Regular Article

Plant and Soil

, Volume 341, Issue 1, pp 399-412

Seasonal water use patterns of woody species growing on the continuous dolostone outcrops and nearby thin soils in subtropical China

  • Yun-peng NieAffiliated withKey Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of SciencesHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of SciencesGraduate School of Chinese Academy of Sciences
  • , Hong-song ChenAffiliated withKey Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of SciencesHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of Sciences Email author 
  • , Ke-lin WangAffiliated withKey Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of SciencesHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of Sciences
  • , Wei TanAffiliated withKey Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of SciencesHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of Sciences
  • , Peng-yan DengAffiliated withHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of Sciences
  • , Jing YangAffiliated withKey Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of SciencesHuanjiang Observation and Research Station for Karst Eco-systems, Chinese Academy of SciencesGraduate School of Chinese Academy of Sciences

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Abstract

In karst regions, forests often grow on bedrock outcrops, however the water sources used by the forest vegetation are not known. This study aimed at investigating whether there were seasonal shifts (dry/wet season) of water sources for plants growing on the continuous dolostone outcrops, and comparing their differences with those growing on nearby thin soils in karst areas of southwest China. Rainwater, soil water within 0–30 cm depths, spring water (as a reflection of local deep water sources) and plant xylem water were sampled in March (late dry season) and July (mid rainy season) 2009, respectively. A direct inference approach and the IsoSource mixing model were used to estimate the contributions of different sources to the plant xylem water. On the outcrops, the deciduous tree species Radermachera sinica mainly used deep water sources during the dry season and a mixture of rainwater and deep water sources during the wet season. By contrast, the deciduous small shrub Alchornea trewioides largely relied on recent rainwater during both dry and wet seasons. Three non-deciduous species (Sterculia euosma, Schefflera octophylla and Ficus orthoneura) appear to rely on deep water sources during the wet seasons. In nearby thin soils, R. sinica mainly utilized deep water in the dry season and a mixture of soil water and deep water in the wet season. A. trewioides relied on the same water sources (rainwater-derived soil water) in the different seasons. The above results indicate that inter-specific differences in rooting patterns and leaf phenologies may lead to the differences in the sources of water used by coexisting plant species in karst regions.

Keywords

Continuous dolostone outcrops Spring water Water use patterns Stable isotopes IsoSource Southwest China