Pielou's Evenness (J') Calculator
Calculate species evenness using Pielou's index (J'), which measures how evenly individuals are distributed among species in a community. Essential for biodiversity and ecological assessment.
Pielou's Evenness (J')
intermediateCalculate species evenness from Shannon diversity
Formula
J' = H'/ln(S)
How It Works
Pielou's evenness index (J') measures how equally abundant species are in a community. It ranges from 0 (complete dominance by one species) to 1 (all species equally abundant).
First calculate Shannon diversity: H' = −Σ pᵢ × ln(pᵢ)
Then: J' = H' / ln(S), where S = number of species
Example
A community with species counts: 20, 15, 10, 5, 2
Total = 52, S = 5 species
H' = 1.3677
J' = 1.3677 / ln(5) = 1.3677 / 1.6094 = 0.8498
J' = 0.85 indicates relatively even distribution, though skewed towards the first two species.
Frequently Asked Questions
What is the difference between richness and evenness?
Species richness (S) is the count of different species. Evenness (J') measures how evenly individuals are distributed among those species. A community can have high richness but low evenness (one species dominates).
What does J' = 0 mean?
J' = 0 indicates complete dominance by a single species (all individuals belong to one species). J' = 1 means all species have identical abundances (perfect evenness).