Topic 1

World ecosystems

Index

• Natural environment.

• Green house effect

• Human effects on ecosystem cycles.

Natural environment

• An ecosystem is a community of trees, plants, animals and insects living in a particular environment.

• All living things are linked and depend on the land, water and air.

What is an ECOSYSTEM?

• An ecosystem is a group of living things plus the non-living things they need.

• The parts of an ecosystem are linked together.

• For example: in a woodland ecosystem, rain is an input which makes the trees grow. Evaporation is an output.

• Copy the diagram and add examples to each box.

• Human action also affects.

At what SCALE do ecosystems operate?

• There are many different ecosystems in the world.

• Some are small-scale, such as a pond.

• Others are large-scale and cover vast areas, such as a rainforest.

FOOD CHAINS

• Living things in the ecosystem are linked together by the flows of energy and matter as things eat each other.

• These links can be shown as food chains

FOOD CHAINS

This shows a food chain in the sea. Removing one animal from this would seriously harm the system.

HOW?

FOOD WEBS

This shows a food web in a woodland area.

What would happen if the RABBITS were removed from the ecosystem?

Sections

• Abiotic

• Biotic

World ecosystems

8 types

Lets go to the rainforest and find out what its like, the

types of vegetation &

its soil

1.Tropical rainforest

LocationLocation

Equatorial EcosystemHot all year

Wet all yearHigh annual rainfall over 2000mm

Wide biodiversity

Plants love the heat & humidity

Trees are evergreen Trees have thin barks –

no need for protection against the cold

Characteristics of vegetation in the rainforest

Tall straight trunks no side branches

Aerial roots of epiphytes absorb moisture from the air

Shallow spreading root system Buttress roots

Thick, waxy surface of leaves protects against hot sun, heavy rain, and strong winds

Rainforest Floor

Dark Forest FloorDark Forest Floor

FACTSFACTS•The Amazon Rainforest has been described as The Amazon Rainforest has been described as the "Lungs of our Planet" because it provides the the "Lungs of our Planet" because it provides the essential environmental world service of essential environmental world service of continuously recycling carbon dioxide into continuously recycling carbon dioxide into oxygen. More than 20 percent of the world oxygen oxygen. More than 20 percent of the world oxygen is produced in the Amazon Rainforest. is produced in the Amazon Rainforest.

•One and one-half acres of rainforest One and one-half acres of rainforest are lost every second with tragic are lost every second with tragic consequences for both developing and consequences for both developing and industrial countries. industrial countries.

A Discontinuous Canopy of treeCrowns of the Tallest trees 40 – 50m(Emergent)

B 25 – 40m Continuous layer of Main canopy

C 10 -25m Discontinuous underCanopy of

D Layer of shrubs & Young trees

E Herb layer with Ferns 6m+ high

5

10

15

20

25

30

35

40

45

Rainforest Floor

Dark Forest FloorDark Forest Floor

Human impact on Tropical Rainforest

Before clearance• Rain intercepted• Organic matter decays

quickly• Nutrients released• Nutrients taken up by the

trees

After Clearance• All rain reaches the

surface• No trees left to supply

nutrients• Nutrients already in the

soil are washed out• Increased surface runoff• Increased soil deposited

into the rivers

Solutions?

Management

• Making a survey of the area’s resources before using them

• Selecting only a few trees per hectare

• Cutting down only fully grown trees

• Replanting those cut down

• Checking the work is done according to the plans

2.Tropical Grassland

• Resistant trees

• Waxy leaves and thorns=espinas

3.Desert• Drought

resistant plants, such as cacti, with very long roots to reach water supplies deep underground.

Desert

Savanna

Equatorial Rainforest

Savanna

Desert

Sahel

Baobab

Acacia

Almost uninhabited• Nomads

– Tuaregs in Sahara– Mongols in Gobi

Some towns have developed in deserts around the oil and natural

gas industries

Dubai

Dubai Airport

Las Vegas in Mojave Desert

4.Mediterranean• Evergreen woodland, such as cork and

pine, thorny shrubs.

Holm oaks = Encina

Pine trees

Shrubs = bush

Lavender

5.Temperate grassland

• Grasses up to 2 metres tall, some trees such as willow=sauce

Prairies of tall grass

Landscapes of low grass = Steppes

Willow

6. Decidous forest or woodland

• Trees which shed their leaves in winter, such as oak and ash, shrubs and short grasses.

Deciduous forests (Bosques de hoja caduca)

7.Coniferous forest

• Dense evergreen trees, such as fir=abeto, pine.

Coniferous trees

• Fir ( Abeto)

• Pine (Pino)

8.Tundra

• Short plans, such as moors, heather and lichen.

• Some stunted trees

Tundra landscapes

• Moss (musgo)

• Lichens (líquenes)

• Small trees

Animals

• Reindeer

• Foxes

• Wolves

Small groups of Sami and Inuits

How are ecosystem affected by human action?

• Almost all ecosystems around the world have been affected by human activity.

• In some areas little remains of the orginal ecosystem.

• Today large areas of untouched tropical rainforest are under threat from deforestation.

• The greenhouse effect is a natural phenomenon that controls the balance of heat within the Earth's atmosphere.

What is the “greenhouse effect”?

• It is the process whereby the natural layer of gases in our atmosphere trap a small percentage of the sun's radiation reflected from the earth's surface. Without the greenhouse effect, the average surface temperature would be about -18 degrees Celsius.

Greenhouse effect

• Global warming is caused by the increases in the amount of carbon dioxide and other gases being released into the atmosphere by the burning of fossil fuels. These gases add to the natural greenhouse effect are causing global temperatures to rise.

What problems are caused by global warming?

Sea levels will rise due to the melting of the ice caps.

Consequences

• Sea temperatures will rise

Ice caps and glaciers will start to melt

Low-lying areas will be flooded

Violent storms, and extreme hot weather

Deserts will spread

Vegetation and climatic belts will move

Increasement in insect pests

Tropical diseases may spread

Global warming is thought to be due to the greenhouse effect.

Climate changing gases

Kyoto Protocol-1997

• In 1997, the Kyoto Protocol brought agreement between countries that greenhouse gases should be reduced. So far, many European countries, including Britain, have admitted difficulty in achieving the target.

• http://www.youtube.com/watch?v=Jh02eZFRIh4&feature=related

Activity: the Kyoto Protocol

• http://www.youtube.com/watch?v=oJAbATJCugs&feature=player_embedded#t=184

• Watch it and answer the questions.

Human effects on ecosystem cycles: floods and deforestation

Floods and deforestation

Activities that alter the natural landscape

The development of agriculture The construction of towns and cities

The concentration of industries and other economic activities

Serious disturbances-Intervention of human societies

• Erosion and desertification

• Deforestation

• Pollution

Why do some floods have disastrous consequences?

• The flood plain is the area around the river that is likely to flood. The more people there are living and working on the flood plain, the more damage a flood will do.

FLOODS CAN CAUSE EXTENSIVE DAMAGE

MEDC flood example-Lynmouth 1952

• Very heavy rain for 2 weeks before flood.

• Another heavy storm on 15 August .

• Lynmouth is situated by a confluence, increasing chance of flooding

• Small bridges on the river trapped boulders and trees.

http://www.youtube.com/watch?v=u6Urpw3AQDU

Effects

• 34 people died

• 90 buildings destroyed

• 1000 people homeless

• 150 cars/boats destroyed.

Floods - Bangladesh, 1998 (LEDC)

• 80% of Bangladesh on flood plain

• Strong winds lead to storm.• Rivers flood in summer due to

monsoon rain. • Deforestation in Nepal .• River Ganges used for

irrigation upstream – less silt in downstream to build up the floodplain

• Rising population –slope collapse

http://www.youtube.com/watch?v=1tMMcrl_foo

Effects

• 1040 people died

• Over half the country flooded

• 23 million homeless

• 130 million cattle drowned

• Crops ruined

• Drinking water polluted

• Communities destroyed

http://environment.nationalgeographic.co

m/environment/photos/floods-general/#/amazon-

river_50_600x450.jpg

DeforestationWhat can we do to stop it?

Deforestation in Brazil-5 reasons

• 1. Trees are logged and exported to MEDCs.

• LEDCs don't plan for the future because they are more concerned with making money today.

• 2. The population is increasing and the government wants to build settlements and roads in the tropical rainforest.

• Trees have to be cut down to make space.

• 3. The forest is cleared to set up cattle ranches which quickly make the land useless.

• 4. Mineral extraction helps Brazil pay foreign debts — In Brazil is the world's largest iron reserve.

• Forest is removed to make way for roads and mines.

• 5. Hydro-electric power (HEP) development has meant that large areas of land have been flooded.

5 reasons

http://www.historiasiglo20.org/MEC-BC/Ecosystems/

quizmaker.html