Field investigation

• How would you use random sampling to estimate the population size of a plant species? ● Create a grid of the area using tape measures ● Use a random number generator to generate coordinates ● Set down quadrat at coordinates and record number of required species within quadrat ● Repeat using many sampling sites ● Estimate population size: area sampled / total area x number of plants species counted
• Why would you use a random number generator to determine coordinates? To avoid bias and obtain representative results
• What is random sampling? Sampling technique in which each sample has an equal probability of being chosen
• What is systematic sampling? Sampling technique where there is a fixed, periodic interval between consecutive samples
• Describe how you would use continuous sampling to investigate the effect of an abiotic factor in the distribution of a plant species ● Create hypothesis on the effect of the change in an abiotic factor on the distribution of a plant species ● Lay tape measure along an area with an ecological gradient ● Place quadrat at start and count number of plants ● Repeat at 5m intervals along the transect ● Record the value of the abiotic factor eg. light intensity at each sampling site ● Produce a graph of plant numbers (y) against the abiotic factor (x)