Journal of Resources and Ecology ›› 2012, Vol. 3 ›› Issue (4): 308-315.DOI: 10.5814/j.issn.1674-764x.2012.04.003

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Isotopic Model Estimate of Relative Contribution of Potential Water Pools to Water Uptake of Pinus sylvestris var. mongolica in Horqin Sandy Land

WEI Yafen1,2, FANG Jie1,2, ZHAO Xueyong3, YI Mei4, ZHANG Ruijun4, LI Shenggong1   

  1. 1 Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2 University of Chinese Academy of Sciences, Beijing 100094, China;
    3 Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou 730000, China;
    4 Chifeng Academy of Forestry, Chifeng 024000, China
  • Received:2012-11-24 Revised:2012-12-07 Online:2012-12-30 Published:2012-12-29
  • Supported by:

    the National Science Foundation of China (30770339).

Abstract: We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model (IsoSource) to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine (Pinus sylvestris var. mongolica) plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil (up to 80 cm in this study). Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.

Key words: isotope model, Mongolian pine plantation, stable isotope composition, tree water uptake sources