Annual variations of T/ET in a semi-arid region: Implications of plant water use strategies

Ruiqiang Yuan; Li Ling Chang; Guoyue Niu

doi:10.1016/j.jhydrol.2021.126884

Annual variations of T/ET in a semi-arid region: Implications of plant water use strategies

Ruiqiang Yuan^*, Li Ling Chang, Guoyue Niu

^*Corresponding author for this work

Geography, Earth and Environmental Sciences

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

1 Citation (Scopus)

Abstract

Understanding the annual variation in the transpiration to evapotranspiration ratio (T/ET) remains a challenge and is essential for a thorough understanding of plant responses to the changing environment. We obtained the annual dynamics of T/ET in a semi-arid area of the southwestern United States based on the medians of monthly T/ET derived from two ET partitioning methods. The variation in monthly T/ET was analysed, and plant water use strategies were discussed based on the water use efficiency evaluated by the transpiration (WUE_T). The results show that physiological changes in plants are vital in the annual dynamics of T/ET. Switches in plant physiological status (growth and dormancy) at the start and end of growing seasons induce two dramatic changes in T/ET. Consequently, there is an annual bimodal dynamic of monthly T/ET, with a maximum of 0.84 in October and a minimum of 0.14 in December. Physiological/biochemical variations of plants indicated by solar-induced chlorophyll fluorescence (SIF) are linearly related to T/ET in growing seasons at a monthly scale (T/ET = 3.40 × SIF + 0.36, R² = 0.987). Generally, a stable high monthly T/ET occurs under sufficient energy and water conditions and a highly variable monthly T/ET occurs under energy and water deficient conditions. In semi-arid regions, plants can flexibly adjust WUE_T following different water use strategies to survive or gain as much gross primary productivity (GPP) to compete. Saving water by greatly elevating WUE_T is the main strategy by which plants survive the non-growing season when WUE_T is linearly related to SIF (WUE_T = -114.93 × SIF + 3.25, R² = 0.970). However, GPP and not WUE_T, becomes the goal of plants in growing seasons when they employ a stable and moderate WUE_T (around 2.1 gC kg⁻¹ H₂O) despite the abundant energy and precipitation. There are obvious reductions in WUE_T during the transition periods of the plants’ ‘growth-dormancy’ cycle. Our study highlights the importance of studying annual T/ET variations and water-use efficiency dynamics to better understand water use strategies in plants.

Original language	English
Article number	126884
Number of pages	9
Journal	Journal of Hydrology
Volume	603
Early online date	10 Sept 2021
DOIs	https://doi.org/10.1016/j.jhydrol.2021.126884
Publication status	Published - Dec 2021

Bibliographical note

Funding Information:
This research project was funded by the NASA MAP Program (80NSSC17K0352), NOAA OAR’s OWAQ (NA18OAR4590397), and the China scholarship council (201708140009). We thank the anonymous reviewers for their valuable comments on our draft paper. We thank Dr. Russell L. Scott for his support with flux tower data processing. We thank Dr. Sha Zhou for her support with the quantile regression in R.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

Adaption
Changing environment
Leaf scale WUE
Plant
Transpiration
Water use strategies

ASJC Scopus subject areas

Water Science and Technology

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10.1016/j.jhydrol.2021.126884Licence: None: All rights reserved

Cite this

@article{b2bc0f136c424fabae13db8fe7b663ad,

title = "Annual variations of T/ET in a semi-arid region: Implications of plant water use strategies",

abstract = "Understanding the annual variation in the transpiration to evapotranspiration ratio (T/ET) remains a challenge and is essential for a thorough understanding of plant responses to the changing environment. We obtained the annual dynamics of T/ET in a semi-arid area of the southwestern United States based on the medians of monthly T/ET derived from two ET partitioning methods. The variation in monthly T/ET was analysed, and plant water use strategies were discussed based on the water use efficiency evaluated by the transpiration (WUE_T). The results show that physiological changes in plants are vital in the annual dynamics of T/ET. Switches in plant physiological status (growth and dormancy) at the start and end of growing seasons induce two dramatic changes in T/ET. Consequently, there is an annual bimodal dynamic of monthly T/ET, with a maximum of 0.84 in October and a minimum of 0.14 in December. Physiological/biochemical variations of plants indicated by solar-induced chlorophyll fluorescence (SIF) are linearly related to T/ET in growing seasons at a monthly scale (T/ET = 3.40 × SIF + 0.36, R2 = 0.987). Generally, a stable high monthly T/ET occurs under sufficient energy and water conditions and a highly variable monthly T/ET occurs under energy and water deficient conditions. In semi-arid regions, plants can flexibly adjust WUE_T following different water use strategies to survive or gain as much gross primary productivity (GPP) to compete. Saving water by greatly elevating WUE_T is the main strategy by which plants survive the non-growing season when WUE_T is linearly related to SIF (WUE_T = -114.93 × SIF + 3.25, R2 = 0.970). However, GPP and not WUE_T, becomes the goal of plants in growing seasons when they employ a stable and moderate WUE_T (around 2.1 gC kg−1 H2O) despite the abundant energy and precipitation. There are obvious reductions in WUE_T during the transition periods of the plants{\textquoteright} {\textquoteleft}growth-dormancy{\textquoteright} cycle. Our study highlights the importance of studying annual T/ET variations and water-use efficiency dynamics to better understand water use strategies in plants.",

keywords = "Adaption, Changing environment, Leaf scale WUE, Plant, Transpiration, Water use strategies",

author = "Ruiqiang Yuan and Chang, {Li Ling} and Guoyue Niu",

note = "Funding Information: This research project was funded by the NASA MAP Program (80NSSC17K0352), NOAA OAR{\textquoteright}s OWAQ (NA18OAR4590397), and the China scholarship council (201708140009). We thank the anonymous reviewers for their valuable comments on our draft paper. We thank Dr. Russell L. Scott for his support with flux tower data processing. We thank Dr. Sha Zhou for her support with the quantile regression in R. Publisher Copyright: {\textcopyright} 2021 Elsevier B.V.",

year = "2021",

month = dec,

doi = "10.1016/j.jhydrol.2021.126884",

language = "English",

volume = "603",

journal = "Journal of Hydrology",

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T1 - Annual variations of T/ET in a semi-arid region

T2 - Implications of plant water use strategies

AU - Yuan, Ruiqiang

AU - Chang, Li Ling

AU - Niu, Guoyue

N1 - Funding Information: This research project was funded by the NASA MAP Program (80NSSC17K0352), NOAA OAR’s OWAQ (NA18OAR4590397), and the China scholarship council (201708140009). We thank the anonymous reviewers for their valuable comments on our draft paper. We thank Dr. Russell L. Scott for his support with flux tower data processing. We thank Dr. Sha Zhou for her support with the quantile regression in R. Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/12

Y1 - 2021/12

N2 - Understanding the annual variation in the transpiration to evapotranspiration ratio (T/ET) remains a challenge and is essential for a thorough understanding of plant responses to the changing environment. We obtained the annual dynamics of T/ET in a semi-arid area of the southwestern United States based on the medians of monthly T/ET derived from two ET partitioning methods. The variation in monthly T/ET was analysed, and plant water use strategies were discussed based on the water use efficiency evaluated by the transpiration (WUE_T). The results show that physiological changes in plants are vital in the annual dynamics of T/ET. Switches in plant physiological status (growth and dormancy) at the start and end of growing seasons induce two dramatic changes in T/ET. Consequently, there is an annual bimodal dynamic of monthly T/ET, with a maximum of 0.84 in October and a minimum of 0.14 in December. Physiological/biochemical variations of plants indicated by solar-induced chlorophyll fluorescence (SIF) are linearly related to T/ET in growing seasons at a monthly scale (T/ET = 3.40 × SIF + 0.36, R2 = 0.987). Generally, a stable high monthly T/ET occurs under sufficient energy and water conditions and a highly variable monthly T/ET occurs under energy and water deficient conditions. In semi-arid regions, plants can flexibly adjust WUE_T following different water use strategies to survive or gain as much gross primary productivity (GPP) to compete. Saving water by greatly elevating WUE_T is the main strategy by which plants survive the non-growing season when WUE_T is linearly related to SIF (WUE_T = -114.93 × SIF + 3.25, R2 = 0.970). However, GPP and not WUE_T, becomes the goal of plants in growing seasons when they employ a stable and moderate WUE_T (around 2.1 gC kg−1 H2O) despite the abundant energy and precipitation. There are obvious reductions in WUE_T during the transition periods of the plants’ ‘growth-dormancy’ cycle. Our study highlights the importance of studying annual T/ET variations and water-use efficiency dynamics to better understand water use strategies in plants.

AB - Understanding the annual variation in the transpiration to evapotranspiration ratio (T/ET) remains a challenge and is essential for a thorough understanding of plant responses to the changing environment. We obtained the annual dynamics of T/ET in a semi-arid area of the southwestern United States based on the medians of monthly T/ET derived from two ET partitioning methods. The variation in monthly T/ET was analysed, and plant water use strategies were discussed based on the water use efficiency evaluated by the transpiration (WUE_T). The results show that physiological changes in plants are vital in the annual dynamics of T/ET. Switches in plant physiological status (growth and dormancy) at the start and end of growing seasons induce two dramatic changes in T/ET. Consequently, there is an annual bimodal dynamic of monthly T/ET, with a maximum of 0.84 in October and a minimum of 0.14 in December. Physiological/biochemical variations of plants indicated by solar-induced chlorophyll fluorescence (SIF) are linearly related to T/ET in growing seasons at a monthly scale (T/ET = 3.40 × SIF + 0.36, R2 = 0.987). Generally, a stable high monthly T/ET occurs under sufficient energy and water conditions and a highly variable monthly T/ET occurs under energy and water deficient conditions. In semi-arid regions, plants can flexibly adjust WUE_T following different water use strategies to survive or gain as much gross primary productivity (GPP) to compete. Saving water by greatly elevating WUE_T is the main strategy by which plants survive the non-growing season when WUE_T is linearly related to SIF (WUE_T = -114.93 × SIF + 3.25, R2 = 0.970). However, GPP and not WUE_T, becomes the goal of plants in growing seasons when they employ a stable and moderate WUE_T (around 2.1 gC kg−1 H2O) despite the abundant energy and precipitation. There are obvious reductions in WUE_T during the transition periods of the plants’ ‘growth-dormancy’ cycle. Our study highlights the importance of studying annual T/ET variations and water-use efficiency dynamics to better understand water use strategies in plants.

KW - Adaption

KW - Changing environment

KW - Leaf scale WUE

KW - Plant

KW - Transpiration

KW - Water use strategies

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DO - 10.1016/j.jhydrol.2021.126884

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VL - 603

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ER -

Annual variations of T/ET in a semi-arid region: Implications of plant water use strategies

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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