Chin J Plant Ecol ›› 2017, Vol. 41 ›› Issue (5): 519-528.DOI: 10.17521/cjpe.2016.0381

Special Issue: 稳定同位素生态学

• Research Articles • Previous Articles     Next Articles

Water sources of Populus euphratica and Tamarix ramosissima in Ejina Delta, the lower reaches of the Heihe River, China

Ya-Fei LI1,2,3,4, Jing-Jie YU1,5,*, Kai LU1,4, Ping WANG1, Yi-Chi ZHANG1, Chao-Yang DU1   

  1. 1Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;

    2University of Chinese Academy of Sciences, Beijing 100049, China

    3Sino-Danish Center for Education andResearch, Beijing 100190, China
    4 Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100190, China

    5College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
  • Online:2017-05-10 Published:2017-06-22
  • Contact: Jing-Jie YU
  • About author:KANG Jing-yao(1991-), E-mail: kangjingyao_nj@163.com

Abstract:

Aims We aim to evaluate the water sources of typical riparian arbor species (Populus euphratica) and shrub species (Tamarix ramosissima), and analyze the spatial and temporal dynamics of plant water source in Ejina Delta, the lower reaches of the Heihe River, China.Methods Eight sampling sites were selected in the riparian zones along the East River and West River in Ejina. The plant xylem water, soil moisture, rainwater, stream water and groundwater were taken and pretreated during the growing season in 2015-2016, and the stable oxygen isotope ratio (δ18O) for each water sample was measured. The δ18O of plant xylem water and soil moisture were compared to estimate the dominant depth of root water uptake, and the linear-mixed model called “IsoSource” were applied to determine plant water sources and quantify their proportions.Important findings This study indicated that the main recharge sources for P. euphratica and T. ramosissima were stream water and groundwater. The contributions of rain water to them was negligible due to the limited amount and the shallow infiltration depth of local rainfall. As affected by groundwater level fluctuation, soil physical properties, as well as lateral and vertical recharge of stream water on soil moisture, the dominant depth of root water uptake spatially varied. However, the relative contributions of stream water or groundwater to plant water sources did not change significantly across space. Populus euphratica used more stream water (68%), while T. ramosissima used more groundwater (65%). Plant water sources were sensitive to environmental flow controls. The contributions of stream water to the water sources of the two species went up to 84% and 48% for P. euphratica and T. ramosissima respectively during the discharge period, but dropped to 63% and 30% during the non-discharge period. On the other hand, the contributions of groundwater decreased to 16% and 52% during the discharge period, but increased to 37% and 70% during non-discharge period. It is noteworthy that the high similarity of δ18O between stream water and groundwater due to extensive water exchange in the riparian zone made increase the uncertain in quantifying plant water sources.

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Key words: arid region, riparian zone, plant water source, stable oxygen isotope, environmental flow controls