21.4 Changes in communities, page 731

1. 21.4 Changes in communities, page 731 • Key Concepts: How do primary and secondary succession differ? • Key terms: succession, primary succession, pioneer species, secondary succession

2. Succession • A series of predictable changes that occur in a community over time

3. Primary succession • Primary succession is the series of changes that occur in an area where no soil or organisms exist • Like a new island recently formed or a rock uncovered recently by ice • Pioneer species – the first species to populate an area • Usually mosses or lichens (fungi and algae growing in a symbiotic relationship) • Break up the rocks, then die and enrich the soil • Then plants come in and grow

4. Secondary succession • A series of changes that occur in an area where the ecosystem has been disturbed, but where soil and organisms still exist • Fires, hurricanes, tornadoes • Farming, logging, mining • Occurs where an ecosystem already exists • Occurs more rapidly than primary.

5. Please complete • Assessment section 4 pg 733 • 1abc