How Ecosystems Change: Ecological Succession ES Textbook, Chapter 5 Pages

Ecological Succession Is a gradual process of change and replacement of some or all of the species in a community. Can take hundreds or thousands of years Each new community makes it harder for the previous one to survive.

Primary Succession The type of succession that occurs on a surface where no ecosystem existed before, such as on rocks or sand dunes.

Secondary Succession Is more common than primary succession. Occurs on a surface where an ecosystem has previously existed. Occurs in ecosystems that have been disturbed or disrupted by humans or by natural disasters such as storms, floods, earthquakes, and volcanoes.

Example of Secondary Succession 1980 – Mt. St. Helens erupted in Washington State. It was one of the worst volcanic disasters because more than 44,460 acres of forest were burned and flattened by hot ash and volcanic debris. Have a look: ount+st.+Helens&fq_grade=PK&fq_grade=PS ount+st.+Helens&fq_grade=PK&fq_grade=PS

Secondary Succession (cont.) After the eruption, plants began to colonize the volcanic debris. Such plants are called pioneer species. Pioneer species – the first organisms to colonize any newly available area and begin the process of ecological succession.

Secondary Succession (cont.) Over time, pioneer species will make the new area habitable for other species. Grasses

Climax Community A final and stable community.

Fire and Secondary Succession Natural fires, caused by lightening, are a natural cause of secondary succession. Jack Pine Tree – a species of tree that can release their seeds only after they have been exposed to the intense heat of fire.

Old-field Succession Another example of secondary succession Old-field succession occurs when farmland is abandoned. 12

Old Field Succession 3 4 5

Primary Succession On new islands created by volcanic eruptions, areas exposed when a glacier retreats, or any other surface that has not previously supported life. Much slower than secondary succession because no soil. It takes several hundred to several thousands of years to create fertile soil.