Phenomena of succession in forest 3.pptx

phenomena of forest succession ,, how succession occurs in forest.
it takes a long period of time to create a climax community from a pioneer one

1. Dr. Harisingh Gour Central University, Sagar, MP Department of Botany A group presentation on subject Forest Ecology Paper Code: BOT-MDM-222 Topic: Phenomenon of succession in forest Presented by: MANOJ THAPA M.Sc Botany 2nd sem. Presented to- Prof.M L Khan Abhay pratab singh

2. CONTENTS  Introduction  Stages of forest succession  Process of succession  Factor influencing succession  Importance of forest succession  Case study  Conclusion

3. INTRODUCTION □ Succession is the natural replacement of plant and animal species or species association in area over time , when we discuss forest succession we are usually talking about replacement of trees species or tree association.  Each stage of succession creat the condition for the next stage , temporary plant community are replaced by more community unit a sort of equilibrium is reached between the plant and environment.

4. STAGES Primary succession: Begins in an area where no biotic community previously existed, such as on bare rock or sand. Secondary succession: Occurs in an area where a previous community has been disturbed but soil remains intact, such as after a fire or logging. Primary Succession Pioneer species: The first organisms to colonize a barren area, often lichens and mosses, which can grow on bare rock and begin soil formation. Early successional species: Grasses, shrubs, and fast-growing trees that establish in the nutrient-rich soil created by pioneer species. Mid-successional species: Shade-tolerant trees that grow taller and outcompete early successional species for sunlight.

5. Secondary Succession  Begins with the colonization of pioneer species on disturbed land.  Early successional species rapidly colonize the area and create favorable conditions for the establishment of more complex plant communities.  Eventually, climax species, which are well-adapted to the local climate and soil conditions, dominate the ecosystem.

6.  The following sequence is usually observed if sufficient time passes and no disturbance occurs. Plant community Description  Grass-forb  Forbs, grasses and shrubs dominate the site. Seedlings may be present.  Shrub-seedling  Trees tend to share and then begin to dominate the site. The intolerant species grow rapidly and dominate over tolerant species.

7.  Sapling - pole  Trees eventually overtop and out-compete the forbs and shrubs. The intolerant trees continue rapid height growth while the tolerant trees occupy their respective niche.  Young  Growth is still rapid. Tree-to-tree competition may be severe resulting in competition caused mortality. Any intolerant individuals that drop behind may die and their growing space may be occupied by tolerant trees.  Mature  Competition caused mortality continues. Both intolerant and tolerant trees may share the main canopy. In mixed conifer stands there may be a distinct layering of intolerants and tolerants.

8.  Climax  A relatively stable plant community which has a dominant plant population suited to the environment. Tolerant species dominate the site and the climax species will reproduce successfully under their own shade. These species will maintain the community under the current climatic conditions. Intolerant trees cannot reproduce.

9. PROCESS  There are four step to complete this process ;- A) Stand initiation or open shrub stage B) Stem exclusion C) Understory reinitiation D) Old growth stage

10. Stand initiation, or open shrub stage: The open condition after disturbance allows colonization by a variety of plants. Forest floor herbs, shrubs and seedlings may have survived the disturbance; new individuals and pioneer species invade over a period of several years. This is generally a period of diverse species composition. Planted seedlings are part of this stage (Figure below).

11. Stem exclusion stage : Crown closure occurs as tree crowns touch and available growing space is occupied. Overstory competition for light and growing space intensifies, and roots compete for soil moisture and nutrients. Some species die out and understory seedlings become scarce. This is generally a period of low biodiversity.

12. Understory reinitiation stage: Small gaps of light in the canopy are created by breakage or death of individual trees – those lost to suppression, pests, windthrow, etc. This creates an opportunity for new species or individuals to establish in the understory, or for shade tolerant saplings already established in the understory to grow quickly into the gap. This stage generally contains more plant and animal species than the stem exclusion stage, but fewer than the stand initiation stage (Figure).

13. Old-growth stage: Large overstory trees are replaced by younger understory trees. As the original cohort making up the crown gradually dies, very large gaps allow the trees in the lower forest layers to grow into the canopy. This happens in an irregular fashion, so a multilayered structure emerges. This is the stage of the greatest structural diversity, and is complemented by high species diversity (Figure).

14. FACTOR INFLUCING SUCCESSION Climatic factors: Temperature, precipitation, and sunlight influence the rate and direction of succession. Soil development: Soil fertility, pH, and texture determine the types of plant species that can establish and thrive. Disturbance regime: The frequency and intensity of disturbances, such as fire, flooding, or human activity, shape the trajectory of succession.

15. IMPORTANCE Biodiversity: Succession increases species diversity as different plant communities establish and evolve over time. Ecosystem stability: Mature forests provide habitat for a variety of wildlife and perform important ecological functions, such as carbon sequestration and water regulation. Human impact: Understanding forest succession helps us manage and restore ecosystems, such as through reforestation efforts and conservation strategies.

16. CASE STUDY;- Yellowstone national park  After the devastating wildfires in 1988, Yellowstone underwent extensive secondary succession.  Pioneer species, such as fireweed and aspen, quickly colonized the burned areas.  Over time, a diverse array of plant communities emerged, leading to the regeneration of the forest ecosystem.

17. CONCLUSION  Forest succession is a dynamic process that shapes the structure and function of ecosystems.  By understanding the factors influencing succession, we can better conserve and manage forest ecosystems for future generations.

18. References......... Jeff Martin and Tom Gower (November 1996).Forestry facts : Forest Succession , Department of Forest ecology and management , School of natural resource , University of Winconsis-Madison Odum, E. P. (1969). The strategy of ecosystem development. Science, 164(3877), 262-270. Connell, J. H., & Slatyer, R. O. (1977). Mechanisms of succession in natural communities and their role in community stability and organization. The American Naturalist, 111(982), 1119-1144. Pickett, S. T. A., & White, P. S. (1985). The ecology of natural disturbance and patch dynamics. Academic Press. Walker, L. R., & del Moral, R. (2003). Primary succession and ecosystem rehabilitation. Cambridge University Press.

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