Ecological succession

It is necessary to understand about the succession which happens in the surroundings

1. Submitted by: Tejaswini Uppuluri Jr.M.Sc Seed Science and Technology . S ubmitted to: Jayaprakash Nidugundi Genetics and plant breeding. 3/2/2018 1 PRESENTATION ON ECOLOGICAL SUCCESSION

2. 3/2/2018 2 Contents

3. What actually the succession is? 3/2/2018 3 Ecological Succession: The series of changes in an ecosystem when one community is replaced by another community as a result of changes in biotic and abiotic factors. Occurs in all types of ecosystems i.e., forests, ponds, coral reefs, etc.

4. Ecological succession is characterised by 3/2/2018 4 Increased productivity The shift of nutrients from the reservoir Increased diversity of organisms with increased niche development Gradual increase in the complexity of food webs. 

5. Ecological Succession 3/2/2018 5

6. Causes of plant succession: 3/2/2018 6 Autogenic succession - can be brought by changes in the soil caused by the organisms there. For example, when larger species like trees mature, they produce shade on to the developing forest floor that tends to exclude light-requiring species. Shade-tolerant species will invade the area. Allogenic succession- caused by external environmental influences and not by the vegetation. For example, soil changes due to erosion, leaching or the deposition of silt and clays can alter the nutrient content and water relationships in the ecosystems.

7. Causes of ecological succession 3/2/2018 7 Physical environment Natural disturbance Human disturbance Can result in gradual changes in the physical environment or from sudden disturbance. Clearing land Climate change Introduction of non native species Natural disasters such as volcanic, eruptions, forest fires, hurricanes and floods.

8. Why Does Ecological Succession Occur? 3/2/2018 8 • Because it is the process of life for plants, soil and other living organisms. • Because organisms alter soil structure, chemistry, and microclimates, the species composition of ecological communities constantly changes over time. Succession will continue until the environment reaches it’s final stage…the Climax Community.

9. Mechanism of succession 3/2/2018 9 According to Clements , succession is a process involving several phases: Nudation : Succession begins with the development of a bare site, called Nudation (disturbance). Migration : It refers to arrival o f  propagules . Ecesis : It involves establishment and initial growth of vegetation. Competition : As vegetation becomes well established, grow, and spread, various species begin to compete for space, light and nutrients. Reaction : During this phase autogenic changes such as the buildup of humus affect the habitat, and one plant community replaces another. Stabilization: A supposedly stable climax community forms. [

10. Stages of ecological succession 3/2/2018 10 Pioneer community Intermediate community Climax community

11. Types of succession 3/2/2018 11 Primary succession Seconday succession

12. Types of succession 3/2/2018 12 Primary Succession The process of creating and developing an ecosystem in an area that was previously uninhabited. Examples of uninhabited areas: • Sides of volcanoes • Sites of glacier recession

13. Examples of Primary Succession 3/2/2018 13

14. In this example, a volcanic eruption has destroyed the previous ecosystem. The first organisms to appear are lichens. Mosses soon appear, and grasses take root in the thin layer of soil. Eventually, tree seedlings and shrubs sprout among the plant community. 3/2/2018 14

15. 3/2/2018 15

16. Secondary succession 3/2/2018 16 The disturbed area undergo series of changes similar to primary succession in which smaller, faster growing species are gradually replaced by larger and more stable species. Secondary succession is a never ending process.

17. 3/2/2018 17

18. 3/2/2018 18

19. 3/2/2018 19

20. AN EXAMPLE OF SECONDARY SUCCESSION 3/2/2018 20

21. An example of Secondary Succession by stages : 1. A stable deciduous forest community 2. A disturbance, such as a wild fire, destroys the forest 3. The fire burns the forest to the ground 4. The fire leaves behind empty, but not destroyed, soil 5. Grasses and other herbaceous plants grow back first 6. Small bushes and trees begin to colonize the area 7. Fast growing evergreen trees develop to their fullest, while shade-tolerant trees develop in the understory 8. The short-lived and shade intolerant evergreen trees die as the larger deciduous trees overtop them. The ecosystem is now back to a similar state to where it began. 3/2/2018 21

22. 3/2/2018 22

23. 3/2/2018 23 Threats to Succession The grasses that move in as pioneer species are often thought of as weeds • The subsequent growth of shrubs are considered undesirable "brush". • Without these intermediate stages, the disturbed habitat can't return to a natural forest. • The fragility and stability of the ecological community are dependent upon several factors.

24. 3/2/2018 24 • Also, over long periods of time (“geological time”) the climate conditions and other fundamental aspects of an ecosystem change. • These geological time scale changes are not observable in our “ ecological” time, but their fundamental existence and historical reality cannot be disputed. • No ecosystem, then, has existed or will exist unchanged or unchanging over a geological time scale. ECOLOGICAL SUCCESSION NEVER ENDS

25. 3/2/2018 25 ENDLESS ECOLOGICAL SUCCESSION...

26. 3/2/2018 26 References Modern concepts of ecology - H D Kumar https://en.wikipedia.org/wiki/Ecological_succession https://www.britannica.com/science/ecological-succession

27. 3/2/2018 27