Inter-annual variations and factors controlling evapotranspiration in a temperate Japanese cypress forest

Kenji Tsuruta, Yoshiko Kosugi, Satoru Takanashi, Makoto Tani

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Abstract

This study was undertaken to evaluate the effects of climatic variability on inter-annual variations in each component of evapotranspiration (ET) and the total ET in a temperate coniferous forest in Japan. We conducted eddy covariance flux and meteorological measurements for 7years and parameterized a one-dimensional multi-layer biosphere-atmosphere model (Kosugi et al., ) that partitions ET to transpiration (Tr), wet-canopy evaporation (Ewet), and soil evaporation (Esoil). The model was validated with the observed flux data. Using the model, the components of ET were estimated for the 7years. Annual precipitation, ET, Tr, Ewet, and Esoil over the 7years were 1536±334mm, 752±29mm, 425±37mm, 219±34mm, and 108±10mm, respectively. The maximum inter-annual fluctuation of observed ET was 64mm with a coefficient of variance (CV) of 2.7%, in contrast to relatively large year-to-year variations in annual rainfall (CV=20.1%). Tr was related to the vapour pressure deficit, incoming radiation, and air temperature with relatively small inter-annual variations (CV=8.2%). Esoil (CV=8.6%) was related mainly to the vapour pressure deficit. Ewet was related to precipitation with large inter-annual variations (CV=14.3%) because of the variability in precipitation. The variations in Ewet were counterbalanced by the variations in Tr and Esoil, producing the small inter-annual variations in total ET.

Original languageEnglish
JournalHydrological Processes
DOIs
Publication statusAccepted/In press - 2016
Externally publishedYes

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Keywords

  • Eddy covariance
  • Evapotranspiration
  • Japanese cypress
  • Multi-layer biosphere-atmosphere model
  • Water balance

ASJC Scopus subject areas

  • Water Science and Technology

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