Responses of root growth of Alhagi sparsifolia Shap. (Fabaceae) to different simulated groundwater depths in the southern fringe of the Taklimakan Desert,China |
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Authors: | FanJiang ZENG Cong SONG HaiFeng GUO Bo LIU WeiCheng LUO DongWei GUI Stefan ARNDT DaLi GUO State |
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Institution: | Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences , Urumqi 830011, China; 2 Cele National Station of Observation and Research for Desert-Grassland Ecosystem, Cele 848300, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China; 4 School of Forest and Ecosystem Science, University of Melbourne, Victoria 3363, Australia; 5 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China |
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Abstract: | Alhagi sparsifolia Shap. (Fabaceae) is a spiny, perennial herb. The species grows in the salinized, arid regions in North China. This study investigated the response characteristics of the root growth and the distribution of one-year-old A. sparsifolia seedlings to different groundwater depths in controlled plots. The ecological adaptability of the root systems of A. sparsifolia seedlings was examined using the artificial digging method. Results showed that: (1) A. sparsifolia seedlings adapted to an increase in groundwater depth mainly through increasing the penetration depth and growth rate of vertical roots. The vertical roots grew rapidly when soil moisture content reached 3%–9%, but slowly when soil moisture content was 13%–20%. The vertical roots stopped growing when soil moisture content reached 30% (the critical soil moisture point). (2) The morphological plasticity of roots is an important strategy used by A. sparsifolia seedlings to obtain water and adapt to dry soil conditions. When the groundwater table was shallow, horizontal roots quickly expanded and tillering increased in order to compete for light resources, whereas when the groundwater table was deeper, vertical roots developed quickly to exploit space in the deeper soil layers. (3) The decrease in groundwater depth was probably responsible for the root distribution in the shallow soil layers. Root biomass and surface area both decreased with soil depth. One strategy of A. sparsifolia seedlings in dealing with the increase in groundwater depth is to increase root biomass in the deep soil layers. The relationship between the root growth/distribution of A. sparsifolia and the depth of groundwater table can be used as guidance for harvesting A. sparsifolia biomass and managing water resources for forage grasses. It is also of ecological significance as it reveals how desert plants adapt to arid environments. |
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Keywords: | Alhagi sparsifolia Shap simulated groundwater depth root system growth and distribution ecological adaptability root morphological plasticity |
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