Sampling Organisms Flashcards

All 6 cards in this deck

What are the steps to estimate the total number of a species in an area using quadrat data?
e.g. counts of 3, 4, 5 and 4 daisies in four $1\text{ m}^2$ quadrats in a $200\text{ m}^2$ field

1. Place quadrats randomly and count the organisms in each: 3, 4, 5, 4.
2. Calculate the mean per quadrat: $16 \div 4 = 4$ per $1\text{ m}^2$.
3. Multiply the mean by the total area: $4 \times 200 = 800$ daisies.

What are the steps to place quadrats randomly in a field?
e.g. sampling daisies in a grassy field

1. Lay two tape measures at right angles to make a grid.
2. Use a random number generator to get pairs of coordinates.
3. Place the quadrat at each coordinate and count the daisies — random placement avoids bias and gives a representative sample.

What are the steps to carry out a belt transect?
e.g. how seaweed changes up a rocky shore

1. Lay a tape measure in a straight line along the environmental gradient (low shore to high shore).
2. Place a quadrat at regular intervals along the tape, e.g. every $2\text{ m}$.
3. Record the abundance of each species in every quadrat, plus abiotic factors such as light or water.

What are the steps to estimate the percentage cover of a species in a quadrat?
e.g. moss in a quadrat divided into 100 small squares

1. Count the small squares the species covers, counting a square if it is more than half covered: 35 squares.
2. Percentage cover $= \frac{35}{100} \times 100 = 35\%$.

True or false? The type of food used to bait a pitfall trap can affect the number of different invertebrates caught.

True. One type of food may attract only some invertebrates, so the sample is not representative.

What does a kite diagram show?

How the abundance of each species changes with distance along a transect.