4.3: Succession

Ecological Succession gradual changes in the types of species that live in an area ~ changes until it reaches its stable ecosystem

Primary Succession begins in a place without soil (bare rock) ~ glacial retreat; volcanic eruption volcanic rock – NOT soil!

primary succession begins with a pioneer species – group of organisms that begin the soil-building process usually lichens (rootless plants)

soil starts to form as lichens and the forces of weathering break down rocks into smaller pieces when lichens die, they decompose and add small amounts of organic matter to make soil

simple plants like mosses and ferns can grow in the new soil

simple plants die, adding more organic material soil layer thickens then grasses, wildflowers, and other plants begin to take over

these plants die, and they add more nutrients to the soil so shrubs and trees can survive

Climax Community stable group of plants and animals that is the end result of the succession process does NOT always mean big trees Examples: grasses in prairies; cacti in deserts

typical hardwood forest succession Starts with BARE ROCK – no soil initially.

Secondary Succession begins in a place that already has soil and was once the home of living organisms occurs faster and has different pioneer species than primary succession Examples: after forest fires; abandoned farms

Starts WITH soil – not bare rock!