Area-based counts, distance methods, and mark–recapture studies are the three general categories of methods for estimating abundance.
Community structure in turn provides the quantitative basis needed to create hypotheses and experiments that help to increase understanding of how communities work.
In community B, the number of individuals are evenly divided among the four species, (25% each).
The Shannon index is the most commonly used way to quantitatively determine species diversity, H, as modeled by the following equation:
The Shannon index factors in both species evenness and species richness, as represented by the variables pi and s, respectively.