Ecological Succession
4-2 What Shapes an Ecosystem?
Ecosystems Change
• Ecosystems are constantly changing in response to natural and human disturbances.
• As an ecosystem changes, older inhabitants die out and new organisms move in. – This is ecological succession.
Primary Succession
• Succession that occurs on surfaces where no soil exists.
• Occurs on the surfaces that are left bare after– Volcanic eruptions – Glaciers melting
• Pioneer species – the first species to populate an area– Often lichens because they can grown on bare
rock
Lichens
Primary Succession
Secondary Succession
• Change in an ecosystem after a disturbance (leaves soil behind)– Examples: after wildfires, clear-cutting a forest,
natural disasters• Ecosystems usually recover from natural
disasters, but may not always recover from long-term human disturbances.
Secondary Succession
Boreal Forest Biome - Succession
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