Sampling Methods
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What is the purpose of using a point quadrat over a grid quadrat.
If the plants are tall, as they could be flattened by the grid quadrat.
Why would a Tullgren funnel be used?
To sample a population of mobile animals in leaf litter.
How would a Tullgren funnel be used?
A sample of leaf litter is placed on a mesh with a bulb above it. Invertebrates are repelled by the light and heat of the bulb. So the invertebrates move through the mesh into the collecting pot.
Explain 1 way using a Tullgren funnel can be standardised.
Same time left in position each time. Same volume of leaf litter added each time.
Explain 1 limitation of using a Tullgren funnel
Only species repelled by the light or heat of the bulb will be collected. Some organisms may die due to the bulb’s heat. Some organisms may be too large to pass through the mesh.
Name the two methods to sample insects in long grass or the air.
Suction samplers and sweep nets.
Explain 1 way using a suction sampler can be standardised.
Same amount of time collecting samples. Same size area covered with sampler. Same flow rate of suction.
Explain 1 limitation of using a suction sampler.
Some flying organisms will fly away from the suction. Some organisms may not be dislodged from grass.
Explain 1 way using a sweep nets can be standardised.
Same number of sweeps Same length of sweeps Same area sampled
Explain 1 limitation of using a sweep net.
Mobile/flying insects may escape.
Why would a beating trap be used?
To collect a sample of insects from trees
How would a beating trap be used?
A net is held under a tree branch and the tree branch is hit. This will dislodge organisms who will fall into the net underneath.
Explain 1 way using a beating traps can be standardised.
Same force of hits. Same number of hits Same thickness of branch
Explain 1 limitation of using a beating trap.
Higher branches cannot be reached. Flying samples may escape.
Why would a aerial insect net be used?
To sample flying insects
Explain 1 way using an aerial insect net can be standardised.
Same number of sweeps. Same length of sweeps. Same area size sampled.
Explain 1 limitation of using an aerial insect net.
Insects could fly out again!
Why would a light trap be used?
To sample night flying insects- like moths and butterflies
How would a light trap be used?
Moths are attracted to the lamp. Moths go into the container underneath.
Explain 1 way using a light trap be standardised.
Same wavelength of lightbulb. Same amount of time left on. Same weather conditions and seasons.
Explain 1 limitation of using a light trap
Only catches insects in the flying stage of their lifecycle
Why would soil flooding, soil pit extraction or a soil auger be used?
Sampling earthworms.
How are earthworms extracted by soil flooding?
The soil is saturated with an irritant. The worms come to the surface to get away from the irritant. Earthworms are collected.