Starter Activity:
How many different plant species are in this field?
How would you find this out?
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Sampling Techniques
Learning Intention:
• Using quantitative techniques to sample plants
and animals.
Success Criteria:
• Describe ways to measure abundance of
organisms in an ecosystem.
• Identify errors in sampling techniques and
suggest how errors can be minimised.
Sampling Techniques
• Studying an ecosystem involves:
– Finding out what plants and animals live there.
– Finding out how many of them live there.
– Finding out why they live there.
Think: How would you do this?
Pair: Discuss with a partner how would carry out each of
the above
Share: With another pair discuss your ideas.
Abundance
• Abundance is the measure of how
frequently a species of plant or animal
appears in particular area.
• Abundance can be measured using
sampling techniques.
Counting plants
• It would be very difficult to count
every single plant in a field. How could
you resolve this problem?
• We can sample using a quadrat.
• Sampling using a quadrat:
– A quadrat is a square frame with a known area
such as 1m2
– It is used to estimate numbers of plants or slow
moving animals (slugs or snails).
1m
1m
Example 1
Estimating the abundance of thistles in a field:
• Quadrat placed at random and number of thistles in
quadrat counted.
• Repeated several times.
• Average number per square metre is calculated.
• Area of whole field measured
• Estimate of total number of thistles in field calculated
Example 2
Calculate the abundance of flowers in a field
with a total area of 150m2
12
_______flowers
in 1m2.
12
150
_______
x ________=
flowers
1m
1m
1800
____
in a field of 150m2.
In reality, to make
the results of
abundance more
reliable, many
samples would be
taken using quadrats
and the results then
averaged before
calculating the
abundance of the
entire area.
Quadrat
1
2
3
4
Average
Number of
flowers
12
10
8
14
11
So for the 150m2 area, Abundance = 11 x 150
= 1650 flowers
Possible sources of error with quadrats
Match up correct method of minimising error to the source of error:
Sources of Error
1. Organisms in the quadrat
may be wrongly identified.
2. Organisms in the quadrat may
be wrongly counted.
3. Too few samples have been
taken to be representative of
the habitat.
Method of minimising errors
A. Use the same rule for each quadrat to
count part of organisms or not.
B. Use a key to make sure that the
organisms are correctly identified.
C. If you notice that organisms are in
clusters, increase the sample size.
1. Pair the numbers and letters on a show me board.
2. Create a table in your notebook to show a summary of these errors.
Sampling Using a Pitfall Trap
– A container is placed in a hole in
ground to trap animals that are
active at the soil surface.
– Several traps should be set up to
increase reliability of the results.
Pitfall Trap
• Traps can be placed to compare
different areas and see what animals
are more abundant in each.
Possible sources of error in Pitfall traps
Match up correct method of minimising error to the source of error:
Sources of Error
1. Type of animals trapped
may not be representative
of the area
2. Birds eat trapped animals
3. Within trap, some animals eat
other animals
4. Rainwater collects in trap
killing animals
Method of minimising errors
A. Camouflage the opening of the trap
B. Set up more pitfall traps
C. Punch holes in the base of the trap
D. Check traps regularly, removing animals
1. Pair the numbers and letters on a show me board.
2. Create a table in your notebook to show a summary of these errors.
Other Methods of Sampling
Your task…
Use page 284 – 285 of the National 5 text book to make
notes about further sampling techniques, adding possible
sources of error and how you would overcome these.
You may present the information any way you wish.
•
•
•
•
•
Tullgren funnel
Pooters
Tree beating
Sweep netting
Pond netting
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Clip art to
topic
Sampling Techniques
Learning Intention:
• Using quantitative techniques to sample plants
and animals.
Success Criteria:
• I can describe ways to measure abundance of
organisms in an ecosystem.
• I can identify errors in sampling techniques and
suggest how errors can be minimised.
Starter Activity: Ideas on a show me board
How would you explain to a small child how
to identify the following organisms?
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Classification Keys
Learning Intention:
• Paired statement keys.
Success Criteria:
• I can construct paired statement keys to
identify unknown plants or animals found
during sampling an ecosystem.
Classification Keys
• When using sampling methods, it is
important that you are able to identify
the plants or animals you have found.
• One method of identification is to use a
key.
Keys
• Used to identify organisms while
sampling.
• There are two types
– Branched keys
– Paired Statement keys
Branching keys
• A key is a series of
questions. Each
question leads to
another until
eventually the name
of the organism is
found.
Paired Statement Key
• Instead of asking questions at branching
points on a diagram, you are asked to
choose between two statements.
• Each pair of statements is numbered and
the instructions send you to the next
relevant pair of statements.
1.
Has green coloured body ......go to 2
Has purple coloured body ..... go to 4
2.
Has 4 legs .....go to 3
Has 8 legs .......... Deerus octagis
3.
Has a tail ........ Deerus pestis
Does not have a tail ..... Deerus magnus
4.
Has a pointy hump ...... Deerus humpis
Does not have a pointy hump.....go to 5
5.
Has ears .........Deerus purplinis
Does not have ears ......Deerus deafus
Vertebrates
Remember to use obvious visible
characteristics when constructing paired
statement keys.
What are the obvious
visible characteristics?
Invertebrates
Remember to use obvious visible
characteristics when constructing paired
statement keys.
wasp
centipede
earwig
What are the obvious
visible characteristics?
spider
Invertebrates
Remember to use obvious visible characteristics when
constructing paired statement keys.
Caddis fly larva
mayfly
Fresh water shrimp
What are the
obvious visible
characteristics?
limpet
flatworm
stonefly
1.
Paired Statement Key
2.
4.
5.
6.
3.
Click on a leaf number 1 to start, then
complete leaves 2-6 in that order
Construct a paired statement key for the animals below:
1.
2.
3.
4.
5.
Example 1
Construct a paired statement key for
the information below:
Invertebrate
Spider
Wasp
Fly
Springtail
Number of
legs
8
6
6
6
Wings Body Stripe
No
Yes
Yes
No
No
Yes
No
No
Example 2
Construct a paired statement key for
the information below:
Plant
Presence of
chlorophyll
Presence of Presence
cones
of flowers
Aquatic
Grass
Yes
No
Yes
No
Spruce
Yes
Yes
No
No
Yeast
No
No
No
No
Moss
Yes
No
No
No
Seaweed
Yes
No
No
Yes
Example 3
Construct a paired statement key for
the information below:
Bird
Type of feet
Crest on
head
Beak
shape
Head
colour
Swan
Webbed
Absent
Straight
White
Curlew
Not Webbed
Absent
Curved
Brown
Rook
Not Webbed
Absent
Straight
Black
Puffin
Webbed
Absent
Straight
Black
Skylark
Not Webbed
Present
Straight
Brown
Avocet
Not Webbed
Absent
Curved
Black
Example 4
Construct a paired statement key for the information
below:
Name
Body
Design
External
or
Internal
Suckers
Wings
Legs
Size
Liver
fluke
Unsegmented
Internal
2
None
None
Macroscopic
Polystoma
Unsegmented
Internal
More than 2
None
None
Macroscopic
Mange
Mite
Segmented
External
None
None
4 pairs
Microscopic
Sheep
tick
Segmented
External
None
None
4 pairs
Macroscopic
Sheep ked
Segmented
External
None
None
3 pairs
Macroscopic
Tetse fly
Segmented
External
None
Present
3 pairs
Macroscopic
Leech
Segmented
External
Present
None
None
Macroscopic
Diplozoon
Unsegmented
External
Present
None
None
Macroscopic
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topic
Classification Keys
Learning Intention:
• Paired statement keys.
Success Criteria:
• I can construct paired statement keys to
identify unknown plants or animals found
during sampling an ecosystem.
Starter Activity:
How would you sample this field?
Appropriate
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topic
Sampling Techniques
Learning Intention:
• Using quantitative techniques to sample plants
and animals.
Success Criteria:
• Measure abundance of organisms in an
ecosystem.
• I can identify errors in sampling techniques and
suggest how errors can be minimised.
Appropriate
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topic
Sampling Techniques
Your task… measure the abundance of
grass species in the school grounds.
Think: What equipment will you need to do this?
Pair: Discuss the size of area are you going to sample and
where this area will be. How will you record your results?
Share: Explain how you will measure the abundance of
grass species in the school grounds.
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Sampling Techniques
Equipment List:
Classification key – common grasses
Quadrat
Tape measure
Results table
Clipboard
Method:
1. Mark out your area e.g. 5m x 5m
2. Decide how you will take random samples. e.g. using
coordinates from a random numbers table.
3. Decide how you will record your data using the quadrat, to
ensure you are consistent each time and a valid sample.
4. Record the name of each species you find in each quadrat
and the NUMBER of each species (% coverage)
5. Repeat this for 10 quadrat samples
How to sample abundance with a quadrat:
You are going to use a 25m²quadrat to investigate the % coverage of plant species.
The easiest way to calculate % coverage is to imagine each box split into 4, so each
quarter is worth 1% (or each square is worth 4%) and count how many sections of
squares that particular plant species is covering.
E.g. Look at the yellow dandelion flowers, how many sections does it cover?
Answer: 1 quarter of a square = 1%
In this picture the dandelion flowers cover 1 quarter of a square = 1%
1 quarter
of a square
= 1%
1 square
= 4%
Quadrat Sampling
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Sampling Analysis
Use your data and knowledge about quadrat sampling to answer
the following in FULL sentences:
1.
2.
3.
4.
5.
How many different plant species did you identify?
Which plant species was most abundant?
Which plant species was least abundant?
What sources of error could have affected your results?
How did you overcome these sources of error?
Appropriate
Clip art to
topic
Sampling Techniques
Learning Intention:
• Using quantitative techniques to sample plants
and animals.
Success Criteria:
• Measure abundance of organisms in an
ecosystem.
• I can identify errors in sampling techniques and
suggest how errors can be minimised.
Wet weather alternative for
quadrat sampling:
Click this link for the online resource