QUESTION 133 (5 marks)
Two similar abandoned grasslands initially retain soil and seed banks. One experiences a major flood every six years; the other does not. Floods remove most woody seedlings but leave soil and many grass roots. After 30 years, the frequently flooded site remains grass-dominated while the other has extensive woodland.
a) Identify the initial succession type at both sites and justify. [2 marks]
b) Explain how recurrent flooding could account for the difference after 30 years. [3 marks]
Practice marking scheme
Answer
Both began secondary succession. Repeated removal of woody seedlings can maintain an earlier grass-dominated stage; succession need not reach the same late community under different disturbance regimes.
Working
Soil retained at the start identifies secondary succession at both sites. Frequent floods repeatedly reduce establishing woody plants, while surviving grass roots allow rapid regrowth. The conditions and disturbance frequency differ, so the grass-dominated outcome need not indicate that time alone was insufficient or that succession had never begun.
Marking criteria
- Identifies secondary succession at both sites. [1 mark]
- Uses retained soil as the justification. [1 mark]
- Identifies repeated removal of woody seedlings. [1 mark]
- Links surviving roots/rapid grass recovery to continued grass dominance. [1 mark]
- Explains that repeated disturbance can interrupt or reset progression to a later community. [1 mark]
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
View the QCAA syllabusCompare your working with the guide above.