Compositional response of Amazon forests to climate change
Authors: Esquivel‐Muelbert Adriane , Baker Timothy R. , Dexter Kyle G. , Lewis Simon L. , Brienen Roel J. W. , Feldpausch Ted R. , Lloyd Jon , Monteagudo‐Mendoza Abel , Arroyo Luzmila , Álvarez-Dávila Esteban , Higuchi Niro , Marimon Beatriz S. , Marimon-Junior Ben Hur , Silveira Marcos , Vilanova Emilio , Gloor Emanuel , Malhi Yadvinder , Chave Jerôme , Barlow Jos , Bonal Damien , Davila Cardozo Nallaret , Erwin Terry , Fauset Sophie , Hérault Bruno , Laurance Susan , Poorter Lourens , Qie Lan , Stahl Clement , Sullivan Martin J. P. , ter Steege Hans , Vos Vincent Antoine , Zuidema Pieter A. , Almeida Everton , Almeida de Oliveira Edmar , Andrade Ana , Vieira Simone Aparecida , Aragão Luiz , Araujo‐Murakami Alejandro , Arets Eric , Aymard C Gerardo A. , Baraloto Christopher , Camargo Plínio Barbosa , Barroso Jorcely G. , Bongers Frans , Boot Rene , Camargo José Luís , Castro Wendeson , Chama Moscoso Victor , Comiskey James , Cornejo Valverde Fernando , Lola da Costa Antonio Carlos , del Aguila Pasquel Jhon , Di Fiore Anthony , Fernanda Duque Luisa , Elias Fernando , Engel Julien , Flores Llampazo Gerardo , Galbraith David , Herrera Fernández Rafael , Honorio Coronado Eurídice , Hubau Wannes , Jimenez‐Rojas Eliana , Lima Adriano José Nogueira , Umetsu Ricardo Keichi , Laurance William , Lopez‐Gonzalez Gabriela , Lovejoy Thomas , Aurelio Melo Cruz Omar , Morandi Paulo S. , Neill David , Núñez Vargas Percy , Pallqui Camacho Nadir C. , Parada Gutierrez Alexander , Pardo Guido , Peacock Julie , Peña‐Claros Marielos , Peñuela‐Mora Maria Cristina , Petronelli Pascal , Pickavance Georgia C. , Pitman Nigel , Prieto Adriana , Quesada Carlos , Ramírez‐Angulo Hirma , Réjou‐Méchain Maxime , Restrepo Correa Zorayda , Roopsind Anand , Rudas Agustín , Salomão Rafael , Silva Natalino , Silva Espejo Javier , Singh James , Stropp Juliana , Terborgh John , Thomas Raquel , Toledo Marisol , Torres‐Lezama Armando , Valenzuela Gamarra Luis , van de Meer Peter J. , van der Heijden Geertje , van der Hout Peter , Vasquez Martinez Rodolfo , Vela Cesar , Vieira Ima Célia Guimarães , Phillips Oliver L. 
Published: November 2018

Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate‐induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long‐term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO2 concentrations): maximum tree size, biogeographic water‐deficit affiliation and wood density. Tree communities have become increasingly dominated by large‐statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry‐affiliated genera have become more abundant, while the mortality of wet‐affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry‐affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate‐change drivers, but yet to significantly impact whole‐community composition. The Amazon observational record suggests that the increase in atmospheric CO2 is driving a shift within tree communities to large‐statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.