Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest

Yilin Fang; Cristina Santos da Silva; Adam Collins; Bruno O. Gimenez; Kolby Jardine; Robinson I. Negrón-Juárez; Regison Oliveira; Valdiek da Silva Menezes; Kurt Solander; Gustavo Spanner; Jeffrey M. Warren; Cynthia L. Wright; Alfonso Zambrano; Adriano Lima; Niro Higuchi; Jeffrey Q. Chambers; Charlie Koven; L. Ruby Leung; Nate G. McDowell

doi:10.1016/j.agrformet.2025.110914

Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest

Yilin Fang
, Cristina Santos da Silva
, Adam Collins
, Bruno O. Gimenez
, Kolby Jardine
, Robinson I. Negrón-Juárez
, Regison Oliveira
, Valdiek da Silva Menezes
, Kurt Solander
, Gustavo Spanner
, Jeffrey M. Warren
, Cynthia L. Wright
, Alfonso Zambrano
, Adriano Lima
, Niro Higuchi
, Jeffrey Q. Chambers
, Charlie Koven
, L. Ruby Leung
, Nate G. McDowell

Ecosystem Processes

Research output: Contribution to journal › Article › peer-review

Abstract

Tropical forest tree mortality is increasing due to more severe droughts, yet our understanding of how tree traits and life strategies are linked to drought stress has been limited by measurement scarcity. The BIONTE (BIOmass and NuTrient Experiment) near Manaus, Brazil hosts one of the world's largest sap flow installations, with sensors in 90 canopy trees across a wood density gradient monitored since June 2022. The 2023 El Niño drought provided a unique opportunity to evaluate how water availability impacts tree transpiration. An interpretable machine learning framework was used to study the complex interactions between transpiration and multiple environmental variables such as soil water availability and vapor pressure deficit (VPD), and how these interactions vary with wood density and individual trees. We found varying responses of transpiration from different trees during the El Niño drought. Transpiration generally increased with temperature, with stronger effects in wetter areas and in trees with low to medium wood density. However, this response was modulated by stomatal sensitivity to VPD, which constrained transpiration under high atmospheric demand, particularly in intermediate-moisture area. The inflection in transpiration rate at high temperatures (>32°C) underscores the role of stomatal and hydraulic regulation in limiting water loss and protecting trees from excessive evaporative demand. Analysis of soil water contribution to transpiration revealed unimodal patterns in wetter area, with peak contributions near 0.45 cm³ cm⁻³ of surface soil water and declining or flat responses beyond that threshold, suggesting a shift from water- to energy-limited transpiration. In contrast, drier areas exhibited limited transpiration sensitivity to soil water conditions and minimal trait-based variation in VPD responses, indicating supply-limited conditions. Despite higher wood density trees being generally more resilient, this study shows diverse tree drought resilience, prompting further investigation into the specific traits and dynamics between environmental variables in regulating transpiration and other physiological processes in trees.

Original language	English
Article number	110914
Journal	Agricultural and Forest Meteorology
Volume	376
DOIs	https://doi.org/10.1016/j.agrformet.2025.110914
State	Published - Jan 15 2026

Funding

This work was supported by the U.S. Department of Energy Office of Biological and Environmental Research as part of the Terrestrial Ecosystem Systems program through the Next Generation Ecosystem Experiment (NGEE) Tropics project under contract number KP1702010. PNNL is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830. Oak Ridge National Laboratory is operated by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. DOE. We also thank INCT Madeiras da Amazônia project funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and the Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM). Notice: This manuscript has been authored, in part, by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). Notice: This manuscript has been authored, in part, by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This work was supported by the U.S. Department of Energy Office of Biological and Environmental Research as part of the Terrestrial Ecosystem Systems program through the Next Generation Ecosystem Experiment (NGEE) Tropics project under contract number KP1702010 . PNNL is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830 . Oak Ridge National Laboratory is operated by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. DOE. We also thank INCT Madeiras da Amazônia project funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) , and the Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM) .

Keywords

Drought
Machine learning
Stomatal regulation
Tropical forests
Water stress

Access to Document

10.1016/j.agrformet.2025.110914

Cite this

Fang, Y., da Silva, C. S., Collins, A., Gimenez, B. O., Jardine, K., Negrón-Juárez, R. I., Oliveira, R., Menezes, V. D. S., Solander, K., Spanner, G., Warren, J. M., Wright, C. L., Zambrano, A., Lima, A., Higuchi, N., Chambers, J. Q., Koven, C., Leung, L. R., & McDowell, N. G. (2026). Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest. Agricultural and Forest Meteorology, 376, Article 110914. https://doi.org/10.1016/j.agrformet.2025.110914

@article{38025104936441269455c2a6e9540009,

title = "Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest",

abstract = "Tropical forest tree mortality is increasing due to more severe droughts, yet our understanding of how tree traits and life strategies are linked to drought stress has been limited by measurement scarcity. The BIONTE (BIOmass and NuTrient Experiment) near Manaus, Brazil hosts one of the world's largest sap flow installations, with sensors in 90 canopy trees across a wood density gradient monitored since June 2022. The 2023 El Ni{\~n}o drought provided a unique opportunity to evaluate how water availability impacts tree transpiration. An interpretable machine learning framework was used to study the complex interactions between transpiration and multiple environmental variables such as soil water availability and vapor pressure deficit (VPD), and how these interactions vary with wood density and individual trees. We found varying responses of transpiration from different trees during the El Ni{\~n}o drought. Transpiration generally increased with temperature, with stronger effects in wetter areas and in trees with low to medium wood density. However, this response was modulated by stomatal sensitivity to VPD, which constrained transpiration under high atmospheric demand, particularly in intermediate-moisture area. The inflection in transpiration rate at high temperatures (>32°C) underscores the role of stomatal and hydraulic regulation in limiting water loss and protecting trees from excessive evaporative demand. Analysis of soil water contribution to transpiration revealed unimodal patterns in wetter area, with peak contributions near 0.45 cm³ cm⁻³ of surface soil water and declining or flat responses beyond that threshold, suggesting a shift from water- to energy-limited transpiration. In contrast, drier areas exhibited limited transpiration sensitivity to soil water conditions and minimal trait-based variation in VPD responses, indicating supply-limited conditions. Despite higher wood density trees being generally more resilient, this study shows diverse tree drought resilience, prompting further investigation into the specific traits and dynamics between environmental variables in regulating transpiration and other physiological processes in trees.",

keywords = "Drought, Machine learning, Stomatal regulation, Tropical forests, Water stress",

author = "Yilin Fang and \{da Silva\}, \{Cristina Santos\} and Adam Collins and Gimenez, \{Bruno O.\} and Kolby Jardine and Negr{\'o}n-Ju{\'a}rez, \{Robinson I.\} and Regison Oliveira and Menezes, \{Valdiek da Silva\} and Kurt Solander and Gustavo Spanner and Warren, \{Jeffrey M.\} and Wright, \{Cynthia L.\} and Alfonso Zambrano and Adriano Lima and Niro Higuchi and Chambers, \{Jeffrey Q.\} and Charlie Koven and Leung, \{L. Ruby\} and McDowell, \{Nate G.\}",

note = "Publisher Copyright: {\textcopyright} 2025",

year = "2026",

month = jan,

day = "15",

doi = "10.1016/j.agrformet.2025.110914",

language = "English",

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Fang, Y, da Silva, CS, Collins, A, Gimenez, BO, Jardine, K, Negrón-Juárez, RI, Oliveira, R, Menezes, VDS, Solander, K, Spanner, G, Warren, JM, Wright, CL, Zambrano, A, Lima, A, Higuchi, N, Chambers, JQ, Koven, C, Leung, LR & McDowell, NG 2026, 'Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest', Agricultural and Forest Meteorology, vol. 376, 110914. https://doi.org/10.1016/j.agrformet.2025.110914

TY - JOUR

T1 - Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest

AU - Fang, Yilin

AU - da Silva, Cristina Santos

AU - Collins, Adam

AU - Gimenez, Bruno O.

AU - Jardine, Kolby

AU - Negrón-Juárez, Robinson I.

AU - Oliveira, Regison

AU - Menezes, Valdiek da Silva

AU - Solander, Kurt

AU - Spanner, Gustavo

AU - Warren, Jeffrey M.

AU - Wright, Cynthia L.

AU - Zambrano, Alfonso

AU - Lima, Adriano

AU - Higuchi, Niro

AU - Chambers, Jeffrey Q.

AU - Koven, Charlie

AU - Leung, L. Ruby

AU - McDowell, Nate G.

PY - 2026/1/15

Y1 - 2026/1/15

N2 - Tropical forest tree mortality is increasing due to more severe droughts, yet our understanding of how tree traits and life strategies are linked to drought stress has been limited by measurement scarcity. The BIONTE (BIOmass and NuTrient Experiment) near Manaus, Brazil hosts one of the world's largest sap flow installations, with sensors in 90 canopy trees across a wood density gradient monitored since June 2022. The 2023 El Niño drought provided a unique opportunity to evaluate how water availability impacts tree transpiration. An interpretable machine learning framework was used to study the complex interactions between transpiration and multiple environmental variables such as soil water availability and vapor pressure deficit (VPD), and how these interactions vary with wood density and individual trees. We found varying responses of transpiration from different trees during the El Niño drought. Transpiration generally increased with temperature, with stronger effects in wetter areas and in trees with low to medium wood density. However, this response was modulated by stomatal sensitivity to VPD, which constrained transpiration under high atmospheric demand, particularly in intermediate-moisture area. The inflection in transpiration rate at high temperatures (>32°C) underscores the role of stomatal and hydraulic regulation in limiting water loss and protecting trees from excessive evaporative demand. Analysis of soil water contribution to transpiration revealed unimodal patterns in wetter area, with peak contributions near 0.45 cm³ cm⁻³ of surface soil water and declining or flat responses beyond that threshold, suggesting a shift from water- to energy-limited transpiration. In contrast, drier areas exhibited limited transpiration sensitivity to soil water conditions and minimal trait-based variation in VPD responses, indicating supply-limited conditions. Despite higher wood density trees being generally more resilient, this study shows diverse tree drought resilience, prompting further investigation into the specific traits and dynamics between environmental variables in regulating transpiration and other physiological processes in trees.

AB - Tropical forest tree mortality is increasing due to more severe droughts, yet our understanding of how tree traits and life strategies are linked to drought stress has been limited by measurement scarcity. The BIONTE (BIOmass and NuTrient Experiment) near Manaus, Brazil hosts one of the world's largest sap flow installations, with sensors in 90 canopy trees across a wood density gradient monitored since June 2022. The 2023 El Niño drought provided a unique opportunity to evaluate how water availability impacts tree transpiration. An interpretable machine learning framework was used to study the complex interactions between transpiration and multiple environmental variables such as soil water availability and vapor pressure deficit (VPD), and how these interactions vary with wood density and individual trees. We found varying responses of transpiration from different trees during the El Niño drought. Transpiration generally increased with temperature, with stronger effects in wetter areas and in trees with low to medium wood density. However, this response was modulated by stomatal sensitivity to VPD, which constrained transpiration under high atmospheric demand, particularly in intermediate-moisture area. The inflection in transpiration rate at high temperatures (>32°C) underscores the role of stomatal and hydraulic regulation in limiting water loss and protecting trees from excessive evaporative demand. Analysis of soil water contribution to transpiration revealed unimodal patterns in wetter area, with peak contributions near 0.45 cm³ cm⁻³ of surface soil water and declining or flat responses beyond that threshold, suggesting a shift from water- to energy-limited transpiration. In contrast, drier areas exhibited limited transpiration sensitivity to soil water conditions and minimal trait-based variation in VPD responses, indicating supply-limited conditions. Despite higher wood density trees being generally more resilient, this study shows diverse tree drought resilience, prompting further investigation into the specific traits and dynamics between environmental variables in regulating transpiration and other physiological processes in trees.

KW - Drought

KW - Machine learning

KW - Stomatal regulation

KW - Tropical forests

KW - Water stress

UR - https://www.scopus.com/pages/publications/105020731442

U2 - 10.1016/j.agrformet.2025.110914

DO - 10.1016/j.agrformet.2025.110914

M3 - Article

AN - SCOPUS:105020731442

SN - 0168-1923

VL - 376

JO - Agricultural and Forest Meteorology

JF - Agricultural and Forest Meteorology

M1 - 110914

ER -

Multivariate environmental and trait-based controls of transpiration in the Central Amazon Rainforest

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Keywords

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