2.5.5—Primary success HLion
- Syllabus
- First assessment 2026
- Objective
- 2.5.5
- Level
- HL
Identify Primary Succession by the Absence of Soil
Primary succession starts on newly exposed substratum with no soil and no established community.
Pioneers tolerate harsh conditions and help build soil from mineral particles and organic matter. The decisive test is starting soil, not how recently the site formed.
A retreating glacier exposes bare moraine; lichens and microbes begin soil formation before larger plants establish.
This is primary succession because the starting surface lacks soil; nearby colonists do not change that classification.
‘New’ alone is insufficient—check whether soil or biological legacies remain.