Sampling Designs for Monitoring Ecological Diversity

The analysis of ecological diversity on a given study region constitutes a key topic in environmental studies. The quantitative aspects of ecological diversity are usually detected by means of the diversity indexes, which are ad hoc functions of the species abundance. Obviously, species abundance is unknown in practice. Hence, in order to obtain inference on diversity indexes, species abundance must be estimated by using a suitable sampling method for natural populations. The present chapter is devoted to species abundance estimation when the design-based approach is considered. Since the design-based approach avoids any assumption on the underlying population, it seems the appropriate setting when dealing with ecological populations which are usually difficult to model. More specifically, this work focuses on two large classes of sampling designs for species abundance inference, i.e., unit and area sampling respectively.