1. Measuring Biodiversity
You need to know:
What we mean by ‘biodiversity’
How to estimate biodiversity

2. Biodiversity Species richness Species evenness
Number of different species in the habitat
Qualitative measurement
Relative abundance of individual species
Quantitative measurement

3. Measuring species richness =Quantitative.
Count the number of different species.
Can use random quadrat technique
No need to identify the species
NB this measurement means that 1 daisy is worth as much as 100 buttercups…..so…

4. Measuring species evenness = Quantitative
Plants – use random quadrats , count the number of each species or % cover.
Calculate RELATIVE abundance.

5. Species evenness - Animals
Count individuals or use mark and recapture method.
Mark individuals and release. = C1
After period of time catch new sample = C2
Count number of marked individuals = C3
Catch a sample of animals eg using sweep net
Calculate total population = (C1 x C2) C3

6. Worked example:- Two different fields were sampled for wildflowers
Numbers of individuals
Species Sample 1 Sample 2
Daisy
Dandelion
Buttercup
Total
Which field do you think is the most biodiverse, and why?

7. A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance.
As species richness and evenness increase, so diversity increases. Simpson's Diversity Index is a measure of diversity which takes into account both richness and evenness.

8. Simpsons diversity index
D = 1 - [ Σ(n / N)2 ]
D = diversity of habitat
Σ = sum of
n = the total number of organisms of a particular species or percentage cover
N = the total number of organisms of all species or % cover
Using 1- means that as D increases so does the diversity.

9. Species n n/N (n/N)² Daisy Dandelion Buttercup Sum Σ 1 - Σ
Work out the Simpsons Diversity index for the 2 fields.
Numbers of individuals
Species Sample Sample 2
Daisy
Dandelion
Buttercup
Total
Species n
n/N
(n/N)²
Daisy
Dandelion
Buttercup
Sum Σ
1 - Σ

10. Now try this example on your own.
Species n
n/N
(n/N)²
Woodrush 2
Holly 8
Bramble 1
Yorkshire fog
Sedge 3

11. Ans. Simpsons index of diversity for this area = 0.7
The results that you have just used were collected from 1 quadrat.
Is this a reliable indication of the diversity of the habitat?
Explain your answer.