Download - Unit 1 Tropical rainforests-- what and where are they? Unit 1 Tropical rainforests--what and where are they?

Unit 1

Tropical rainforests--Tropical rainforests--

what and where are they?what and where are they?

Unit 1 Tropical rainforests--what and where are they?

What are the characteristics of tropical rainforests?



What is an ecosystem?

An ecosystem is a community in which all plants and animals live together and are interdependent on each other for survival.




What is an ecosystem?

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The tropical rainforest is an old, rich and complex ecosystem.

Tropical rainforests have a great variety of plant and animal species.

The rich and dense vegetation provides abundant food for a large number of insects, birds and animals living in the forests.




The tropical rainforests have a great variety of plant and animal species.




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Tropical rainforests are luxuriant and trees are evergreen.

Trees are tall and straight because they have to compete

for sunlight.

Trees develop plank-like buttress roots for firm support.




Trees in tropical rainforests are tall and straight. They develop plank-like buttress roots for fir

m support.




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Trees have waxy leaves with downward-dipping points or drip tips to shed rainwater.There are a lot

of climbing and creeping plants.

There are ferns, lichens and mosses.




The structure of a tropical rainforest

Top layer

Main layer

Lower layer

Ground layer

This is the highest layer with trees rising up to 40 m.

The trees form a continuous canopy effectively cutting off the forest floor from sunlight.

This is a layer of young, short trees about 5 m to 15 m high.

This layer is covered with plant litter. It is dark and has little undergrowth as sunlight cannot reach it.

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The structure of a tropical rainforest




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Tropical rainforests are found between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). They form a broken green belt around the world.

Dense tropical rainforests are found in lower latitudes between 10 north and south of the equator.

There are three main tropical rainforest regions:


Where are the tropical rainforests?Where are the tropical rainforests?

1. The Amazon Basin in South America2. Indonesia in Southeast Asia3. The Congo Basin of Central Africa

The Amazon Basin The Amazon Basin The Amazon basin covers 6.4 million km².

The Amazon spreads across much of South America,

which includes Colombia, Ecuador, Peru, Bolivia, Brazil and Venezuela.

Mestizos is the indigenous people in the Amazon Basin. Their lifestyle was called subsistence

because they hunted and grew only what they needed to subsist, or survive. They practiced a kind of agriculture called slash and burn.

They mainly grow coffee, maize and cacao.


Indonesia Indonesia Indonesia has the third largest area of tropical rainforests

in the world, which is 10% of the world total.

The richest areas are the primary lowland forests of

Borneo, Sumatra, Java and Irian Jaya, with Borneo

supporting the largest expanse of tropical rainforest in

Southeast Asia.

Lumbering plays an important role in Indonesia. In 1993,

forest products accounted for 7% of the country's GDP.

Many tropical rainforests are designated for non-forest

uses such as agriculture, settlement and transmigration.


The Congo Basin The Congo Basin The Congo Basin is located in West Africa.

Nearly 90 % of the original moist forest is gone, and what remains is heavily fragmented and degraded.

Most of the people in the Congo Basin are Bantus who live in tribal settlements.

For their own use, the people grow cassavas, corn, yams, peanuts, and beans. The villagers may also raise bananas, rice millet, sugarcane, tobacco and cotton. Some villagers keep chickens and goats.


Where are the tropical rainforests?Where are the tropical rainforests?Unit 1 Tropical rainforests--what and where are they?

km

Congo Basin

Tropical rainforests

S. E. Asia

Amazon Basin

N

S

N

Indonesia

Why are the rainforests there?Why are the rainforests there?High TemperatureHigh Temperature

Tropical regions are hot

throughout the year. The annual range of temperature is only about 2°C.

During the day, the temperature may reach 35°C in the afternoon.

At night the temperature may fall to 18°C.


Heavy rainfallHeavy rainfall

Tropical rainforests lie in the low pressure belt at the equator where warm, moist winds from the ocean meet.

The air rises upwards to form strong convection currents bringing heavy rain.

The monthly rainfall in most tropical rainforests is over 200 mm. The annual rainfall is between 1 500 mm and 2 500 mm a year.

The humidity is always high in these areas. The sky is often cloudy and rain comes in downpours.


Why are the rainforests there?Why are the rainforests there?


Why are the rainforests there?Why are the rainforests there?

Warm, wet air

Clouds

Low pressure

RainStrong convection current

Air cooled to form clouds and rain

Hot, wet air rises when heated

Hot ground

Terms to learn

Ecosystem ( 生態系統 ) -- a community in which living things are interdependent on each other for their survival.

Buttress roots ( 板根 ) -- plank-like roots branching out from the trunk above the ground.

Drip-tipsDrip-tips ( 滴水葉尖 ) -- the downward-dipping points of leaves for shedding rainwater.


Terms to learn

LichensLichens ( 地衣 ) -- small plants growing like a crust on rocks, trunks and branches of trees.

MossesMosses ( 苔蘚 ) -- small plants with simple stems and leaves but no roots growing on the trunks and branches of trees like a green velvet layer.

CanopyCanopy ( 冠層 ) -- the dense mass of leaves and branches of a tree that covers the ground underneath.


Terms to learn

Plant litterPlant litter ( 枯枝落葉 ) -- the fallen leaves and branches lying on the forest floor.

UndergrowthUndergrowth ( 樹林低層植物 ) -- the small trees and shrubs that grow beneath and among the taller trees.

Convectional rainConvectional rain ( 對流雨 ) -- rain which is formed when moist air heated by hot ground expands and rises upwards to form strong convection current.


Download - Unit 1 Tropical rainforests-- what and where are they? Unit 1 Tropical rainforests--what and where are they?

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