Sampling techniques

Question 1

Explain how to use a pitfall trap to measure biodiversity

Answer 1

1. Dig a hole in the ground and put a container inside
2. Place a cover on to to prevent rainfall entering
3. Leave overnight
4. Use an identification key to identify the different species and count the different species
5. Repeat the sampling technique in 10 different locations

Question 2

Explain how to use a interrupted belt transect to measure biodiversity

Answer 2

1. Use a tape measure to mark the line on the ground
2. Make observations at fixed 1m intervals along the line
3. Use a quadrat to record percentage cover
4. Use an identification key to identify the different species
5. Repeat your sampling technique and use other group data

Question 3

Explain how to do random sampling using a qudrats

Answer 3

1. Lay two tape measures at right angles to eachother on the ground to create a grid
2. Use a random number generator to randomly generate the first point to place the quadrat
3. Place the bottom left hand side of the on the point and use the quadrat to measure percentge cover
4. Use an identification key to identify the different species in the quadrat
5. Use the random number generator 10 more times and repeat the process in the random points
6. Plot a kite diagram to illustrate the results

Question 4

Explain how to do random sampling using quadrats

Answer 4

1. Place two tape measures at right angles to eachother on theg round the create a grid, use a random number generator to randomly generate the first point to place your quadrat
2. Place the bottom left corner on the point and use the quadrat to measure percentage cover
3. Use an identification key to identify the species in the quadrat
4. Find 10 more randomly generated numbers nd repeat the sampling technique 10 more times
5. Plot a kite diagram to illustrate the results

Question 5

Explain the importance of sampling in measuring biodiversity

Answer 5

• It is impossible to count every individual
• Sampling provides a representative estimation of the whole area

Question 6

What is random sampling?

Answer 6

Site are selected randomly

Question 7

What are the positives of random sampling

Answer 7

It prevents selective sampling and bias

Question 8

What are the four types of sampling?

Answer 8

• Random sampling
• Stratified sampling
• Opportunistic sampling
• Systematic sampling

Question 9

What are the negatives of random sampling

Answer 9

Not all types of habitats are sampled and so this leads to inaccurate data

Question 10

What are the two types of non-random sampling

Answer 10

Stratified sampling
opportunistic sampling

Question 11

What is stratified sampling

Answer 11

When a random sample is taken from each strata

Question 12

What are the positives of stratified sampling?

Answer 12

It ensures that all areas are sampled and prevents smaller populations from being left out

Question 13

What are the negatives of stratified sampling?

Answer 13

Some areas may become OVER-REPRESENTED in the sample

Question 14

What is opportunistic sampling

Answer 14

Sampling areas and organisms which are CONVENIENTLY AVAILABLE

Question 15

What are the positives of opportunistic sampling?

Answer 15

It is easier and quicker than random sampling and so produces more data

Question 16

What are the negatives of opportunistic sampling

Answer 16

Can potentially lead to bias as some species are more noticeable due to colour and size

Question 17

What is systematic sampling?

Answer 17

When samples are taken at fixed distances

Question 18

What are the postives of systematic sampling

Answer 18

It can help to see how biodiversity or a population changes over time

Question 19

What are the disadvantages of systematic sampling

Answer 19

Only a small area is sampled