊ mentinto500-mlplasticroundpotsthatwere9cmwideand

12.5cmhigh.SeedsofP.lanceolataweresown(10seedsperpot).

After1week,seedlingsweremanuallythinnedouttoobtainfive perpot.Intotal,108potswereestablished,12potswiththeinitials oilsin2014and96potsfromthetreatmentsoftheoutdoorexperim entin2015.TheplantsweremaintainedintheopenSigma- Aldrichsunbags,whichprotectfrompo-

tentialinfestationbetweentreatments.Theplantgrowthcham berconditionswereasfollows:temperatureof22±2°Candlight regime270–

280μmolPARphotons×m^−2×s¹,12/12h.Thepotswererandoml ysituated.Thecultureswerewateredonceaweekusing35mlofdi stilledwater.

MaterialharvestingAfter7weeksofgrowth,chlorophyllafluo rescencemeasurementswerecarriedout(seebelow);then,thep lantswereharvested.Theplantswererinsedwithtapandthende ionizedwater.Thebulkedrootsofeachpotwerestainedinorde rtovisualizeAMFmyceliaforthemy-

corrhizalcolonizationassessment(seeabove).Theshootsofea chindividualplantweredriedatroomtemperatureandweigh

edusinganelectronicanalyticalbalance(Radwag,WPA60/c/1) withalevelofprecisionof0.0001g.

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pH,CT,CORG,NT,N-NO3, N-NH⁴, P^T,PEX,KT,KEX,CaT, CaEX;Stefanowiczetal.2018)wereusedtorunacanonicaldisc riminantanalysis(CDA)toidentifywhichattributewasthemo stimportantforseparationofparticularplanttreatmentsandto verifyhowwelldiscriminatoryvariablesdistinguishparticul arplanttreatments.Duetolargedifferencesinsoilchemical propertiesbetweentwosoiltypes,thisanalysiswasappliedse paratelyfortheBfallow^andBvalley^soiltreat-

ments,withrespecttoBpredictor^variables.Forwardstepwise analysiswasused.DiscriminatorypowerwasexpressedbyW ilks’lambdastatistic.Beforetheanalysis,thecorrelationbet weenallvariableswascheckedinordertoavoidthematrixill- conditioningproblem.

Two-

waypermutationalmultivariateanalysisofvariance(PERM ANOVA)wasusedtoanalyzethedifferencesinAMFspecies compositionbetweentheplantandsoiltreat-

ments(Anderson2001).Theanalysiswasbasedonthematrixo fspeciespresence/absenceinparticulartreatmentsusingJacc ardcoefficient,with9999permutations.

Wealsoaimedtoinvestigatewhichsoilpropertiescouldha vebeencausaldriversofthefeedbackeffect.Asthemycor- rhizalparameters(F,M,andA)stronglycorrelatedwitheach

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other(R>0.9),onlytherelativemycorrhizalrootlength(M)wasi ncorporatedinfurtheranalysis.Theeffectofsoilchem-

icalproperties(Stefanowiczetal.2018)andAMFcommunitypr opertiesonM,shootmass,andPIABSo fP.lanceolatawasevaluat edbyseparatestepwisemultiplelinearregressionsusingforwa rdvariableselectionwithathresholdofp<0.05toentry.Strongl ycorrelatedindependentvariables(R>0.95)wereremovedprio rtotheanalysis.Adetailedresidualanaly-

siswasperformedinordertoobtainreliableregressioncoef- ficientsanddetectpotentialoutliers(extremecases).

TheanalyseswerecarriedoutusingSTATISTICAv.

12(Statsoft,Tulsa,OK,USA)andPASTv.3.10(Hammere tal.2001).

Result s

Theoutdoorexperiment

AMFcolonizationofinvasiveandnativeplants

Therootsofallsurveyedplantspecieswerecolonizedb yAMFexceptthoseofR.japonica.Themycorrhizalfrequency (F)wasinfluencedbybothplantspeciesandsoiltype(significantplant×soilinteraction;Table1,Fig.1),withthelowestFval uesforA.vulgaris+P.arundinaceainthefallowsoil.Thehighest meanvaluesofrelativemycorrhizalrootlength(M)andrelativ earbuscularrichness(A)wereobservedin

A.vulgaris,R.laciniata,andS.gigantea,andthelowestin A.vulgaris+ P.arundinacea,P.arundinacea,and I.glandulifera(significantplanteffect).Meanvaluesofthese

parameterswerehigherintherivervalleythaninthefallowsoil(s ignificantsoileffect;Table1,Fig.1).

AMFabundanceassessedbyPLFAmarker

The16:1ω5PLFAconcentrationwasinfluencedbybothplant andsoiltype(significantplant× soilinteraction;Table1).The highestmeanvaluesofthisparameterwereobservedinth esoilfromunderA.vulgaris,whereasthelow-

estinthetreatmentwithoutplants.A.vulgarisalsoincreased16:

1ω5PLFAconcentrationsincomparisontotheinitialsoils.Th edecreasedvaluesofthismarkerincomparisontobothinitials oilswerefoundforsoilwithoutplants,

I.glandulifera,andR.japonicainthevalleysoils,aswellas S.giganteainthefallowsoil(Fig.2).

AMFsporenumber,speciesrichness,andspeciescomposition ThehighestmeanvaluesofAMFsporenumberwererecordedint hecaseofR.laciniata,independentofsoiltype,andfor

S.giganteagrowinginthefallowsoil(significantplant×soilinte raction;Table1).Inthesecases,bothplantspeciesin- creasedthenumberofAMFsporesincomparisontotheirnu mbersinothertreatments(Fig.2).

Intotal,thesporesof20AMFspecieswereisolatedfromalltre atments.ThesporesofSeptoglomusconstrictum,Acaulosp orapaulinae,Diversisporaepigaea,andFunneliformism osseaeweremostfrequent,beingfoundin39,21,21,and19sam ples(pots)

(TableS1).ThenumberofAMFspecies(speciesrichness)wasi nfluencedbytheplantspecies(Table1).ItwashigherunderR.l aciniataand

Table1 Theresultsoftwo-

wayANOVAfortheeffectsofplant,soiltype,andtheirinteractiononplantandsoilparametersintheoutdoorandlaboratorysoilfeedbackexperiments

Parameters Plant Soil Plant×soil Error

F p df F p df F p df df

Outdoorexperiment

Mycorrhizalparameters F—mycorrhizalfrequency 5.42 <0.001 5 13.88 <0.001 1 2.64 0.032 5 60 M—relativemycorrhizalrootlength 18.55 <0.001 5 8.31 0.005 1 1.79 0.129 5 60 A—relativearbuscularr ichness 18.79 <0.001 5 8.20 0.006 1 1.63 0.165 5 60

Concentrationof16:1ω5PLFA 27.49 <0.001 8 0.07 0.798 1 6.83 <0.001 8 90

NumberofAMFspores 27.03 <0.001 8 0.83 0.365 1 2.72 0.010 8 90

NumberofAMFspecies(speciesrichness) 7.26 <0.001 8 0.05 0.949 1 1.58 0.142 8 90

Laboratorysoilfeedbackexperiment

Mycorrhizalparameters F—mycorrhizalfrequency 17.524 <0.001 8 51.122 <0.001 1 2.184 0.036 8 90 M—relativemycorrhizalrootlength 16.916 <0.001 8 55.738 <0.001 1 1.502 0.168 8 90 A—relativearbuscularr ichness 15.212 <0.001 8 46.328 <0.001 1 1.489 0.172 8 90

Shootmass 27.821 <0.001 8 89.837 <0.001 1 8.045 <0.001 8 90

PIABS—photosyntheticperformanceindex 9.818 <0.001 8 82.775 <0.001 1 5.715 <0.001 8 90

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Relativearbuscularrichness(%)Relativemycorrhizalrootlength(%)Mycorrhizalfrequency(%) Withoutplants A.vulgaris P.arundinacea A.vulgaris+P.arundinacea I.gladnulifera R.japonica R.laciniata S.gigantea NumberofAMFspeciesNumberofAMFspores16:1ω5PLFA(nMg-1) Initialsoils Withoutplants A.vulgaris P.arundinacea A.vulgaris+P.arundinacea I.gladnulifera R.japonica R.laciniata S.gigantea Theeffectsinitalicsarestatisticallysignificant

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80 60 40 20 0 100 80

A

B

A A

*

A A

B B

15

10 a

5 aa aa a

aa0

5 4

a

a a aa

b

a

C C A

6 0

40 20

3BCABBC BC

2 1

ABABA

0 0

Fallowsoil Valleysoil

Fig.1Mycorrhizalfrequency(F),relativemycorrhizalrootlength(M),and relativearbuscularrichness(A)

(means±SD;N=6)inthetreatments:withoutplants,A rtemisiav u lgaris,P h alarisa r undinacea,A rtemisiavulgaris+ P h a larisa r u n d i nacea,I m p a t i ensg l a n d u lifera,R e y n outriajaponica,Rudbeckialaciniata,andSoli dagogiganteainthefallowandrivervalleysoils.Lowercaselettersabove thebarsindicatethestatisticallysignificantinteractionbetweenthep lantandsoileffects,capitallettersabovethebarsshowthesignificantmai neffectofplant,thedifferentlettersabovethebarsindicatestatisticallysig nificantdifferences,andasterisksindicatethesignificantmaineffectofsoil

;foreachp<0.05.SeeTable1fordetailsonthemaineffectsandinteractions

S.giganteaincomparisontothetreatments:withoutplants,

A.vulgaris+P.arundinacea,I.glandulifera,andR.japonica.AMF speciesrichnessint heA.vulgaris+P.aru ndinacea

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Fig.2Theconcentrationof16:1ω5phospholipidfattyacidinsoil,thenum berofarbuscularmycorrhizalfungi(AMF)sporesin50goffreshsoil,and AMFspeciesnumber(speciesrichness)

(means±SD;N=6)forinitialsoilsandthetreatments:withoutplants,Art emisiavulgaris,Phalarisa rundinacea,Artemisiavulgaris+Phalarisaru ndinacea,Impatiensglandulifera,Reynoutriajaponica,Rudbeckial aci niata,andSolidagogiganteainthefallowandrivervalleysoils.Lowercase lettersabovethebarsindicatethestatisticallysignificantinteractionbetw eentheplantandsoileffects,capitallettersabovethebarsshowthesignific antmaineffectofplant,thedifferentlettersabovethebarsindicatestatisti- callysignificantdifferences,foreachp<0.05.SeeTable1fordetailsonthe maineffectsandinteractions

treatmentwasalsolowerthanthoseinA.vulgaris, P.arundinacea,andinitialsoils(Fig.2).

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3

4

PERMANOVAshowedsignificantdifferencesinAMFspe ciescompositionbetweenbothplant(F=1.61,p<0.05)andsoil (F=4.19,p<0.05)treatments.Theinteractionbe-

tweenplanttreatmentsandsoilswasnotsignificant(F=1.19,p=

0.07;TableS2).

Factorsdifferentiatingplanttreatmentsintheoutdoore xperiment

Factorsdifferentiatingplanttreatmentsvariedinparticularsoilt ype.Canonicaldiscriminantanalysis(CDA)showedthatpar- ticularplanttreatmentsonfallowsoildifferedsignificantlyinter msoftwomycorrhizalandsixsoilparameters.Theremain- ingparametersdidnothaveasignificantdiscriminatingpower(

TableS3).Standardizedcanonicalcoefficientsindicatedthatth ePTandPEXaswellas KEXandC aEXconcentrationsi n soilswerer elatedtothefirstcanonicaldiscriminantfunction,alongwhichin itialsoilwasthemostclearlyseparatedduetolowPTandCaEXand highP₊EXandKEXconcentrations.N-

thanintheinitialsoilofthistype.Themeanvalueofthispara meterwasalsodecreasedinR.japonicavalleysoilincompa risontoinitialsoilofthistype(Fig.4).P.lanceolataindividuals growinginthesoilfromtreatmentswithoutplantsandR.japonic awerecharacterizedbylowestmeanvaluesofrelativemycorrhi zalrootlength(M)thanintheothertreat-

ments(significantplanteffect).Similartrendswerefoundforrel ativearbuscularrichness(A),withthelackofdifferencesbetwe enI.glanduliferaandR.japonica(Fig.4).TheMandAparameter swerehigherintherivervalleysoilthaninthefallow(sig nificantsoiltypeeffect;Table1,Fig.4).

P.lanceolatashootmass

TheshootmassofP.lanceolataindividualswasinfluencedbyboth plantandsoiltypes(significantplant×soilinteraction;Table1).Th ehighermeanvaluesofthisparameterwereob-

servedforplantsgrowinginthefallowthaninvalleysoilinthecase ofA.vulgaris,P.arundinacea,A.vulgaris+

NH4 concentration,AMFsporenumber,andKTandCaEX P.arundinacea,andS.gigantea.P.lanceolatashootmasswas concentrationswererelatedtothesecondcanonicaldiscrimi-

nantfunction.Inthiscase,invasivespecies,i.e.,R.laciniata, S.gigantea,andR.japonica,wereclearlyseparatedfrom anotherinvasivespeciesI.glanduliferaalongthesecondca- nonicaldiscriminantfunctionduet o l owN-

NH4+andKTconcentrationsaswellashighAMFsporenumbera ndCaEXconcentration.Thesametrendwasfoundfornativespec ies,

A.vulgarisandP.arundinacea(Fig.3).

Asregardstreatmentsonvalleysoil,altogether,tenvari- ables(including2mycorrhizaland8soilparameters)hadthelarg estcontributiontothediscriminationofparticularplanttreatm ents,whereastheremainingparametersdidnothaveasignifican tdiscriminatingpower(TableS3).PEXandN-

NO^−hadthegreatestcontributiontoseparateplanttreatmentsal ongthefirstcanonicaldiscriminantfunction,alongwhich I.glanduliferatreatmentswerethemostclearlyseparatedduet ohighervaluesoftheseparameters.Initialsoiltreatmentswerecl earlyseparatedalongthesecondcanonicaldiscrimi-

nantf u nctiondueto l owC aEXandh ighKEXandN -

NH^{+ c}oncentrations.Analogouslytothecaseofinitialsoiltreat -

ments,nativeplantspeciestreatmentsandsoilwithoutplantswe reseparatedfrominvasiveplantspeciestreatmentsalongthisca nonicaldiscriminantfunction(Fig.3).

Thelaboratorysoilfeedbackexperiment

AMFcolonizationofP.lanceolata

Themycorrhizalfrequen cy(F)ofP.lanceolatawasinflu-

significantlyincreasedinthetreatmentswithoutplants(fallow), A.vulgaris,P.arundinacea,A.vulgaris+P.arundinacea(fallow),I . g landulifera,R . l aciniata( fallow),a ndS . g igantea(fa llow)incomparisontobothinitialsoils.Inthecaseofvalleysoil,the highershootmasswasalsofoundforsoilwithoutplants,

R. japonica,R.laciniata,andS.giganteaincomparisontotheinitia lsoilofthistype(Fig.5).

PhotosyntheticperformanceindexofP.lanceolata

Photosyntheticperform ancei ndex (PIABS)ofP.lanceol at awasaffectedbybothplantspeciesandsoiltype(significantpla nt×soilinteraction;Table1).Themeanvalueofthispa-

rameterwaslowestfortheinitialfallowsoilincomparisontoallo thertreatments.ThehighervaluesofPIABSinfallowthaninvalley soilwerealsofoundforsoilwithoutplantsand

S. gigantea(Fig.5).

EffectofAMFcommunityandsoilchemicalparametersonP .l anceolata(driversofthesoilfeedbackeffect)

Theselectionmodelsinlinearregressionanalysesarepresent- edinTable2.Forwardstepwiseregressionanalysiswithsoiland AMFcommunitypredictorvariablesandtherelativemy- corrhizalrootlength(M)ofP.lanceolataasthedependentvaria bleshowedthatthisparameterwassignificantlyinflu- encedby16:1ω5PLFAandtheconcentrationsofN-

NH^{+ a}ndPT.Foursoilchemicalfactorsprovedtohavesignificant impactonshootmass,whichwaspositivelyassociatedwith₋

encedbybothplantandsoiltype(significant plant×so

il theN-NO3 andCaEXconcentrationsaswellaspH,whereas

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interaction;Table1).ThelowestmeanvaluesofFparameterwer eobservedforfallowsoilsinthecaseofthesoilwithoutplantsan dR.japonica.Theywerealsosignificantlylower

negativelywiththeconcentrationofKEX.Fromthe15evalu- atedsoilandAMFfactors,onlythreesoilpropertiesprovedtobes ignificantlyassociatedwithphotosyntheticperformance

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Fig.3S catterplotpresentingther esultsofcanonicaldiscriminanta nalysisoftreatmentsrepresentin gdifferentplantspeciesfortwosoi ltypesseparatelyontothefirstand seconddiscriminantfunctions(c anonicalroots).Standardizedcoe fficientsforcanonicalvariablesa realsoprovided.SeetheBMateri alsandmethods^sectionforadesc riptionofvariables

(PIABS)ofP.lanceolata,i.e.,theconcentrationofCaEXandKEXas

wellaspH(Table2).

Discussion

Ourinvestigationisthefirststudyontheinfluenceoffourmost successfulandhigh-

impactglobalorEuropeaninvaders,i.e.,I.glandulifera,R.japon ica,R.laciniata,andS.gigantea,onAMFabundance,speciesric hness,andspeciescomposi-

tioninthepotexperiment.Moreover,wecomparedforthefirst timetheeffectsofinvasiveandexpansivenativeplantsontheafor ementionedAMFcommunityattributesandtheper-

formanceofanativeplantgrowninsoilsconditionedbybothgrou psofplants.

Inlinewithourfirstandthirdhypotheses,butcontrarytothesec ondone,bothinvasiveandnativeplantshadsignificantim- pactonAMFcommunity;however,thedirectionandmagnitudeof theseeffectsdependedonplantspeciesidentityratherthanbeingc onsistentwithingroupsofinvadersandnatives.LowAMFabund ance,sporenumber,andspeciesrichnessinthesoilsfromunderR.j aponicaconfirmedearlierreportsfromthefield

investigationsontheeffectsofthisnon-

mycorrhizalspecies(TannerandGange2013;Zubeketal.2016).

DetrimentaleffectsonAMFcommunityseemtobearuleforAMF non-hostsassimilartrendswerealsoshowedforothernon- mycorrhizalspe-

cies,i.e.,AlliariapetiolataandBrassicanigra(Brassicaceae),thein vadersofNorthAmericathatdecreasedAMFabundanceanddive rsity(Callawayetal.2008)andreducedsporegerminationrates(Pa kpourandKlironomos2015),respectively.However,similarlyto A.petiolataandB.nigra,R.japonicadidnotelim-

inateAMFfromsoil,asrevealedbythepresenceofspores,theconc entrationsofAMF-PLFAmarker,andthecolonizationof P.lanceolatagrownsubsequentlyinthesesoils.Theabundanceof AMFpropagulesunderR.japonicainourexperimentcouldbedue tothepersistenceofsporesfromtheinitialsoilsand/orthegrowthof AMFinsymbioseswithliverwortsandmossesthatoccurredinthe pots.Theseseemtobesupportedbythecompa-

rablelevelofpropagulesinthetreatmentwithoutplants.

ThereducedAMF-PLFAabundanceincomparisonto someothertreatmentswasalsofoundinthecaseof I.glandulifera.Similarly,Rucklietal.

(2014)andTannerandGange(2013)showedthatI.glandulifer areducedAMFabundanceinsoilsasrevealedbydecreasedcol onizationof

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Relativearbuscularrichness(%)Relativemycorrhizalrootlength(%)Mycorrhizalfrequency(%) Initialsoils withoutplants A.vulgaris P.arundinacea A.vulgaris+P.arundinacea I.gladnulifera R.japonica R.laciniata S.gigantea PIABSShootmass(g) Initialsoils Withoutplants A.vulgaris P.arundinacea A.vulgaris+P.arundinacea I.gladnulifera R.japonica R.laciniata S.gigantea

100 cd 80 60 40 20 0

d c cd ab

cdcdcdcdcdd cd

d cdcd abccd

0.25 0.2 0.15 0.1

0.05^{a b}

a

0 2.5

e de

bcd d

e e

cd abc

e e

bcd abcd

de bcd

e

bcd

100 B C BC * ef ef

2 ^def ^defbcdef^bcdef bcdef ef f

80 60 40 20 0 100

BC C B A

*

BCBC A

1.5 1 0.5 0

bcdef

a

bcdefb c d

bc bcdb c bcdef bcde

CDD

80 CD CD

60 BC

CDCD

40 A AB

20 0

Fig.5S h o o t massandphotosyntheticperformanceindex(PIABS) ofPlantagolanceolata(means±SD;N=6)grownintheinitialsoilsandinthes oilsfromthetreatments:withoutplants,Artemisiavulgaris,Phalarisarundin acea,A rtemisiav u lgaris+ P halarisa r undinacea,I mpatiensglandulife ra,Re ynoutriaj aponica,R u dbeckiala ciniata,a ndS olidagogigantea.Lo wercasel ettersa bovet heb arsi ndicatethestatisticallysignificantinteracti onbetweentheplantandsoileffectsandthedifferentlettersabovethebarsindi catestatisticallysignificantdifferences;foreachp<0.05.SeeTable1fordetai ls

Fig.4Mycorrhizalcolonization(means±SD;N =6)ofPlantagolanceolat agrowninthefallowandrivervalleyinitialsoilsandthesoilsfromthetreatm ents:withoutplants,Artemisiavulgaris,Phalarisarundinacea,A rtemisi av ulgaris+ P halarisa r undinacea,I mpatiensglandulifera,Reynoutriaj aponica,Ru dbeckiala ciniata,andSo lidagogigantea.L owercaseletters a bovet hebarsindicatet hestatisticallysignificantinteractionbetweenthe plantandsoileffects,capitallettersabovethebarsshowthesignificantmai neffectofplant,thedifferentlettersabovethebarsindicatestatisticallysig nificantdifferences,andasterisksindicatethesignificantmaineffectofso il;foreachp<0.05.

SeeTable1fordetailsonthemaineffectsandinteractions

nativeplantsgrownsubsequentlyinthesesoils.Speciesfromthi sgenusarereportedtobefacultativelymycorrhizal,having

usuallylowmycorrhizaldependencies(ChmuraandGucwa- Przepióra2012;TannerandGange2013).AsAMFcontributeto themaintenanceofpropersoilqualityduetoparticle-

bindingpropertiesofhyphaeandtheirexudates(SmithandRea d2008),itispossiblethatthenegativeeffectonAMFcommu nityinducedbyI.glanduliferaobservedinthisandtheaforem entionedstudiesmayinadditionbeafactorcon-

tributingtosoilerosioncausedbythisspecies(Greenwoodand Kuhn2014).

ThespeciesspecificityintheimpactonAMFcommunitycha racteristicswasfurtherconfirmedevenwithinonefamily,Aster aceae;however,inthiscase,theeffectswererelativelyconsisten t,beingneutralorpositive.IncreasedconcentrationsofAMF- PLFAmarkerwerefoundforA.vulgaris,whereashighernum berofsporesandhigherspeciesrichnessweredetectedf orR.laciniataandS.giganteaincomparisonwith

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Table2Resultofstepwisemultipler egressionanalysisf ortheeffectofA MFcommunityand

Variable Standardized

βcoefficient

SE t p

soilparametersonrelative

mycorrhizalrootlength(M), M—R²=0.51

shootmass,andphotosynthetic Intercept 0.044 0.965

performanceindex(PIABS)of 16:1ω5PLFA 0.457 0.076 6.010 <0.001

Plantagolanceolata.Seethe ₊

BMaterialsandmethods^section N-NH4 0.303 0.078 3.882 <0.001

foradescriptionofvariables PT 0.225 0.109 2.053 0.043

ThenumberofAMFspores 0.139 0.079 1.753 0.083

CaT −0.292 0.196 −1.488 0.140

KEX 0.398 0.315 1.264 0.209

− −0.138 0.117 −1.177 0.242

KT 0.320 0.351 0.910 0.365

Shootmass—R²=

Intercept 0.67 −3.790 <0.001

N-NO₃⁻ 0.643 0.096 6.688 <0.001

CaEX 0.310 0.077 4.042 <0.001

K_EX −0.991 0.261 −3.801 <0.001

pH 0.723 0.264 2.741 0.007

P_EX 0.140 0.073 1.924 0.057

16:1ω5PLFA 0.125 0.068 1.851 0.067

CaT 0.278 0.169 1.649 0.103

ThenumberofAMFspecies −0.095 0.061 −1.554 0.124

PT 0.130 0.095 1.368 0.175

PIABS—R²=

Intercept 0.57 2.454 0.016

KEX −1.638 0.223 −7.336 0.000

CaEX 0.253 0.079 3.213 0.002

pH 0.645 0.286 2.254 0.026

16:1ω5PLFA 0.132 0.070 1.882 0.063

ThenumberofAMFspores −0.117 0.074 −1.572 0.119

NT −0.313 0.236 −1.322 0.189

N-NH₄⁺ −0.089 0.075 −1.193 0.236

640 BiolFertilSoils(2018)54:631–643

N-NO3

Theresultsinitalicsarestatisticallysignificant

someothertreatments.PlantsfromAsteraceae,includingin- vasiveones,areusuallyhighlymycorrhizalanddependentonA Mfortheirgrowthand/orelementacquisition(Shahetal.2008;

Lekbergetal.2013;Majewskaetal.2015,2017;Zubeketal.201 6).Therefore,attaininglocaldominance,theymayhavenoeffe ctorcanenhanceAMFabundancesrelativetonativemixedpla ntcommunitiesormonospecificpatchesofnon-

mycorrhizal/lessAM-dependentplants.

Thedual-speciestreatmentwithA.vulgarisand P.arundinaceahadinsomecasesdetrimentaleffectonAMFco mmunitycharacteristics,namelythenumberofAMFspecies andspores,whencomparingtobothsingletreatmentsoftheset woplantsandothertestedspecies.Themechanismsaredifficult toexplain,butitispossiblethatthisisduetointerspecificcompe titionbetweenthesetwoexpansiveplants.DeDeynetal.

(2010)foundthattheeffect

ofparticularplantspeciesonAMFabundanceinmixedplantco mmunitiesdependsontheirabundanceand/orinteractionswith otherplantspecies.

VariouseffectsofplantspeciesonAMFabundance,species richness,andspeciescompositioncouldbeduetosever almechanisms.First,a non-mycorrhizalplant,suchas R.japonica,canreduceAMFabundancebythelackoforganicCin putstofungi(TannerandGange2013;Zubeketal.2016).Second, plantsmayimpactAMFcommunityduetoproductionofsecondar ymetabolitesthateithersuppressAMFdevelop-

ment,asinthecaseofAMFnon-

hostA.petiolata(Stinsonetal.2006;Callawayetal.2008;Cantor etal.2011),orselec-

tivelymodifycompositionofAMFcommunitybyenhancingthe mostbeneficialAMFandinhibitinglessfavorableones,asitwassu ggestedforamycorrhizalinvaderS.canadensis(Yuanetal.2014) .Third,plantsthroughtheirinfluenceonsoil

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physicochemicalpropertiesmayindirectlyaffectAMFcom- munities(Shahetal.2009).Asrevealedinourfieldinvestiga- tions(Stefanowiczetal.2017)andalsofurthersupportedinthisex periment(Stefanowiczetal.2018),theplantsunderstudysign ificantlychangedsomechemicalsoilproperties.Thiswasill ustratedbyCDAwhichrevealedthatsoilchemicalpropertiespla yedanimportantroleinthedifferentiationofparticulartreatme ntsinourexperiment.

WefoundthatchangesinAMFspeciescompositioncanoccu runderplantmonocultureevenaftertwogrowingseasons.Similar ly,Zhangetal.

(2010)showedthatthecompositionofAMFcommunitychange dinresponsetoS.canadensisinva-

sioninthesametimescale.Incontrast,Dayetal.(2015)re-

photosyntheticperformanceand/orelementconcentrationsof P.lanceolataandTrifoliumrepens.However,thedirectionsan dmagnitudeoftheirresponsedependedonbothspeciesidenti tyandthemycorrhizalstatusofinvaders.Asfarasthesoilfeedba cksonP.lanceolatainthisexperimentarecon-

cerned,thedecreasedAMFcolonizationratesinthesoilwith- outplantsandR.japonicatreatments,butincreasedbiomassinm osttreatmentsandenhancedphotosyntheticperformanceindex inthevalleysoilincomparisontotheinitialsoils,werefound.Pla ntspeciesidentityandsoiltypeinteractionshadsignificantef fectsonP.lanceolata.However,asrevealedbystepwisemultipl eregressionanalysis,theseeffectswerelarge-

lydrivenbysoilchemicalproperties.AMFabundanceinthe₊ vealedthatdecadesofinvasionbyVincetoxicumrossicumre- soilalongwiththeconcentrationsofN-NH4 andtotalPhad sultedinalterationsinAMFcommunitycompositionbutthesech

angesdidnotoccuroverthecourseofonegrowingseason.

R.japonica,R.laciniata,andS.giganteawerefoundnotto changeAMFcommunitycompositioninthefield(Zubeketal.201 6).Thepresentstudywasbasedonsporeassays;therefore,molec ulartoolsneedtobeappliedonsoilsamplestoelucidateiftheseare aresultofdifferencesinsporulationorthatsomeAMFspeciesdec lineorareeliminatedbytheplantsunderstudy(Oehletal.201 7;Turrinietal.2016,2018).Nevertheless,Bunnetal.

(2015)foundthatAMFcommunitycompositionwasalteredininv adedareasinthecaseof78%ofthestudiesexaminedinthemeta- analysis.Thiscouldbeduetoachangeinhostidentityasplantspeci escanharbordifferentAMFtaxa(Bunnetal.2015;Turrinietal.20 16,2018).

TheeffectsofplantspeciesidentityonAMFabundance,spe ciesrichness,andspeciescompositionwerealsoinflu- encedbysoiltype,whichisinlinewithourfourthhypothesis.The refore,thestrengthanddirectionoftheimpactofplantsontheseso ilmicroorganismscandifferamongsitesduetovari-

ousedaphicconditions.

Differenteffectsontheperformanceofseveralnativeplantsp ecieswerefoundonsoilsovergrownbyalienplantsincom- parisontosoilsfromundernativevegetation,withthedomi- nanceofnegative(Rucklietal.2014;Sanonetal.2012;Zhanget al.2010;Stinsonetal.2006;Callawayetal.2008;Vogelsangand Bever2009;Wilsonetal.2012;Zubeketal.2016)overneutrala ndpositive(Shannonetal.2014;Zubeketal.2016)feedbacks.F orexample,Shannonetal.

(2014)foundthattwoinvaders,LoniceramaackiiandLigust rumvulgare,decreased,whereasElaeagnusumbellatainva sionincreasedAMFcolonizationofthenativecommunity;how -

ever,theseeffectsdidnotimpactthebiomassofnativeplants.Th edecreasedlevelsofAMFcolonizationand/orbiomassof P.lanceolata,Trifoliumpratense,andLotuscorniculatusinthe field-collectedsoilconditionedbyR.japonicaand

I.glanduliferawerefoundbyTannerandGange(2013).Zubeke tal.(2016)observedthatfield-

collectedsoilsfromunderR.japonica,R.laciniata,andS.gigant

eahadnoeffectontheAMFcolonizationrateandbiomass,butaff ectedthe

(16)

significanteffectonthedegreeofP.lanceolatacolonization.H owever,fortheshootmassandphotosyntheticperformancein dex,onlychemicalpropertiesplayedasignificantrole.Thus, possiblealterationsinsoilchemicalpropertiescausedbyplant sattaininglocaldominance,ratherthaninAMFcom-

munity,maybemajordriversofdifferencesinnativeplantpe rformancegrownsubsequentlyonthesesoils.Thefluctua- tionsofelementavailabilityinsoilsconditionedbytheplantsp eciesmightberesponsiblefortheenhancedshootmassandpho tosyntheticperformanceindexofP.lanceolataincompar- isontotheeffectsofinitialsoils.Furthermore,theeffectsofsoil microorganismsotherthanAMFonP.lanceolataparam- eterscannotberuledout.

ExceptforR.japonica,whichoriginatedfromrhizomes,thesh ootmassfromothertreatmentsinourpotexperimentwascompar able(Stefanowiczetal.2018).Innature,however, S.gigantea,R.japonica,R.laciniata,andI.glanduliferacan reachca.2mandproducehigherbiomassperparticulararea/soil volumeincomparisontoA.vulgarisandP.arundinacea.Theincr easedbiomassoftheinvadersovernativeplantsinthefieldcanen hancetheeffectsobservedinthisexperiment.

Conclusion s

PlantspeciesidentityhadalargerimpactonAMFabundance,s peciesrichness,andspeciescompositionaswellastheef- fectsonplantsgrownsubsequentlyinthesoilsthanoriginofthe species(alienvs.native).Thiscouldbeduetothecharac- teroftherelationshipwithplants,i.e.,theirmycorrhizalstatusa ndtheirdependencyonAMF.However,alterationsinsoilche micalpropertiescausedbyplantsattaininglocaldomi- nanceratherthaninAMFcommunitymaybemajordriversofd ifferencesinbiomassandphotosyntheticperformanceofnativ eplantsgrownsubsequentlyinthesesoils.Thechangescaused bytheinvasive/expansiveplantsinsoilpropertiesde-

velopoversuchashortperiodastwogrowingseasons.Morestu diesareneededtorevealifsoilpropertiesalteredbytheinvasi ve/nativeplantsmaycontributetothecompetitive

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BiolFertilSoils(2018)54:631–643 17

abilityofthesespeciesincolonizingnewareasoverotherpl ants.Mechanismsresponsiblefortheeffectsobservedneedtobe elucidated,includingstudiesinsecondarymetabolitesthatma yberelatedtothemodificationsofsoilenvironment.

Fromtheconservationalpointofview,ourstudyshowedthat notonlyinvasivebutalsoexpansivenativeplantsformingmono specificpatchescanaffectAMFcommunity.Itthusseemstobe importanttomonitorchangesinsoilsalsoundernativeplantsatta ininglocaldominance.Nevertheless,theef-

fectsofplantsunderstudyonAMFattributesandthemodelplant performancewerenotdrastic,eveninthecaseofanon-

mycorrhizalplant.Moreover,theywerepositivefor P.lanceolatagrowthandphotosyntheticperformanceinsomec ases.Thisseemstobepromisingforrestorationofsitesafterremo valoftheseplants.

Authors’contributionsS.Z.andM.L.M.plannedanddesignedthere- search.M.L.M.,S.Z.,A.M.S.,andM.N.performedtheexperiments;JBide ntifiedAMFspecies;M.L.M.,K.R.,andS.Z.analyzedthedataandprepare dfiguresandtables;andM.L.M.andS.Z.wrotethepaperwiththeinputofoth erco-authors.

FundinginformationTheresearchwasfundedbythePolishNationalScie nceCentre,underprojectDEC-2011/03/B/NZ8/00008.Italsore- ceivedfinancialsupport,inpart,fromthe InstituteofBotanyattheJa giellonianUniversity(K/ZDS/006300,K/ZDS/007340,andK/DSC/003 932).

OpenAccessThisarticleisdistributedunderthetermsoftheCreativeCo m mo nsAt tribu t ion4. 0In t ernat iona lLicen se(ht tp://creativecommo ns.org/licenses/by/4.0/),whichpermitsunrestricteduse,distribution,and reproductioninanymedium,providedyougiveappropriatecredittotheori ginalauthor(s)andthesource,providealinktotheCreativeCommonslicens e,andindicateifchangesweremade.

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