アマゾンの熱帯雨林は、将来の干ばつにどのように対処するのでしょうか。(How the Amazon rainforest is likely to cope with the effect of future drought)

2023-04-26 バーミンガム大学

＜関連情報＞

• https://www.birmingham.ac.uk/news/2023/how-the-amazon-rainforest-is-likely-to-cope-with-the-effect-of-future-drought
• https://www.nature.com/articles/s41586-023-05971-3

アマゾン森林の炭素収支を予測する樹木の水力安全マージンの流域幅の変動 Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

Julia Valentim Tavares,Rafael S. Oliveira,Maurizio Mencuccini,Caroline Signori-Müller,Luciano Pereira,Francisco Carvalho Diniz,Martin Gilpin,Manuel J. Marca Zevallos,Carlos A. Salas Yupayccana,Martin Acosta,Flor M. Pérez Mullisaca,Fernanda de V. Barros,Paulo Bittencourt,Halina Jancoski,Marina Corrêa Scalon,Beatriz S. Marimon,Imma Oliveras Menor,Ben Hur Marimon Jr,Max Fancourt,Alexander Chambers-Ostler,Adriane Esquivel-Muelbert,Lucy Rowland,Patrick Meir,Antonio Carlos Lola da Costa,Alex Nina,Jesus M. B. Sanchez,Jose S. Tintaya,Rudi S. C. Chino,Jean Baca,Leticia Fernandes,Edwin R. M. Cumapa,João Antônio R. Santos,Renata Teixeira,Ligia Tello,Maira T. M. Ugarteche,Gina A. Cuellar,Franklin Martinez,Alejandro Araujo-Murakami,Everton Almeida,Wesley Jonatar Alves da Cruz,Jhon del Aguila Pasquel,Luís Aragāo,Timothy R. Baker,Plinio Barbosa de Camargo,Roel Brienen,Wendeson Castro,Sabina Cerruto Ribeiro,Fernanda Coelho de Souza,Eric G. Cosio,Nallaret Davila Cardozo,Richarlly da Costa Silva,Mathias Disney,Javier Silva Espejo,Ted R. Feldpausch,Leandro Ferreira,Leandro Giacomin,Niro Higuchi,Marina Hirota,Euridice Honorio,Walter Huaraca Huasco,Simon Lewis,Gerardo Flores Llampazo,Yadvinder Malhi,Abel Monteagudo Mendoza,Paulo Morandi,Victor Chama Moscoso,Robert Muscarella,Deliane Penha,Mayda Cecília Rocha,Gleicy Rodrigues,Ademir R. Ruschel,Norma Salinas,Monique Schlickmann,Marcos Silveira,Joey Talbot,Rodolfo Vásquez,Laura Vedovato,Simone Aparecida Vieira,Oliver L. Phillips,Emanuel Gloor & David R. Galbraith   Published:26 April 2023
DOI:https://doi.org/10.1038/s41586-023-05971-3

Nature

Abstract

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, Ψ₅₀) and hydraulic safety margins (for example, HSM₅₀) are important predictors of drought-induced mortality risk^3,4,5, 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 Ψ₅₀ and HSM₅₀ vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both Ψ₅₀ and HSM₅₀ influence the biogeographical distribution of Amazon tree species. However, HSM₅₀ was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM₅₀ are gaining more biomass than are low HSM₅₀ 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 HSM₅₀ in the Amazon^6,7, with strong implications for the Amazon carbon sink.