PiscesLogoSmallerStill Essential steps for the analysis of diversity

Top  Previous  Next


In the light of present knowledge the following may be taken as a guide to the analysis of diversity data for a single locality.


(1) Plot graph(s) of log abundance on rank.

It has always been important to examine the form of your data and is easily done on a computer. Do the data form a straight line? Which are the species that depart most from it? Is there anything unusual in their biology (e.g. they could be vagrants)? The consideration of these graphs should indicate whether, exceptionally (Taylor et al., 1976), other models or indices should be used in addition to those outlined below. These graphs may be an excellent means of presenting the data for publication.


(2) Plot the species accumulation curve(s) and calculate total species richness, SMAX.

The species accumulation curve gives insight into the sufficiency of the sampling effort. As there is no best method to calculate SMAX it is recommended that most of the methods given under Species Richness Estimators are explored.


(3) Determine alpha of the log series.


(4) Calculate the Berger- Parker dominance index


(5) Calculate other parameters or statistics. This will be done where the graphs (1 above) reveal a special need.


(6) If sites are to be compared, undertake diversity ordering to ensure that they can be compared using a diversity index.


(7) Jackknife or bootstrap estimates as appropriate and run randomisation tests to compare indices.