TROPICAL GEOGRAPHY ›› 2015, Vol. 35 ›› Issue (3): 416-421.

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Water Sources of Typical Plants in Different Rocky Desertification Grades in Guangxi

DENG Yan1,2,JIANG Zhongcheng2,LI Yanqing1,2,HU Yang2   

  1. (1.China University of Geosciences (Wuhan),Wuhan 430074,China;2.Institute of Karst Geology,CAGS// Key Laboratory of Karst Ecosystem and Rocky Desertification Treatment,Guilin 541004,China)
  • Online:2015-06-05 Published:2015-06-05

Abstract:

Using the stable isotope technique and water potentials, we research the water sources of typical plants in Guangxi and their respond to rocky desertification in three different rocky desertification grades. Results show that: Plant water potential and carbon isotope reduce with the increase of rocky desertification. No significant difference is found between the two dominant species both in water potential and carbon isotope in different rocky desertification areas. In slight and moderate rocky desertification area, an average of >70% of water for the two species comes from soil water, where soil is scattered only in rock fractures and is underlain by rigid carbonate rock. In intense rocky desertification area, V. negundo mainly uses rainwater which stored in fissures, and A. trewioides relies on a mixture of soil water and rainwater, which account for 57.6% and 42.4% of the total, respectively. These two deciduous shrub species use more previous rainwater (>40%) and little recent rainwater in intense rocky desertification area. Soil water is the important water sources for plant growth in rocky desertification area. Water quantity that plant uptake from shollow fractured rock zone is increased gradually in intense rocky desertification area. Plants have the same water use strategy against rocky desertification, such as low water potential and photosynthetic rate, high water use efficiency, and change of water sources.

Key words: rocky desertification, water use strategy, water sources, stable isotope, karst, dominant shrub