Sampling Techniques Flashcards
Quadrant
Standardisation
Limitations
Same size quadrats
Based on human eye- some could be overlapping so not counted for
Pond net
standardisation
Limitaion
Number of sweeps
Length of sweep
Mobile species are hard to catch
Accurate standardisation is hard
Kick sampling
Standardisation
Limitaion
Number and length of kicks
Mesh size of net
Standardisation if difficult
Buried organisms and those fixed to rocks won’t be collected
Swimming organisms can escape
Surber sampling
Standardisation
Limitaion
Same are of frame and mesh
Can only be used in water flow that is fast enough to carry organisms into the net
Large organisms may escape
Plankton net
Standardisation
Limitation
Drag for same length of time
Drag for same distance
Drag at same depth of water
Nets with coarse mesh sizes may miss smaller plankton
Fine meshes can be clogged and prevent water flow
Sweep net
Same number of sweeps for a set distance
Length of sweep the same size
More motile organisms may escape
Aerial insect net
Some organisms could be hurt
Success depends on the ability of the researcher
Hard to standardise
Colonisation media
Same size of colonisation media
Not all species monitored
Not possible to get accurate population as proportion that colonised the media is unknown
Pitfall traps
Leave traps for the same length of time
Organisms below the surface won’t be counted
Some repelled by the killing fluid
Organisms may eat each other
Cover animals are most lightly to be caught
Beating trays
Select branches of the same thickness
But branches with same forces
Difficult to hit branches with same force
Some species may not move/ dislodge
Some will fly away
High branches can’t be hit
Light trap
Leave traps for same length of time
Trap at same height
Power of light same
Moths only fly in adult phase.
Weather and seasons may affect flying organisms
Different species attracted to different power, wavelength
Tullgren funnel
Same volume of samples
Leave tunnel of for same length of time (24 hrs)
Only species repels by light collected
Some organisms will die due to heating before collected
Pooter/motor driven suction sampler(aerial)
Power of motor
Time at which the suction sampler is on
Height of suction sampler tube
Some invertebrates may not be caught due to the noise of the sampler
Soil flooding
Count works for a set time
Solutions may not penetrate deeper worms-not counted
Some escape down or across
Soil pit extraction
Sample volume
Time taken sorting through the soil
Smaller worms may be over looked
Digging may cause worms to run away
