Globally assessing the hysteresis between sub-diurnal actual evaporation and vapor pressure deficit at the ecosystem scale: Patterns and mechanisms

Shiqin Xu*, Tim R. McVicar, Lingcheng Li, Zhongbo Yu, Peng Jiang, Yuliang Zhang, Zhaoxin Ban, Wanqiu Xing, Ningpeng Dong, Hua Zhang, Mingjun Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Hysteresis between sub-diurnal actual evaporation (AET) (or one of its components, transpiration) and vapor pressure deficit (VPD) at the species or individual ecosystem level has been extensively studied, but the global variation and seasonal variability of this hysteresis across biomes and climates is yet to be fully explored and the limiting mechanisms remain unclear. We hypothesize that the sub-diurnal AET-VPD hysteresis results from the interplay between evaporative demand and soil moisture supply limitations. To test our hypothesis, we quantify the sub-diurnal AET-VPD hysteresis across a broad range of biomes and climates based on the observations from the 89 FLUXNET sites (703 site-years) across the globe. We find that the magnitude of hysteresis varies with biomes and climates and is mostly attributable to evaporative demand limitation in all ten sampled biomes. In seasonally dry locations, however, low soil moisture availability amplifies the hysteresis during the dry season. Sensitivity analysis using a hydraulic model suggests that most ecosystems exhibiting seasonal drought display a more isohydric behavior during the dry season, while shift toward a more anisohydric response during the wet season. Our findings have important implications for understanding sub-diurnal dynamics between vegetation and its surrounding environment, reducing uncertainties in AET simulation at fine spatial and temporal scales, and improving understanding of the ecosystem response to hydrologic stress.

Original languageEnglish (US)
Article number109085
JournalAgricultural and Forest Meteorology
Volume323
DOIs
StatePublished - Aug 15 2022

Bibliographical note

Funding Information:
This work was funded by the National Natural Science Foundation of China (Grant No. 42101045 ); the Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (Grant No. 2020490711 and 2021490311 ); and the Foundation for Improving Young Faculty's Scientific Research Capability of Northwest Normal University (Grant No. NWNU-LKQN2021-35 ). TRM was supported by TERN Landscapes ( https://www.tern.org.au/tern-observatory/tern-landscapes/ ), part of Terrestrial Ecosystem Research Network (TERN; https://www.tern.org.au/ ). We thank the editor and three anonymous referees for the detailed and constructive comments.

Publisher Copyright:
© 2022

Keywords

  • Canopy-atmosphere coupling
  • Climate regime and seasonality
  • Ecosystem-scale isohydricity
  • Hysteresis index
  • Water and energy fluxes

ASJC Scopus subject areas

  • Forestry
  • Global and Planetary Change
  • Agronomy and Crop Science
  • Atmospheric Science

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