Transient response of sap flow to wind speed

Chia R. Chu, Cheng I. Hsieh, Shen Yuang Wu, Nathan G. Phillips

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Transient responses of sap flow to step changes in wind speed were experimentally investigated in a wind tunnel. A Granier-type sap flow sensor was calibrated and tested in a cylindrical tube for analysis of its transient time response. Then the sensor was used to measure the transient response of a well-watered Pachira macrocarpa plant to wind speed variations. The transient response of sap flow was described using the resistance-capacitance model. The steady sap flow rate increased as the wind speed increased at low wind speeds. Once the wind speed exceeded 8.0 m s-1, the steady sap flow rate did not increase further. The transpiration rate, measured gravimetrically, showed a similar trend. The response of nocturnal sap flow to wind speed variation was also measured and compared with the results in the daytime. Under the same wind speed, the steady sap flow rate was smaller than that in the daytime, indicating differences between diurnal and nocturnal hydraulic function, and incomplete stomatal closure at night. In addition, it was found that the temporal response of the Granier sensor is fast enough to resolve the transient behaviour of water flux in plant tissue.

Original languageEnglish
Pages (from-to)249-255
Number of pages7
JournalJournal of Experimental Botany
Volume60
Issue number1
DOIs
StatePublished - Jan 2009

Keywords

  • Nocturnal transpiration
  • Sap flow
  • Transient response
  • Wind speed

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