Starter Activity:

How many different plant species are in this field?

How would you find this out?

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.

Appropriate Clip art to topic

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:Think: How would you do this?

Pair: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

Calculate the abundance of flowers in a field with a total area of 150m2

_______flowers in 1m2.

_______ x ________= ____ flowers

in a field of 150m2.

Example 2

12

12 1800150

1m

1m

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 Number of flowers

1 12

2 10

3 8

4 14

Average 11

So for the 150m2 area, Abundance = 11 x 150 = 1650 flowers

Possible sources of error with quadrats

Sources of Error Method of minimising errors

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.

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.

Match up correct method of minimising error to the source of error:

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.

– 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.

Sampling Using a Pitfall Trap

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

Sources of Error Method of minimising errors

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

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

Match up correct method of minimising error to the source of error:

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.

Your task…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

Other Methods of Sampling

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.

Appropriate Clip art to topic

Starter Activity: Ideas on a show me board

How would you explain to a small child how to identify the following organisms?

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.

Appropriate Clip art to topic

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 2Has purple coloured body ..... go to 4

2. Has 4 legs .....go to 3Has 8 legs .......... Deerus octagis

3. Has a tail ........ Deerus pestisDoes not have a tail ..... Deerus magnus

4. Has a pointy hump ...... Deerus humpisDoes 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

spiderWhat are the obvious

visible characteristics?

Invertebrates

Remember to use obvious visible characteristics when constructing paired statement keys.

mayflyCaddis fly larva

stoneflyflatworm

limpet

Fresh water shrimp

What are the obvious visible

characteristics?

Paired Statement Key

Click on a leaf number 1 to start, then complete leaves 2-6 in that

order

1.

2.

3.

4.5.

6.

Construct a paired statement key for the animals below:

1.

2.

3.

4.

5.

Invertebrate

Number of legs

Wings

Body Stripe

Spider 8 No No

Wasp 6 Yes Yes

Fly 6 Yes No

Springtail 6 No No

Construct a paired statement key for the information below:

Example 1

Plant Presence of chlorophyll

Presence of cones

Presence 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

Construct a paired statement key for the information below:

Example 2

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

Construct a paired statement key for the information below:

Example 3

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

Construct a paired statement key for the information below:

Example 4

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.

Appropriate Clip art to topic

Starter Activity:

How would you sample this field?

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 Clip art to topic

Sampling Techniques

Your task…Your task… measure the abundance of grass species in the school grounds.

Appropriate Clip art to topic

Think:Think: What equipment will you need to do this?

Pair:Pair: Discuss the size of area are you going to sample and where this area will be. How will you record your results?

Share:Share: Explain how you will measure the abundance of grass species in the school grounds.

Sampling Techniques

Equipment List:Equipment List:Classification key – common grassesQuadratTape measureResults tableClipboard

Appropriate Clip art to topic

Method: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 square

= 4%

1 quarter of a

square = 1%

Quadrat Sampling

Sampling Analysis

Use your data and knowledge about quadrat sampling Use your data and knowledge about quadrat sampling to answer the following in FULL sentences:to answer the following in FULL sentences:

1. How many different plant species did you identify?2. Which plant species was most abundant?3. Which plant species was least abundant?4. What sources of error could have affected your results?5. 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.

Appropriate Clip art to topic

Wet weather alternative for quadrat sampling:

Click this link for the online resource