Sampling

Sampling animals

• Pooters

  • small invertebrates

  • first tube is placed over the organism and the second tube is used by the scientist to create suction

  • once inside the organisms can be easily viewed and identified

  

• Sweep nets

  • flying insects and insects that live on leaves

  • swept across vegetation

  • large strong nets made from a material with very small holes

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• Pitfall traps

  • ground dwelling invertebrates

  • cans or jars sunk into the ground

  • invertebrates fall in and cannot climb out

  • lid ensures it does not fill with rainwater

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  Tree beating

  • animals that live on the leaves/branches of trees

  • large white cloth stretched out under the tree

  • shake/beat tree to make animals fall

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• kick sampling

  • aquatic invertebrates

  • disturbs material on the bed of river

  • catch organisms in a net that were freed by the disruption

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Mark and recapture

Sampling plants

• two quadrat types

  • point quadrat

    • frame containing horizontal bar

    • at set intervals long pins pushed through to reach the ground

    • each species of the plant the pin touches is recorded

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  • Frame quadrat

    • square frame divided into a grid of equal sections

    • type and number of species within each section of the quadrat is recorded

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Random sampling

• avoids bias

• ensures samples are representative of whole area

• randomly generated coordinates

Non random sampling

• opportunistic sampling

  • carried out on the basis of opportunity

• stratified sampling

  • the number of random samples taken within each habitat type is proportional to the area covered by each habitat type

• systematic sampling

  • samples are taken across a habitat with reference to the changes in habitat conditions

Transect sampling

• line

  • samples are taken at regular intervals along a line between two points

• belt

  • samples are taken in an area along a line or between two parallel lines by using quadrats placed either side by side (continuous) or at regular intervals (interrupted)

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