Changes in Ecosystems:Changes in Ecosystems:

Ecological SuccessionEcological Succession

SuccessionSuccession Definition: Definition:

Natural, gradual changes in the types of Natural, gradual changes in the types of species that live in an area; can be species that live in an area; can be primary or secondary primary or secondary

The gradual replacement of one plant The gradual replacement of one plant community by another through natural community by another through natural processes over timeprocesses over time

Primary SuccessionPrimary Succession

Begins in a place without any soil Begins in a place without any soil Sides of volcanoesSides of volcanoes LandslidesLandslides FloodingFlooding

Starts with the arrival of living things Starts with the arrival of living things such as lichens that do not need soil to such as lichens that do not need soil to survivesurvive Called Called PIONEER SPECIESPIONEER SPECIES

http://botit.botany.wisc.edu

http://www.saguaro-juniper.com/

Primary SuccessionPrimary SuccessionSoil starts to formSoil starts to form

Lichens and the forces of weather Lichens and the forces of weather and erosion help break down rocks and erosion help break down rocks into smaller piecesinto smaller pieces

When lichens die, they decompose, When lichens die, they decompose, adding small amounts of organic adding small amounts of organic matter to the rock to make soil matter to the rock to make soil

http://www.life.uiuc.edu

Primary SuccessionPrimary Succession Simple plants like mosses and ferns can Simple plants like mosses and ferns can

grow in the new soil grow in the new soil

http://uisstc.georgetown.edu

http://www.uncw.edu

Primary SuccessionPrimary Succession The simple plants die, adding more The simple plants die, adding more

organic materialorganic material The soil layer thickens, and grasses, The soil layer thickens, and grasses,

wildflowers, and other plants begin to wildflowers, and other plants begin to take over take over

http://www.cwrl.utexas.edu

Primary SuccessionPrimary SuccessionThese plants die, and they add These plants die, and they add

more nutrients to the soilmore nutrients to the soil• Shrubs and trees can survive nowShrubs and trees can survive now

http://www.rowan.edu

Primary SuccessionPrimary Succession Insects, small birds, and Insects, small birds, and

mammals have begun to move inmammals have begun to move inWhat was once bare rock now What was once bare rock now

supports a variety of life supports a variety of life

http://p2-raw.greenpeace.org

Secondary SuccessionSecondary Succession Begins in a place that already has soil Begins in a place that already has soil

and was once the home of living and was once the home of living organisms organisms Occurs faster and has different pioneer Occurs faster and has different pioneer

species than primary succession species than primary succession • Example: after forest firesExample: after forest fires

http://www.geo.arizona.edu

http://www.ux1.eiu.edu

http://www.agen.ufl.edu

Climax CommunityClimax CommunityA stable group of plants and A stable group of plants and

animals that is the end result of animals that is the end result of the successionthe succession processprocess Does not always mean big treesDoes not always mean big trees Grasses in prairiesGrasses in prairies Cacti in desertsCacti in deserts