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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (10): 3376-3384.doi: 10.13287/j.1001-9332.202010.015

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Responses of transpiration to variation in evaporative demands and soil water in a larch plantation at the south side of Liupan Mountains, China

CAO Gong-xiang1,2, WANG Yun-ni1,2, GUO Zhong1*, JI Meng1, WANG Yan-hui2, XU Li-hong2   

  1. 1Inner Mongolia Academy of Forestry, Hohhot 010010, China;
    2Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
  • Received:2020-06-30 Accepted:2020-08-02 Online:2020-10-15 Published:2021-04-15
  • Contact: * E-mail: nmglkynmg@163.com
  • Supported by:
    Natural Key R&D Program of China (2017YFC0506604) and the National Natural Science Foundation of China (41471029).

Abstract: Quantifying the response of tree transpiration (T) to the variation of soil water supply capability and atmospheric evaporative demand is beneficial for a better prediction of water use and hydrological cycles in forests and deepen the understanding of the relationship between forest and water. Larix principis-rupprechtii in the Xiangshuihe watershed at the south side of Liupan Mountains was used as the research object. We simultaneously monitored sap flow density by thermal diffusion probe and the environmental factors. The response of the T to the soil volumetric water content (VWC) and potential evapotranspiration (PET) was analyzed. The results showed the response curve of T to VWC was quite similar under any different PET levels. With increasing VWC, T increased rapidly and then slowly, and began to be stable when VWC reached a threshold. This process could be well fitted by the saturated exponential function. However, the VWC threshold was different, and its value increased with rising PET. The relationship of daily T to PET was a quadra-tic equation, and PET also had a threshold effect. A stand transpiration model considering the effect of soil water supply capacity and atmospheric evaporative potential was founded which coupled the response relationship of T to PET and VWC in the rapid growth season. This model could well estimate the diurnal variation of transpiration, and provide guidance for the management of plantation water control.

Key words: forest transpiration, sap flow, soil water content, potential evapotranspiration