Transpiration from a Cryptomeria japonica plantation, part 2: Responses of canopy conductance to meteorological factors

Hikaru Komatsu, Yihuei Kang, Tomonori Kume, Natsuko Yoshifuji, Norifumi Hotta

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9 Citations (Scopus)


To our knowledge, there is no information on the canopy conductance of Cryptomeria japonica plantations, although such forests are very common in Japan. We examined the canopy conductance Gc of a C. japonica plantation based on 1-year sap-flow data using the simplified Penman-Monteith equation. After selecting data based on the criterion proposed in part 1 of this study (Komatsu et al., 2006. Hydrological Processes 20: this issue), we now examine Gc responses to meteorological factors. Gc was expressed using functions of solar radiation S (W m-2), the vapour pressure deficit D (kPa), and air temperature T (°C). The resulting functions were f1 (S) = [(1000 + 30)S]/[1000(S + 30)], f2(D) = exp(-0.54D)/exp (-0.54), and f3(T) = {[(30 - 5) + 14](T - 5)}/1{(30 - 5) [(T - 5) + 14]}, where f1(S), f2(D), and f3(T) are functions expressing the Gc responses to S, D, and T respectively. The functions were characterized by comparing general functions for coniferous forests, which showed that it was necessary to consider f3(T) to reproduce the 1-year transpiration at the site, and that f1(S) and f2(D) determined here were not very different from the general functions. This paper is the first to determine Gc responses to meteorological fa ctors for a C. japonica plantation. When predicting transpiration from a C. japonica plantation using hydrological or ecological models, the functions determined here should be used instead of the default functions of the models.

Original languageEnglish
Pages (from-to)1321-1334
Number of pages14
JournalHydrological Processes
Issue number6
Publication statusPublished - Apr 15 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Water Science and Technology


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