BRAINCAKESuccession
Succession is the progressive change in a community of organisms in an area over time. One community is gradually replaced by another until a stable community is reached.
The stages
• Pioneer species are the first organisms to colonise. They are adapted to harsh abiotic conditions, for example they can fix nitrogen, tolerate drought or extreme temperature, or produce many seeds that spread easily.
• Each stage is called a seral stage, and the whole sequence is a sere.
• Each community changes the abiotic conditions. As organisms die and decompose, they add humus to the soil, making it deeper, better at holding water and richer in minerals. This makes the environment more suitable for other species, which then outcompete the earlier ones.
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Key terms in this lesson
- community
- All the populations of different species living in the same area at the same time.
More in Ecosystems
- The Nitrogen Cycle
- Nitrogen-Fixing Bacteria
- Nitrification and Denitrification
- The Carbon Cycle
- Primary Succession
- Secondary Succession
- Deflected Succession
- Sampling Distribution and Abundance
All 21 lessons in Ecosystems · All OCR A-level Biology topics