Which combination indicates lower species diversity?

To understand why the combination of high richness and low evenness indicates lower species diversity, it’s important to clarify the concepts of richness and evenness in the context of ecology.

Richness refers to the number of different species present in a given area, while evenness refers to how similarly abundant the various species are within that area. High richness means that there are many different species present, which is a positive aspect of diversity. However, if evenness is low, it suggests that a few species are dominating the community, meaning that while there are many species (high richness), they are not evenly distributed.

In this scenario, the community may have a high number of species, but if they are not represented evenly, it undermines the overall diversity because ecological function and resilience depend on not just the presence of various species but also on their relative abundances. A community dominated by a few species may not respond as well to disturbances, have lower functional redundancy, and exhibit reduced ecological resilience.

In contrast, combinations with low richness and low evenness or high evenness with no specification of richness would typically suggest poorer overall diversity. High richness and high evenness would indicate a more robust ecosystem as both the number of species and their population sizes are balanced