Changes in Ecosystems: Ecological Succession

Succession is… a series of predictable changes in types of species that occurs in a community over time Two types: primary and secondary

Primary Succession Occurs on surfaces where no soil exists Events which expose bare rock: volcanoes flooding Glaciers

Begins with arrival of organisms such as lichens that do not need soil Lichen are a pioneer species (first organisms to arrive in an area like lichen)

Primary Succession Soil starts to form as lichens decompose and weathering and erosion break down rocks into smaller pieces Over time, the soil layer thickens, and grasses, wildflowers, and other plants begin to take over

Primary Succession

Secondary Succession started by an event (e.g. forest fire, harvesting, hurricane) that destroys most of an ecosystem  occurs in an area with soil that contains seeds, spores, roots, or other plant parts

Secondary Succession happens faster and has different pioneer species than primary succession http://www.ux1.eiu.edu/~cfruf/bio3002/secondary_succession.htm

Climax Community Mature community made up of plants and animals Does not always mean big trees tall grasses in prairies cacti in deserts Species can continue to change in response to climate and other factors