zonation

zonation
[zəʊˈneɪʃ(ə)n]
noun
  1. [mass noun]distribution in zones or regions of definite character
    成带;分带;分区,区划
    quartz grains can exhibit zonation and rounding.
    石英砂具有显示成带和变圆的特性。
    ■(Ecology)the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species
    (生态)(动,植物)种群成带现象;(动,植物)种群分布,分区
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