Ecological Succession

A series of predictable changes that occur in a community over time.

Ecosystems change over time especially after disturbances, as some species die out and new species move in.

Ecological model: a model scientists use to predict changes that will happen in an ecosystem that occurs over a long distance or over a long period of time.

number of different species present typically increases.

How many changes over time can you find?

Primary Succession Succession that begins in an area with no remnants of an older

community

No life present

only rock and eventually soil

Occurs at a very slow rate

Examples:

retreating glaciers

emerging islands

formation of new lake

Secondary Succession

The existing community almost completely destroyed by disturbances.

Proceeds faster than primary succession, because soil is present.

As a result, new and surviving vegetation can regrow rapidly, reach climax community faster

Examples:

Fire

Floods

Bulldozers

Climax Community Last stage of succession

Succession does not always follow the same stages for every community.

Healthy ecosystems will often reach the original climax community.

Example: succession caused by storms and forest fires

Some ecosystems, due to extensive human caused disturbances, may never fully recover

Examples: succession due to clearing and farming of tropical rainforests (deforestation)

Caused by pollution