• 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

The results and working out are seen in the table below. The figures have been?rounded to three decimal places?for columns 3 and 4

D = 1 - 0.172 = 0.828

As the value of D is much closer to 1 than 0, it can be said that this is a relatively high value for biodiversity.