Measuring biodiversity change – how useful are indices?

Biodiversity indices are widely used to measure diversity differences between areas or within the same area but through time. However, conclusions may be made about the study area based on the calculation of one value with confidence intervals or standard errors of the index rarely reported. The aim of this study it to assess the use of biodiversity indices in detecting diversity change with time using a bootstrap technique. The abundance of beetle species at 12 terrestrial sites in the UK Environmental Change Network (ECN) from 1993-2008 were used to calculate 4 biodiversity indices: Shannon-Weiner, Simpson’s, Berger-Parker and Pielou’s indices. 90% confidence intervals for each index per site per year were generated using a bootstrap technique. The size of the confidence interval for all indices varied across sites and time periods, however, the intervals did not always overlap. Preliminary results indicate that the biodiversity indices can be used to detect differences between habitat types and time periods. The effect of the sampling unit on the bootstrap technique will be investigated further