CHAPTER 8DYNAMIC ECOSYSTEM

ECOSYSTEM COMPONENT

BIOTIC COMPONENT

ABIOTICCOMPONENT

ABIOTIC COMPONENTThe non living components

of an ecosystem

pH value

Temperature

Light intensity

Humidity

Water Topography

Microclimate

pH value

Temperature

• affects the physiological activities of organisms

• most of organisms cannot tolerate extremes temperatures

• the pH value of soil and water has important effect on the types of organisms

• a drastic change in pH may kill the organisms

Light intensity

• affects the distribution and growth of organisms

• the sun is the source of energy

• some plants show adaptation to reach the light

• most animal need sunlight but some show adaptation to live in the dark

Humidity

• is the amount of water vapour in the air

• plant and animal that live in wet have special adaptation

Water

• important for living process in all organisms

• but some organisms are able to survive under condition where there is a limited supply of water such as camel and cactus

Microclimate

• Refers to local climate in a small area

• Humidity, temperature and light intensity affect the microclimates

Topography

• influence local climate and soil development

• the main factor is altitude and aspect

• higher altitude : lower atmospheric pressure and temperature so different plants growing at different altitude

• sloppy areas receive more sunlight compared to valley

•Gradient : steepness of a slope cause a faster drainage and run off the water

BIOTIC COMPONENTSThe living components

in an ecosystem

Producers Consumers

Decomposers

Producers

• mainly green plants

• manufacture complex organic food substances from raw materials

•Convert light energy → chemical energy

• affect the lives of other organisms because they start the food chain and food web

Consumers

• Obtain their energy from the other organisms they feed on

• Cannot make their own food : heterotrophs (herbivores, carnivores, omnivores, saprophytes or decomposers )

Decomposers

• break down dead organisms through the decomposition process

• the product in this process is returned to environment and will used again by green plants

• saprophytic fungi and saprophytic bacteria

CLASSIFICATION OF BIOTIC COMPONENTS INTO TROPHIC LEVEL

Food chain

• A series of organisms through which energy is transferred in the form of food

• trophic level - each stages in the food change and can be shown in the form of pyramid number

• pyramid number show the interaction between a producers and consumers and the number of organisms

• during food transfer from one trophic level to next level a lot of energy is lost ( through undigested matter, excretory products, lost as heat during respiration)

• 90% : energy is lost

• 10% : transfer from one trophic level to the next

http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ec/m3/s2/ecm3s2_6.htm

Food web

• in a community, food chains are linked together to form a food web

• gives a more complete picture of the feeding relationship in a community

Pyramids of numbers

INTERACTION BETWEEN ORGANISMS

Symbiosis Saprophytism Prey-predator Competition

Commensalism Mutualism Parasitism

Symbiosis

• Interaction in which there is a close and permanent relationship between two specific organisms.

• One species : benefits

• One species : unaffected, harmed or helped

Symbiosis

Commensalism • ( + , 0 )• example - clown fish & sea anemones - pigeon orchid

Mutualism

• ( + , + )

• example

- lichens

- root nodules

Parasitism

• ( + , - )

• example

- flea

- tapeworm

+ : benefits0 : neither benefit nor harm- : harm

Epiphytes(plant)

Epizoics(animal)

Ectoparasite Endoparasite

Lichens (alga + fungus)

Alga : produces foods for itself & fungus

Fungus : supplies CO2 &

nitrogenous products

Mutualism

Root nodules (bacteria & plant)

Nitrogen fixing bacteria :

convert Nitrogen into ammonium

Plant : provide energy-rich organic

compounds

Saprophytism

A type of interaction in which living organisms obtain food from dead and decaying organic matter

Enzymes are secreted onto the food and digestion occurs outside the cell

Example : saprophyte (plant) : fungus saprozoite (animal) : earthworm

Prey-predator(+ ,- )

• predator

- kills other animal for food

- larger and fewer in number than its prey

- the number of predator affects the

size of prey population

• prey

- the animal that kill by the predator

- must be able to protect itself from being killed

• example : owls & snakes, frogs & snakes

prey

predator

Time

Number

• In favourable condition, population of prey increases and followed by an increase of predator’s population

• When the population of prey decreases owing to increasing of predation and spread of diseases, the population of predator decreases.

• This interaction takes place in a cycle that keeps the populations of both organisms in a dynamic equilibirium

Competition

An interaction between organisms which live together in a habitat and compete for the same resources that are

in limited supply

Intraspecific

Competition between individuals of the same species

Compete for light, water, space and nutrients

Example : Bryophyllum sp

Interspecific

Competition between individualsof different species

Example : paramecium aurelia& paramecium caudatum

Bryophyllum sp

Paramecium aurelia and Paramecium caudatum.

Intraspecific competition

Interspecific competition

Number

the winner

the loser

Time

ECOSYSTEM

• An ecological system formed by the interaction of living organisms and their non-living environment

• Example : Mangrove swamp, desert, marine, forest

THE PROCESS OF COLONISATION AND SUCCESSION IN AN ECOSYSTEM

COMMUNITY

• Several populations of different organisms living together within the same habitat

• represent biotic components of an ecosystem

•Example : various group of organisms living in forest

POPULATION

• A group of individuals of the same species occupying the same habitat

• expressed by density

•The rate of change of a population density depends on birth rate, death rate and migration

SPECIES

•A group of closely related organisms which are capable of interbreeding to produce fertile offspring

ECOSYSTEM

COMMUNITY

POPULATION

SPECIES

HABITAT

• The place where the organism lives

• organism obtain its food, shelter and reproduces in its habitat

• example : ponds, rivers, forests

• within an ecosystem there will be several habitats

• microhabitat : smaller division of an a habitat

NICHE

• Is the function of an organism or the role it plays in the habitat

• organisms can live in the same habitat but they occupy different niches

• includes its habitat, its interaction, the types of food it consumes, the range of temperature it tolerate and the spaces it occupies

•Example : a caterpillar and aphid live in the same habitat (caterpillar eats the leaf but aphid sucks sap from the leaf)

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COLONISATION & SUCCESSION IN DISUSED PONDS

How does a disused pond become tropical rainforest ?

Mangrove swampPond

LEARNING OUTCOMES

• Explain the process of colonization,• Explain the process of succession,• Identify the successors in an ecosystem,• Identify the dominant species in an ecosystem• Identify the adaptive characteristic of pioneer species,• Identify the adaptive characteristics of successors,• Explain the changes in habitat caused by pioneer

species,• Explain the changes in habitat caused by successors at

every level of succession until a climax community is reached,

• Relate the abiotic components with the biotic components in an ecosystem during the processes of colonization and succession.

COLONISASION• Occurs in newly formed areas where no life

previously existed • The first colonisers : pioneer species• Special adaptation of pioneer species

1) hardy plant 3) have good dense root system (bind sand particles and hold water + humus)4) have short life cycle5) when die, their remains add to humus

content• Examples : grasses, ferns & sedges

SUCCESSION• The process in which one community changes its

environment so that it is replaced by another community

• The gradual & continuous process• Leads to a final and stable community which is in

equilibrium with its environment and is known as climax community

• Successor species : a series of plant that replaced the pioneer species (herbaceous plant)

• Successor : 1) grow bigger than pioneer thus reduced the

amount of sunlight 2) have small wind- dispersable seeds (able to spread and grow rapidly)3) can change the structure and quality of soil for

larger plant to grow example shrubs

• Dominant species : grow faster and dominate the slower growing pioneer and successor species

• Dominant species turn modify the environment which allows larger tree to grow

• The larger trees provide shade and the shrubs cannot compete and are replaced by forest floor species

• Ecological succession leads to a relatively stable community which is a climax community

EXAMPLE :

From bare ground → forest

COLONISATION & SUCCESSION IN DISUSED PONDS

1 Submerged/ sunken plant

Plankton

• Begin pioneer species which is submerged plant like Hydrilla sp., Cabomba sp., Elodea sp.

• Submerged species are autotrophs (carry out photosynthesis)• When they die, they contributes debris/humus (which supplies

nutrients for next group, successor) • The decomposition of dead pioneers species & soil erosion will add

silt & reduce water level• The new environment is now suitable for 1st successor (floating

plant)

2

• The floating plant like Lemna sp., Eichornia sp., Nymphea sp. will replace the pioneer group

• They have broad leaves which cover the water surface• The pioneer group receive less light for photosynthesis • Thus, the population of pioneer group decreases • The accumulation of humus increases gradually• The pond become shallower • This leads to the growth of 2nd successor (emergent/amphibian

palnt)

Floating plant

3

• The emergent plant such as cattails & sedges (Thypa sp., Cyperus sp.) will replace the floating plants

• They can live both water and on land • In earlier stages, these plant grow near the pond side – rhizomes

grows rapidly from edge to the middle pond – bind soil together.• As the accumulation of humus and silt increases, they will dominate

further in until the whole pond becomes land

Emergent/ amphibian plant

4

• The accumulation of humus makes land more fertile• The creepers, herb plants and shrub will replace the emergent

plants• The land now covered by bushes

Grasses

5

• Over a period of time, the bushes will replaced by a primary forest

• Finally, it reaches the climax community • Example :

tropical rain forest in Malaysia

Hydrilla sp. (water weed)

Elodea sp. (water weed)

Cabomba sp. (fan wort)

Submerged/ sunken plant

Lemna sp. (duck weed)

Eichornia sp. (water hyacinth)

Nymphaea sp. (water lily)

Floating plant

Thypa sp. (cattails) Cyperus sp. (sedges) Fimbristylis sp. (sedges)

Emergent / amphibian plant

MANGROVE SWAMP

MANGROVE SWAMP

• Found in tropical & subtropical regions where freshwater meets salt water

• Characteristics :

1) Soft & muddy soil

2) High concentration of salt

3) Low level of oxygen

4) Exposed to high intensities of sunlight & strong wind

• 4 species of mangrove :

1) Avicennia sp.

2) Sonneratia sp.

3) Rhizophora sp.

4) Bruguiera sp.

• The mangrove plants are well adapted to the harsh conditions of these regions.

ADAPTATIONS OF MANGROVE PLANTS

PROBLEMS ADAPTATIONS

Soft, muddy soilStrong coastal wind

Waterlogged conditions of soil

(↓ amount of O2)

Avicennia sp. : underground cable roots (long & branch)Rhizophora sp. : prop roots (aerial roots)- for anchor & aeration

Avicennia sp. : breathing roots (pneumatophores), grow vertically upwardsGaseous exchange through lenticels (on the bark)

PROBLEMS ADAPTATIONS

Direct exposure to the sun (↑ rate of transpiration)

High salinity of the sea water (soil hypertonic compared to the cell sap of the root cells)

Seeds which fall onto the ground die (submerged in the soft & waterlogged)

Leaves are covered by a thick layer of cuticle Leaves are thick & succulent (able to store water)

The cell sap in the roots cells has a higher osmotic pressure (hypertonic) than the soil.The excess salt is excreted as crystalline salt from hydatodes (pores on the lower epidermis)

Viviparity : seeds are able to germinate while still attached to the mother plant

Props roots

Excretion of crystalline salt from hydatodes Viviparity

Pneumatophores

Cable roots

Avicennia sp.

(pokok api-api)

Sonneratia sp. (pokok perepat)

Rhizophora sp.(bakau minyak)

Bruguiera parviflora(tumu merah)

Pioneer speciesAdaptations :

• pnematophores• aerenchyma tissue

• viviparous seedlings

Successor speciesAdaptations:• props roots

Successor speciesAdaptations :

• buttress roots• viviparous seedlings

• hydatodes• thick & succulent leaves

• waxy cuticles

Avicennia sp. & Sonneratia sp.

(pioneer species)

Rhizophora sp.1st successor)

Bruguiera sp.(2nd successor)

terrestrial plants(3rd successor)

COLONISATION & SUCCESSION IN MANGROVE SWAMPS

Colonisation

Succession

Climax community

COLONISATION

• The pioneer species : Avicennia sp. & Sonneratia sp.

• The extensive roots system of Avicennia sp. & Sonneratia sp. collect sediments & organic matter

• As times passes, the soil become more compact & firm

COLONISATION & SUCCESSION IN MANGROVE SWAMPS

SUCCESSION

• Rhizophora sp. replaces the pioneer species

• The arcing roots of Rhizophora sp. trap silt & mud, creating a firmer soil structure.

• As times passes, the ground becomes higher & the soil becomes drier

• Bruguiera sp. replaces Rhizophora sp.

COLONISATION & SUCCESSION IN MANGROVE SWAMPS

• The buttress roots of Bruguiera sp. form loops which protrude from the soil to trap more silt and mud. The soil structure changes

• Over time, terrestrial plants ( Nypa fruticans & Pandanus sp. replace Bruguiera sp.

• As times passes, the tropical plants replace the terrestrial plants to form climax community

COLONISATION & SUCCESSION IN MANGROVE SWAMPS

giant mudskipper (Periophthalmodon schlosseri)

POPULATION ECOLOGY

POPULATION ECOLOGY• Population ecology : a branch of ecology that

studies the structure and dynamics of populations• Population density : the number of organisms per

unit area of the habitat• Population density is affected by abiotic, biotic, birth

rate, death rate immigration & emigration.• Sampling technique : estimate the total population

size of the organisms• Type of sampling technique :

1) quadrat sampling technique (plant)2) the capture, mark, release &

recapture technique (animal)

Quadrat sampling technique (plant)

• Used to estimating the size of plant populations

• Made from a metal or a wooden frame

• The quadrat is placed randomly in the ecosystem

FORMULA

Frequency : the number of times a particular species is found present when a quadrat is thrown a certain number of times

Frequency : Number of quadrats containing the species Number of quadrats

X 100%

Density : the mean number of individuals of a species per unit area

Density : Total number of individuals of a species in all quadrats Number of quadrats X quadrat area

Percentage coverage : an indication of how much area of the quadrat is occupied by a species.

Percentage coverage : Aerial coverage of all quadrats (m2) Number of quadrats X quadrat area

X 100%

Frequency

Density

Example of percentage coverage

Capture, mark, release & recapture technique (animal)

• Used to estimate the populations of mobile animals• The method :

1) A specific animal sample is captured 2) The animal is marked (a ring, a tag or waterproof coloured ink/paint). 3) The marked animals are released into the general population 4) After suitable period of time, a second sample are recaptured 5 ) The number of marked animal is recorded

FORMULA

Population size : (no of individuals in the 1st sample) X (no of individuals in the 2nd sample) no of marked individuals recaptured

BIODIVERSITY

• Refers to the diverse species of plants and animals interacting with one another on Earth

• Taxonomy : a branch of biology concerned with identifying, describing and naming organisms

• Organism are classified into 5 major kingdoms :1) Monera2) Protista3) Fungi4) Plantae5) Animalia

MONERA

• composed of prokaryoteorganisms

• Unicellular, have cell walls, no membrane bound nuclei and organelles.

• photosynthetic and non-photosynthetic

• typical shapes: rod,round,spiral

• examples : cyanobacteria (blue-green algae) & bacteria

bacteria

cyanobacteria

PROTISTA

• Unicellular, algae, protozoa

• membrane-bound nuclei and organelles.

• Autotrophic , heterotrophic or both

• examples :Amoeba sp. , Paramecium sp.algae

FUNGI

• multicellular eukaryotes• Saprophytic , have

hyphae called mycelium• they have no

chlorophyll • examples :

moulds (Mucor sp.) mushrooms & yeast

Mucor sp.

yeast

PLANTAE

• all green plants• Multicellular, autotrophic

eukaryotes, immobile, photosynthetic

• have cellulose cell walls• examples :

flowering plants, ferns, conifers, moss

ANIMALIA

• multicellular heterotrophic

• eukaryotes• Well- developed

tissues• examples :• Mammals, reptiles,

fishes, amphibians, birds

HIERARCHY OF CLASSIFICATION OF ORGANISM