Characterisation of hydrogen isotope profiles in an agroforestry system : implications for tracing water sources of trees
Characterisation of hydrogen isotope profiles in an agroforestry system : implications for tracing water sources of trees
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DOI：
10.1016/s0378-3774(00)00105-0
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发表时间：
2000-08
影响因子：
6.7
通讯作者：
S. S. Burgess-S.;M. Adams;N. Turner;B. Ward
中科院分区：
文献类型：
--
作者：
S. S. Burgess-S.;M. Adams;N. Turner;B. Ward
追踪植物利用的水源对于了解间作/农林复合系统中的物种相互作用很重要，特别是在物种生命形式差异很大的情况下。同位素技术是追踪水源的一种越来越常见的手段。水的稳定同位素在土壤-植物-大气连续体中的分布表明了一系列水文过程和植物功能。在我们可以推断植物或其他生物对同位素分布的影响之前，我们需要对环境中的同位素分布进行彻底的描述，并了解决定这种分布的物理过程。除非在植物周围的同位素“景观”中可以辨认出不同的特征，否则植物的功能和环境之间就无法建立联系。为了追踪四种桉树在农林复合种植中的水分吸收情况，我们测试了一种简单的“终端成员”方法，以及一种更广泛的表征澳大利亚西南部农业土壤中氢和氚分布的方法。氢同位素在土壤中的分布高度均匀；这是气候因素、土壤物理性质和树根重新分配土壤水分的能力的明显结果。当试图量化植物对不同土壤来源的水的利用时，这些发现对测量策略和实验设计具有重要意义。在水源之间没有大的同位素区别的情况下，简单的“末端成员”模型可能具有误导性，同位素标记技术可能在某些环境中更合适。
Tracing sources of water utilised by plants is important to understand species interactions in intercropping/agroforestry systems, particularly where species vary greatly in life-form. Isotopic techniques are an increasingly common means to trace water sources. The distribution of stable isotopes of water within the soil–plant–atmosphere continuum is indicative of a range of hydrologic processes and plant functions. Before we can infer plant or other biological effects on the distribution of isotopes we require a thorough characterisation of the environmental isotope distribution as well as an understanding of the physical processes that determine this distribution. Unless distinct features are recognisable in the isotopic ‘landscape’ surrounding a plant, links cannot be made between plant function and environment. As a means to trace water acquisition by four Eucalyptus species in an agroforestry planting, we tested a simple ‘end member’ approach and a more extensive characterisation of hydrogen and deuterium distribution profiles within an agricultural soil in south-western Australia. Hydrogen isotope distribution within the soil was highly uniform; an apparent result of climatic factors, soil physical properties and the ability of tree roots to redistribute soil water. Such findings have important implications for measurement strategies and experimental design when attempting to quantify plant use of water from differing soil sources. In the absence of large isotopic discrimination among water sources, simple ‘end member’ models are likely to be misleading and isotopic labelling techniques may be more appropriate in some environments.