Why is using an index of diversity more informative than simply counting species richness?

Using an index of diversity provides a more comprehensive understanding of biodiversity because it considers the abundance of each species within an ecosystem. While species richness—the simple count of different species—gives a snapshot of diversity, it does not convey information about how many individuals of each species are present. An index of diversity takes into account both the number of species and their relative abundance, allowing for a clearer picture of the ecosystem's health and stability.

For example, in a community with high species richness but uneven distribution (where a few species are very common while others are rare), the diversity index would reflect this imbalance, indicating lower overall diversity than what species richness alone would suggest. This richer data enables better conservation decisions and ecological assessments, making it a vital tool in understanding the complexities of ecosystems.