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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (5): 1518-1524.doi: 10.13287/j.1001-9332.202005.001

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Adaptability of Granier empirical formula in sap flow measurement of Populus tomentosa based on whole tree weighing method

MA Yu-jie1, WU Peng-fei1, WANG Xiao1, ZHANG Jin-song2, YIN Chang-jun2, MA Chang-ming1*   

  1. 1College of Forestry, Hebei Agricultural University, Baoding 071000, Hebei, China;
    2Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
  • Received:2019-12-03 Online:2020-05-15 Published:2020-05-15
  • Contact: * E-mail: machangming@126.com
  • Supported by:
    This work was supported by the National Key R&D Program of China (2016YFC0500101).

Abstract: We evaluated the adaptability of Granier’s empirical formula in the measurement of trunk sap flow in Populus tomentosa. The thermal diffusion probe method (TDP) was used to mea-sure sap flow rate, and the whole tree weighing was simultaneously measured for each tree. We compared results from the Granier empirical formula with that from the whole tree weighing to find out whether Granier formula had any error in measuring the trunk sap flow of P. tomentosa. The transpiration rate by the whole tree weighing method and the temperature difference coefficient K by the thermal diffusion method were fitted with power exponential regression to establish a corrected Granier formula. Compared with the transpiration rate measured by the whole tree weighing method, sap flow rate calculated by the Granier empirical formula was underestimated by 67.7%. Therefore, a calibrated Granier correction formula of P. tomentosa was established: Fd=0.0135K0.6952(R2=0.77). The calculated result from this calibrated formula was only 3.4% lower than the transpiration rate estimated with the whole tree weighing method, which showed good consistency. Thus, the calculation of the P. tomentosa sap flow rate should be corrected when using the Granier empirical formula.

Key words: Populus tomentosa, Granier empirical formula, thermal dissipation probe (TDP), sap flow