Sophie Fauset, Michelle O. Johnson, Manuel Gloor, Timothy R. Baker, Abel Monteagudo M., Roel J.W. Brienen, Ted R. Feldpausch, Gabriela Lopez-Gonzalez, Yadvinder Malhi, Hans ter Steege, Nigel C.A. Pitman, Christopher Baraloto, Julien Engel, Pascal Pétronelli, Ana Andrade, José Luís C. Camargo, Susan G.W. Laurance, William F. Laurance, Jerôme Chave, Elodie Allie, Percy Núñez Vargas, John W. Terborgh, Kalle Ruokolainen, Marcos Silveira, Gerardo A. Aymard C., Luzmila Arroyo, Damien Bonal, Hirma Ramirez-Angulo, Alejandro Araujo-Murakami, David Neill, Bruno Hérault, Aurélie Dourdain, Armando Torres-Lezama, Beatriz S. Marimon, Rafael P. Salomão, James A. Comiskey, Maxime Réjou-Méchain, Marisol Toledo, Juan Carlos Licona, Alfredo Alarcón, Adriana Prieto, Agustín Rudas, Peter J. van der Meer, Timothy J. Killeen, Ben-Hur Marimon Junior, Lourens Poorter, Rene G.A. Boot, Basil Stergios, Emilio Vilanova Torre, Flávia R.C. Costa, Carolina Levis, Juliana Schietti, Priscila Souza, Nikée Groot, Eric Arets, Victor Chama Moscoso, Wendeson Castro, Euridice N. Honorio Coronado, Marielos Peña-Claros, Clement Stahl, Jorcely Barroso, Joey Talbot, Ima Célia Guimarães Vieira, Geertje van der Heijden, Raquel Thomas, Vincent A. Vos, Everton C. Almeida, Esteban Álvarez Davila, Luiz E.O.C. Aragão, Terry L. Erwin, Paulo S. Morandi, Edmar Almeida de Oliveira, Marco B.X. Valadão, Roderick J. Zagt, Peter van der Hout, Patricia Alvarez Loayza, John J. Pipoly, Ophelia Wang, Miguel Alexiades, Carlos E. Cerón, Isau Huamantupa-Chuquimaco, Anthony Di Fiore, Julie Peacock, Nadir C. Pallqui Camacho, Ricardo K. Umetsu, Plínio Barbosa de Camargo, Robyn J. Burnham, Rafael Herrera, Carlos A. Quesada, Juliana Stropp, Simone A. Vieira, Marc Steininger, Carlos Reynel Rodríguez, Zorayda Restrepo, Adriane Esquivel Muelbert, Simon L. Lewis, Georgia C. Pickavance, Oliver L. Phillips

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few 'hyperdominant' species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region.