The use of replicated plot, line and point sampling for estimating speciesabundance and ecological diversity

The paper deals with the problem of estimating diversity indexes for an eco logical community. First the species abundances are unbiasedly and consiste ntly estimated using designs based on n random and independent selections o f plots, points or lines over the study area. The problem of sampling elusi ve populations is also considered. Finally, the diversity index estimates a re obtained as functions of the abundance estimates. The resulting estimato rs turn out to be asymptotically (n large) unbiased, even if a considerable bias may occur for a small n. Accordingly, the method of jackknifing is ma de use of in order to reduce bias.