Primary Succession

Edexcel A-level BiologyThe Nature of EcosystemsLesson 7 of 39

Succession is the gradual change in the community of an area over time. Primary succession starts on bare ground where there is no soil and no previous life, such as bare rock after a glacier retreats, cooled volcanic lava or newly formed sand dunes.

The stages are:
• Pioneer species colonise first. On bare rock these are usually lichens and algae. They are adapted to harsh conditions: they tolerate drying out and extreme temperatures, need few nutrients and spread by spores carried on the wind. Lichens slowly break down the rock surface (weathering).
• When pioneers die, they are decomposed and form humus. Mixed with weathered rock particles, this makes a thin, simple soil that holds water and mineral ions.

More in The Nature of Ecosystems

• Community
• Abiotic Factors
• Biotic Factors
• Biosphere
• Climax Community
• Secondary Succession
• Case Study: Sand Dune Succession
• Light

All 39 lessons in The Nature of Ecosystems · All Edexcel A-level Biology topics