Body size and abundance relationship: an index of diversity for herbivores

It is evident to any biologist that small-bodied species within a given hig her taxon (order, class, phylum, etc.) tend to be represented by more indiv iduals. Hence small-bodied species are generally more abundant than large-b odied species. We analyzed large herbivore species data collected in Kenyan rangelands. An index of biological diversity derived from the negative rel ation between animal species body size and its local abundance is proposed. We compared the new index with species abundances at landscape scale (10 x 10 km) in individual districts, as well as in the combined regional data. The results show a consistently strong positive relation between the new di versity index and species abundances. The proposed diversity index has the advantage of incorporating information on species abundances without the ne ed for time-consuming surveys.