sampling techniques

• Pooter 


  = used to catch insects by sucking on a mouthpiece, insects are drawn into the holding chamber via the inlet tube. - filter before the mouthpiece to stop insects entering the mouth.

  • slow and long process.
• sweep net 


  = used to catch insects in areas of long grass.
• pitfall traps


  = hole is dug into the ground- insects fall into it and can't crawl out. -Covered by a roof structure for protection from the rain. They fall onto sheet so they can be collected and studies.

  • type= small crawling invertebrates
  • can't escape or drown, not all organisms will fall into the trap.
• tree beating 


  = large white cloth stretched out under the tree. The tree is shaken/beaten to dislodge species- fall onto the sheet so it can be collected and studies.

  • type= invertebrates living in a tree or bush
  • not all organisms will fall from the tree.
• kick sampling 


  = river bank is kicked for a period of time to disturb substrate. Net is held downstream to capture organisms released.
• Quadrats


  -point quadrat= a frame containing a horizontal bar. At a set of intervals along the bar, long pins are pushed through the bar to reach the ground, each species of plant the pin touches is recorded.

  -frame quadrat= square frame divided into a grid of equal sections. The type and number of species within the quadrat is recorded.
• what quadrats measure:


  -density= if individual plants can be seen clearly, count the number of species in the quadrat, not an estimate, an absolute measure.

  -frequency= used where individual members of a special are hard to count. eg: grass, moss. Using small grids within a quadrat, count the number of squares a particular species is present it.

  -percentage cover= used for speed as lots of data can be collected quickly useful when particular species is abundant or difficult to count.
• estimating animal population size

  capture- mark- release- recapture= capture as many individuals of a species in an area as possible, organisms marked and released back into the community.

  • time is allowed for organisms to redistribute themselves throughout the habitat before another sample is collected.
  • by comparing number of marked individuals with number of unmarked in 2nd sample, can estimate population size.
  • the greater the number of marked individuals recaptures the smaller the population.
• measuring abiotic factors


  abiotic factors= non-living conditions in a habitat, have a direct effect on the living organisms that live there. eg: amount of light, water.

  • wind speed= anemometer
  • light intensity= light meter
  • relative humidity= humidity sensor
  • pH= pH probe
  • temperature= temperature probe
  • oxygen content in water= probe
• advantages of using sensors 


  -rapid changes can be detected.

  -human error taking reading reduced.

  -high degree of precision can be achieved.

  -data can be stored and tracked on a computer.