E. 11: Species Diversity

Species Diversity

Reflects the stability, aesthetics, and health of ecosystems.

Species Richness

The number of species present in a community.

Species Evenness

The relative abundance of species within a community

Shannon-Wiener Index (H')

❖A widely used diversity index that combines

richness and evenness.

❖Higher index values indicate greater

diversity.

H' = - Σ(pi * ln pi) where pi is the proportion of the i-th species.

Shannon-Wiener Index (H') Formula

Species Evenness (J')

❖Derived from the Shannon-Wiener index.

❖Ranges from 0 to 1, with higher values

indicating a more even distribution of

species.

J' = H' / Hmax' where Hmax'= ln(s) and s is the number of species.

Species Evenness (J') Formula

Simpson's Index (D)

❖Another diversity index that weighs

dominant species more heavily than rare

species.

❖Ranges from 0 to ∞.

D = 1 / Σ(pi2) where pi2 is the squared proportion of the i-th species.

Simpson's Index (D) Formula

Insects

Often used to reflect overall community diversity due to their high inherent diversity.

Rank Abundance Curve

A graph where species rank is plotted against their abundance.

Shannon-weiner (H’)

Species Evenness (J’)

Simpson’s (J’)

Enumerate indices: