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Divergent environmental responses of long-term variations in evapotranspiration over four grassland ecosystems in China based on eddy-covariance measurements.

Authors :
Zheng, Han
Yu, Guirui
Wang, Qiufeng
Chen, Zhi
Zhu, Xianjin
Bao, Han
Sun, Yuchen
Niu, Panpan
Li, Yingnian
Shi, Peili
Hao, Yanbin
Zhang, Fawei
Niu, Zhongen
Source :
Journal of Hydrology. 2023 Part A, Vol. 625, pN.PAG-N.PAG. 1p.
Publication Year :
2023

Abstract

• Dominant factor for the IAVs of ET varied among the four grassland ecosystems. • Net radiation dominated the IAV of ET at the alpine marsh meadow. • Water availability mainly regulated the IAVs of ET for relatively arid sites. • Environmental responses of surface conductance varied across the grasslands. Understanding the long-term variation in evapotranspiration (ET) for the spatially distributed grasslands is crucial for the accurate prediction of ET response to climate change. In this study, we analyzed the interannual variability (IAV) of ET and its responses to environmental conditions at four grassland ecosystems across a wide range of climatic and biome conditions based on the long-term (9–11 years) eddy-covariance measurements. The four ecosystems encompassed the most prevalent grassland vegetations in China, containing a typical temperate steppe, an alpine meadow-steppe, an alpine shrubland meadow, and an alpine marsh meadow. The IAVs of annual ET at the typical temperate steppe and the alpine meadow-steppe were primarily affected by either change in precipitation (P) or relative humidity (RH). Leaf area index (LAI) was the dominant factor controlling the IAVs of annual and growing-season ET at the alpine shrubland meadow, and the IAV of LAI was significantly correlated with P variation. As to the alpine marsh meadow, net radiation turned to be the dominant factor for the IAV of annual ET, additionally with significant effects from water supply condition (P and RH) on the IAV of growing-season ET. Similar environmental responses were also found for the IAVs of mean surface conductance (g s) across the sites. Specifically, annual and growing-season mean g s significantly increased with increases in LAI at the alpine shrubland meadow, and appeared to be more sensitive to changes in water availability and VPD at the typical temperate steppe and the alpine meadow-steppe. Significant linear relationships were also observed among the IAVs of mean Priestley-Taylor coefficient (α = ET/ET eq , where ET eq is the equilibrium evaporation), decoupling coefficient (Ω), and g s on both the annual and growing-season basis in this study. Moreover, the variabilities of annual mean g s , Ω , and α further demonstrated the energy-limited conditions at the alpine marsh meadow, and the overall water-limited conditions at the other three grasslands. This study reveals the divergent environmental responses of long-term ET variations over grassland ecosystems, and contributes to the comprehensive understanding on the ET process and modeling efforts as well. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00221694
Volume :
625
Database :
Academic Search Index
Journal :
Journal of Hydrology
Publication Type :
Academic Journal
Accession number :
172307781
Full Text :
https://doi.org/10.1016/j.jhydrol.2023.130030