PAG 3: sampling techniques

• how should a field be set up for random sampling?

  by laying two tape measures at right angles on the field to set up a coordinate system
• how should students decide where the quadrats are placed?

  by using a random-number generation to produce coordinates, place quadrat down at the coordinates using the tape measure as a guideline
• how is population size for the site measured?

  population size = total area / area of quadrat x mean number of individuals counted in a quadrat
• state the controlled variables of this practical

  • size of quadrat
  • coordinate system
  • number of quadrats per site
  • area of sites
• why does a random number need to be used?

  to avoid bias in random sampling
• state a hazard and safety precaution involved in this practical

  • certain plants may cause allegeric reactions or stings
  • wear gloves when handling
• when is a transect used?

  when there is an ecological gradient in the sampling area
• two of the types of sampling using a transect

  • continuous
  • interrupted
• five examples of an abiotic factor than may change along a transect

  • light intensity
  • soil pH
  • compacting
  • moisture content
  • temperature
• outline the procedure to sampling using a transect line

  1. lay down a tape measure along the ecological gradient
  2. place the quadrat at the '0' mark, record the number of required species
  3. repeat the process 5m up the tape measure until the end of the transect
  4. plot the graph of 'number of individuals' against a selected factor