Ecology of a habitat

Question 1

List 3 abiotic factors.

Answer 1

Light intensity, humidity, temperature, day length, rainfall, water supply.

Question 2

List 3 biotic factors.

Answer 2

Predation, competition for resources, disease

Question 3

How is percentage cover calculated?

Answer 3

Use a quadrat with squares. Count how many squares the required species is present in. Only count a square if more than half of the square is covered.

Question 4

Outline the procedure to randomly sample at 2 different sites.

Answer 4

1. Choose an area to take samples from. Use a random number generator to
   generate 20 sets of random coordinates.
2. Use two tape measures to create a set of axes off which coordinates can be
   read.
3. Place the quadrat at each of the coordinates, placing the bottom left corner on
   the coordinate every time. Record the percentage cover for the chosen
   species.
4. After sampling at all 20 coordinates, repeat steps 1-3 at another different site.

Question 5

How can results from 2 sites with random sampling be compared?

Answer 5

Use the statistical T test, which compares two means.

Question 6

In which type of area is a transect the appropriate sampling method?

Answer 6

A site where there is a clear ecological gradient.

Question 7

Outline the procedure to sampling using a transect.

Answer 7

1. Lay a tape measure along the ecological gradient.
2. Place a quadrat at the 0m mark and count the number of organisms,
   or find percentage coverage. Also take a measurement of the
   independent variable at the site, eg. light intensity.
3. Repeat step 2, placing the quadrat every 2 metres down the transect
   to take samples until you have taken 10 along the 20m line.
4. Repeat steps 1-3 in different areas at the site with the same
   environmental gradient being investigated.

Question 8

Which statistical test is suitable for correlating the results from a transect line?

Answer 8

Spearman’s rank coefficient.