Download Succession

Succession
Changes in Communities
What is Succession?
The orderly process of change over
time in a community.
 Occurs both on land and water

Primary Succession
Succession in a newly formed area
 Occurs in new lakes, ponds, cooled
lava, sand dunes and bare rock
 Takes place in areas that have never
previously supported life
 Ex - rock -> lichen -> moss -> grass ->
shrub -> trees -> oak hickory forest

Secondary Succession
Sometimes an storms or fire destroy
the species growing in a community.
 Succession resumes again until there
is a climax community.
 Succession that occurs where an area
has been disturbed.
 Ex - grass -> shrub -> trees -> oak
hickory forest

Secondary Succession

Human activities usually cause secondary
succession.
– Cutting for timber
– Clearing for farming
– Construction

Some Natural Causes
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–
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–
Forest fires
Volcanoes
Hurricanes
Tornados
Stages of Succession
1.
Pioneer Community
– First inhabitants of the area
– r-strategists
– Ex. Lichen and mosses
Sere
A set of communities that succeed one
another over the course of succession
at a given location
 Succession from start to finish

Stage of Successsion
2.
Seral Stages – stages at which species
are replaced through competition
 Ex – grasses, small herbs, shrubs, coniferous
trees
3.
Climax Community – final stage of
succession.
 Ecosystem has stopped changing
 Reached a state of permanence
Climax Community
High stability
 High species diversity
 Complex food chains
 K-strategists
 Ex. oak - hickory trees

To sum up
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During succession species modify the
environment making it more suitable for new
species
Pioneer species are often poor competitors
and are replaced by stronger competitors
with greater environmental demand
Later communities are more complex than
the communities they replace.
Animated link
Zonation
The sub-classification of biomes into
smaller zones that share unique
physical characteristics.
 A unique habitat that will favor various
species will in turn exist in these
zones.

Comparison of Structure of
Early and Late Succession

Immature
Ecosystem

Mature
Ecosystem
1.
Small plant size
Low species diversity
Mostly producers, few
decomposers
Few ecological
niches (generalized)
Low community
organization
1.
Large plant size
High species diversity
Mixture of producers,
consumers and
decomposers
Many ecological
niches (specialized)
High community
organization
2.
3.
4.
5.
2.
3.
4.
5.
Comparison of Function of
Early and Late Succession

1.
2.
3.
4.
5.
Immature
Ecosystem
Low biomass
High primary productivity
Simple food chains and
webs (mostly plants
herbivore with few
decomposers
Low efficiency of nutrient
recycling
Low efficiency of energy
use

1.
2.
3.
4.
5.
Mature Ecosystem
High biomass
Low primary
productivity
Complex food chains
and webs (dominated
by decomposers)
High efficiency of
nutrient recycling
High efficiency of
energy use