Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau

Abstract Water use efficiency (WUE, the ratio of gross primary productivity to evapotranspiration (ET)) is a robust indicator of ecosystem response to climate change, with soil moisture serving as a crucial determinant. Soil moisture varies across soil layers due to ET and soil structure, thereby di...

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Main Authors: Yang Liu, Cheng Chen, Qiuwen Chen, Jianyun Zhang, Zhen Cui, Zhenzhong Zeng
Format: Article
Language:English
Published: Wiley 2025-06-01
Series:Water Resources Research
Subjects:
Online Access:https://doi.org/10.1029/2024WR038645
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author Yang Liu
Cheng Chen
Qiuwen Chen
Jianyun Zhang
Zhen Cui
Zhenzhong Zeng
author_facet Yang Liu
Cheng Chen
Qiuwen Chen
Jianyun Zhang
Zhen Cui
Zhenzhong Zeng
author_sort Yang Liu
collection DOAJ
description Abstract Water use efficiency (WUE, the ratio of gross primary productivity to evapotranspiration (ET)) is a robust indicator of ecosystem response to climate change, with soil moisture serving as a crucial determinant. Soil moisture varies across soil layers due to ET and soil structure, thereby differentially impacting vegetation. However, the influence of soil moisture at various soil layers on grassland WUE remains poorly understood. Using random forest and Shapley additive explanations, we examined grassland WUE sensitivity to soil moisture at different soil layers across alpine meadow and steppe ecosystems on the Tibetan Plateau. We found that grassland WUE was more sensitive to deep soil moisture (deepSM) than surface (surSM) and middle (midSM) over 2001–2020. Structural equation modeling indicated deepSM was less influenced by temperature, vapor pressure deficit (vpd) and wind speed (ws), thus providing more stable water to vegetation and exerting greater influence on WUE under the same moisture change. Additionally, alpine steppes exhibited lower sensitive to soil moisture than alpine meadows due to greater ecological adaptations and deeper root systems. Over time, WUE sensitivity to deepSM remained stable, whereas sensitivity to surSM and midSM significantly decreased in both grassland types on the Tibetan Plateau. This decrease in WUE sensitivity to surSM and midSM was associated with increased precipitation, decreased ws, and increased vpd. These findings highlight differences in WUE sensitivity to soil moisture across soil layers and ecosystems, emphasizing the importance of deepSM in sustaining grassland water‐carbon coupling. This study provides a foundation for future validations at broader spatial scales.
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spelling doaj-art-3a8b0c29dcce4e8aa2ec97e8d2174f6e2025-08-20T03:31:40ZengWileyWater Resources Research0043-13971944-79732025-06-01616n/an/a10.1029/2024WR038645Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan PlateauYang Liu0Cheng Chen1Qiuwen Chen2Jianyun Zhang3Zhen Cui4Zhenzhong Zeng5The National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing ChinaThe National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing ChinaThe National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing ChinaThe National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing ChinaThe National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing ChinaSchool of Environmental Science and Engineering Southern University of Science and Technology Shenzhen ChinaAbstract Water use efficiency (WUE, the ratio of gross primary productivity to evapotranspiration (ET)) is a robust indicator of ecosystem response to climate change, with soil moisture serving as a crucial determinant. Soil moisture varies across soil layers due to ET and soil structure, thereby differentially impacting vegetation. However, the influence of soil moisture at various soil layers on grassland WUE remains poorly understood. Using random forest and Shapley additive explanations, we examined grassland WUE sensitivity to soil moisture at different soil layers across alpine meadow and steppe ecosystems on the Tibetan Plateau. We found that grassland WUE was more sensitive to deep soil moisture (deepSM) than surface (surSM) and middle (midSM) over 2001–2020. Structural equation modeling indicated deepSM was less influenced by temperature, vapor pressure deficit (vpd) and wind speed (ws), thus providing more stable water to vegetation and exerting greater influence on WUE under the same moisture change. Additionally, alpine steppes exhibited lower sensitive to soil moisture than alpine meadows due to greater ecological adaptations and deeper root systems. Over time, WUE sensitivity to deepSM remained stable, whereas sensitivity to surSM and midSM significantly decreased in both grassland types on the Tibetan Plateau. This decrease in WUE sensitivity to surSM and midSM was associated with increased precipitation, decreased ws, and increased vpd. These findings highlight differences in WUE sensitivity to soil moisture across soil layers and ecosystems, emphasizing the importance of deepSM in sustaining grassland water‐carbon coupling. This study provides a foundation for future validations at broader spatial scales.https://doi.org/10.1029/2024WR038645Tibetan Plateauwater use efficiencysoil moisturesensitivityShapley additive explanations
spellingShingle Yang Liu
Cheng Chen
Qiuwen Chen
Jianyun Zhang
Zhen Cui
Zhenzhong Zeng
Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
Water Resources Research
Tibetan Plateau
water use efficiency
soil moisture
sensitivity
Shapley additive explanations
title Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
title_full Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
title_fullStr Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
title_full_unstemmed Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
title_short Widespread Sensitivity of Grassland Water Use Efficiency to Deep Soil Moisture on the Tibetan Plateau
title_sort widespread sensitivity of grassland water use efficiency to deep soil moisture on the tibetan plateau
topic Tibetan Plateau
water use efficiency
soil moisture
sensitivity
Shapley additive explanations
url https://doi.org/10.1029/2024WR038645
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