1. Measuring biodiversity

2. Starter - Key Term Definitions
Species
A group of organisms whose members are similar to each other in morphology, physiology, biochemistry and behaviour; who can interbreed to produce fertile offspring
Habitat
Place where an organism or population lives
Biodiversity
Number and variety of living things to be found in the world/ecosystem/habitat

3. Learning Objectives Success criteria
To understand how to calculate diversity and what is all means
Success criteria
Describe how to measure species richness and species evenness in a habitat
Use Simpson’s Index of Diversity (D) to calculate the biodiversity of a habitat, using the formula D = 1-(Σ(n/N)2)
Outline the significance of both high and low values of Simpson’s Index of Diversity (D)

4. Key Term Definitions Species richness Species evenness
Number of species present in habitat
Species evenness
Measure of abundance of individuals in each species (ACFOR)
The greater the species richness and evenness the
higher the biodiversity

5. Measuring Species Richness
Number of species present in habitat
Qualitative survey
Use sampling techniques best suited to habitat (e.g. transect, quadrats)
Walk round see if any species you’ve missed

6. Measuring Species Evenness
Measure of abundance of individuals in each species
Quantitative surveying
Plants - use sampling techniques measuring species per unit area or percentage ground cover
With large animals use observation
With small animals can use mark and recapture method
C1: number on first capture;
C2 number on second capture;
C3 number of already marked animals on second capture
Total population = (C1 x C2) / C3

7. Species richness and evenness
Habitat X
Habitat Y
Species 1 28 15
Species 2 2
Total 30
What can you deduce about species richness and evenness for these 2 habitats?
Species richness (2) is the same for both habitats
Habitat Y has a greater species evenness

8. Simpson’s Index of Diversity
Measure biodiversity of a habitat taking into account species richness and species evenness
D = 1-(Σ(n/N)2)
n = number of individuals of a particular species (or percentage cover for plants)
N = total number of all individuals of all species (or percentage cover for plants)

9. Simpson’s Index of Diversity
Simpson’s index is always a value between 1 and 0.
Significance of high values of D (close to 1)
Diverse habitat
Small change in habitat may only affect one species
Habitat stable and can withstand change
Significance of low values of D (close to 0)
Habitat dominated by just a few species
Small change in habitat may effect one of the key species and damage whole habitat

10. Simpson’s Index of Diversity
Species n
n/N
(n/N)2 A 12 B 7 C 2 D 6 E 5 F 8
n=
This is N
(n/N)2 =
What is the species richness?

11. Simpson’s Index of Diversity
Species n
n/N
(n/N)2 A 12 B 7 C 2 D 6 E 5 F 8
n=
(n/N)2 =
Work out n (sum of all the species present)
Then work out n/N for all species

12. Simpson’s Index of Diversity
Species n
n/N
(n/N)2 A 12
0.300 B 7
0.175 C 2
0.050 D 6
0.150 E 5
0.125 F 8
0.200
n= 40
(n/N)2 =
Work out (n/N)2 for all species
Then add them all up for (n/N)2

13. Simpson’s Index of Diversity
Species n
n/N
(n/N)2 A 12
0.300
0.09 B 7
0.175
0.031 C 2
0.050
0.003 D 6
0.150
0.023 E 5
0.125
0.016 F 8
0.200
0.040
n= 40
(n/N)2 =
WHAT’S WRONG WITH THE TABLE? (3DP)
D = 1 - (Σ(n/N)2)
D = = 0.797

14. Learning Objectives Success criteria
To understand how to calculate diversity and what is all means
Success criteria
Describe how to measure species richness and species evenness in a habitat
Use Simpson’s Index of Diversity (D) to calculate the biodiversity of a habitat, using the formula D = 1-(Σ(n/N)2)
Outline the significance of both high and low values of Simpson’s Index of Diversity (D)