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### 黄土丘陵区混交林中油松和沙棘树干液流对降雨脉冲的响应

1. 1 西北农林科技大学林学院, 陕西杨凌 712100
2 中国科学院教育部水土保持与生态环境研究中心, 陕西杨凌 712100
3 中国科学院水利部水土保持研究所, 陕西杨凌 712100
• 出版日期:2017-11-18 发布日期:2017-11-18
• 通讯作者: *mail:ymchen@ms.iswc.ac.cn
• 作者简介:卢森堡, 男, 1991年生, 硕士研究生.主要从事植物生理生态与植被恢复生态研究.E-mail:senbaolu_91@163.com
• 基金资助:
本文由国家自然科学基金项目(41501576,41371506)、公益性行业(国家气象局)科研专项(重大专项)(GYHY2015060013)和中央高校基本科研业务费专项(2452016105)资助

### Sap flux density in response to rainfall pulses for Pinus tabuliformis and Hippophae rhamnoides from mixed plantation in hilly Loess Plateau

LU Sen-bao1, CHEN Yun-ming2,3*, TANG Ya-kun3, WU Xu2, WEN Jie1

1. 1 College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China
2 Research Center of Institute of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling 712100, Shaanxi, China
3 Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China
• Online:2017-11-18 Published:2017-11-18
• Contact: *mail:ymchen@ms.iswc.ac.cn
• Supported by:
This work was supported by the National Natural Science Foundation of China (41501576, 41371506), the China Special Fund for Meteorological Research in the Public Interest (Major Project) (GYHY2015060013) and the Fundamental Research Funds for the Central Universities (2452016105)

Abstract: Thermal dissipation probe (TDP) was used to continuously measure the sap flux density (Fd) of Pinus tabuliformis and Hippophae rhamnoides individuals in hilly Loess Plateau, from June to October 2015, and the environmental factors, i.e., photosynthetic active radiation (PAR), water vapor pressure deficit (VPD), and soil water content (SWC), were simultaneously monitored to clarify the difference of rainfall utilization between the two tree species in a mixed plantation. Using the methods of a Threshold-delay model, stepwise multiple regression analyses, and partial correlation analyses, this paper studied the process of Fd in these two species in response to the rainfall pulses and then determined the effects of environmental factors on Fd. The results showed that, with the increase of rainfall, the response percentages of Fd in both P. tabuliformis and H. rhamnoides increased at first but then decreased; specifically, in the range of 0-1 mm rainfall, the Fd of P. tabuliformis (-16.3%) and H. rhamnoides (-6.3%) clearly decreased; in the range of 1-5 mm rainfall, the Fd of P. tabuliformis decreased (-0.4%), whereas that of H. rhamnoides significantly increased (9.0%). The lower rainfall thresholds (RL) of Fd for P. tabuliformis and H. rhamnoides were 6.4 and 1.9 mm, respectively, with a corresponding time-lag (τ) of 1.96 and 1.67 days. In the pre-rainfall period, the peak time of Fd of P. tabuliformis converged upon 12:00-12:30 (70%), while the Fd of H. rhamnoides peaked twice, between 10:30 and 12:00 (48%) and again between 16:00 and 16:30 (30%). In the post-rainfall period, the peak time of Fd of P. tabuliformis converged upon 11:00-13:00 (40%), while that of H. rhamnoides peaked twice, between 12:00 and 13:00 (52%) and again between 16:30 and 17:00 (24%). Among the environmental factors, the rank order of factors associated with the Fd of both P. tabuliformis and H. rhamnoides was PAR>VPD, before rainfall. However, the rank order of factors influencing the Fd of P. tabuliformis was PAR>VPD>0-20 cm SWC (SWC0-20), whereas this order was different for H. rhamnoides: SWC0-20 >PAR >VPD, after rainfall. This mixed plantation of P. tabuliformis and H. rhamnoides trees had a high stability of water utilization.