Practise 1:
Number of individuals of each species in each habitat
Species
Barley
field
a
b
c
d
e
f
g
h
i
j
k
l
Species
richness
Total number
of insects (N)
Simpson’s
index (D)
32
78
0
0
0
0
0
0
0
0
86
0
196
n(n-1)
Wheat field
n(n-1)
4
0
126
5
0
0
25
10
0
0
56
0
n(n-1)
0
1
2
12
8
9
3
3
2
5
0
7
n(n-1)
n(n-1)
=
N(N-1)
=
=
N(N-1)
=
226
Hedge
n(n-1)
=
N(N-1)
52
=
0.14
Table 1
(a) State what is meant by the term species richness. Calculate for each ecosystem:
(b) (i) Calculate the value for Simpson’s index (D) for all ecosystems.
Show your working in table and write your answer in the box in Table 1.
(ii) Using the data in Table 1, suggest reasons why the value of Simpson’s index (D) for
the vegetation under the hedge is much lower than that for the wheat field.
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(c) Describe how the students may have determined the numbers of individuals of each
species in each habitat.
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(d) Studies of biodiversity are an integral part of an environmental impact assessment
(EIA). Suggest why some conservationists might object to these studies.
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