Required Practical 9 - Sampling

• Estimating the total population of daisies in an area (random sampling)

  1. Place 2 tape measures at right angles 20m in length
  2. Randomly generate a set of coordinates and place the quadrat at this location.
  3. Repeat this process 9 more times for a total of 10 samples
  4. Estimate the total population of daises in the whole field by using: Total population size = (total area / area sampled) x number of organisms of daisies in the sample
  5. (400m^2 / 2.5m^2) x 300 = 48,000 daisies in total
• Why is the population of daisies only an estimate?

  • There might be regions with much higher or much lower daisies than average
• Investigating the effect of light intensity on distribution of daisies (from tree into field)

  1. Place a tape measure at the tree (transect)
  2. Use a quadrat to count the number of daisies at the start of the transect and record the light intensity using a light meter
  3. Move the quadrat 1m down the tape measure and repeat the measurements all the way down the tape measure