biostudies-literatureFadrique BEuropean Research CouncilNational Science Foundation (NSF)RCUK | Natural Environment Research Council (NERC)Royal Society267-280https://www.ebi.ac.uk/biostudies/studies/S-EPMC12890586biostudies-literatureUnknown10(2)Climate and atmospheric changes are impacting forest function and structure worldwide, but their effects on tropical forest diversity are unclear. Nowhere is the scientific challenge greater than in the Andes and the Amazon, which together include the world's most diverse forests. Here, using 406 permanent plots spanning four decades of intact lowland and montane forest dynamics, we test for long-term change in species richness and assess the influence of climate and other variables. We show that, at a continental scale, species richness appears stable, but this masks substantial regional variation. Species richness increased in Northern Andean and Western Amazon plots, yet declined in the Central Andes, Guyana Shield and Central-Eastern Amazon. Overall, warmer, drier and more seasonal forNature ecology & evolutionTree diversity is changing across tropical Andean and Amazonian forests in response to global change.PMC12890586NE/W006448/1291585758873DHF\R1\2410212020424Manzatto AGFeldpausch TRVerbeeck HZuidema PACosta FMacia MJBrienen RPennington RTMetzker TSilva RSATer Steege HBurban BPerez AJDisney MCayuela LLaurance SGWPenuela MCBaccaro FSchietti JCuesta FReynel CGloor EPhillips OLMorandi PSSantana FDi Fiore ABennett ACFeeley KJBarbosa Camargo PMagnusson WESerrano JAlvarez-Davila ETorres-Lezama ARojas RSilva CDraper FCIdarraga ALopez WVieira SAStorck-Tonon DBerenguer EPalacios-Ramos SPeres CAPrieto AEmilio TDel Aguila-Pasquel JNieto-Ariza BHuillca-Aedo YTJadan-Maza OValenzuela Gamarra LThomas RBongers FPeacock JAlexiades MNHonorio Coronado ENMartinez-Villa JACarvalho SPCde Oliveira RLCda Costa LAymard CGABlanc LFerreira LPickavance GCNascimento HMDe Rutte JFerreira JFarfan-Rios WRestrepo ZNeill DCoelho de Souza FVedovato LBauters MPipoly JBarni PEVasquez Martinez RLevesley Avan der Hout PMelo LPitman NEsquivel-Muelbert ASilva-Espejo JStropp JHuaraca Huasco WReis SMGrandez-Rios JMBrown FPardo Molina GTerborgh JVinceti BRamirez-Angulo HBarlow JPallqui-Camacho NCSilveira MMarimon BSBurnham RJGarcia Criado MAyala ESilva CAMyers JASimon MFGalbraith DNascimento RRudas ABaez SBarroso JKalamandeen MFauset SVieira Ide Lima RBVale JDde Oliveira EABenchimol MPena MADuque AFearnside PMBonal DPinto ESilva RCMarimon Junior BHSoto-Shareva YCGarcia-Cabrera KArellano GZagt RRibeiro SRivas-Torres GVos VABaker TRTello JSSalinas NSalomao RPBaraloto CChave JSchwartz GHerault BKilleen TJLaurance WFSouza PFHomeier JVilanova EFadrique BPalacios WAvan der Heijden GMalhi YArets EAguirre-Mendoza ZBt Andrade MCastilho CFlores Llampazo GRComiskey JAguirre-Gutierrez Jde Oliveira Perdiz RDerroire GMonteagudo ACamargo JLMelgaco Kvan der Meer PJMedeiros MBBarbosa RIHuamantupa-Chuquimaco ISilman MSwamy VfalseTree diversity is changing across tropical Andean and Amazonian forests in response to global change.Climate and atmospheric changes are impacting forest function and structure worldwide, but their effects on tropical forest diversity are unclear. Nowhere is the scientific challenge greater than in the Andes and the Amazon, which together include the world's most diverse forests. Here, using 406 permanent plots spanning four decades of intact lowland and montane forest dynamics, we test for long-term change in species richness and assess the influence of climate and other variables. We show that, at a continental scale, species richness appears stable, but this masks substantial regional variation. Species richness increased in Northern Andean and Western Amazon plots, yet declined in the Central Andes, Guyana Shield and Central-Eastern Amazon. Overall, warmer, drier and more seasonal for2026-01-01T00:00:00Z2026 Feb2026-07-16T20:24:25.566Z2026-07-10T03:09:55.815ZS-EPMC128905864157782910.1038/s41559-025-02956-5