Species richness estimators: how many species can dance on the head of a pin?
R. B. O’Hara, Department of Mathematics and Statistics, PO Box 68 (Gustaf Hällströmin katu 2b), FIN-00014 University of Helsinki, Finland. Tel: +358 9 191 23743; mobile: +358 50 5990540; fax: +358 9 191 22 779; e-mail: email@example.com
- 1Several species richness estimators (two non-parametric, four based on rarefaction curves and two from fitting of abundance distributions) were compared by examining their performance in estimating the species richness for two moth data sets from the United Kingdom. Comparisons were also made using data simulated from the fitted abundance distributions.
- 2The different species richness estimators gave different estimates. The non-parametric estimates and the rarefaction estimates were similar, but were smaller than the parametric estimates. When the simulated data were used, the only methods to give estimates near the true value was the parametric method using the distribution from which the data were simulated.
- 3At present it is impossible to decide whether any of the estimation methods will give a realistic estimate, as not enough is known about the true numbers of species in communities. Until this is rectified, the most that can be hoped for is to obtain upper and lower bounds on species richness.