GEOGRAPHY & CARTOGRAPHY CALCULATOR
Richnesssimpson Diversity Index
A precise tool.
What is the Richnesssimpson Diversity Index & How does it work?
The Simpson Diversity Index measures the likelihood that two individuals drawn at random from a region belong to different species. It captures both species richness (the number of distinct species) and evenness (how evenly individuals are distributed among those species), making it a robust indicator of biodiversity in geographic studies.
Mathematically, the index is expressed as the ratio of the sum of the products of each species’ count and one less than that count, to the product of the total number of individuals and one less than that total. This formulation penalises dominance by any single species and rewards a balanced community.
In practice, values of D range from 0 (no diversity, a single species dominates) to just under 1 (high diversity). Cartographers often transform the index into a “diversity of habitats” layer, helping visualise ecological richness across spatial extents.
D = frac{sum_{i=1}^{S} n_i (n_i – 1)}{N (N – 1)}
D = Simpson’s Diversity Index, n_i = count of species i, S = total number of species, N = sum_{i=1}^{S} n_i (total individuals)
Parameters
Result
—
Frequently Asked Questions
What is the Simpson Diversity Index?
The Simpson Diversity Index measures biodiversity by calculating the probability that two randomly selected individuals belong to different species.
How do I calculate the Simpson Diversity Index?
To calculate it, sum the products of each species' count and one less than that count, then divide by the product of the total number of individuals squared minus the total number of individuals.
Why is the Simpson Diversity Index important in geography?
It helps assess biodiversity by considering both the number of species (richness) and their even distribution among the population (evenness).
What does a higher Simpson Diversity Index indicate?
A higher index indicates greater diversity, meaning more species are present and they are evenly distributed.
Can the Simpson Diversity Index be used for any type of species?
Yes, it can be applied to various types of species in different geographic contexts.
How does the Simpson Diversity Index differ from other diversity indices?
Unlike some other indices that focus solely on richness or evenness, the Simpson index considers both factors simultaneously.
What is the range of values for the Simpson Diversity Index?
The index ranges from 0 to 1, where 0 indicates no diversity (all individuals belong to one species) and 1 indicates maximum diversity (each individual belongs to a different species).
Results are for informational purposes only and do not constitute professional advice.