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Ecological SuccessionEcological Succession
Ecological SuccessionEcological Succession
• Ecosystems are constantly changing due to natural and human disturbances
Examples:
• Natural disturbances– Forest fires
• Human disturbances– Clearing a forest for agriculture
Ecological SuccessionEcological Succession
• Succession- orderly, natural changes and species replacements that occur in an ecosystem
– Basically, older organisms die out and new organisms move in, causing further changes in the community
Steps in SuccessionSteps in Succession
1. Grass gets taller and weeds start to grow area looks like a meadow
Steps in SuccessionSteps in Succession
2. Bushes grow, trees appear Different animals enter the area to live
Steps in SuccessionSteps in Succession
3. Less light now reaches the ground Grass slowly disappears
Steps in SuccessionSteps in Succession
4. 30 years later, area will resemble a forest
SuccessionSuccession
• At each stage, different species of plants and animals may be present– Conditions at each stage are suitable for
some, but not others
2 types of Succession2 types of Succession
• Primary and Secondary
• Primary Succession- takes place on land where there are no living organisms– Ex: when lava from a volcano cools and forms
new land
Primary SuccessionPrimary Succession
• Pioneer species- first organisms to occupy new land– Ex: lichens
• Decaying lichens and other pioneer species combine with bits of rock to make soil
Lichen on Lichen on RockRock
Primary SuccessionPrimary Succession
• Seeds move into small patches of soil and begin to grow
Primary SuccessionPrimary Succession
• Primary succession slows down and community becomes stable
• Climax community- a stable, mature community that undergoes little or no species change
Secondary SuccessionSecondary Succession
• Secondary Succession – occurs when community is destroyed or altered but soil is still there– Ex – fire, clear cutting
– Regrows to mature, stable community called climax community
– May take less time than primary succession
Forest Fire RegrowthForest Fire Regrowth
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