Ricotta Carlo
Department of Environmental Biology University of Rome 'La Sapienza' Rome Italy.
Ecol Evol. 2017 May 26;7(13):4835-4843. doi: 10.1002/ece3.2980. eCollection 2017 Jul.
The amount of variation in species composition among sampling units or beta diversity has become a primary tool for connecting the spatial structure of species assemblages to ecological processes. Many different measures of beta diversity have been developed. Among them, the total variance in the community composition matrix has been proposed as a single-number estimate of beta diversity. In this study, I first show that this measure summarizes the compositional variation among sampling units after nonlinear transformation of species abundances. Therefore, it is not always adequate for estimating beta diversity. Next, I propose an alternative approach for calculating beta diversity in which variance is substituted by a weighted measure of concentration (i.e., an inverse measure of evenness). The relationship between this new measure of beta diversity and so-called multiple-site dissimilarity measures is also discussed.
采样单元间物种组成的变化量即β多样性，已成为将物种组合的空间结构与生态过程相联系的主要工具。人们已开发出许多不同的β多样性测度方法。其中，群落组成矩阵的总方差已被提议作为β多样性的单一数值估计。在本研究中，我首先表明，该测度在对物种丰度进行非线性变换后，总结了采样单元间的组成变化。因此，它并非总是足以估计β多样性。接下来，我提出一种计算β多样性的替代方法，其中方差被浓度的加权测度（即均匀度的倒数测度）所取代。还讨论了这种新的β多样性测度与所谓的多地点差异测度之间的关系。
