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- Title
Evapotranspiration Partitioning Based on Leaf and Ecosystem Water Use Efficiency.
- Authors
Yu, Liuyang; Zhou, Sha; Zhao, Xining; Gao, Xiaodong; Jiang, Kongtao; Zhang, Baoqing; Cheng, Lei; Song, Xiaolin; Siddique, Kadambot H. M.
- Abstract
Partitioning evapotranspiration (ET) into evaporation (E) and transpiration (T) is essential for understanding the global hydrological cycle and improving water resource management. However, ecosystem‐level ET partitioning remains challenging. Here we proposed a novel ET partitioning method that uses the unified stomatal conductance model to estimate T:ET by calculating the ratio of the ecosystem water use efficiency (WUEeco) to leaf WUE (WUEleaf) using half‐hourly flux data. The WUEleaf values estimated by the unified stomatal conductance model agree with an independently measured ratio of hourly photosynthetic rate to T rate (R2 = 0.69). The sensitivity of T:ET to the key parameter g1 varied among different plant functional types (PFTs), but the T:ET variations for each PFT were all controlled within 20% when g1 altered within its 95% confidence interval. The mean annual T:ET was highest for evergreen broadleaf forests (0.63), followed by deciduous broad forests (0.62), grasslands (0.52), evergreen needleleaf forests (0.43) and woody savannas (0.40). C3 croplands had higher T:ET (0.65) than C4 croplands (0.48). Seasonal variations in T:ET varied across PFTs and the leaf area index explained about 50% of the variation in seasonal T:ET. Our method is not only consistent with other three EC‐based methods: Z16, N18, and L19 (R = 0.92, 0.94, and 0.68), but also shows high correlations to sap flow‐based T (R = 0.70) at three different forest sites. The method developed in this study provides a feasible and universal approach for ET partitioning of global EC sites, improving the understanding of ecosystem T characteristics across climates and PFTs. Key Points: An evapotranspiration (ET) partitioning method based on flux data was developed using the unified stomatal conductance modelThe soundness of the method is confirmed by validation, application and intercomparison between methods across climates and biomesThe method avoids the major assumptions of T ≈ ET during some periods which makes wider applications at EC sites
- Subjects
WATER management; LEAF anatomy; LEAF area index; BROADLEAF forests; WATER efficiency; HYDROLOGIC cycle; EVAPOTRANSPIRATION
- Publication
Water Resources Research, 2022, Vol 58, Issue 9, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2021WR030629