IB ESS HL 2.5.6 Secondary Succession Question Bank
Explain secondary succession after disturbance where soil or biological legacies remain.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify the successional stage or disturbance response
- trace community and abiotic changes through time
- justify the interpretation using ecological evidence
2.5.6—Secondary succession question 1
[Maximum number: 3]
Figure:Fact file on giant sequoia trees
Figure: Fact file on giant sequoia trees: Fact file on giant sequoia trees
Giant sequoias are legally protected in California. They are adapted to periodic fire; historically, wildfires have occurred in California every 6-35 years. They have thick bark up to 46 cm to protect the core from fire. Fire dries cones and releases seeds, while ash creates nutrient-rich soils. Seeds can also be released by the long-horned beetle, which lays eggs in cones; larvae eat the cone, releasing seeds.
Describe the process of succession after a wildfire has occurred in the forest.
a. removal of trees open the canopy, allowing sunlight to reach the forest floor/removing limiting factor of shade conditions;
b. burning trees produce nutrient-rich ash increasing soil fertility;
c. growth of seeds which survived the fire/released by the fire/were blown/carried in from surrounding unburnt areas;
d. rapid growth of annual plants / in early stages of succession there are pioneer species/r-selected species;
e. replaced in time by slower growing species / change from r-selected species to K-selected species;
f. climax community of (coniferous) forest reached after many years;
g. large time delay due to slow growth of climax community;
h. each new sere changes the abiotic conditions, allowing for different plants to survive / as conditions change some species will outcompete/replace others;
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