Sampling methods Flashcards
What are the four sampling methods?
Pooters, sweepnets, pitfall traps and quadrants
How do pooters work?
The user sucks through the mouthpiece. The insects are sucked into the holding chamber via the inlet tube. There is a fine mesh at the end of the tube you suck to stop you from sucking the insects into your mouth.
What are the ad advantages and disadvantages of using the pooter sampling technique?
Advantage: you get to find out which species are actually present
Disadvantage: you have to be systematic about your sampling in order to get representative results. It is difficult to get ideas of numbers.
Where are sweepnets used and how do they work?
Sweepnets are used in long grass or moderately dense woodland where there are a lot of shrubs. You literally sweep the net through the grass/woodland and record what is in your net.
How do pitfall traps work?
A pitfall trap consists basically of a glass, plastic or metal container, sunk into the soil so that the mouth is level with the soil surface. Many ground dwelling animals fall into the trap and are unable to escape (although some do). To get a more representative sample and ensure no insects can escape, sometimes a mixture of ethanol or detergent and water is placed at the bottom of the trap to kill the samples and therefore stop them from escaping.
What are quadrats?
Quadrats are square frames that typically have a side length of 0.5m
How do quadrats work?
You count how many of each species are within the quadrat and can then use that to estimate the total number of the species.
For example: if an average of 4 dandelion plants are found in each 0.25m squared quadrat, a scientist could estimate that 16 dandelion plants would be find in each metre squared and 16,000 dandelion plants in a 1000m squared field.
What is a population?
A population is the total number of individuals of the same species that live in a certain area.
Example: the number of field mice in a meadow
