Using parametric models based on relative abundance

Given quantitative data, species abundance models describing the relative abundance of species within the community such as the log normal can be used to estimate the total species complement, Smax. If the data fit a log normal distribution then the number of unsampled species is given by the missing part of the distribution to the left of the veil-line. Alternative distributions which have been suggested include the Poisson-log normal (Bulmer, 1974) and the log series (Williams, 1964) amongst others. It is unlikely that parametric methods yield reliable estimates for Smax and they should probably be avoided. An estimate of total species richness can be obtained using the Truncated log normal option within Species Diversity and Richness.