Lesson 12 - Alaska Geobotany Center

Species diversityThere are two meanings of diversity in the literature:(1) (The most common application of the term.) The total number ofspecies in a community, more accurately called richness.(2) (Probably the more accurate way to use the term.) A measure thatcombines richness with relative abundance or evenness:– Richness: the number of species per unit area.– Evenness: the distribution of individuals among the species. This ismaximized when all the species have the same number of individuals.– Diversity: A combination of richness and evenness, i.e. richnessweighted by evenness.If community A has 5 species with uneven numbers of individuals,and community B has 4 species with equal numbers ofindividuals, A will have higher species richness, but B may have ahigher diversity.