Sensitivity of South American tropical forests to an extreme climate anomaly
Authors: Bennett Amy C. , Rodrigues de Sousa Thaiane , Monteagudo-Mendoza Abel , Esquivel-Muelbert Adriane , Morandi Paulo S. , Coelho de Souza Fernanda , Castro Wendeson , Duque Luisa Fernanda , Flores Llampazo Gerardo , Manoel dos Santos Rubens , Ramos Eliana , Vilanova Torre Emilio , Alvarez-Davila Esteban , Baker Timothy R. , Costa Flávia R. C. , Lewis Simon L. , Marimon Beatriz S. , Schietti Juliana , Burban Benoît , Berenguer Erika , Araujo-Murakami Alejandro , Restrepo Correa Zorayda , Lopez Wilmar , Delgado Santana Flávia , Viscarra Laura Jessica , Elias Fernando , Vasquez Martinez Rodolfo , Marimon-Junior Ben Hur , Galbraith David , Sullivan Martin J. P. , Emilio Thaise , Prestes Nayane C. C. S. , Barlow Jos , Alencar Fagundes Nathalle Cristine , Almeida de Oliveira Edmar , Alvarez Loayza Patricia , Alves Luciana F. , Aparecida Vieira Simone , Andrade Maia Vinícius , Aragão Luiz E. O. C. , Arets Eric J. M. M. , Arroyo Luzmila , Bánki Olaf , Baraloto Christopher , Barbosa Camargo Plínio , Barroso Jorcely , Bento da Silva Wilder , Bonal Damien , Borges Miranda Santos Alisson , Brienen Roel J. W. , Brown Foster , Castilho Carolina V. , Cerruto Ribeiro Sabina , Chama Moscoso Victor , Chavez Ezequiel , Comiskey James A. , Cornejo Valverde Fernando , Dávila Cardozo Nállarett , de Aguiar-Campos Natália , de Oliveira Melo Lia , del Aguila Pasquel Jhon , Derroire Géraldine , Disney Mathias , do Socorro Maria , Dourdain Aurélie , Feldpausch Ted R. , Ferreira Joice , Forni Martins Valeria , Gardner Toby , Gloor Emanuel , Gutierrez Sibauty Gloria , Guillen René , Hase Eduardo , Hérault Bruno , Honorio Coronado Eurídice N. , Huaraca Huasco Walter , Janovec John P. , Jimenez-Rojas Eliana , Joly Carlos , Kalamandeen Michelle , Killeen Timothy J. , Lais Farrapo Camila , Levesley Aurora , Lizon Romano Leon , Lopez Gonzalez Gabriela , Maës dos Santos Flavio Antonio , Magnusson William E. , Malhi Yadvinder , Matias de Almeida Reis Simone , Melgaço Karina , Melo Cruz Omar A. , Mendoza Polo Irina , Montañez Tatiana , Morel Jean Daniel , Núñez Vargas M Percy , Oliveira de Araújo Raimunda , Pallqui Camacho Nadir C. , Parada Gutierrez Alexander , Pennington Toby , Pickavance Georgia C. , Pipoly John , Pitman Nigel C. A. , Quesada Carlos , Ramirez Arevalo Freddy , Ramírez‐Angulo Hirma , Flora Ramos Rafael , Richardson James E. , Rodrigo de Souza Cléber , Roopsind Anand , Schwartz Gustavo , Silva Richarlly C. , Silva Espejo Javier , Silveira Marcos , Singh James , Soto Shareva Yhan , Steininger Marc , Stropp Juliana , Talbot Joey , ter Steege Hans , Terborgh John , Thomas Raquel , Valenzuela Gamarra Luis , van der Heijden Geertje , van der Hout Peter , Zagt Roderick , Phillips Oliver L. 
Published: September 2023

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.