Transcript Unit 1 Tropical rainforests-

Unit 1 Tropical rainforests--what and where are they?
Unit 1
Tropical rainforests-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.
Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
What is an ecosystem?

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Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
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.
Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
The tropical rainforests have a great variety of
plant and animal species.

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Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
 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.
Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
 Trees in tropical rainforests are tall and straight. They
develop plank-like buttress roots for firm support.
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Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
Trees have waxy
leaves with downwarddipping points or drip
tips to shed rainwater.
There are a lot of
climbing and creeping
plants.
There are
ferns, lichens
and mosses.
Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
The structure of a tropical rainforest
m
Top layer
This is the highest layer with
trees rising up to 40 m.
The trees form a continuous
Main layer 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
Ground layer
has little undergrowth as sunlight cannot reach it.
Lower layer
Unit 1 Tropical rainforests--what and where are they?
What are the characteristics of tropical
rainforests?
The structure of a tropical rainforest

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Unit 1 Tropical rainforests--what and where are they?
Where are the tropical rainforests?
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:
1. The Amazon Basin in South America
2. Indonesia in Southeast Asia
3. The Congo Basin of Central Africa
Unit 1 Tropical rainforests--what and where are they?
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.
Unit 1 Tropical rainforests--what and where are they?
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.
Unit 1 Tropical rainforests--what and where are they?
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.
Unit 1 Tropical rainforests--what and where are they?
Where are the tropical rainforests?
N

N
S. E. Asia
Congo
Basin
Indonesia
Amazon
Basin
S
Tropical rainforests
km
Unit 1 Tropical rainforests--what and where are they?
Why are the rainforests there?
High 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.
Unit 1 Tropical rainforests--what and where are they?
Why are the rainforests there?
Heavy 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.
Unit 1 Tropical rainforests--what and where are they?
Why are the rainforests there?
Clouds
Strong convection current
Warm, wet air
Rain
Low pressure
Hot ground
Air cooled to
form clouds and
rain
Hot, wet air rises
when heated
Unit 1 Tropical rainforests--what and where are they?
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-tips (滴水葉尖) -- the downward-dipping
points of leaves for shedding rainwater.
Unit 1 Tropical rainforests--what and where are they?
Terms to learn
Lichens (地衣) -- small plants growing like a crust
on rocks, trunks and branches of trees.
Mosses (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.
Canopy (冠層) -- the dense mass of leaves and
branches of a tree that covers the ground
underneath.
Unit 1 Tropical rainforests--what and where are they?
Terms to learn
Plant litter (枯枝落葉) -- the fallen leaves and
branches lying on the forest floor.
Undergrowth (樹林低層植物) -- the small trees and
shrubs that grow beneath and among the taller trees.
Convectional rain (對流雨) -- rain which is formed
when moist air heated by hot ground expands and
rises upwards to form strong convection current.