Ecological succession is the process by which the structure of a biological community evolves over time from a barren habitat to a stable community. Pioneer species are the first to colonize barren environments, such as lichens, ferns and mosses. Succession occurs through five sequential stages: nudation, invasion, competition/co-action, reaction, and stabilization or climax. Primary succession occurs on newly exposed rock surfaces, while secondary succession occurs in previously inhabited areas disturbed by events like fires or landslides.

1. ECOLOGICAL
SUCCESSION
PRESENTED BY
SAIKAT JANA
SEM-IV
ROLL-91
DEPT. OF BOTANY
NARAJOLE RAJ COLLEGE

2. WHAT IS ECOLOGICAL SUCCESSION
This is the process by which the structure of a biological
community evolves from a life less barren habitat to a stable
community over time. The time scale can be million of years
after a mass extinction due to some disturbances.

3. WHAT IS PIONEER SPECIES
The pioneer species are hardy species which are the first to
colonize barren environments or previously biodiverse steady-
state ecosystems that have been disrupted, such as by fire.
LICHEN FERN MOSS

4. PROCESS OF ECOLOGICAL
SUCCESSION
Ecological succession is completed through a series of
sequential steps–
1. Nudation
2. Invation
3. Competition and co-action
4. Reaction
5. Stabilization or climax.

5. 1. NUDATION –
● Nudation is the initiation of a
new plant succession by a major
environmental disbalance.
CAUSES OF NUDATION
● CLIMATIC: Due to glaciers, dry
periode, landslide etc.
● BIOTIC: Like forest destruction,
agriculture, disease epidemics etc.
Volcanic eruption
Nudation of an area

6. Volcanic eruption
Nudation of an area
● It is is second step of succession.
● Invasion is the successful establishment
of a species in the bare area.
● Invation is completed in three steps–
i. Migration
ii. Ecasis
iii. Aggregation
2. INVATION–
Mosses grow on rock

7. i. MIGRATION
● Seeds, spores, propagule are reach in a bare
area.
ii. ECASIS
● Process of successful establishment of
species.
● Seeds/spores germinate, grow and
reproduce.
● Only few progenies survives.
iii. AGGREGATION
● Individuals of a species increase their
number and they stay close to each other.
MIGRATION
ECASIS
AGGRESSION
2. INVATION

8. 3.COMPETITION AND CO-ACTION–
● Aggregation means a large number of
species within a limited space.
● Competetion for space and nutrition.
● Competetion may be inter-specific or
inter-specific.
● Individuals of a species effect each
other (Co-action).
● Competetion and co-action results in:
Elimination of unfit individuals.
Survival of fit individuals.
INTER-SPECIFIC
INTRA-SPECIFIC

9. 4. REACTION–
● Most important stage in ecological succession.
● It is the modification of the environment through the
influence of living organisms present on it.
● Due to reaction, change in soil, water, light and temperature
etc.
● Due to the modification, the present community become
unsuitable for the existing environmental condition.
● Such communities will be replaced by another community.
● SERE– The whole sequence of communities that replaces one
another in the given area is called sere.
● Various communities contributing sere are called serial
community.

10. 5. STABILIZATION OR CLIMAX
● Last stage of ecological succession.
● The community becomes more or less established for a
longer period of time.
● The final community is not replaced and is known as
climax community and the stage known as climax stage.
Example of climax community
FORESTGRASS LAND

11. TYPES OF ECOLOGICAL SUCCESSION
ECOLOGICAL
SUCCESSION
PRIMARY
SUCCESSION
SECONDERY
SUCCESSION

12. PRIMARY SUCCESSION
This is a type of ecological succession in which plants and
animals first colonize in a barren, lifeless habitat like rock
surface.
E.g.– A new island formed by volcanic activity.
Bare rock surface Grassy rock Forest

13. EXAMPLE OF PRIMARY SUCCESSION
The island of Surtsey formed by volcanic eruption off of
the coast of Iceland during the period from 1963–1967
VOLCANIC ERUPTION

14. SURTSEY― POST ERUPTION

15. SURTSEY― TODAY

16. SECONARY SUCCESSION
Secondary succession is the is the series
of community changes which take place on a
previously colonized but disturbed or
damaged habitat.
E.g. – Succession of a burned forest.
A grassland
The grassland on fire The bare area after fire New grass growing

17. EXAMPLE OF SECONDARY SUCCESSION
Devastating forest fires at Yellowstone National Park ― 1988
It was the largest wildfire in the history of Yellowstone National
Park in the United States.
FOREST FIRE AT
YELLOWSTONE
NATIONAL PARK

18. YELLOWSTONE NATIONAL PARK AFTER FOEST FIRE

19. ONE YEAR AFTER FIRE (1989) TEN YEARS AFTER FIRE (1998)

20. 20 YEAR AFTER FIRE (2008)

21. THANK YOU