IB ESS HL 2.5.6 Secondary Succession Questions
Explain secondary succession after disturbance by tracing retained soil and biological legacies through pioneer growth and later community change.
- Syllabus
- First assessment 2026
- Course
- ESS HL
- Level
- HL
Exam points
- identify or outline secondary succession after a disturbance such as deforestation or wildfire, recognising that soil or biological legacies remain
- explain the sequence from disturbance through pioneer colonisation and changing abiotic conditions to later communities, using retained seeds, soil nutrients, ash, competition and climax development where supported
IB ESS HL 2.5.6 Secondary Succession Questions 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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