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

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

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

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.

Please complete Assessment section 4 pg 733 1abc