Changes in Ecosystems: Ecological Succession · What is Ecological Succession? •A series of...
Transcript of Changes in Ecosystems: Ecological Succession · What is Ecological Succession? •A series of...
Changes in Ecosystems:Ecological Succession
What is Ecological Succession?
• A series of predictable changes that occur in a community over time due to events in the environment.
• The changes may happen suddenly or very slowly.
Primary Succession
• The series of changes that occur in an area where no ecosystem previously existed
Primary Succession
• Glacier retreat: An area of rock uncovered by a melting ice sheet
• New island formed by the eruption of an undersea volcano
• Side of volcano
First, lichensthat do not need soil to survive grow
on rocks
Lichens break down rock to form soil.
A combination of
fungus and algae
Primary Succession
• Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
• When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil
Primary Succession
• The first species to populate an area are the pioneer species.
• They break up rock and begin soil formation.
Primary Succession
• Simple plants like mosses and ferns can grow in the new soil
Primary Succession
• The simple plants die, adding more organic material (nutrients to the soil)
• The soil layer thickens, and grasses, wildflowers, and other plants begin to take over
Primary Succession
• These plants die, and they add more nutrients to the soil
• Shrubs and trees can survive now
Primary Succession
• Insects, small birds, and mammals have begun to move into the area
• What was once bare rock, now supports a variety of life
Larger plants with deep roots continue to break up rock and make more soil.A diverse forest ecosystem takes hundreds of years
1. Ground is solid rock
2. Rock begins to weather, pioneer species begin
3. Weeds and grasses grow in soil -making thicker, richer soil
4. Eventually trees and shrubs sprout - community of organisms develops
Stages of Primary Succession
Secondary Succession
• Begins in a place that already has soil and was once the home of living organisms – Example: after forest fires
• Occurs faster than primary succession
Human disturbances:•A pasture abandoned by a farmer•Logging, or mining
Examples of Secondary Succession
Natural disturbances:
Fires, hurricanes, and tornadoes
1. Varies depending on the type of disturbance
2. A disturbed area returns to its previous condition
3. Soil and seeds are already present
4. Organisms move in
5. There is a quick recovery of the ecosystem
Stages of Secondary Succession
Climax Community
• A stable group of plants and animals that is the end result of the succession process
• Does not always mean big trees
–Grasses in prairies
–Cacti in deserts
A Succession Review
Primary Secondary
What
happens to
the
ecosystem
Length of
Time
Example
Creates a new ecosystem
Restores a previous
ecosystem
May take a long time to reach equilibrium
A shorter time to reach equilibrium
New land created by volcanic eruption
An area destroyed by fire