Required practical 9 - Field investigation

Question 1

How would you use random sampling to estimate the population size of a plant species?

Answer 1

• Create a grid of the area using tape measurers.
• Use a random number generator to generate coordinates.
• Set down quadrats at coordinates and record number of required species within quadrat.
• Repeat using many sampling sites.
• Estimate population size: )Area sample / total area) x number of plants species counted

Question 2

Why would you use a random number generator to determine coordinates?

Answer 2

To avoid bias and obtain representative results.

Question 3

What is random sampling?

Answer 3

Sampling technique in which each sample has an equal probability of being chosen.

Question 4

What is systematic sampling?

Answer 4

Sampling technique where there is a fixed, periodic interval between consecutive samples.

Question 5

Describe how you would use continuous sampling to investigate the effect of an abiotic factor in the distribution of a plant species

Answer 5

• Create hypothesis on the effect of the change in an abiotic factor on the distribution of a plant species.
• Lay tape measurer along an area with an ecological gradient.
• Place quadrat at start and count number of plants.
• Repeat at 5m intervals along the transect line.
• Record the value of the abiotic factor such as light intensity at each sampling site.
• Plot a graph of plant numbers (y) against the abiotic factors (x).