Shannon-Wiener多样性指数两种计算方法的比较研究

Comparative study on two computing methods for estimating Shannon-Wiener diversity index

在应用群落多样性指数评价调查海域群落物种多样性或进行海域生态环境评价时,常用基于样方数据(方法 1)或基于区域混合样数据(方法 2)2种方法计算Shannon-Wiener多样性指数。为了比较哪种方法所得结果能更好地反映调查海域群落多样性状况,并且分析多样性指数与样本含量的关系,本实验根据2009年胶州湾潮滩湿地大型底栖动物季度调查数据,应用再抽样模拟方法对2种多样性指数计算方法进行了比较研究。结果表明,对于相同样本含量,基于样方数据计算的Shannon-Wiener多样性指数值小于基于区域混合样数据计算的结果。方法 1所计算的群落多样性指数与样本含量无关;而方法 2计算的多样性指数值随样本含量的增加而增加,并在样本含量为20时接近"真值"并趋于稳定,其相对估计误差(REE)和相对偏差(RB)较小,表明样本含量影响方法 2的多样性指数的计算。在评价调查海域群落物种多样性或进行海域生态环境评价时,应该使用基于区域混合样数据的计算方法,并保证足够的样本含量,才能客观地反映海域群落生物多样性现状。

Shannon-Wiener diversity index is commonly used in measuring the community species diversity or assessing the ecological status of marine environments. There are two methods to compute the Shannon Wiener diversity index in the surveyed region,which is calculated based on each sample data（ M ethod 1） or based on the pooled data of the survey region（ M ethod 2）. In order to find out which method is better to reflect the species diversity of the survey region,as well as to examine the relationship between the ShannonWiener diversity index and the sample size,a comparative study of these two methods was carried out using simulation study based on the data from the macrozoobenthos survey in tidal flat wetland of northwestern Jiaozhou Bay in 2009. The results showed that the Shannon-Wiener diversity index calculated by M ethod 1was lower than that from M ethod 2. The estimated Shannon-Wiener diversity index calculated by M ethod 1was independent of sample size,and the Shannon-Wiener diversity index by M ethod 2 became greater with the sample size increasing,and then kept stable approaching the ＂true value＂at the sample size of 20. Both the relative estimation error（ REE） and the relative bias（ RB） of the diversity index estimation from M ethod 2 were getting smaller when the sample size was greater than 20,which indicated that the sample size affected the calculating results of M ethod 2. M ethod 2 with enough or optimal sample size would be used in estimating the species diversity or in evaluating the ecological quality of the entire survey area,which would objectively reflect the status of species diversity in the survey area.