Sensitivity of South American tropical forests to an extreme climate anomaly

The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha⁻¹ per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.

Amy C. Bennett, Thaiane Rodrigues de Sousa, Abel Monteagudo-Mendoza, Adriane Esquivel-Muelbert, Paulo S. Morandi, Fernanda Coelho de Souza, Wendeson Castro, Luisa Fernanda Duque, Gerardo Flores Llampazo, Rubens Manoel dos Santos, Eliana Ramos, Emilio Vilanova Torre, Esteban Alvarez-Davila, Timothy R. Baker, Flávia R. C. Costa, Simon L. Lewis, Beatriz S. Marimon, Juliana Schietti, Benoît Burban, Erika Berenguer, Alejandro Araujo-Murakami, Zorayda Restrepo Correa, Wilmar Lopez, Flávia Delgado Santana, Laura Jessica Viscarra, Fernando Elias, Rodolfo Vasquez Martinez, Ben Hur Marimon-Junior, David Galbraith, Martin J. P. Sullivan, Thaise Emilio, Nayane C. C. S. Prestes, Jos Barlow, Nathalle Cristine Alencar Fagundes, Edmar Almeida de Oliveira, Patricia Alvarez Loayza, Luciana F. Alves, Simone Aparecida Vieira, Vinícius Andrade Maia, Luiz E. O. C. Aragão, Eric J. M. M. Arets, Luzmila Arroyo, Olaf Bánki, Christopher Baraloto, Plínio Barbosa Camargo, Jorcely Barroso, Wilder Bento da Silva, Damien Bonal, Alisson Borges Miranda Santos, Roel J. W. Brienen, Foster Brown, Carolina V. Castilho, Sabina Cerruto Ribeiro, Victor Chama Moscoso, Ezequiel Chavez, James A. Comiskey, Fernando Cornejo Valverde, Nállarett Dávila Cardozo, Natália de Aguiar-Campos, Lia de Oliveira Melo, Jhon del Aguila Pasquel, Géraldine Derroire, Mathias Disney, Maria do Socorro, Aurélie Dourdain, Ted R. Feldpausch, Joice Ferreira, Valeria Forni Martins, Toby Gardner, Emanuel Gloor, Gloria Gutierrez Sibauty, René Guillen, Eduardo Hase, Bruno Hérault, Eurídice N. Honorio Coronado, Walter Huaraca Huasco, John P. Janovec, Eliana Jimenez-Rojas, Carlos Joly, Michelle Kalamandeen, Timothy J. Killeen, Camila Lais Farrapo, William E. Magnusson, Yadvinder Malhi, Simone Matias de Almeida Reis, Flavio Antonio Maës dos Santos, Karina Melgaço, Omar A. Melo Cruz, Irina Mendoza Polo, Tatiana Montañez, Jean Daniel Morel, M Percy Núñez Vargas, Raimunda Oliveira de Araújo, Nadir C. Pallqui Camacho, Alexander Parada Gutierrez, Toby Pennington, Georgia C. Pickavance, John Pipoly, Nigel C. A. Pitman, Carlos Quesada, Freddy Ramirez Arevalo, Hirma Ramírez-Angulo, Rafael Flora Ramos, James E. Richardson, Cléber Rodrigo de Souza, Anand Roopsind, Gustavo Schwartz, Richarlly C. Silva, Javier Silva Espejo, Marcos Silveira, James Singh, Yhan Soto Shareva, Marc Steininger, Juliana Stropp, Joey Talbot, Hans ter Steege, John Terborgh, Raquel Thomas, Luis Valenzuela Gamarra, Geertje van der Heijden, Peter van der Hout, Roderick Zagt, Oliver L. Phillips