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Chinese Journal of Applied Ecology ›› 2016, Vol. 27 ›› Issue (3): 761-768.doi: 10.13287/j.1001-9332.201603.031

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Rainfall effects on the sap flow of Hedysarum scoparium

YANG Qiang1,2, ZHA Than-shan1,2, JIA Xin1,2*, QIN Shu-gao1,2, QIAN Duo1,2, GUO Xiao-nan1,2, CHEN Guo-peng3   

  1. 1School of Soil and Water Conservation, Beijing Forestry University, Yanchi Research Station, Beijing 100083, China;
    2Key Laboratory of Soil and Water Conservation of State Forestry Administration, Beijing Forestry University, Beijing 100083, China;
    3Institute of Forestry Sciences, Bailongjiang Forestry Management Bureau of Gansu Province, Lanzhou 730070, China
  • Received:2015-06-29 Online:2016-03-18 Published:2016-03-18
  • Contact: * E-mail: xinjia@bjfu.edu.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (31270755, 31200537,31361130340), National Basic Research Program of China (2013CB429901) and the Fundamental Research Funds for the Central Universities (2015ZCQ-SB-02).

Abstract: In arid and semi-arid areas, plant physiological responses to water availability depend largely on the intensity and frequency of rain events. Knowledge on the responses of xerophytic plants to rain events is important for predicting the structure and functioning of dryland ecosystems under changing climate. The sap flow of Hedysarum scoparium in the Mu Us Sand Land was continuously measured during the growing season of 2012 and 2013. The objectives were to quantify the dynamics of sap flow under different weather conditions, and to examine the responses of sap flow to rain events of different sizes. The results showed that the daily sap flow rates of H. scoparium were lower on rainy days than on clear days. On clear days, the sap flow of H. scoparium showed a midday plateau, and was positively correlated with solar radiation and relative humidity. On rainy days, the sap flow fluctuated at low levels, and was positively correlated with solar radiation and air temperature. Rain events not only affected the sap flow on rainy days through variations in climatic factors (e.g., solar radiation and air temperature), but also affected post-rainfall sap flow velocities though changes in soil moisture. Small rain events (<20 mm) did not change the sap flow, whereas large rain events (>20 mm) significantly increased the sap flow on days following rainfall. Rain-wetted soil conditions not only resulted in higher sap flow velocities, but also enhanced the sensitivity of sap flow to solar radiation, vapor pressure deficit and air temperature.