4.2.5 Simpsons Index

Question 1

What is Simpsons index of diversity?

Answer 1

Once the abundance of different species in an area has been recorded the results can be used to calculate the species diversity or biodiversity for that area

Species diversity looks at the number of different species in an area (species richness) but also the evenness of abundance across the different species in that area (species evenness)

Simpson’s index of diversity (D) can be used to quantify the biodiversity of an area
Simpson’s index

The formula is:
Simpson’s Index equation

Where:
n = total no. of organisms for a single species
N = total no. of organisms for all species

To calculate Simpson’s Index:
Step 1: First calculate n / N for each species
Step 2: Square each of these values
Step 3: Add them together and subtract the total from 1

To understand what the value of D means you need to know the following:
The value of D can fall between 0 and 1
Values near 1 indicate high levels of biodiversity
Values near 0 indicate low levels of biodiversity