QUESTION 3 (4 marks)
A glacier has retreated, leaving a large amount of gravel, small rocks, sand and mud.
a) Explain the steps of succession that would occur if the glacier continues to retreat.
[3 marks]
b) Identify the type of ecological succession.
[1 mark]
QCAA guide · typeset solution
QCAA sample response and mark allocation
3a) | Pioneer species, such as lichens will begin the process of soil formation by breaking down the substrate and adding organic material through their own death and decay. This will allow new species to colonise/inhabit the area, changing the community composition. The community composition will continue to change over time until a climax community is established. | • explains - pioneer species’ role in establishing soil [1 mark] - changes in community composition [1 mark] - establishment of a climax community [1 mark] |
3b) | Primary succession | • identifies primary succession [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.