15 - Effect of different sampling methods on estimates of the size of a population

What equipment is needed for this practical?

• 0.5m x 0.5m quadrat

• 1m x 1m quadrat

• 2x tape measure

• Random number generator

• Clipboard

What is the method for this practical?

1. Pick one species to study that is easy to identify

2. Set up a 10 × 10 m area using two tape measures to create coordinates

3. Use a random number generator to get at least 10 random coordinates for sampling

4. At each coordinate, place the 0.5 × 0.5 m quadrat (bottom-left corner on the coordinate)

5. Record percentage cover → count how many of the 100 squares in the quadrat contain the species (only count if ≥ 50% of the square is covered)

6. Record point frame data → count how many times the species touches pins or intersection points (sample of species coverage)

7. Record density → count individual organisms inside the quadrat (only count if ≥ 50% of the organism is within the quadrat)

8. Repeat steps 4–7 with a 1 × 1 m quadrat to compare & calculate density per m²

What is the risk, safety precaution & in emergency for the hazard: biohazard

Risk:

• allergies

• soil bacteria

• contamination

Safety precaution:

• wash hands after practical

In emergency:

• seek assistance

What is the risk, safety precaution & in emergency for the hazard: slippery surfaces

Risk:

• slip hazard

Safety precaution:

• wear appropriate footwear

• don’t run

In emergency:

• seek appropriate medical attention

How do you analyse the data from this practical?

1. Work out mean percentage ground cover for the frame & point quadrat

2. Work out the mean density per m² for the different sized quadrats

3. Construct a bar chart or histogram

What is the conclusion from this practical?

• Should be able to find out if there is a significant difference between density per m² for the different sized quadrats

• Should be able to find out if there is a significant different between mean percentage cover for the different types of quadrat