8.2 -The Processes of ion & Succession

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CHAPTER 8


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8.2 : THEPROCESSES OF

COLONISATION &

SUCCESSION INAN ECOSYSTEM


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Ecosystem, Community & Population

Ecosystem : natural system formed by the

interaction of plants & animals between oneanother & also with their environment.

Interaction between biotic & abiotic components balanced ecosystem balancedenvironment

1 of components is disturbed

wholeecosystem upset not in balance

Ecosystem = niche + habitat + population

+ community


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Niche: the status / role of an organism in itsenvironment

Each species has its own niche in an ecosystem The types of food it consumes & the activity it carriesout

Examples : aphids, grass, ringed plover (kedidigelang) - picked food from the surface of the shore,

curlew probe deep into the mud (long, curve beak)

Habitat: the natural place in which anorganism lives

A Population: a group of organisms fromthe same species living in certain area

A community: the plants & animals thatlive in a certain habitat


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Process of Colonisation &Succession

The process of colonisation: plants startto inhabit an uninhabited place & form acolony in the place

Pioneer species 1st plant species toinhabit a new place

Has special adaptive characteristics to adapt to thenew environment

Change the new habitat gradually to make thehabitat more suitable for another species Newhabitat not suitable for the pioneer species replaced by another species succession begins


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The process of succession: a certaindominant plant speciesin a habitat is

gradually replaced by another plantspecies (successor species)

Proceed stage by stage until a stable &

matured communityclimaxcommunity(Eg. : tropical rain forest inMsia)


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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 suitablefor any organism to live

Pioneer species : phytoplankton (microscopic algae),submerged water plants (Hydrilla sp., Elodea sp., Utriculariasp., Cabomba sp.)


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These pioneer organisms carry out photosynthesisto provide food for other organisms

Pioneer die & decompose organic substance

produced will be deposited at the bottom of thepond

The banks of the pond are eroded & the soil settlesthe bottom of the pond more shallow, notsuitable 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. keladibunting) & lotus (Nelembium sp.) grow rapidly cover the surface prevent sunlight from

penetrating into the pond


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The pioneer species cannot carry outphotosynthesis die

The decayed organic substance from the pioneerspecies continued to be deposited pondsbecomes 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 tothe centre of the pond

The plants died more decayed organic substanceis deposited at the bottom of the pond

The pond become more shallow & dried up suitable for other land plants


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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


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Colonisation & Succession ina Mangrove Swamp

Mangrove swamp can be found at rivermouth that are sheltered from strong wave

The mangrove swamp environmentalcondition (unsuitable for habitation) :

Soft muddy soil

Waterlogged soil which lacks of O2

Seawater with high salinity (high salt content) Strong sunlight & extreme heat


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3 types of mangrove trees are involved inthe process of colonisation & succession :

Avicennia sp. & Sonneratia sp. (pioneer) Rhizophora sp. (successor)

Bruguiera sp. (successor)

Mangrove trees adaptive characteristicsto overcome the problems it faces in theenvironment :

A root systemthat 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)


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The roots of mangrove trees can withstand thehighly saline seawater by having the higherosmotic pressure of the cell sap than the

surrounding water osmosis occurs [hydathodein the epidermis of leaves secrete excess saltsfrom the plants to control the osmotic pressure]

Leaves : have thick cuticle & sunken stomatato

reduce transpiration, thick & succulent to storewater

Have viviparity seeds begin to germinate whilestill attached to the parent tree. the seeds will

get sufficient O2 from the atmosphere duringgermination & will not suffocated for lack of air in awaterlogged environment. Also preventdehydration of seed


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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 mudaccumulate the bank slowly raised, less

water More suitable for Rhizophora sp. As the

successor


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Rhizophora sp. Zone Higher & less waterlogged The adaptations :

Has prop roots to support & anchor the tree in the soft muddysoil

Has viviparity seeds to ensure the seedlings can grow, notcarries away by the seawater

The prop roots are able to trap mud. Thepioneer species & the Rhizophora sp. die &decay, adding humus to the soil

The banks are raised up even higher moresolid/ compact, fertile & less saline

Not suitable for Rhizophora sp. replaced bythe Bruguiera sp.


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Bruguiera sp. Zone Grow well in hard clay soil

Have buttress roots for support & knee-shapedpneumatophores for gaseous exchange

More sedimentation of decayed substances

new bank are being build up seawards, oldbanks move further inland, away from the seasoil becomes harder, dry land is formed

Bruguiera sp. are replaced by other types ofplants (coconut trees, Pandanus sp.) climaxcommunity (a few hundred years)


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8.2 -The Processes of ion & Succession