19Increasingaridityreducessoilmicrobialdiver

IncreasingaridityreducessoilmicrobialdiversityandabundanceinglobaldrylandsFernandoT.Maestrea,1,ManuelDelgado-Baquerizob,ThomasC.Jeffriesb,DavidJ.Eldridgec,VictoriaOchoaa,BeatrizGozaloa,JoséLuisQuerod,MiguelGarcía-Gómeze,AntonioGallardof,WernerUlrichg,MatthewA.Bowkerh,TulioArredondoi,ClaudiaBarraza-Zepedaj,DonaldoBrank,AdrianaFlorentinol,JuanGaitánm,JulioR.Gutiérrezj,n,o,ElisabethHuber-Sannwaldi,MohammadJankjup,RebeccaL.Mauq,MariaMiritir,KamalNaserip,AbelardoOspinal,IlanStavis,DeliWangt,NatashaN.Woodsr,XiaYuant,EliZaadyu,andBrajeshK.Singhb,vaDepartamentodeBiologíayGeología,FísicayQuímicaInorgánica,EscuelaSuperiordeCienciasExperimentalesyTecnología,UniversidadReyJuanCarlos,28933Móstoles,Spain;bHawkesburyInstitutefortheEnvironment,WesternSydneyUniversity,Penrith,2751,NSW,Australia;cSchoolofBiological,EarthandEnvironmentalSciences,UniversityofNewSouthWales,Sydney,NSW2052,Australia;dDepartamentodeIngenieríaForestal,EscuelaTécnicaSuperiordeIngenieríaAgronómicaydeMontes,UniversidaddeCórdoba,CampusdeRabanales,C.P.14071,Córdoba,Spain;eDepartamentodeIngenieríayMorfologíadelTerreno,EscuelaTécnicaSuperiordeIngenierosdeCaminos,CanalesyPuertos,UniversidadPolitécnicadeMadrid,28040Madrid,Spain;fDepartamentodeSistemasFísicos,QuímicosyNaturales,UniversidadPablodeOlavide,41013Sevilla,Spain;gChairofEcologyandBiogeography,NicolausCopernicusUniversityinToru
n,Lwowska1,87-100Toru
n,Poland;hSchoolofForestry,NorthernArizonaUniversity,Flagstaff,AZ86011;iDivisiondeCienciasAmbientales,InstitutoPotosinodeInvestigacionCientificayTecnologica,SanLuisPotosí,SLP,México;jDepartamentodeBiología,FacultaddeCiencias,UniversidaddeLaSerena,Benavente980,Casilla554,LaSerena,Chile;kNacionaldeTecnologíaAgropecuaria,EstaciónExperimentalSanCarlosdeBariloche,SanCarlosdeBariloche,RíoNegro,Argentina;lInstitutodeEdafología,FacultaddeAgronomía,UniversidadCentraldeVenezuela,CampusUCV-Maracay,ZP2101,EstadoAragua,Venezuela;mInstitutodeSuelos,CentrodeInvestigaciónenRecursosNaturales,InstitutoNacionaldeTecnologíaAgropecuaria,NicolasRepettoydelosReserosSinNúmero,1686Hurlingham,BuenosAires,Argentina;nCentrodeEstudiosAvanzadosenZonasÁridas(CEAZA),LaSerena,Chile;oInstitutodeEcologíayBiodiversidad,FacultaddeCiencias,UniversidaddeChile,LasPalmeras3425,Casilla653,Ñuñoa,Santiago,Chile;pDepartmentofRangeandWatershedManagement,FerdowsiUniversityofMashhad,Mashhad,91775-1363,Iran;qCenterforEcosystemScienceandSociety,NorthernArizonaUniversity,Flagstaff,AZ86011;rDepartmentofEvolution,EcologyandOrganismalBiology,OhioStateUniversity,Columbus,OH43210;sDeadSeaandAravaScienceCenter,Yotvata88840,Israel;tInstituteofGrasslandScience,KeyLaboratoryforVegetationEcology,NortheastNormalUniversity,Changchun,Jilin130024,China;uDepartmentofNaturalResources,AgricultureResearchOrganization,MinistryofAgriculture,GilatResearchCenter,MobilePostNegev85280,Israel;andvGlobalCentreforLand-BasedInnovation,WesternSydneyUniversity,Penrith,2751,NSW,AustraliaEditedbyWilliamH.Schlesinger,CaryInstituteofEcosystemStudies,Millbrook,NY,andapprovedNovember10,2015(receivedforreviewAugust21,2015)Soilbacteriaandfungiplaykeyrolesinthefunctioningofterrestrialecosystems,yetourunderstandingoftheirresponsestoclimatechangelagssignificantlybehindthatofotherorganisms.Thisgapinourunderstandingisparticularlytruefordrylands,whichoccupy∼41%ofEarth´ssurface,becausenoglobal,systematicassessmentsofthejointdiversityofsoilbacteriaandfungihavebeenconductedintheseenvironmentstodate.Herewepresentresultsfromastudyconductedacross80drylandsitesfromallcontinents,exceptAntarc-tica,toassesshowchangesinaridityaffectthecomposition,abun-dance,anddiversityofsoilbacteriaandfungi.Thediversityandabundanceofsoilbacteriaandfungiwasreducedasaridityincreased.Theseresultswerelargelydrivenbythenegativeimpactsofaridityonsoilorganiccarboncontent,whichpositivelyaffectedtheabun-danceanddiversityofbothbacteriaandfungi.Ariditypromotedshiftsinthecompositionofsoilbacteria,withincreasesintherelativeabundanceofChloroflexiandα-ProteobacteriaanddecreasesinAcid-obacteriaandVerrucomicrobia.Contrarytowhathasbeenreportedbypreviouscontinentalandglobal-scalestudies,soilpHwasnotamajordriverofbacterialdiversity,andfungalcommunitiesweredom-inatedbyAscomycota.Ourresultsfillacriticalgapinourunderstand-ingofsoilmicrobialcommunitiesinterrestrialecosystems.Theysuggestthatchangesinaridity,suchasthosepredictedbyclimate-changemodels,mayreducemicrobialabundanceanddiversity,are-sponsethatwilllikelyimpacttheprovisionofkeyecosystemservicesbyglobaldrylands.bacteria|fungi|climatechange|arid|semiaridClimatechangeisamajordriverofbiodiversitylossfromlocaltoglobalscales,inbothterrestrialandaquaticecosystems(1,2).Giventhedependenceofcrucialecosystemprocessesandservicesonbiodiversity(3–5),climate-change-drivenbiodiversitylosseswilldramaticallyalterthefunctioningofnaturalecosys-tems(4,6).Keyecosystemprocesses—suchasnutrientcycling,carbon(C)sequestration,andorganicmatterdecomposition—dependonsoilbacteriaandfungi(7–9).However,wehavelimitedknowledgeoftheroleofclimaticfactorsasdriversoftheirabundan