11.4 - Calculating biodiversity

Question 1

What is the simplest way of calculating biodiversity, and what issue does this method pose?

Answer 1

• Simplest way: counting number of species present (species richness) – doesn’t consider number of individuals present.
• E.g., there might be many species of plant in a field, but 1000 buttercups, compared to 10 daffodils, so the species richness may seem large, but species evenness is low.

Question 2

Give another method for calculating biodiversity and how it works.

Answer 2

Simpsons Biodiveristy Index (D)

D = 1-Σ(n/N)²

n = total number of organisms of a particular species

N = total number of organisms present

0 <= D <= 1

• 1 represents infinite biodiversity, 0 represents no biodiversity.

Question 3

What does a high Simpson’s Index number represent?

Answer 3

• High biodiversity
• High species richness
• High species evenness
• Stable habitat and can survive disruption
• Worth conserving

Question 4

What does a low Simpson’s Index number represent?

Answer 4

• Low biodiversity
• Habitat dominated by one or a few species
• Unstable habitat, may be damaged if there is disruption
• Could be a man made habitat

Question 5

Why is it important to maintain biodiversity?

Answer 5

• It is important to conserve habitats of low biodiversity, as they may have very specific adaptations only for that habitat, they would not be able to survive elsewhere.