• 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
• An?index of diversity?is a measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community
• It is a much more informative measurement than species richness
  • For example, habitat A has 10 different plant species and habitat B has 7 different plant species
  • Habitat A would have a greater species richness score than habitat B
  • However, in habitat A there is only one individual of each plant species present (10 individuals present) while in habitat B there are over 20 individuals of each species present (over 140 individuals present)
  • Habitat B would have a greater index of diversity than habitat A

   

The index of diversity formula

• The formula is:

• Where:
  • n?= total no. of organisms for a single species in the community
  • N?= total no. of organisms in the community
  • Σ?= sum of

   

• ?The?larger the number?obtained, the?higher the level of diversity

• To calculate:
  • Step 1:?Calculate N(N-1) to find?value A
  • Step 2:?Calculate n(n-1) for each species
  • Step 3:?Add these numbers together to find value B
  • Step 4:?Divide?value A?by?value B

   

• The possible values of index diversity are significant:
  • The?larger the number?obtained, the?higher the levels of diversity

   

?????? Step one:?????? Calculate N(N-1) to find?value A

N(N-1) = 202(202-1) = 202(201) = 40602

Step two:?????? Calculate n(n-1) for each species

Step three:???? Add these numbers together to find?value B

????? Step four:????? Divide?value A?by?value B

40602÷ 6884 = 5.898

Index of Diversity,d = 5.90