VCE Environmental Science: Unit 3: Area of Study 2: Biodiversity.

1. VCE Environmental Science
Unit 3: Biodiversity
Measuring Biodiversity

2. Biological Sampling
• The study of any species requires an estimate of
their density in different habitats. Scientists use
many different methods of measuring density,
depending on the size, abundance, behaviour and
habitat of the species. Sometimes a line transect
and quadrats are used to measure the abundance
and cover of different floral species in a grassland
reserve.
• Reference: Charles J. Krebs (1985) “Ecology – The
Experimental Analysis of Distribution and
Abundance” Harper International, New York.

3. Sampling techniques:
• Aerial photographs (eg. whales, herds of moose or other hoofed mammals
during migration, flamingos)
• Capture-recapture (or mark and release)
• Traps (eg. Elliot traps for small mammals, pit-fall traps for reptiles, light
traps for insects, harp traps for bats)
• Number of fecal pellets
• Vocalisation frequency
• Pelt records
• Catch per unit fishing effort
• Number of artifacts (nests, pupal cases, burrows etc.)
• Questionnaires (of hunters and trappers for example)
• Cover (of plants)
• Feeding capacity (amount of bait taken)
• Roadside counts
• Bird surveys (OBP and red-tailed black cockatoos)

4. Aerial photographs are suitable for large
mammals that congregate in known
locations.

5. Surveys for birds

6. Harp nets for bats

7. Pit traps for reptiles and invertebrates
http://www.bobtrlin.com/Fauna/Australian-
Wildlife/Herps/12840134_tRhHKj/1463524527_f
DL6Wgz#!i=1463524527&k=fDL6Wgz

10. Counting artefacts – nesting sites, tree hollows, skins.

11. Leadbeater’s Possum –
Critically Endangered

12. Brush-tailed Rock Wallaby –
Critically Endangered

13. Biological Sampling
• Each method has it’s advantages and
disadvantages and is most valuable when used as
an adjunct to more direct methods. This article
from the CSIRO, “Estimating whale numbers in
the Southern Ocean” explains how scientists go
about estimating the abundance and population
structure of minke whales.
• This activity, Counting Smarties, from Maths by
Email, models the “Mark and Recapture” or “Tag
and Release” methods using smarties.

14. Quadrats

15. Transects

16. Species Site A Site B
Shrub 1 3 1
Shrub 2 7 2
Understorey 1 5 0
Understorey 2 6 2
Understorey 3 94 94
Understorey 4 75 75
Weed 1 0 2
Weed 2 0 20
D = 1 – p2 0.5961 0.6129

18. Simpson’s Index
• Simpson's Diversity Index (D) is a measure of
diversity. In ecology, it is often used to
quantify the biodiversity of a habitat. It takes
into account the number of species present,
as well as the abundance of each species.
• This index is based upon the probability that
two specimens belong to the same species.
• It ranges from 0 (low diversity) to 0.9999
(high diversity)

19. Simpson’s Index
Page 49 (1st ed) Page 53 (2nd ed)
Calculate the ‘p’ value = no. of individuals
Total Number
Calculate p2 (site A)= p x p = 0.4039
Simpson’s Index (D) = 1-0.4039= 0.5961
Calculate p2 (site B) = p x p = 0.3871
Simpson’s Index (D) = 1 – 0.38712=
0.6129

20. Discussion Questions:
• Describe the species diversity before and after
sheep grazing
• What does the calculated Simpson’s Index for
the site tell you about species richness before
and after impact?
• Describe and compare the species
composition of Site A before and after the
impact. How does this analysis compare with
the analysis by the Simpson’s Index?

21. Discussion Questions:
• What effect has sheep grazing had on the
species composition at this site?
• Using this example, explain the limitations of
relying only on Simpson’s Index as a
determinate for species diversity. What do you
suggest to improve the data collection and
analysis to determine the site’s diversity?
• If you were asked to manage this site for
species diversity what would you aim to do?

22. Shannon-Weiner Index
• Another commonly used index is the
Shannon-Weiner Diversity Index (H).
• Mostly used in freshwater ecology
• Based on the question: “How difficult is it to
predict correctly the species of the next
individual collected?”
• The higher the value, between 0 and logS, the
higher the species diversity.

23. Endemism
• Australia, as one of the 12 mega-diverse regions on
earth, is defined in terms not only of species richness
but also in terms of the level of endemism. (species
unique to Australia, that exist nowhere else)
Number of species % endemic
Vascular plants 250,000 85%
Mammals 369 82%
Birds 825 45%
Reptiles 633 89%
Frogs 176 93%
Invertebrates 193,470 95%

24. “SAFE” Index
• Read the Mathsmasters article in The Age
• http://education.theage.com.au/cmspage.php
?intid=147
• “Will maths kill the rhino?” by Polster and
Ross
• Is the “SAFE” Index a good measure of the
threat of extinction?
• Do you agree with the article?

26. C
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27. http://www.dse.vic.gov.au/__data/assets/pdf_file/0006/103389/Advisory_List_of_Threatened_
Vert_Fauna_in_Victoria_-_2007_amended_11_august_2009.pdf