Changes in Ecosystems: Ecological Succession

Definition: Natural, gradual changes in types of species living in area; can be primary or secondary Succession based on changes in plant communities over time.

Primary Succession Begins in place w/o soil Sides of volcanoes where lava flow has occurred. Landslides Flooding Step 1: Starts w/ arrival of living things (ex: lichens) - do not need soil to survive Called PIONEER SPECIES

http://botit.botany.wisc.edu http://www.saguaro-juniper.com/

Primary Succession Step 2: Soil starts to form Weathering & erosion break down rocks into smaller pieces Lichens die & decompose - adding small amounts of organic matter (N,P,C) to the rock to make soil

http://www.life.uiuc.edu

Primary Succession Step 3: Simple plants (mosses & ferns) grow in the new soil http://www.uncw.edu http://uisstc.georgetown.edu

Primary Succession The simple plants die, adding more organic material The soil layer thickens, and grasses, wildflowers, and other plants begin to take over http://www.cwrl.utexas.edu

Primary Succession Step 4: Lower plants die, adding more nutrients to the soil Step 5: Shrubs and tress can survive now http://www.rowan.edu

Primary Succession Insects, small birds, and mammals have begun to move in What was once bare rock now supports a variety of life http://p2-raw.greenpeace.org

LAVA FLOWS & PRIMARY SUCCESSION

Secondary Succession Begins in a place that already has soil and was once the home of living organisms Occurs faster because the land doesn’t have to build up the soil. has different pioneer species than primary succession Very often occurs after natural disasters such as forest fires, volcanic eruptions involving the spewing of ash.

The Cedar Wildfire was the biggest wildfire in California The Cedar Wildfire was the biggest wildfire in California. It was ignited was caused by a hunter when he lit a flammable shrub called chapparral. These fires burned down about 280,000 acres of land. 2 years after the fire…..

Mt. St. Helens Washington 1980’s

http://www.geo.arizona.edu

http://www.ux1.eiu.edu

Climax Community A stable group of plants and animals that is the end result of the succession process Climax Community!

Climax Communities are NOT always big hardwood trees such as oaks and maples!!! Desert Climax Community Beach Climax Community http://www.agen.ufl.edu Taiga Climax Community Grasslands Climax Community