calculating population sizes by scaling up and quadrats

  • Created by: tia5sos
  • Created on: 22-09-20 16:46
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  • quadrats
    • a quadrat is a square frame enclosing a known area, e.g. 1m .
    • To compare how common an organism is in 2 sample areas, follow steps 1 to 6.
    • 1. Place a 1m   quadrat on the ground at a random point within the first sample area.
      • e.g. divide the area into a grid and use a random number generator to pick co-ordinates.
        • Otherwise, if all your samples are in one spot and everywhere else is different, the results you get won't be valid.
    • 2. Count all the organisms you're interested in within the quadrat.
    • 3. repeat steps 1 and 2 lots of times. (The larger the sample size, the better)
    • 4. work out the mean number of organisms per quadrat within the first sample area.
      • mean = total number of organisms/ number of quadrats
    • 5. repeat steps 1 to 4 in the second sample area
    • 6. compare the two means.


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