Ecological succession is the gradual and continuous change in species composition and community structure over time in an area. It occurs through two main types - primary succession, which establishes communities on new areas like bare rock, and secondary succession, which occurs in previously inhabited areas affected by disturbances. Succession proceeds through stages from pioneer to climax communities as conditions change. Deforestation in the Amazon has led to large-scale land use changes and succession, with many secondary forest bird species colonizing but few displacing original forest birds over time. Roads may facilitate some species invasions but succession appears reversible through forest regrowth.

1. ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
S. V. AGRICULTURAL COLLEGE, TIRUPATI
ENT-505, 2(1+1)
INSECT ECOLOGY
TOPIC : ECOLOGICAL SUCCESSION
SUBMITTED BY:
M. Lokeswaridevi
TAM -2020-030,
Dept of Entomology
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2. Succession
• Succession is a unidirectional progressive series of changes which
leads to the established ofa relatively stable community.
-Hult (1885)
• Large number of pioneer plant communities give way to small number
of relatively stable communities.
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3. Ecological succession
• Ecological succession is the gradual and continuous change in the
species composition and community structure over time in the same
area.
• The time scale can be decades or even millions of years after a mass
extinction due to some disturbances.
• It allows new areas to be colonized and damaged ecosystems to be
recolonized, so organisms can adapt to the changes in the environment
and continue to survive.
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Environment is
always kept on
changing over a
period due to
Variations in climatic
and physiographic
factors and
The activities of the
species of the
communities
themselves

5. History
• The French naturalist A D la Malle was the first to
make use of the word succession concerning the
vegetation development after forest clear-cutting.
• In 1859 Henry David Thoreau wrote an address called
"The Succession of Forest Trees "in which he described
succession in an oak-pine forest.
• TheAustrian botanistAnton Kerner published a study
about the succession of plants in the Danube river basin
in 1863.
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6. Characteristics
of Ecological
succession
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increase in the total matter of
community.
increased Nutrient conservation.
Tropic levels increases.
Population of decomposer
component.

7. • Community become more diverse in a terms of number of species and
their balance.
• The community become more heterogeneous.
• Simple food chains will be replaced by complex food chains.
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8. Types of
Ecological
Succession
• Classification based on different criterions
Autogenic and allogenic succession
Autotrophic and heterotrophic succession
Primary and secondary succession
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9. Primary Succession
Succession occurring in bare area or newly exposed site thatwas not previously
occupied by any sort of living organism.
* In primary succession, the unoccupied terrestrial site is first colonised by a few
pioneerspecies which are often microbes, lichens and mosses.
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10. Primary Ecological Succession Over Several Hundred Years Of PlantCommunities On Bare Rock .
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Pioneer Species
The first species that colonise the bare area in the beginning of succession are called pioneers,
primary community or primary colonisers.
Pioneers' species whichare microbes, lichens and mosses.

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13. Examples of
primary succession
• The island of Surtsey formed by
volcanic eruption off the coast of
Iceland during the period from
1963 - 1967
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Surtsey – Post Eruption Surtsey Today

15. • Can reach a climax community in 1,000 years
• ROCK  Lichen & Moss  Grass  small plants & insects 
grass, rabbits  shrubs/bushes  Forest.
• Change in number of species is very slow at the beginning 15

16. Secondary Succession
Secondary succession starts at a site that has alreadypreviously
built-up substrate with already existing living matter.
 Secondary succession starts on a well-developed soil. Secondary
succession faster ascompared to primary succession which may
often require hundreds of year.
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17. Secondary succession
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18.  Can reach a climax community in 100 years
 Grass  small plants & insects  grass, rabbits  shrubs/bushes  Forest
 Change in number of species happens at a steady rate
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Examples of Secondary Succession
• The Yellowstone fires of 1988 was the largest wildfire in the recorded
history of Yellowstone National Park in the United States.
• Starting as many smaller individual fires, the flames quickly spread out of
control with increasing winds and drought and combined into one large
fire.
• Only the arrival of cool and moist weather in the late autumn brought the
fires to an end.
• A total of 793,880 acres (3,213 km2) of the park was affected by the
wildfires.

20. Forest fire at Yellowstone National Park.
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One year after the fires
Ten years after the
fires (1998)

22. Twenty years after
the fires (2008)
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23. Differences between Primary and Secondary Succession
• Occurrence
• Time to complete
• Physical conditions
• Humus
• Seral community
• Environment
• Reproduction
• Examples
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24. Types of communities
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Pioneer community
Climax community
Seral Community / Transitional Community

25. Climax Community
A climax community is a mature, stable community that is the final stage of ecological
succession.
This type of community remains the same through out the time, if it is not disturbed.
A stable group of plants and animals which is the result of succession process, does not
always mean only big trees.
 They could be:
Cacti in deserts or
 Grasses in fields
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The vegetation is tolerant of environmental
conditions
It has a wide diversity of specie and complex food
chains.
Individuals in the climax stage are replaced by others of
the same kind. Thus the species composition maintains
equilibrium.
It is an index of the climate of the area. The life or
growth forms indicate the climatic type.
Characteristics of climax community

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28. CAUSES OF ECOLOGICAL SUCCESSION
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INITIAL OR
INITIATING
CAUSE
ECESIS OR
CONTINUING
CAUSES
STABLISING
CAUSES

29. MECHANISM OF ECOLOGICAL SUCCESSION
• NUDATION
• INVASION OR MIGRATION
• ECESIS ( ESTABLISHMENT)
• AGGREGATION
• COMPETITION AND CO-ACTION
• REACTION
• STABILISATION (CLIMAX)
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30. Clements (1916)
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31. Seral Community / Transitional Community
• The whole sequence of communities that replaces one another from beginning till the climax stage in
thegiven area is called sere (sera).
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Types of Seres Explanation
Hydrosere Succession in aquatic habitat.
Xerosere Succession in dry habitat.
Lithosere Succession on a bare rock surface.
Psammosere Succession initiating on sandy areas.
Halosere Succession starting in saline soil or water.
Senile Succession of microorganism on dead matter.
Eosere Development of vegetation in an era.
Different types of seres:

32. Why does Ecological Succession Occur?
• It is the process of life for plants and other living organisms.
• Organisms alter soil structure, and the species communities constantly
change over a period.
• Succession will continue until the environment reaches its final stage-
Climax Community
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33. Threats to Succession
• The grasses that move in as pioneer species are often thought as
weeds.
• But, without these intermediate stages, the disturbed habitat can’t
return to forest.
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34. How do Humans affect Ecological
succession?
• Clearing the land for garden and preparing the soil for planting is a
type of major external event that radically re-structure and disrupt a
previously stabilized ecosystem.
• This disturbance may immediately begin a process of ecological
succession.
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35. Does Ecological Succession ever stop?
• Over a long period of time, the climate conditions of an ecosystem is
bound to change.
• No ecosystem has existed or will remain unchanged over a Geological
Time Scale
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36. CASE STUDIES ON ECOLOGICAL SUCCESION
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38. • 1. Approximately 20% of the Brazilian Amazon has now been deforested, and the Amazon is
currently experiencing the highest rates of deforestation in a decade, leading to large‐scale
land‐use changes. Roads have consistently been implicated as drivers of ongoing Amazon
deforestation and may act as corridors to facilitate species invasions. Long‐term data, however,
are necessary to determine how ecological succession alters avian communities following
deforestation and whether established roads lead to a constant influx of new species.
• 2. They used data across nearly 40 years from a large‐scale deforestation experiment in the
central Amazon to examine the avian colonization process in a spatial and temporal framework,
considering the role that roads may play in facilitating colonization.
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39. • 3. Since 1979, 139 species that are not part of the original forest avifauna have
been recorded, including more secondary forest species than expected based on
the regional species pool.
• Among the 35 species considered to have colonized and be‐ come
established, a disproportionate number were secondary forest birds (63%), almost
all of which first appeared during the 1980s. These new residents comprise about
13% of the current community of permanent residents.
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40. • 4. Widespread generalists associated with secondary forest colonized quickly
following deforestation, with few new species added after the first decade, despite a
stable road connection. Few species associated with riverine forest or specialized
habitats colonized, despite road connection to their preferred source habitat.
Colonizing species remained restricted to anthropogenic habitats and did not in‐
filtrate old‐growth forests nor displace forest birds.
• 5. Deforestation and expansion of road networks into terra Firme rainforest will
continue to create degraded anthropogenic habitat. Even so, the initial pulse of
colonization by nonprimary forest bird species was not the beginning of a protracted
series of invasions in this study, and the process appears to be reversible by forest
succession
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41. • https://en.wikipedia.org/wiki/Ecological succession
• http://sciencing.com/factors-ecological-succession
• Plant ecology and applied ecology by Vasishta and Gill.
• Elements of insect ecology by S S Yazdani, M.L. Agarwal.
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