Sampling Techniques To know how to use different sampling techniques.

Sampling TechniquesTo know how to use different sampling techniques

Adaptations

Sampling Biologists often want to find out what organisms are

present in an environment / what these organism do /where these organisms go etc…

Often it isn’t feasible to identify all the organisms present, so instead samples can be taken

Samples look at a small section, allowing us to predict what the whole is like – e.g. we couldn’t feasibly measure the height of every blade of grass, but we could look at a small sample grass and get an idea of what all the rest may be like

Sampling Techniques How can we sample this organism

Tagging – e.g. a few whales can be tagged and tracked, to give us an idea of where their migration routes are

Sampling Techniques How can we sample this organism?

Pitfall traps – e.g. a small trap can be set to collect a range of organisms within an area

Pit-fall trap

Sampling Techniques How can we sample organisms / areas?

Quadrat – e.g. a quadrat is thrown in an area, and the number of organisms within the quadrant are counted to give an estimate for a much larger area

Sampling Techniques Sampling is a good way to estimate population size – although

is not 100% accurate, if done properly it can give good estimates and is very time efficient!

Your task is to sample the number of daisies growing in the open and the number growing under trees

Do More Daisies grow in the open or under trees?

How long do you think it will take?

How many times will you have to do it?

How will you choose which part to sample?

What do you think you will

find out?

How are you going to

sample your daisies?

How will you

record your

results?

How will you make it safe?

Recording your Results

Design a table to collect your results in

This is usually

the thing you

change

These are usually the things you have measured

NEVER FORGET YOUR UNITS!!! (e.g. s, m, cm, N)

Use a PENCIL and RULER

Results

Number of Daisies

Sample 1

Sample 2

Sample 3

Average

In Open

Under Trees

Analysis Can you suggest reasons why the population sizes are

different? The daisies need a

variety of conditions to survive, including light – around the trees light is less abundant than out in the open field, so less daisies are able to grow there

There may also be less nutrients / water available allowing less daisies to grow in this area

Moving Quadrats are usually used for plants, but they can also

be used to estimate some animal population sizes (as long as these only move a little)!