水深环境梯度下柽柳种群分布格局的分形分析

Fractal Analysis on the Distribution Patterns of Tamarix Chinensis Under Environmental Gradients of Different Water Table Depth

利用计盒维数和信息维数两种分形方法分析了黄河三角洲湿地柽柳种群的空间分布特征及其随水深梯度的变化。结果表明,不同水深梯度下柽柳种群分布格局的计盒维数均较大,随着水深的增大而逐渐减小,但变化幅度较小,反映了不同水深梯度下柽柳种群对水平空间的占据程度较大;信息维数总体上随水深的增大而减小,在水深低于-1.55 m范围内,信息维数较大,柽柳种群的微观结构较为复杂,格局强度较高,水深高于-1.55 m时,信息维数较小,柽柳种群的微观结构较为简单,格局强度较弱。水深-1.55 m可能是黄河三角洲湿地柽柳种群分布格局的一个阈值。

The distribution patterns of Tarnarix chinensis population under the environmental gradient of dif- ferent water table depth were analyzed using two fractal analysis methods-box dimension and information dimension. The box dimension changed little with different water table depths and kept a high dimension, which means that Tamarix chinensis population may keep a high spatial possessive degree for different water table depth. However, the information dimension in general decreased with the decline of water table depth. When water table depth was below --1.55 m, the information dimension was large, indicating that in this section of water table depth gradient, the micro-structure of Tarnarix chinensis population was much com- plex and the pattern intensity was high. When water table depth was above --1.55 m, the information di- mension was generally very small, indicating that the micro-structure of Tamarix chinensis population was very simple and the pattern intensity was low. The water table depth of --1.55 m may be a threshold of the distribution patterns of Tamarix chinensis in wetlands of the Yellow River Delta.