• 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 but also the evenness of abundance across the different species
• Simpson’s index of diversity (D) can be used to quantify the biodiversity of an area

Simpson’s index

• The formula is:

•  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 step is to calculate n / N for each species
  • Step 2: Square each of these values
  • Step 3: Add them together and subtract the total from 1
• The possible values of D are significant:
  • • 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