Geography Book 6 6.2

8/2/2019 Geography Book 6 6.2

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Characteristics of a TRF

(1) Layered structure (5 LAYERS)

(1) EMERGENT LAYER(Giant trees called emergent)- may grow up to 5o metres- widely-spaced umbrella-shaped crowns (absorb most of the

sunlight)- tall, straight, smooth trunks (space is limited, to survive in the

high density)

-High branches (complete for sunlight)

- Buttress root

How does climate affect TRF toform 5 layers? (how the climateresults to different layers)- hot and wet help trees to

grow to a great height (form

dense canopy)- thick canopy blocks sunlight;

limits the no. of plants inlower layer

- some tress may grow abovecanopy layer as they competefor sunlight

(2) CANOPY LAYER(dense, tall trees)

- 20-35 metres- medium-spaced oval-shaped crowns- more closely packed than emergent layer- straight trunks

- high branches- close and continuous layer (little light can penetratedown to the forest floor)- buttress roots

(3) YOUNG TREE LAYER (young trees that will somedaybecome emergent)

- low in height (wont exceed 15 metres)- densely-packed conical-shaped crowns

- narrow (absorb sunlight between gap of 2 trees)- biggest size of leaves (compete sunlight for photosynthesis grows to canopy layer then to emergent layer..size of leavesreduced by then)- little sunlight can penetrate through the dense canopy youngtree layer easily dies

(4) SHURB LAYER

- less than 5 metres high- most of them are woody shrubs- sparse vegetation of shrubs

(5) Undergrowth and ground layer

- mostly mosses and fungi (dont need much sunlight)- little vegetation cover/ undergrowth ; few plants cansurvive on forest floor (canopy blocks most of thesunlight)- undergrowth usually found in open gaps produced byfallen trees & along river banks(more sunlight can reach

the lower layers)


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(2) Wide range ofanimals species(some active in day some active atnight)

- canopy layer: birds, monkeys

- young tree layer: butterflies,frogs and snakes

undergrowth layer: larger animals like

tiger, gorillas, jaguars

The rich and dense vegetation provides a large variety of

habitats for animals.

e.g. mammals, birds, reptiles, amphibians, colourful insects

(3) EVERGREEN= TRF grow continuously

throughout the year.

Reason: there is enough energy for

photosynthesis to occurevergreen

Plants grow luxuriantly under high temperatures and

abundant rainfall, (hot and wet all year)provide a

favourable environment for plants to grow well all year.

no seasonal patternin flowering, fruiting,

and leaf fall

new leaves quickly replace shed leaves

forest looks evergreen

(4) High density of

treesHigh temperature and abundant rainfall provide a luxuriant

growth for the plants.


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(4) Special Characteristics of roots and

leaves of trees

SHALLOW ROOTS

BUTTRESS ROOTS

BROAD-LEAFED

THICK WAXY SURFACE

DRIP-TIPS

Take up the nutrients in the topsoil

Provide strong mechanical support for tall trees

Compete for sunlight (receive larger amount of sunlight for

growth

- prevent loss of water from plants

- shed away rainwater (to receive more sunlight &

infection of leaves)

- cool down leaves when reflecting sunlight (reduce

transpiration)

- drain away excess amount of rainwater (to receive

more sunlight & infection of leaves)

(5) Rich diversity of plant species

mixed stands of trees 40-100 different tree species per hectare of land most trees are hardwoods other plants in the TRF:

Epiphytes - mainly small shrubs or herbs (attach

themselves to trunks or branches; X roots

into soil) grow up high in the canopy layer

and capture sunlight for photosynthesis

- aerial roots to capture moisture from the air

- harmless to the host

*aerial roots

Climbers-

woody plants that start from the ground layer- climb along trees to reach to canopy layer

e.g. Lianas


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(capture sunlight for growth)

- when reach canopy layer, they will spread

out from tree to tree to get as much sunlight

Saprophytes - grown in places where sunlight cannot

penetrate

- do not produce own food

- feed on dead or decaying organic matter

(e.g. dead leaves and old wood)

e.g. fungus

Parasites - grow on other host plants

- dont produce own food

-live by taking up nutrients from host plants

e.g. smelly Corpse flower

(largest flora species in the

world), reach 1m in diameter

Stranglers

(stranglerfig)

- killer trees

- start their life as a epiphyte

as they grow

send roots down to ground level to surround host tree

grow quicklyand block sunlight kill host tree (inherit host trees place in canopy)


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The rich diversity of plants and animals &the natural environment of a tropicalrainforest make up a closely inter-relatedcommunity. [Ecosystem]

How does the climate affect the characteristics of the TRF?

The hot and wet climate support a large variety(rich and luxuriant) of plant species. (produces

the complicated structure of the TRF) creates a large variety of habitats

e.g. TRF in west Africa: 100,000 plant species

TRF in south-east Asian: 250,000 plant species

TRF in French Guiana: 6,000 flora species

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Geography Book 6 6.2