Ecology

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  • Created by: romy kale
  • Created on: 01-10-13 11:27

Random Sampling

1) Use a tapemeasure to form a grid

2) Generate random coordinates using a calculator

3) place quadrat at coordinates

4) measure abundance/ frequency/% cover (make relevant to question)

5) Repeat many times

6) continue until you reach a running mean

7) Use an appropriate stats test to compare sites A + B (if relevant)

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Systematic Sampling

1) Select random start point (relevant to question e.g. circle-360 or beach-pependicular to direction of travel) 

2) Place transect line

3) At regular intervals along the transect, place quadrat

4) Mesure frequency/% cover dependent on the question

5) take average or mean perpendicular to the transect line

6) Continue along transect line until desired point is reached

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Mark, Release, Recapture

1) Capture organisms in a non-lethal trap and count them e.g. pitfall trap

2) Mark the caught organisms and release back into population. Must allow sufficient time for organisms to redistribute into population

3) Mark must be non toxic and not reduce organisms chance of survival

4) Capture organisms 2nd time and count them! Record total number caught (n2) and number that are marked (NM)

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Considerations with Mark, Release, Recapture

  • Dont mark in a toxic way. Must not reduce organisms chance of survival
  • Mark should not rub off or be lost
  • sufficient time must be left for the individuals to fully disperse into population
  • Population doesnt change between the two capture times. There should be few or no births/deaths/emmigration/immigration
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