UNIT 7: WORLD LANDSCAPES
1.
NATURAL
LANDSCAPES
Natural landscapes are found
around the world, sharing conditions such as climate, vegetation, soil and fauna.
These large regional habitats are called biomes. We can classify the
world’s biomes in different groups, according to their latitude. They include the following:
- Cold climates: the
tundra and the perpetual ice of polar regions.
-Temperate climates:
oceanic, continental and Mediterranean landscapes.
-Hot climates:
equatorial and tropical rainforests, the savannah and hot deserts.
-Other landscapes:
mountain areas and humid areas, like mangroves and dunes.
2.
NATURAL
LANDSCAPES IN COLD CLIMATES
Two types of climate are found near the polar circles: the Arctic tundra and the perpetual ice of the polar regions.
THE TUNDRA
The tundra is a vast area of
low land near the Arctic Ocean in the Northern Hemisphere. Moss, lichen and small shrubs grow
in the topsoil. However, the frozen
subsoil, or permafrost, does not allow trees to grow there. Migrating birds eat insects in lakes
and marshes during the summer. Other
animals include reindeer, moose, Arctic
foxes and Arctic hares.
THE TUNDRA IN DANGER
The tundra is threatened by
global warming. As temperatures rise, permafrost melts under the ground. The softened
earth then releases methane gas from
frozen deposits deep underground. This gas is one of the causes of the
greenhouse effect.
PERPETUAL ICE
Perpetual ice is found in
polar regions. The
ground is frozen all the year round so there is no vegetation. Only a few species of animals, like seals and polar bears, can adapt to the cold and lack of vegetation typical of these regions.
3.
THE
NATURAL LANDSCAPES IN TEMPERATE CLIMATES
The natural landscapes of
continental, oceanic and Mediterranean climates are found in the températe latitudes,
between the tropics and the polar circles.
CONIFEROUS FOREST
Coniferous forests, also
known as the taiga, are found in continental climates, south of the Arctic tundra. These forests stretch across the north of Europe, Asia and North
America. Conifers, such as pine and fir trees, can survive very cold winters when the ground freezes. The fauna includes deer, bears and lynxes.
THE TAIGA IN DANGER
The taiga is threatened by
global warming that dries the soil, and increases the risk of forest fires. The taiga is also
threatened by deforestation because millions
of trees are cut down each year to make products like paper.
GRASSLAND AND STEPPE
Grasslands and steppes are
usually found in continental climates, south of the taiga, where temperatures
are higher. The soil is generally fertile in grasslands. Animals include foxes and moles.
DECIDUOUS FOREST
Deciduous forests are found
in oceanic climates, where temperatures are mild and rainfall is abundant. Deciduous trees, such as
oak, beech and maple, lose their leaves in the autumn. These leaves enrich
the soil making it very fertile. The varied fauna includes deer, rabbits
and many species of birds. Bushes
and low grass often grow in areas where the forests have disappeared. Deciduous forests are a threatened
ecosystem. Human activity affects
these forest due to the fertility of the soil that is then used for
agriculture. Climate change is also a great threat to these forests.
MEDITERRANEAN FOREST AND SCRUBLAND
Mediterranean forests are
found in Mediterranean climates. The trees in these forests are perennial,
meaning they don’t lose their leaves.
They include holm oaks, cork oaks and
pine trees. The fauna includes deer, rabbits and birds of prey. We
also find scrubland in areas where there
are fewer trees. Plants like thyme
and rosemary grow in scrubland.
The soil is fertile near river beds, but less fertile where erosion has
occurred.
4.
NATURAL
LANDSCAPES IN HOT CLIMATES
The natural landscapes of
hot climates are found between the Tropic of Cancer and the Tropic of
Capricorn, where it is hot all the year round and there is no winter.
RAINFOREST
Rainforests are vital for
our planet because their vegetation absorbs carbon dioxide, and they supply us
with wood and other products.
-Equatorial rainforests
are found near the Equator in South
America, Africa, Asia and Oceania, where precipitation is abundant and
temperatures are high. Vegetation is
dense and varied, due to the heat
and humidity. At the highest level,
or canopy, the tallest trees receive the
most sunlight. Moss and fungi grow
on the forest floor, where the soil is poor. Plant species include rubber and banana trees and bamboo.
The fauna is varied and abundant. It
includes many species of insects and
colourful birds, as well as apes, reptiles and amphibians.
-Tropical rainforests are found at higher
latitudes, and are similar to equatorial rainforests. However, the trees are not as high and the
vegetation is not as dense. Consequently, more light reaches the forest floor, where smaller trees, shrubs and
ferns grow.
THE AMAZON IN DANGER
The Amazon rainforest is
important for Earth’s biodiversity because it is home to numerous species of
plants and animals. But every year, many trees are cut down and the land is
used for agriculture. The region’s natural reserves are over-exploited, and it is polluted
by the millions of people who live along the Amazon river.
THE SAVANNAH
Savannahs are found in
tropical climates, usually between rainforests and hot deserts. The savannah
has very tall grass during the rainy season. It
also has shrubs and some scattered trees. The fauna is abundant and varied, including elephants, giraffes, lions and zebras.
THE SAVANNAH IN DANGER
The savannah is threatened
by drought. Global warming and the lack of water cause soil erosion and desertification.
Agriculture and stock farming also affect this ecosystem.
HOT DESERT
Hot deserts are found in
tropical areas where rainfall is very scarce.There
is very little vegetation because of the
lack of water, and only a few
plants, like cactuses, can grow. The
water in oases allows palm trees and other plants to grow there. The fauna in deserts is also scarce with reptiles, rodents and some predators.
5.
MOUNTAIN
LANDSCAPES
Not all landscapes are found
in just one climate zone. They are influenced by
other factors such as relief, soil and water. Mountain landscapes are determined by elevation. The higher a mountain,
the colder and windier it is. Vegetation
is denser at lower altitudes, and is also affected by the amount of sunlight
the mountain receives. Some animals, such as mountain goats and birds of
prey, are suited to a mountain environment. Vegetation zones are different in temperate climates and hot climates.
6.
COASTAL
LANDSCAPES
Water has a key role in the
formation of coastal landscapes. Here are three examples:
MANGROVES
Mangroves are coastal seawater
habitats in the tropics. Their vegetation includes a variety of species of
mangrove trees, which adapt to salt water.
They are the habitat for a variety of fish,
reptiles and birds. Many small animals, such as crabs, live in the trees’ twisted roots,
which are exposed to the air at low tide.
WETLANDS
Wetlands are areas of land, such as
marshes, that are partly covered by water. Wetlands may have saltwater, fresh
water or a mixture if the land is close to a river estuary. Aquatic plants adapt to this type of environment. The fauna includes many
species of insects, as well as birds
that feed on the insects.
Unit 7: World landscapes
COASTAL DUNES
Coastal dunes form where sand accumulates
in the sea and the wind blows it inland. Dunes are mounds of sand, caused by
the wind. Only a few strong grasses
can grow in dunes. The fauna is also
scarce, and includes reptiles and
rodents.
7.
HUMAN
INFLUENCE ON LANDSCAPES
Our natural environment is
vital to us in different ways. Most of the world’s population lives in regions
where food is grown easily, and only a few people live in deserts or mountains. We need fresh water for
human consumption and agriculture. It is important for our health to breathe
unpolluted air. Humans change their environment all the time. They build roads and cities. Agriculture and
mining also transform landscapes.
But it is important that these
changes do not cause long-term harm
to the environment: we call this goal
sustainable development.
ENVIRONMENTAL PROBLEMS
-Air pollution is caused by gases released by industry and traffic. This causes problems such as acid rain, depletion of
the ozone layer, and the greenhouse effect.
-Climate change
is also connected to air pollution. Global
warming will cause glaciers and polar ice caps to melt and will raise the level
of the oceans. Desertification will increase.
-Vegetation. We cut down millions of trees every year.
This deforestation causes soil erosion and leads to a loss of biodiversity. It
may also cause desertification.
-Water. The pollution
of rivers and lakes that dry up affect agriculture and livestock.
8.
NATURAL
HAZARDS
Some natural phenomena have
a major impact on people and the environment:
-Earthquakes are the shaking of the Earth’s crust as a
result of the movement of tectonic plates. Most earthquakes are just light
tremors, but violent earthquakes cause
great damage. Underwater earthquakes
create tidal waves, called tsunamis, which may also cause disasters in
coastal areas.
-Volcanic eruptions
change relief, raising mountains and
even islands. Violent eruptions can cause great damage.
-Hurricanes are very strong winds
accompanied by torrential rain. In some parts of the world they are called cyclones
or typhoons.
-Flooding may
occur after torrential rain. Rivers and
lakes overflow and flood the surrounding land.
-Droughts occur when there has been
no rain for a long time. There may
be a shortage of water for agriculture and human consumption.
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