1. CHAPTER 8

2. 8.2 : THE
PROCESSES OF
COLONISATION &
SUCCESSION IN
AN ECOSYSTEM

3. Ecosystem, Community & Population
• Ecosystem : natural system formed by the
interaction of plants & animals between one
another & also with their environment.
• Interaction between biotic & abiotic
components  balanced ecosystem 
balanced environment
• 1 of components is disturbed  whole
ecosystem upset  not in balance
• Ecosystem = niche + habitat + population
+ community

4. • Niche : the status / role of an organism in its
environment
• Each species has its own niche in an ecosystem
• The types of food it consumes & the activity it carries
out
• Examples : aphids, grass, ringed plover (kedidi
gelang) - picked food from the surface of the shore,
curlew – probe deep into the mud (long, curve beak)
• Habitat : the natural place in which an
organism lives
• A Population : a group of organisms from
the same species living in certain area
• A community : the plants & animals that
live in a certain habitat

7. Process of Colonisation &
Succession
• The process of colonisation : plants
start to inhabit an uninhabited place &
form a colony in the place
• Pioneer species – 1st plant species to
inhabit a new place
• Has special adaptive characteristics to adapt to the
new environment
• Change the new habitat gradually to make the
habitat more suitable for another species  New
habitat not suitable for the pioneer species 
replaced by another species  succession begins

8. • The process of succession : a certain
dominant plant species in a habitat is
gradually replaced by another plant
species (successor species)
• Proceed stage by stage until a stable &
matured community  climax
community (Eg. : tropical rain forest in
M’sia)

10. Process of Colonisation &
Succession in a Pond
• In an unused mining pond
• The plants involved :
– Submerged water plants (pioneer)
– Floating water plants
– Amphibious plants
– Land plants
• Colonisation by pioneer species
• Unused & abandoned mining pond is not fertile & not suitable
for any organism to live
• Pioneer species : phytoplankton (microscopic algae),
submerged water plants (Hydrilla sp., Elodea sp., Utricularia
sp., Cabomba sp.)

12. • These pioneer organisms carry out photosynthesis
to provide food for other organisms
• Pioneer die & decompose  organic substance
produced will be deposited at the bottom of the
pond
• The banks of the pond are eroded & the soil settles
the bottom of the pond  more shallow, not
suitable for the submerged water plants,
phytoplankton.
• Succession by floating water plants
• the successor – replace the pioneer species  1st
succession occurs
• Duckweed (Lemna sp. – kiambang), water lettuce
(Pistia sp.), water hyacinth (Eichornia sp. – keladi
bunting) & lotus (Nelembium sp.) grow rapidly 
cover the surface – prevent sunlight from
penetrating into the pond

14. • The pioneer species cannot carry out
photosynthesis  die
• The decayed organic substance from the pioneer
species continued to be deposited  ponds
becomes too shallow for the floating water plants
• Succession by amphibious plants
• 1st successor are replace by amphibious plants
(2nd successor) that live in marshes (paya)
• Initially grow at the side of the ponds  spread to
the centre of the pond
• The plants died  more decayed organic substance
is deposited at the bottom of the pond
• The pond become more shallow & dried up 
suitable for other land plants

15. • Succession by land plants
• 2nd successors are replaced by land plants –
shrubs & woody plants
• The process of succession continues to occur until
a climax community is formed (tropical rain forest)
 take long time to complete

17. Colonisation & Succession in
a Mangrove Swamp
• Mangrove swamp – can be found at river
mouth that are sheltered from strong wave
• The mangrove swamp environmental
condition (unsuitable for habitation) :
• Soft muddy soil
• Waterlogged soil which lacks of O2
• Seawater with high salinity (high salt content)
• Strong sunlight & extreme heat

18. • 3 types of mangrove trees are involved in
the process of colonisation & succession :
• Avicennia sp. & Sonneratia sp. (pioneer)
• Rhizophora sp. (successor)
• Bruguiera sp. (successor)
• Mangrove trees adaptive characteristics
to overcome the problems it faces in the
environment :
• A root system that spread out widely  provide
support in soft muddy soil
• Pneumatophores  breathing roots, protrude out
of the soil – enables gaseous exchange
(waterlogged soil  lack of O2)

19. • The roots of mangrove trees can withstand the
highly saline seawater by having the higher
osmotic pressure of the cell sap than the
surrounding water  osmosis occurs [hydathode
in the epidermis of leaves secrete excess salts
from the plants – to control the osmotic pressure]
• Leaves : have thick cuticle & sunken stomata to
reduce transpiration, thick & succulent to store
water
• Have viviparity seeds  begin to germinate while
still attached to the parent tree. the seeds will
get sufficient O2 from the atmosphere during
germination & will not suffocated for lack of air in a
waterlogged environment. Also prevent
dehydration of seed

21. Avicennia sp. & Sonneratia sp.
Zone
• The adaptations of pioneer :
• A root system that spread out widely
• Have asparagus-shaped pneumatophores  very
spongy & take air for respiration of the root system
• The widely spread roots trap mud 
accumulate  the bank slowly raised, less
water
• More suitable for Rhizophora sp. As the
successor

24. Rhizophora sp. Zone
• Higher & less waterlogged
• The adaptations :
• Has prop roots to support & anchor the tree in the soft muddy
soil
• Has viviparity seeds to ensure the seedlings can grow, not
carries away by the seawater
• The prop roots are able to trap mud. The pioneer
species & the Rhizophora sp. die & decay,
adding humus to the soil
• The banks are raised up even higher  more
solid/ compact, fertile & less saline
• Not suitable for Rhizophora sp.  replaced by
the Bruguiera sp.

27. Bruguiera sp. Zone
• Grow well in hard clay soil
• Have buttress roots for support & knee-shaped
pneumatophores – for gaseous exchange
• More sedimentation of decayed substances 
new bank are being build up seawards, old
banks move further inland, away from the sea 
soil becomes harder, dry land is formed
• Bruguiera sp. are replaced by other types of
plants (coconut trees, Pandanus sp.)  climax
community (a few hundred years)