1. Ecological Succession
Changes in Ecosystems
Ecological Succession

2. Definition of Ecological Succession
Transition in species composition taking place in a given area over ecological time
Natural, gradual changes in the types of species that live in an area
The gradual replacement of one plant community by another through natural processes over time

3. Primary Succession
Begins in a place without any soil (parent material – bedrock to start)
Sides of volcanoes
Landslides
Flooding
Glacier melt
Starts with the arrival of living things such as lichens that do not need soil to survive
Called PIONEER SPECIES

4. A Candidate for Primary Succession

5. Another Candidate for Primary Succession

6. 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

7. Primary Succession

8. Primary Succession
Simple plants like mosses and ferns can grow in the new soil

9. Primary Succession The simple plants die, adding more organic material
The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

10. Primary Succession
These plants die, and they add more nutrients to the soil
Shrubs and trees can survive now

11. Primary Succession
Insects, small birds, and mammals have begun to move in
What was once bare rock now supports a variety of life

13. 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
Forest fires
Floods, hurricanes, tsunamis
Human destruction – clear cutting, abandoned agriculture fields

14. Secondary Succession Begins

16. Secondary Succession
Ecosystems undergo secondary succession following artificial or natural disturbance such as a forest fire or farming.
In 1850, Connecticut was almost entirely open land cleared for farming or timber. Today, Connecticut has been mostly reforested through the process of secondary succession as farming has left the state since the 1800's.

17. Climax Community
An ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.
A climax community is the final stage of succession, remaining relatively unchanged until destroyed by an event such as fire or human interference.
Does not always mean big trees
Grasses in prairies
Cacti in deserts

18. Succession
In the background are the trees of an eastern hardwood forest. This area has not been cleared in over fifty years. These trees represent the climax community for the rainfall, temperature and soil of this area.

19. Succession
The area on the right, behind the fence, in front of the trees, has not been mowed in about ten years. Shrubs and evergreen trees have moved in. These are the intermediate species.

20. Succession
The area in the foreground, in front of the barbed wire fence, has been mowed within the last year. The plants are all annuals or herbaceous perennials. These are the pioneer species.