Measures of Richness, Evenness and Diversity in Tropical Rainforest

The number of species represented in vegetation (its richness) and the way in which individuals are distributed amongst the species (its evenness) are often combined into a single index to represent both these characteristics (its diversity). Many different indices to represent richness, evenness and diversity have been proposed from time to time. The present work examines empirically the suitability, for ecological studies, of a number of these measures using data from tree species of tropical rainforest of north Queensland and Barro Colorado Island, Panama. It is found that all of the richness and most of the evenness measures considered contain similar information about richness and evenness respectively. Of the commonly used diversity measures, Simpson's index seems to be inappropriate for use with tropical rainforest since it was found to represent only evenness and to contain little information about richness. The Shannon-Weaver diversity index was found to contain information about both richness and evenness and appeared to be the most appropriate diversity measure for use with this forest type.