ECOLOGICAL SUCCESSION (2).pptx

ecological succesion

1. ECOLOGICAL SUCCESSION

2. What is Ecological succession? It is a gradual process of change and replacement of the types of species in a ecological community over time. The time scale can be decades or even millions of years after a mass extinction due to some disturbances. Succession may be initiated by some of the disturbances such as a from a lava flow or a severe landslide or by fire or a severe wind throw . A D Malle was the first to make use of the term succession considering development of vegetation after forest clearing. Henry David Thoreau wrote an address called “ The succession of forest trees” in which he described about oak-pine forest. The Austrian botanist Anton Kerner published a study about the succession of plants in the Danube river basin in 1863 Danube river basin Oak pine forest

3. Stages of succession As soon as the suitable bare site for succession is available the process involves the following stages. Colonization This process involves the invasion of the bare area by the seeds and spores of the plant growing in the neighboring communities or from far off places through the agency of wind, water and animals. The nature of bare area determines the type of plants it can grow. Colonization includes following steps – Migration - Arrival of reproductive bodies and plant propagules from other places. Ecesis – This process involves establishment of the initial plants on the bare area. i.e germination of reproductive bodies. Aggregation – The species become establish in an area, they flower, fruit and produce seeds. Increase in no. of species. Competition – Involves struggle for existence between two or more individuals growing in an area. Such struggle is between plant of same kinds. Reaction – This includes effect of plant growth on the habitat. Plants alter habitat conditions If bare area is pond, seeds of water plants will germinate In case of desert seeds of xerophytes will germinate

4. Types of succession The process of creating life in an area where no life previously existed. An example of an area in which a community has never lived before, would be a new lava or rock from a volcano that makes a new island. The process of restabilization that follows a disturbance in an area where life has formed an ecosystem. An example of such an area could be land affected by fires, landslide etc.

5. Primary succession Begins at a place without any soil. In the beginning there is only rocks, sand or volcanic ash . Since there is no soil, there is no community For presence of soil there must be nutrients like nitrogen. Lichens begin to grow on the rocks. Over many years lichens breakdown the rocks into sand. Weathering and erosion process also break down the rock into sand. Lichens do not need soil to survive and are called Pioneer species

6. Nitrogen cycle begins Some lichens grow large and some die. Decomposers arrive and break down the lichens. The dead lichens and waste materials of the decom posers enrich the sand. Eventually enough nutrients enter the sand and it becomes soil. Mosses begin to grow Seeds are blown in by the winds and or carried by the animals. Simple plants like mosses can grow into the new soil. These plants grow and soil gets enriched as these plants die.

7. Herbs and weeds start growing The simple plants die adding more organic material to the soil. The soil layer thickens and grasses, wildflowers and other plants begin to take over. Medium sized animals and birds make this their habitat. Vegetation grows close together, reducing the amount of space available for growing. Lichen and other new species compete for the same space and eventually lichens die out and other species survive. Shrubs and trees start growing These plants die, adding more nutrients to the soil. Shrubs and trees can survive on this soil. Insects, mammals and small birds begin to move in. Once a bare rock now supports a large variety of biodiversity.

8. Large trees start growing. Small trees and shrubs die and add more nutrients to the soil and now large trees can start growing – Climax community A CLIMAX COMMUNITY is a mature, stable community that is the final stage of ecological succession. In an ecosystem with a climax community , the conditions continue to be suitable for all the members of the community. Any particular community has its own set of climax species, which are the plants that are best adapted for the area and will persist after succession has finished, until another disturbance clears the area.

9. Temperature and amount of rainfall are the two main physical factors that determines the nature of community that develops in an area. If we place the amount of rainfall on a graphs x-axis , from 0-10 , 10-20 and 20-30 + inches and the temperature along y axis from hot, moderate to cold, the various types of ecosystems will fit into the graph based on the conditions that they require.

10. PIONEER SPECIES INTERMEDIATE SPECIES CLIMAX COMMUNITY Thousands of years Primary succession

11. What if ?

12. Threats to climax community FOREST FIRES FLOODING, VOLCANIC ERRUPTIONS CLEARING A COMMUNITY FOR AGRICULTURE ANTHROPOGENIC ACTIVITIES Anything that destroys the existing community , but much of the soil remains Sometimes some of the organisms remain as well.

13. Secondary succession Organisms are destroyed but the soil is safe. The soil already contains the seeds of weeds, grasses, and trees. More seeds are carried to the area by wind and birds. Succession begins again but the primary species are different. Because soil is present, this succession is faster. 1. Some seeds in the soil begin to grow. 2. Larger shrubs move in 3 . Fast growing trees (such as pines) move in 4 . These are followed by slower-growing hardwood trees

14. Secondary succession Climax community is a stable group of plants and animals that is the end result of the succession process. Does not always mean big trees, it could be Grasses in prairies Cacti in deserts

15. Secondary succession The process of secondary succession takes lesser time since the soil for growth of vegetation still exists.

16. Circle of life in Secondary succession

17. Secondary succession of an Oak and Hickory forest

18. CLASSICAL SUCCESSION THEORY NEW SUCCESSION THEORY – MIYAWAKI Soil of a natural forest- Soft Moist Fertile Nutritious and presence of fungi Presence of microbes Presence of humus Miyawaki method involves planting of climax species directly and creating a forest in 25-30 years. Tree species identified are native to the particular place these forests are grown. Dr. Akira Miyawaki , Japanese botanist

19. Multi layer forest

20. Till date, 2,21,405 trees have been planted at 43 places using the Miyawaki plantation technique in Mumbai Here are some images from the Urban Forest Plantation using Miyawaki Method at Chandivali Hill Garden that has 27,900 trees. Urban forest in Mumbai

21. Rao Jodha Desert Rock Park Jodhpur city, Rajasthan Aim of the restoration project To eradicate  Prosopis juliflora  from the entire rocky tract and restore the area with plants native to rocky parts of the Thar Desert. This is how it looked before– lots of invasive P. juliflora Team:  Pradip Krishen , Somil Daga Plus employees of the Trust

22. Work in Rao Jodha Desert Rock Park began in 2006 to try and restore the natural ecology of a large, rocky wasteland next to Mehrangarh Fort in Jodhpur . It had suffered years of neglect and was overrun by invasive  Prosopis juliflora  whose seeds had been broadcast from the air in the 1930s. The challenge was to eradicate  P. juliflora  and understand how native rock-loving plants would adapt to conditions here. In 2011 a visitors centre was created and trained Naturalist guides to take visitors around. Clearing the Site Excavation was done upto 45 cm below ground-level in order to "grub out" baavlia 2. Collecting our plants Plants that are adapted to growing in arid, rocky areas of the Thar desert. 2. Planting out and caring for them Understanding what newly introduced plants required.

23. Newly planted species in the Park

24. Eco India: In space-strapped Mumbai, citizens are using a Japanese technique to create green cover https://www.youtube.com/watch?v=uTY6nvA7fZY Forest Making Workshop in Central India- https://www.youtube.com/watch?v=iDoNEdW_KXo Forest Making in Beirut https://www.youtube.com/watch?v=uweu9s4tbFM Maruvan , jodhpur https://www.youtube.com/watch?v=2REXsRK_mqs&t=1s