Use this biodiversity measure when counts or incidences were collected with comparable sampling effort and the estimator matches the study design. It can summarize richness, dominance, evenness, or compositional difference.

Community A species 1 abundance

A finite measured or assumed value greater than or equal to 0, expressed in individuals.

Community A species 2 abundance

A finite measured or assumed value greater than or equal to 0, expressed in individuals.

Community B species 1 abundance

A finite measured or assumed value greater than or equal to 0, expressed in individuals.

Community B species 2 abundance

A finite measured or assumed value greater than or equal to 0, expressed in individuals.

The implementation follows this calculation rule: Quantify compositional dissimilarity between two communities over two species with the Bray-Curtis index.^[1]

Bray-Curtis dissimilarity

The calculated bray-curtis dissimilarity.

Different diversity indices weight rare and common taxa differently. Detection probability, sample coverage, taxonomic resolution, zero counts, and unequal effort can dominate comparisons; proxy estimators are not interchangeable with their full published forms. Preserve the input values and units so the result can be audited and recalculated.

Report observed richness, abundance or incidence data, and sampling effort beside the index. Coverage-based rarefaction, accumulation curves, and more than one Hill-number order provide a fuller view of community structure.

• Brillouin Index

  Compute the Brillouin diversity index HB = (ln(N!) - sum(ln(ni!))) / N from three species counts using loop-based log factorials for communities up to 10000 individuals.

• Shannon Evenness

  Compute Shannon evenness E = H / ln(S) from the Shannon natural-log diversity index and species count, requiring at least two species.

• Whittaker Beta Pairwise

  Compute pairwise Whittaker beta diversity between two sites as the mean site species richness divided by the number of shared species.