Species diversity refers to species richness and how evenly species’ abundance is distributed.
Species diversity refers to species richness and how evenly species’ abundance is distributed. Species richness refers to the number of species in an area. Species abundance refers to the number of individuals per species.
For example in the image below we can see that these two communities are composed of the same species but they differ in regards to species abundance:
A community with twenty different species has greater species richness than a community with only six species. A community with ten species but the majority of individuals in that community are of one specific species does not have an even distribution of species abundance. A community with ten different species and each species has the same number of individuals has a more equal spread of species abundance.
To conclude the number of species factors into species diversity but also the number of individuals in each species is also considered.
Read about other measures of diversity .