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Title: Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest

Abstract

Current climate change scenarios indicate warmer temperatures and the potential for more extreme droughts in the tropics, such that a mechanistic understanding of the water cycle from individual trees to landscapes is needed to adequately predict future changes in forest structure and function. In this study, we contrasted physiological responses of tropical trees during a normal dry season with the extreme dry season due to the 2015–2016 El Niño-Southern Oscillation (ENSO) event. We quantified high resolution temporal dynamics of sap velocity (V s), stomatal conductance (g s) and leaf water potential (Ψ L) of multiple canopy trees, and their correlations with leaf temperature (T leaf) and environmental conditions [direct solar radiation, air temperature (T air) and vapor pressure deficit (VPD)]. The experiment leveraged canopy access towers to measure adjacent trees at the ZF2 and Tapajós tropical forest research (near the cities of Manaus and Santarém). The temporal difference between the peak of g s (late morning) and the peak of VPD (early afternoon) is one of the major regulators of sap velocity hysteresis patterns. Sap velocity displayed species-specific diurnal hysteresis patterns reflected by changes in T leaf. In the morning, T leaf and sap velocity displayed a sigmoidal relationship. Inmore » the afternoon, stomatal conductance declined as T leaf approached a daily peak, allowing Ψ L to begin recovery, while sap velocity declined with an exponential relationship with Tleaf. In Manaus, hysteresis indices of the variables T leaf-T air and Ψ L-T leaf were calculated for different species and a significant difference (p < 0.01, α = 0.05) was observed when the 2015 dry season (ENSO period) was compared with the 2017 dry season (“control scenario”). In some days during the 2015 ENSO event, T leaf approached 40°C for all studied species and the differences between T leaf and T air reached as high at 8°C (average difference: 1.65 ± 1.07°C). Generally, T leaf was higher than T air during the middle morning to early afternoon, and lower than T air during the early morning, late afternoon and night. Our results support the hypothesis that partial stomatal closure allows for a recovery in Ψ L during the afternoon period giving an observed counterclockwise hysteresis pattern between Ψ L and T leaf.« less

Authors:
 [1];  [2];  [1];  [2];  [1];  [1];  [3];  [3];  [2];  [2];  [1];  [4]; ORCiD logo [5];  [6];  [2];  [2];  [7];  [8]
  1. National Institute of Amazonian Research (INPA), Manaus (Brazil)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States)
  4. Embrapa Amazônia Oriental, Belém (Brazil)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  7. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  8. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1530001
Alternate Identifier(s):
OSTI ID: 1530108
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Published Article
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 10; Journal Issue: n/a; Journal ID: ISSN 1664-462X
Publisher:
Frontiers Research Foundation
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; tropical forests; sap velocity; stomatal conductance; direct solar radiation; vapor pressure deficit; leaf temperature; hysteresis

Citation Formats

Gimenez, Bruno O., Jardine, Kolby J., Higuchi, Niro, Negrón-Juárez, Robinson I., Sampaio-Filho, Israel de Jesus, Cobello, Leticia O., Fontes, Clarissa G., Dawson, Todd E., Varadharajan, Charuleka, Christianson, Danielle S., Spanner, Gustavo C., Araújo, Alessandro C., Warren, Jeffrey M., Newman, Brent D., Holm, Jennifer A., Koven, Charles D., McDowell, Nate G., and Chambers, Jeffrey Q. Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest. United States: N. p., 2019. Web. doi:10.3389/fpls.2019.00830.
Gimenez, Bruno O., Jardine, Kolby J., Higuchi, Niro, Negrón-Juárez, Robinson I., Sampaio-Filho, Israel de Jesus, Cobello, Leticia O., Fontes, Clarissa G., Dawson, Todd E., Varadharajan, Charuleka, Christianson, Danielle S., Spanner, Gustavo C., Araújo, Alessandro C., Warren, Jeffrey M., Newman, Brent D., Holm, Jennifer A., Koven, Charles D., McDowell, Nate G., & Chambers, Jeffrey Q. Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest. United States. doi:10.3389/fpls.2019.00830.
Gimenez, Bruno O., Jardine, Kolby J., Higuchi, Niro, Negrón-Juárez, Robinson I., Sampaio-Filho, Israel de Jesus, Cobello, Leticia O., Fontes, Clarissa G., Dawson, Todd E., Varadharajan, Charuleka, Christianson, Danielle S., Spanner, Gustavo C., Araújo, Alessandro C., Warren, Jeffrey M., Newman, Brent D., Holm, Jennifer A., Koven, Charles D., McDowell, Nate G., and Chambers, Jeffrey Q. Fri . "Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest". United States. doi:10.3389/fpls.2019.00830.
@article{osti_1530001,
title = {Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest},
author = {Gimenez, Bruno O. and Jardine, Kolby J. and Higuchi, Niro and Negrón-Juárez, Robinson I. and Sampaio-Filho, Israel de Jesus and Cobello, Leticia O. and Fontes, Clarissa G. and Dawson, Todd E. and Varadharajan, Charuleka and Christianson, Danielle S. and Spanner, Gustavo C. and Araújo, Alessandro C. and Warren, Jeffrey M. and Newman, Brent D. and Holm, Jennifer A. and Koven, Charles D. and McDowell, Nate G. and Chambers, Jeffrey Q.},
abstractNote = {Current climate change scenarios indicate warmer temperatures and the potential for more extreme droughts in the tropics, such that a mechanistic understanding of the water cycle from individual trees to landscapes is needed to adequately predict future changes in forest structure and function. In this study, we contrasted physiological responses of tropical trees during a normal dry season with the extreme dry season due to the 2015–2016 El Niño-Southern Oscillation (ENSO) event. We quantified high resolution temporal dynamics of sap velocity (Vs), stomatal conductance (gs) and leaf water potential (ΨL) of multiple canopy trees, and their correlations with leaf temperature (Tleaf) and environmental conditions [direct solar radiation, air temperature (Tair) and vapor pressure deficit (VPD)]. The experiment leveraged canopy access towers to measure adjacent trees at the ZF2 and Tapajós tropical forest research (near the cities of Manaus and Santarém). The temporal difference between the peak of gs (late morning) and the peak of VPD (early afternoon) is one of the major regulators of sap velocity hysteresis patterns. Sap velocity displayed species-specific diurnal hysteresis patterns reflected by changes in Tleaf. In the morning, Tleaf and sap velocity displayed a sigmoidal relationship. In the afternoon, stomatal conductance declined as Tleaf approached a daily peak, allowing ΨL to begin recovery, while sap velocity declined with an exponential relationship with Tleaf. In Manaus, hysteresis indices of the variables Tleaf-Tair and ΨL-Tleaf were calculated for different species and a significant difference (p < 0.01, α = 0.05) was observed when the 2015 dry season (ENSO period) was compared with the 2017 dry season (“control scenario”). In some days during the 2015 ENSO event, Tleaf approached 40°C for all studied species and the differences between Tleaf and Tair reached as high at 8°C (average difference: 1.65 ± 1.07°C). Generally, Tleaf was higher than Tair during the middle morning to early afternoon, and lower than Tair during the early morning, late afternoon and night. Our results support the hypothesis that partial stomatal closure allows for a recovery in ΨL during the afternoon period giving an observed counterclockwise hysteresis pattern between ΨL and Tleaf.},
doi = {10.3389/fpls.2019.00830},
journal = {Frontiers in Plant Science},
number = n/a,
volume = 10,
place = {United States},
year = {2019},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.3389/fpls.2019.00830

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