Question

Long Answer: Briefly define and describe the terms “species richness” and species “evenness.” When, how, or why are they important?

Answer 1

Species richness: "Species richness" is the number of different species represented in an ecological community, landscape or region. "Species richness" is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions. "Species richness" is sometimes considered synonymous with species diversity.

• "Species richness" is often used as a criterion when assessing the relative conservation values of habitats or landscapes. However, "species richness" is blind to the identity of the species. An area with many endemic or rare species is generally considered to have higher conservation value than another area where "species richness" is similar, but all the species are common and widespread.

Species evenness: "Species evenness" is a measure of the relative abundance of the different species making up the richness of an area.

• "Species evenness" is the proportion of species or functional groups present on a site. The more equal species are in proportion to each other, the greater the "Species evenness" of the site. A site with low "species evenness" indicates that a few species dominate the site. If a community has a large disparity between the number of individuals within each species, it has low evenness. If the number of individuals within a species is fairly constant throughout the community it has high evenness. "Species evenness" compares the similarity of the population size of each species present.