Journal Article

Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

Marimon, Ben Hur, Fancourt, Max, Tavares, Julia Valentim, Ugarteche, Maira T. M., Huaraca Huasco, Walter, Salinas, Norma, da Costa Silva, Richarlly, Espejo, Javier Silva, Castro, Wendeson, Flores Llampazo, Gerardo, Tintaya, Jose S., Cumapa, Edwin R. M., Mencuccini, Maurizio, Galbraith, David R., Gilpin, Martin, Malhi, Yadvinder, Oliveira, Rafael S., Oliveras Menor, Imma, Cuellar, Gina A., Rodrigues, Gleicy, del Aguila Pasquel, Jhon, Tello, Ligia, Coelho de Souza, Fernanda, Baker, Timothy R., Talbot, Joey, Jancoski, Halina, Higuchi, Niro, Gloor, Emanuel, Barros, Fernanda de V., Feldpausch, Ted R., Ferreira, Leandro, da Cruz, Wesley Jonatar Alves, Phillips, Oliver L., Schlickmann, Monique, Esquivel-Muelbert, Adriane, Morandi, Paulo, Acosta, Martin, Almeida, Everton, de Camargo, Plinio Barbosa, Marca Zevallos, Manuel J., Araujo-Murakami, Alejandro, Penha, Deliane, Chambers-Ostler, Alexander, Davila Cardozo, Nallaret, Chama Moscoso, Victor, Ribeiro, Sabina Cerruto, Muscarella, Robert, Baca, Jean, Brienen, Roel, Meir, Patrick, Hirota, Marina, Vásquez, Rodolfo, Rowland, Lucy, Pereira, Luciano, Mar

2023

Overview

Tropical forests face increasing climate risk 1 , 2 , yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, Ψ 50 ) and hydraulic safety margins (for example, HSM 50 ) are important predictors of drought-induced mortality risk 3 – 5 , little is known about how these vary across Earth’s largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters Ψ 50 and HSM 50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both Ψ 50 and HSM 50 influence the biogeographical distribution of Amazon tree species. However, HSM 50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM 50 are gaining more biomass than are low HSM 50 forests. We propose that this may be associated with a growth–mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM 50 in the Amazon 6 , 7 , with strong implications for the Amazon carbon sink. A pan-Amazon study of forests shows large variations in drought tolerance traits and finds that forests in regions of pronounced climate change are losing biomass and may be operating beyond their hydraulic limits.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 704/158/2450 / 704/158/2454 / 704/158/2455 / 704/158/670 / Biodiversity and Ecology / Biomass / Carbon / Carbon - metabolism / Carbon Sequestration / Carbon sinks / Climate Change / Climate prediction / Datasets / Dehydration / Drought / Droughts / Embolism / Environmental risk / Environmental Sciences / Forest biomass / Forests / Geographical distribution / Health risks / Humanities and Social Sciences / Hydraulics / Mortality / Mortality risk / multidisciplinary / Physiology / Plant species / Rain / Rainfall / Regional analysis / Safety margins / Science / Science & Technology - Other Topics / Science (multidisciplinary) / Seasons / Stress, Physiological / Trees / Trees - growth & development / Trees - metabolism / Tropical Climate / Tropical forests / Water resistance / Water stress / Xylem / Xylem - metabolism