A level Biology B · Edexcel 9BI0 · Topic 10D
Succession
Key points
- Succession is the gradual change in a community over time.
- Primary succession starts on bare ground with no soil (e.g. bare rock, sand dunes); secondary succession starts where soil remains (e.g. after fire).
- Pioneer species (e.g. lichens) tolerate harsh conditions; they weather rock and add organic matter as they die, forming soil.
- Each stage changes abiotic conditions, letting new species colonise and outcompete earlier ones; biodiversity and biomass generally increase.
- The final stable stage is the climax community (in the UK often deciduous woodland).
- Deflected succession happens when human activity such as grazing or mowing stops succession, keeping a habitat like grassland; this is used in conservation management.
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Succession is the gradual, directional change in a community over time. Each group of species alters the conditions around it in a way that makes the area more suitable for others, which often leads to its own replacement.
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