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Chinese Journal of Applied Ecology ›› 2018, Vol. 29 ›› Issue (4): 1117-1124.doi: 10.13287/j.1001-9332.201804.021

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Responses of sap flow to natural rainfall and continuous drought of tree species growing on bedrock outcrops

ZHANG Hui-ling1,2,3, DING Ya-li1,2,3, CHEN Hong-song1,2, WANG Ke-lin1,2, NIE Yun-peng1,2*   

  1. 1Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China;
    2 Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, Guangxi, China;
    3University of Chinese Academy of Sciences, Beijing 100049, China;
  • Received:2017-05-18 Online:2018-04-18 Published:2018-04-18
  • Contact: * E-mail: nyp@isa.ac.cn
  • Supported by:

    This work was supported by the National Key Research and Development Program of China (2016YFC0502402), the National Natural Science Foundation of China (31570428) and the Young Scholars of Western China (for Yunpeng Nie).

Abstract: This study focused on bedrock outcrops, a very common habitat in karst region of southwest China. To reveal the responses of plant transpiration to natural rainfall and continuous drought, two tree species typical to this habitat, Radermachera sinica and Triadica rotundifolia, were selected as test materials. A rainout shelter was used to simulate continuous drought. The sap flow dynamics were monitored using the method of Granier’s thermal dissipation probe (TDP). Our results showed that sap flow density increased to different degrees after rain in different stages of the growing season. Sap flow density of the deciduous species T. rotundifolia was always higher than that of the semi-deciduous species R. sinica. After two months without rainfall input, both species exhibited no obvious decrease in sap flow density, indicating that rainfall was not the dominant source for their water uptake, at least in the short-term. Based on the regression relationships between sap flow density and meteorological factors before and after rainfall, as well as at different stages of continuous drought, we found that the dynamics of meteorological factors contributed little to plant transpiration. The basic transpiration characteristics of both species were not changed in the circumstance of natural rainfall and short-term continuous drought, which would be closely related to the special water storage environments of bedrock outcrops and the reliance on deep water sources by tree species.