【摘要】 修正了 Frontier和 Ricotta等关于有效物种丰富度指数 A与物种丰富度指数 S之间幂律关系的定义 ,探讨了 A与 S之间分形关系的生态学意义 ,认为分形维数 D是群落均匀度测度值在物种数 S不断增加的过程中 ,向其逼近的一个理论值 ;提出了利用双对数坐标上建立的 A与 S拟合直线的方程 ,对群落均匀度的 4种变化趋势进行描述的方法。以广东黑石顶自然保护区森林演替系列为例 ,研究了针阔叶混交林和常绿阔叶林样带上 ,随着样带观察长度的逐渐增加群落均匀度的变化情况。结果表明 ,2 30 m长的混交林样带只存在一个线性无标度区间 ,群落均匀度随样带长度的不断增加而逐渐降低 ,向分形维数 D=0 .81 0趋近。 1 70 m长的常绿阔叶林样带存在两个线性无标度区间 ,在 0～ 2 5 m的尺度域内 ,随着样带长度的逐渐增加均匀度不断降低 ,向分形维数 D=0 .5 2 5逼近 ;在 30～ 1 70 m的尺度域内 ,随着样带观察长度的增加 ,群落均匀度也逐渐增加 ,向分形维数 D=0 .92 0趋近更多还原

【Abstract】 Hill defined the effective species richness A=2 H , i.e., the theoretical (diversity equivalent) number of species if all species were equifrequent, where H is the Shannon’s entropy. Frontier suggested that the effective species richness A can generally be expressed as A=S J , where S is the species richness and J is the Pielou’s evenness. The equation A=S J takes the form of a fractal power law relationship, in this way J is thus interpreted as a scale invariant dimension of the distribution of individuals among species in a given community. In the view of Ricotta et al ., it can be interpreted as a scale invariant measure of the relationship between species richness and entropy for a set of q relevés. In fact, the equation A=S J is the form of a deterministic functional relationship, in other words, the value of J varies with the change of S . We believed that the fractal power law relationship between A and S must be presented by the equation A= kS D , where k is a constant, and D is called the fractal dimension. Based on the fractal power law relationship of the equation A= kS D , the relationship between ‘effective species richness’ ( A ) and ’species richness’ ( S ) is discussed in this paper. With the increasement of S , the measuring values of community evenness J are approaching gradually from two sides to the theoretical value D , the fractal dimension, i.e., the slope of the regression of H =log 2 A versus log 2 S. A method for characterizing the changing tendency of community evenness in four cases is also proposed based on this. We describe these applications with the survey data from two transects with various succession series community at Heishiding nature reserve in Guangdong Province. The community evenness on different spatial scales in needle and broad leaves mixed forest and broad leaved evergreen forest are measured. There is a linear scale invariant range in the needle and broad leaves mixed forest transect with the length of 230m. The community evenness decreases gradually with the increasing of the transect length, and approaching to the fractal dimension of D =0.810. In the broad leaved forest transect with the length of 170m, there are two linear scale invariant ranges: the first appears in the range 0～25m, its fractal dimension D is 0.525, its community evenness decreases with the increasing of the transect length; the second appears in the range 30～170m, its fractal dimension D is 0.920, the community evenness increases with the enlargement of transect length.更多还原