The biogeography of the Amazonian tree flora
Bruno Garcia Luize, Hanna Tuomisto, Robin Ekelschot, Kyle G. Dexter, Iêda Leão do Amaral, Luiz de Souza Coêlho, Francisca Dionízia de Almeida Matos, Diógenes de Andrade Lima Filho, Rafael P. Salomão, Florian Wittmann, Carolina V. Castilho, Marcelo de Jesus Veiga Carim, Juan Ernesto Guevara, Oliver L. Phillips, William E. Magnusson, Daniel Sabatier, Juan David Cardenas Revilla, Jean‐François Molino, Mariana Victória Irume, Maria Pires Martins, José Renan da Silva Guimarães, José Ferreira Ramos, Olaf Bánki, María Teresa Fernández Piedade, Dairon Cárdenas López, Nigel C. A. Pitman, Layon Oreste Demarchi, Jochen Schöngart, Evlyn Márcia Leão de Moraes Novo, Percy Núñez Vargas, Thiago Sanna Freire Silva, Eduardo Martins Venticinque, Ângelo Gilberto Manzatto, Neidiane Farias Costa Reis, John Terborgh, Katia Regina Casula, Eurídice N. Honorio Coronado, Abel Monteagudo Mendoza, Juan Carlos Montero, Flávia R. C. Costa, Ted R. Feldpausch, Adriano Costa Quaresma, Nicolás Castaño Arboleda, Charles E. Zartman, Timothy J. Killeen, Beatriz Schwantes Marimon, Ben Hur Marimon, Rodolfo Vásquez, Bonifacio Mostacedo, Rafael L. Assis, Christopher Baraloto, Dário Dantas do Amaral, Julien Engel, Pascal Pétronelli, Hernán Castellanos, Marcelo Brilhante de Medeiros, Marcelo Fragomeni Simon, Ana Andrade, José Luís Camargo, William F. Laurance, Susan G. W. Laurance, Lorena Maniguaje Rincón, Juliana Schietti, Thaiane R. Sousa, Gisele Biem Mori, Emanuelle de Sousa Farias, Maria Aparecida Lopes, José Leonardo Lima Magalhães, Henrique Eduardo Mendonça Nascimento, Helder Lima de Queiroz, Caroline da Cruz Vasconcelos, Gerardo A. Aymard C., Roel Brienen, Pablo R. Stevenson, Alejandro Araujo‐Murakami, Bruno Barçante Ladvocat Cintra, Timothy R. Baker, Yuri Oliveira Feitosa, Hugo F. Mogollón, Joost F. Duivenvoorden, Carlos A. Peres, Miles R. Silman, Leandro Valle Ferreira, José Rafael Lozada, James A. Comiskey, José Júlio de Toledo, Gabriel Damasco, Nállarett Dávila, Frederick C. Draper, Roosevelt García-Villacorta, Aline Lopes, Alberto Vicentini, Fernando Cornejo Valverde, Alfonso Alonso, Luzmila Arroyo, Francisco Dallmeier, Vitor H. F. Gomes, E. Jiménez, David Neill, María Cristina Peñuela Mora
Abstract
We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Within-plot species composition reflected both local environmental conditions (especially soil nutrients and hydrology) and geographical regions. A broader-scale view of species turnover was obtained by interpolating the relative tree species abundances over Amazonia into 47,441 0.1-degree grid cells. Two main dimensions of spatial change in tree species composition were identified. The first was a gradient between western Amazonia at the Andean forelands (with young geology and relatively nutrient-rich soils) and central-eastern Amazonia associated with the Guiana and Brazilian Shields (with more ancient geology and poor soils). The second gradient was between the wet forests of the northwest and the drier forests in southern Amazonia. Isolines linking cells of similar composition crossed major Amazonian rivers, suggesting that tree species distributions are not limited by rivers. Even though some areas of relatively sharp species turnover were identified, mostly the tree species composition changed gradually over large extents, which does not support delimiting clear discrete biogeographic regions within Amazonia.