Ecological Succession

Notes

Ecological Succession

• Ecosystems are constantly changing in response to natural and human disturbances.

• As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.

Definitions• Ecological Succession – a

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

• Includes - slow changes in the physical environment or sudden natural disturbances from human activities like clearing forests.

• Primary Succession – On land, succession that occurs on surfaces where no soil exists.

• Colonization of new sites by communities of organisms – takes place on bare rock

• Pioneer species – the first species to inhabit an area.

• Ex. Lichens are the first to colonize lava rocks

Primary Succession – Ex. #1• When volcanic

eruptions build new islands or cover land with lava rock or volcanic ash.

Primary Succession – Ex #2

• When bare rock is exposed as glaciers melt.

PRIMARY SUCCESSION

• Secondary Succession – when a disturbance of some kind changes an existing community without removing the soil – takes place on existing soil.

Secondary Succession – Ex. #1

• When land cleared and plowed for farming is abandoned.

Secondary Succession – Ex. #2

• When wildfires burn woodlands.

SECONDARY SUCCESSION

• Climax Community –a mature, stable community that undergoes little or no succession.

• Succession Clip and Mt. Saint Helens

 • http://www.google.com/imgres?imgurl=http://www.darkfaery.com/

mount%2520st%2520helen%2520before%2520and%2520after.jpg&imgrefurl=http://www.darkfaery.com/Mount%2520St.%2520Helens.htm&usg=__yUnJj8r4wAXfOdGlLLJN7T8PM6w=&h=664&w=1065&sz=94&hl=en&start=4&itbs=1&tbnid=_tU5P1gCB42ZZM:&tbnh=94&tbnw=150&prev=/images%3Fq%3Dmount%2Bst.%2Bhelens%2Bbefore%2Band%2Bafter%26hl%3Den%26safe%3Dactive%26gbv%3D2%26tbs%3Disch:1

You tube clip: http://www.youtube.com/watch?v=4-5kJmrLWRQ

http://www.youtube.com/watch?v=3eG_O1wEJ40