Sampling

• Sampling


  Methods used to study populations of organisms
• Sampling


  • To find out whether a population is increasing or decreasing
  • To identify the different species of plants or animals present
  • To identify where in the habitat the organisms live, their number and their relationship with each other
• Types of Sampling Methods


  • Quadrat
  • Mark-release capture
  • Line Transects
  • Belt Transect
  • Bottles/Jars
  • Nets
  • Sieves
  • Pooters
• Bottles

  Used to collect aquatic or terrestrial organisms, pitfall traps may be used to capture small organisms like beetles and slugs
• Nets


  The type of mesh or cloth used and the size of the mesh is determined by the environment being studied, a sweep net may be used to capture insects and small animals from grass, water bodies and bushes

  
• Pooters


  A small jar used for collecting insects, has two tubes - one goes into your mouth so you can apply suction, and the other goes over the insect so that is sucked into the jar
• Mark-Release-Recapture


  1. Animals are trapped, marked in a harmless way and then released

  2. Traps are used again a few days later

  3. The numbers of marked and unmarked animals caught in the traps are recorded

  4. The population size is estimated using the equation: (1st sample × 2nd sample)/2nd sample (those previously marked)
• Capture/Recapture method

  Used to estimate the size of a population where it is impractical to count every individual, involves capturing a small number of individuals, marking them, and then recapturing them later
• Transects

  Used to see how the population of an organism changes across an area, a long rope stretched across an area and marked at intervals, the line transect involves recording the organisms that touch the transect at specific intervals, the belt transect uses quadrats along with the rope
• Quadrat

  A square frame used for counting static organisms, placed randomly at several locations and the number of specific organisms within the quadrat are counted and recorded, used to calculate species frequency and species density