sampling

• percentage cover


  we would use percentage cover when there are lots of species in one area. percentage cover is the percentage of the quadrat covered by a certain species.
• formula: number of organisms in the habitat


  mean number of organisms

  ------------------------- x area of habitat

  area of 1 quadrat
• 6 marker on random sampling:


  using a random number generator, calculate 10 coordinates of random numbers. at these coordinates, place a 1m x 1m quadrat. count the number of the required species in the quadrat. repeat for each coordinate. calculate the mean number of organisms, the area of the habitat and the area of the quadrat (1m2). using the formula: mean number of organisms / area of 1 quadrat x area of habitat, find the average number of organisms in the habitat.

  to improve:

  • repeat with 10 more random coordinates
  • using a smaller habitat for more accuracy.
• belt transects


  show how a factor affects the distribution of organisms.
• 6 marker: belt transects


  you would use a belt transect, or a tape measure to measure 30 m away from the factor. place a quadrat every 5 m and count the number of organisms in each quadrat. plot a graph of distance and number of organisms. this should show how the factor affects the distribution of an organism.

  to improve:

  • make the transect longer (e.g. 50m)
  • make the intervals shorter (e.g. every 1m)
• sampling animals

  • beating tray --> caterpillars
  • pooter --> spiders
  • pit fall traps --> woodlice
  • sweep and kick, sampling nets --> dragonfly
• beating tray


  the stick hits the tree trunk and the caterpillars fall into the tray, where they can be counted.
• pooter

  blow into one straw to suck spider into a plastic-beaker-container.
• pit fall traps


  the woodlice are tempted to fall into a camoflagues pot where they are not able to get out from.
• sweep and kick + sampling nets


  one person kicks the grass, the dragonflies fly out snd are captured into a net.
• advantages of sampling animals. 


  • maintain stability in a habitat / ecosystem.
  • identify conservation measures.
  • identify species in decline
  • identify seasonal changes
  • identify the effect of humans
  • identify the conditions needed for survival
• mark and recapture


  1. capture a number of animals and mark them with removable paint or ink. record the numbers.
  2. wait a fixed amount of time
  3. come back to the same habitat after the fixed time period is over.
  4. record how many were marked and the total number of animals in the second sample.

  formula:

  no. caught 1st x no. caught 2nd / no. marked in 2nd (overlap) = total no. of organisms in the habitat.
• disadvantages of animal sampling

  • pitfall traps --> animals can die because it's not the same habitat.
  • the marked organisms can be easily spotted by predators.
  • bias --> animals that are slow / easy to capture are most likely to be captured and marked. this skews data.