Ecological Succession

B 12.F Describe how environmental change can impact ecosystem stability. B 11.D DESCRIBE HOW EVENTS AND PROCESSES THAT OCCUR DURING ECOLOGICAL SUCCESSION CAN CHANGE POPULATIONS AND SPECIES DIVERSITY.

Ecological Succession  Gradual change in living communities that follows a disturbance.

Two types of succession  Primary succession  Secondary succession

Primary succession  takes place in an area that is devoid of life — e.g., a lava flow, rocky mountaintop, or an area of land scraped clean by a glacier.

Primary Succession Characteristics  Pioneer organisms that require little or no soil (lichens and mosses) invade first.  As they grow and die, soil builds up and larger plants such as grasses can now grow.  The growing grasses shade out the lichen and moss communities, which die out.  The process continues with each community being replaced — bushes, small trees, and then larger trees

Primary Succession  Primary Succession – occurs on surfaces where no soil exists.

Primary Succession  Pioneer species - the first species to populate an area.  Example: After a volcanic eruption lichens grow on the rock helping to break it up.  When they die, their remains add organic matter to the soil.

Primary Succession

Secondary Succession  Occurs following a disturbance that destroys a community without destroying the soil.

Secondary Succession  Certain plants have adapted to regular cycles of fire and re- growth. Their seeds won’t sprout unless exposed to fire.

Climax Community  A mature stable community that does not undergo further succession.

Pictures  N04/ N04/  Video  PlQW74EI&list=PL3792C3CB39C22B9C PlQW74EI&list=PL3792C3CB39C22B9C Volcano - DdardM DdardM