Question

What does it mean if one community has a higher Shannon Index, but the other (with the lower Shannon INdex) has a higher evenness factor? What role does evenness (relative species abundance) play in determining which community has the highest biodiversity?

Answer 1

Shannon Index is a type of diversity index among other indices like Simpson index, Margalef diversity index, etc. These diversity indices are used to measure the diversity of organism of an area. If one community has a higher Shannon index then that has a lower diversity and vice-versa. The other community with lower Shannon index will have higher species diversity. That is it also has higher species evenness. Species with higher evenness will be par with the other higher species of the community in terms of their abundance. Overall we can say that higher species evenness with high species richness will contribute to higher biodiversity in an area. On the other hand, lower species evenness and species richness contribute to lower biodiversity. You may remember that evenness is calculated based on all species (equal/even distribution of species), whereas richness of a species solely depends on that specific species only, which is based on its interaction with their environment.