1. Changes in Ecosystems: Ecological Succession

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

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

5. 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)

6. 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

7. Primary Succession

8. 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

9. Secondary Succession
happens faster and has different pioneer species than primary succession

10. 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