Brief audio-visual description of ecological sampling methods explaining how they are used and what organisms can be sampled with each technique.

1. Prepared by Sherrie-Ann Wilson

2. Some Benefits of Ecological Studies
 Ecological studies provides in-depth, scientific understandings of how all
living organisms interact with each other and the abiotic factors of their
environment.
 It improves our understand of how organisms adapt to different
environments.
 It gives insights on how diverse life forms are.
 It paves the way for scientific investigations.

3. Population vs Sample

4. Estimating Numbers of Populations
 Communities and populations are usually too large for each individual to be
observed.
 Samples are needed for observations.
 The sample population must be representative of the group to which they
belong.
 Obtain as many samples as possible to ensure results are representative of the
population.
 Sampling must be random to avoid human bias.

5. Disadvantage of Random Sampling
 Important areas of the habitat might not be sampled.
 Important areas may include:
 densely populated areas
 lightly populated areas
 areas without a specific species of organism
 areas with significantly more of one species of organism than other species
being sampled.

6. In this sample
population, this is
a less populated
area.
This is a densely
populated area
with no ferns.
This area is
populated only
by sun flowers.
Study the flowers field below and identify important areas.
Fern Sun flower Daisy

7. Choosing Sampling Method(s)
 The chosen sampling method should be cost efficient.
 It should also be able to produce precise estimates of the sample
population relative to the real world.
 Sampling organisms requires knowledge of their biology, preferred
habitats and activity patterns.
 Sampling strategies can be deduced for each of the taxonomic groups.

8. Categories of Biotic Sampling Techniques
 There are two main sampling techniques:
1. Actively collecting sample individuals
2. Passively collecting sample individuals
Eg of passive collecting techniques:
 bottle traps
 pitfall traps
 light traps
 camera/video observation
Eg of active collecting techniques:
 quadrats
 line transect
 pooter
 sweep net

9. Quadrates
 Quadrats are flat square frames of known area/size, eg 1 m2
 They can be made from wire, plastic or wood.
 May contain further wires to mark off smaller areas inside,
such as:
 5 × 5 squares
 or 10 × 10 squares.
 Suitable for sampling plants and slow-moving animals, eg:
 slugs
 Snails
 millipedes

10. Line Transects
 A line transect is a tape or string pulled in a
straight line between two poles across the area of
study.
 The line transect acts as a guide to measure the
distribution of organisms.
 Sampling is confined to organisms that are actually
touching the line. Eg, plants and slow moving
animals.

11. Line Transects Cont’d
 A line transect is a very effect sampling
method if:
 one type of habit changes into another
 or in a sloping area. Eg, rocky or
swampy shore.
 In slopes, the height of the line can be
measured at regular intervals.
 This helps the researcher to be able to
describe the slope area.

12. Pooters
 A pooter is a small jar used for collecting
insects.
 It has two tubes:
 one goes into your mouth so you can apply
suction
 the other goes over the insect so that it is
sucked into the jar.
 A fine mesh over the end of the first tube
stops you swallowing the insect.

13. Bottle Traps
 Bottle of known volume can be used for
systematic or random sampling.
 Used to sample small aquatic and terrestrial
species.
 In aquatic areas, water collected in bottle traps
can be observed under a microscope or a strong
hand lens.

14. Pit Fall Traps
 Bottle traps can be used to set pit fall traps for small
insects and other arthropods.
 Traps are sunken randomly into the earth below
ground level.
 Traps may contain food to attract animals.
 The mouth is covered over by sticks and leaves.
 Effective for catching beetles, centipedes, millipedes
and spiders.
 Not reliable for estimating density.

15. Sweep Nets
 Sweep nets are made from light weight materials.
 Sweep nets are useful for collecting:
 insects (especially flying insects)
 other small animals
 Sampling habitats may include bushes, long grass
and ponds.
 Can also be used with line transects and quadrats.
 They come in different sizes.

16. Sweep Nets Cont’d
 The nets are swept at randomly
selected areas through the plants.
 They are swept a fixed number of
times.
 Individuals caught are counted.
 The mean represents a sample of the
insects in that habitat.

17. Two Review Questions

18. Which of the following sampling
methods is most suitable for
estimating the density of
mushrooms in a home garden?
Quadrat
PooterBottle trap
Line transect

19. A sample is a
sub-set of
a population
distribution
a set
data

20. That is correct!
CONGRATULATIONS!
Move on to question
2

21. That is incorrect!
You may try again!
Back to question 1
Move on to question 2

22. That is incorrect!
You may try again!
Back to question 2

23. That is correct!
CONGRATULATIONS!
End of presentation. Go to end
Slide