Download AQA-The Living World- Revision - Henley-in

Question 4:
Ecosystem
The Living World Unit 1
The relationship between living things (biotic) and
their non living environment (abiotic/physical world).
Living = Vegetation / wildlife / bacteria
Non-Living =
Biome
A world-scale ecosystem. It is found worldwide at
similar latitudes. The rainforests are one biome, Hot
deserts are another.
Biosphere
The zone where life is found, it extends to -3m and
+30m and is located between the lithosphere and the
atmosphere.
The Location of Ecosystems
Distribution
Hot Deserts
Are closer to Tropics of Cancer and Capricorn.
Greatest extent is in Sahara, around Egypt and
Northern Africa. Approx 30º N and S
Tropical Rainforests
Are located close to the Equator, and are
located down the wet eastern sides of the
continents in the tropics. 0-20° N and S
Deciduous Forests
Are in temperate latitudes, they’re located
further north and south on western sides of
continents (warmer winters). They cover UK
and much of Europe.
Changing Ecosystems
Global Influences that determine the
Local influences that determine the type of
type of ecosystem
ecosystem
Temperature: Affects plant growth, over
the tropics the sun’s rays are higher and
more concentrated meaning more plant
growth. Poles they are less concentrated
because they are spread out over a wider
surface area.
Altitude: Temperatures drop by 1°C for every
100m, causing less plants to grow.
Continentality: The distance from the sea
changes temperatures. Warms quickly in
summer and cools quickly in winter, with
increased distance
Precipitation: This happens where air
masses meet and rise. Air masses meet
and rise to form low pressure belts that
have all year round rainfall. E.G. The
equator and in the UK.
Nutrient-rich environments encourage plant
growth. Nutrients provided by soil
Geology (rock type), soils. relief, drainage of a
water
High-pressure belts, air descends creating
dry conditions. e.g North and South Poles
Seasons affect pressure belts.
Climate in the key ecosystems
Temperature
Rainforests
Hot Deserts
Deciduous
Forests
28°C Daily
Up to 40°C
Daytime
20-25°C summer
temperature
Above 0°C Winter
Below 0°C night
Rainfall
(precipitation)
Over 2000mm
Less than 250mm
500-1500mm
Of rainfall a year
a year
A year
Rains all year Wettest March
Rains all yearwettest in winter
Adaptations in the key ecosystems
Biome
Adapted to Climate
Adapted to Soil
Hot Desert
Saguaro Cacti have waxy
reflective skin to reduce
transpiration.
Saguaro Cactus has wide and
shallow root system to maximise
water absorption
Barbs to prevent consumption
by animals
Acacia Tree has deep tap roots
(7-10m) to access ground water
in dry periods
Pleated stems expand to absorb
rainfall during wet periods.
Contract in dry periods to
reduce surface area.
Tropical
Rainforest
Grow very tall e.g. Canopy
layer to compete for sunlight tall thin trunks, with few
branches
Trunks have wide/thick buttress
roots to support trees in thin soil
and to access more nutrients
Drip tips to shed heavy rainfall
Wide leaves to absorb sunlight
Deciduous
Forest
Canopy trees grow very tall to
compete for sunlight
Herb layer flowers earlier to
maximise growth before leaves
block out sunlight
Deep roots to reach different
layers in the soil. They access
minerals by breaking apart rocks
and leaching them.
Characteristics of vegetation
Soils in the ecosystems
Hot Desert : Soils are rocky, sandy and grey in colour. They are thin and can
have a crust caused by impact of infrequent rainfall. Evaporation leaves salt
crystals in the soil.
Tropical Rainforest : Soils are red in colour and rich in iron. They are not
very fertile, any nutrients are quickly washed out by heavy rainfall. Thick layer
of leaf litter adds fertility as hot-humid conditions ensure it rots quickly.
Deciduous Forest : Most common soil is called brown earth, which is reddish
brown in colour. Every year fallen leaves decompose to ensure soils fertility.
Soil is about 1 metre deep.
Climate
Small Scale Ecosystem- A UK Hedgerow
Vegetation
UK is maritime (on the coast) /
temperate. This allows certain
plants to grow, e.g. deciduous.
Soils benefit from decomposition of
organic material such as leaves which
returns nutrients to the soil.
Wildlife
Soil
Rich vegetation due to fertile soils
(brown earths) found in lowland
Britain.
Varied vegetation provides habitats for
wildlife, food, shelter and breeding.
Animals help to fertilise soil and spread
seeds.
Food Chains and Food Webs
A Food Chain is a straight line (linear). it shows what animal eats what.
Plants and animals can belong to more than one food chain.
A Food Web is more complex and shows how different food chains link
together. It shows the transfer of energy between consumers and producers.
(90% of energy is lost at each stage)
Relationship: if you remove any stage of a food web, those above it will
reduce in number with a declining food source. Those below it will thrive as
they are no longer being eaten.
Components
Decomposer
Breaks down waste material
returning nutrients to the soil. E.G
Earth Worms and bacteria
Consumer
Eats the stage below it in the food
chain. Can be herbivores,
carnivores or omnivores.
Producer
Uses sunlight, water and CO² to
produce chemical energy through
photosynthesis. All plant life.
What is it?
Hot Desert
Tropical Rainforest
Deciduous Forest
A hot desert is a barren area of land where little
precipitation occurs and consequently living
conditions are hostile for plant and animal life. The
lack of vegetation exposes the unprotected surface of
the ground. vegetation is sparse, with limited variety
and there are few tall plants. There is some wildlife.
There are 2 seasons - Summer and Winter. It gets
very cold at night due to a lack of clouds in the sky to
trap the heat in.
Hot and humid, rainforest is a region of all year
round growth. It has many tall trees and thick
vegetation. There are a wide variety of plants
species. It is continually hot and wet with storms in
the afternoon. It contains a wide range of life, most
of which lives in the canopy layer. There are no
seasons. Cloud cover ensures it stays warm even at
night.
Found in temperate locations, deciduous forests are
wet all year round, with a long growing season (7
months). Plants grow in layers and lose their leaves
seasonally. There is a wider variety of species in the
lower herb layer, this includes plant and animal life.
Leaves are broad and trunks are narrow. There are 4
seasons.
Causes of Deforestation in the Atlantic Forest : A tropical rainforest in Brazil
Population Pressure
70% of Brazils 200 million people live around the Atlantic Forest.
Growth in coastal Cities such as Rio De Janeiro and Sao Paulo has increased pressure on the
forest.
Rainforest areas have experienced increased clearance as the rising population seeks space
for housing and farming.
Many People have set up small, sometimes illegal farms, in a bid to generate incomes and
provide for their families.
Amerindian Tribes
Many indigenous tribes live deep in the rainforest and they employ a method called ‘slash and
burn’ to clear areas of trees.
These tribes create a small and managed space so that they have room to farm and build
their homes. First by removing trees and then burning buttresses to fertilise the soil.
Because of the poor soil they have to migrate to a new location every 5 years.
This is called ‘Shifting Cultivation.’ The aim is to allow the rainforest to recover without
causing permanent harm.
Large Scale farms and Ranching
Brazil has over 1.3 trillion dollars of debt, mainly borrowed between 1965-85. These loans
have forced Brazil to sacrifice its rainforest to meet repayments.
Farmers were put under pressure to clear more land and produce more, to help Brazil pay its
bills.
Farmland is used to grow cash crops until its fertility drops then it is converted into huge
cattle Ranches.
Large areas of the Rainforest have also been bought by multinational companies. These
companies clear the Rainforest in order to graze cattle. This means that they can then export
the beef and make large profits.
Mining
There are many different minerals and resources that are located in the Atlantic Forest
Today the forest has been scarred by opencast mining that creates a giant pit.
Huge deposits of iron ore, gold, copper and tin are mined using these huge mines and lorries
transport minerals for export.
This provides a lot of wealth and tax income for Brazil as they sell these minerals
internationally
Road building
In order for projects such as mines and logging to take place roads need to be built across
the Rainforest, improving communications and enabling coastal exports.
These roads help move products and timber around the Atlantic forest, however they are poor
quality and increase the rate of deforestation.
Deforestation often occurs up to 50km either side of new roads as expansion and
development are uncontrolled and take advantage of improved access.
Impact of deforestation on the Atlantic Forest
The Consequences of deforestation (both positive and negative)
Economic
 Local economy is boosted and jobs are created.
 Valuable raw materials are obtained.
 The country becomes more economically developed.
 While deforestation is economically beneficial, estimates show that conserving
rainforest land is more economically viable.
 Brazil can use the taxes and exports to repay its $1.3 trillion debt
Social
 People may be opposed to deforestation, but governments won’t want to stop
because of the short term economic benefits.
 Improves communications through road building
 Indigenous people can continue their traditional way of life, subsistence farming.
 Indigenous people are lost. Five centuries ago, there were 10 million Indians in the
rainforest. Now there are only 200,000.
Environmental
 Rainforests used to cover 14% of the Earth. Now they cover 6% of it.
 Every second, 1.5 acres of rainforest is lost. 30% of CO2 in the last 150 years is
said to be from deforestation.
 Local environment is polluted – dust and noise pollution.
 Many plant/animal species have become endangered and/or extinct. (endemic
species such as the Golden Headed Lion Tamarin). 40% of tree species are endemic
to the Atlantic Forest (8000).
 Fewer trees stop rainfall reaching the ground (interception), leading to an increased
risk of flooding due to soil erosion blocking rivers.
 Soils become infertile due to leaching and lack of biodiversity.
Political
 Brazil becomes over reliant on exports to generate wealth and other countries
become dependent upon Brazil's mineral and agricultural exports.
Managing the Atlantic Forest
Setting up conservation areas – some areas of the rainforest cannot be developed
on. Groups lie Conservation International have encouraged countries like Germany to
invest in Brazil and establish protected areas such as National Parks. The World Bank
is helping to fund conservation corridors to link up remaining areas of Atlantic Forest
and enable species to move around.
Eco-tourism aims to turn a rainforest into an economic resource without the need
for deforestation. This provides locals with employment, educates visitors and
ensures the government becomes invested in preserving the rainforest. One
destination is Una Ecopark.
Restoration is carried out by REGUA (Reserva Ecologica de Guapiacu),an NGO
made up of local land owners and members of the community. By 2008 they had
replanted 38,000 trees of 50 different species, to regenerate the rainforest
ecosystem. It has set up an environmental programme for local schools. Students
visit the rainforest to learn about conservation.
Reducing Demand by Promoting wood that is sustainably managed or doesn’t come
from rainforests. FSC, the Forest Stewardship Council, allows companies to use its
logo on wood products if they promise to manage the rainforest in a responsible way
so that it can recover.
The ‘debt for nature swaps’ also generates income, because richer countries can
reduce the debt of poorer countries by persuading them to look after the rainforest in
exchange for reducing debt. Therefore, the poor country can reduce debt without
having to cut down the rainforest to generate income. This is usually arranged by
NGO's such as the WWF. (International Co-operation)
Selective logging – only a certain number of trees per hectare can be cut down.
This will ensure that some trees are kept, so the whole area will not disappear.
(preserves canopy layer). However 1/3 of areas are totally cleared by illegal logging
within 3 years and 30 trees can be damaged to access 1 selected tree.
Deciduous forest case study – Epping Forest Epping Forest
Epping Forest Epping Forest is located in south-east England, covering about 2500ha.
It is managed by the City of London Corporation, which produces management plans
to ensure the forest can provide for people as well as be conserved.
Lots of leisure activities take place here, e.g. horse riding, running and biking.
To manage the forest, trees are being pollarded (cut down to a certain height of
about 2-5m), and this gives us a supply of wood but also preserves the 50,000 trees
and 1200 'keystone trees', for future generations.
A large proportion of the forest has been declared a site of special scientific interest,
which protects the trees and animals in the area. Damaging activities, such as
mountain biking are being controlled using signs to inform visitors.
Use of deciduous forest for timber products (National Forest)
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The National Forest was created in 1990, it is located between
Leicestershire and Derbyshire.
It is a new forest and over7 million trees have been planted there. All
trees removed for timber are replanted to maintain the forests
ecosystem.
The forest supplies wood to meet Britain’s needs. 85% of woods is
currently imported at a cost of £8 billion.
The amount of wood created in British forests has increased to 9 million
m³.
Using the National Forest to supply wood products helps to develop a
forest economy in the area.
Woodland ‘thinnings’ are removed to prevent forest fires and are used
to produce woodchips .
Only more mature trees are cut down for timber to enable the forest to
fully develop.
Forest businesses plant and maintain the forest- pollarding and
removing fallen trees allows light to reach vegetation and promote
growth.
Businesses extract and processing the timber to make and sell wood
products. By adding value to the wood and the waste, they ensure that
the area is sustainably managed for future generations.
Managing deciduous forest
Controlled Felling is limiting the number of trees that can be cut down
Replanting, for every tree that is cut down, two or three new ones should be
replanted so the forest does not decrease
Conservation ensures the area is looked after and managed for future generations
Planning for recreational use so the area can be used for leisure without causing
permanent harm.
Protection: More than 2/3rds of Epping Forest has been designated a Site of Special
Scientific Interest (SSSI) and a Conservation area (SCA)
This is because the plants, animals and geography of the area need to be protected
for future generations. As an SCA it is given increased protection by the EU as part of
global efforts to conserve the world's species. This prevents deforestation.
Use of Hot Deserts
Richer- Outback
Covers most of central
Australia
• Mostly uninhabited
• Home to the Aborigine Tribes
Mining
Most people in the outback work in
mines. Australia has some of the world's
largest reserves of quality iron ore, silver
and gems such as opal.
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Coober Pedy in South Australia is the
opal capital of the world - 70% of the
world's opal comes from there
Mining has led to clashes with aboriginal
tribes who can demand compensation as
they control large areas of land in the
outback
Water discharged from the mining
process is contaminating springs with
metals and pollutants, while vegetation
around the mining suffers, offering
withering due to the loss of water in
underground aquifers.
Poorer- Sahara
1/4 of African Continent
North Africa
Includes a region called the
Sahel
Oil and gas extraction
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The Sahara contains large reserves of oil
and gas that are difficult to find and
extract. Transporting the oil across the
desert is equally difficult.
However, Oil and gas supplies are big
earners and Algeria relies on them for
50% of its GDP.
The Hassi Messaoud oilfield in Algeria is a
very difficult place to access but creates
40,000 jobs and pumps oil across the
Sahara to the northern coastline for
export.
Extraction uses and contaminates
underground water supplies found in
aquifers.
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Tourism
Agriculture
Uluru or Ayers Rock is a sacred site for
the aboriginal Anangu people. The
number of visitors has risen dramatically
from 5000 in 1961 to 400,000 in 2005
Egypt increasingly relies on farming to
feed its rising population
Tourism can bring economic benefits to
the local people e.g. when they buy
aboriginal arts and crafts, creating jobs
for local people and developing the local
economy
There are some problems:
Aboriginal culture is often exploited and
adapted to provide entertainment, tribes
are losing their sense of identity and
have slowly become a tourist commodity.
People come for the 'experience' of the
The population has increased by 59
million people in the last 25 years.
62 million of these Egyptians live in the
heavily irrigated Nile Valley. - 4% of
Egypt
The River Nile is the main source of water
and it is expected to suffer acute water
shortages.
There are 5.5 million hectares of
farmland along the Nile
sunset at the sacred rock, but may learn
nothing about aboriginal culture or beliefs
while they are there, often climbing or
walking around the site.
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The Anangu have no role in the
management or development of the
tourist resort where most visitors stay
and rely on the good will of tourists and
signage to protect this sacred site
32% of Egyptians work on farms
The building of the Aswan Dam in Egypt
has prevented silt travelling down the
Nile to farmland. This makes the
farmland less fertile and increases the
need for chemical fertilisers. It is also
increasing the rate of erosion along the
Nile’s banks.
Farming
Renewable Energy
It can be difficult to make a living from
farming in the outback due to the low
rainfall - less than 250mm per year
Just 0.3% of the Sahara's sunlight could
power Europe.
The soils are poor, with little organic
matter to retain moisture, and plants are
low in nutrients, these means crops are
often poor quality and hard to grow
If water is available, there's just about
enough grass to feed cattle or sheep but only in quite low numbers
In order for farmers to make any money
the farms are huge , this leads to the
development of a large areas of the
desert.
Over farming can lead to permanent
damage with soil suffering from
environmental degradation due to the
loss of limited water and nutrients
The lack of water also leads to farmers
using complex irrigation systems that
draw water from underground springs
and aquifers. However, this draws up
dissolved salt that increase salinity of the
soil making it less fertile and more
difficult for vegetation to grow
Hunting and gathering
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13% of Egypt's GDP comes from farming
Australia's aboriginal peoples have
traditionally survived by hunting and
The aim is to reduce Europe's
dependency on fossil fuels by using Solar
Power in the Sahara.
Large areas of Algeria and Tunisia will be
covered in solar plants.
An undersea network of power cables will
use Direct Current, to transmit the
energy over vast distances. The cables
will cross the Mediterranean Sea.
The aim is to start exporting energy to
power Europe by 2018, bringing
economic benefits to Algeria and Tunisia.
Enough for 2 million homes.
The Solar Plants will use mirrors to collect
energy during the day and continue to
operate at night by melting salts to
power heat driven turbines
gathering - finding edible plants and
animals in the outback using weapons
such as spears and boomerangs to catch
animals such as Emu and Kangaroos
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They created conditions in which the
grubs such as Witchetty - the Larvae of
beetles, could live and breed.
They built dams across rivers to catch
fish, and to make pools where birds
would gather to be hunted.
They used fire to drive out animals for
hunting, to clear wood, and to allow
grass to grow. As a result, fire-tolerant
plants (eucalyptus trees) came to
dominate the landscape
Retirement Migration
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People are attracted to the clean
atmosphere and open spaces when
looking for somewhere to retire
Elderly people migrate to the Outback,
where they will then retire to enjoy the
freedom and change of pace
They will live in newly built housing
complexes, often with swimming pools
and nearby luxury facilities such as golf
courses.
These complexes put an immense strain
on the fragile ecosystem, both in terms
of water consumption and power
generation.
Managing the challenges of Hot Deserts
Richer- Outback
Poorer- Sahara and the Sahel
region
Farming
The Toshka Project
Farms use dams and reservoirs to store
water during dry periods.
Egypt is spending $70billion to pump
water from Lake Nasser to western
Egypt.
Farmers use boreholes to tap into
underground water supplies.
Argument is that not enough is being
done.
This helps to create 30% more fertile
farmland and reduces pressure on the
Nile Valley.
They can grow more cash crops such as
olives to increase exports and generate
wealth.
They can stop pumping water from
underground aquifers.
They can use more of the desert in a
productive way.
Tourism
Uluru Cultural Centre helps to educate
tourists about aboriginal culture and
history, using photos and displays and
language learning.
Aboriginal guides lead walks that inform
visitors about life in the desert and the
significance of sacred sites.
Admission fees are charged to help pay
30 employees who are responsible for the
management and restoration of the area
around Uluru.
The Sahel is being managed using a
range of methods.
Reducing the number of farm animals to
stop overgrazing.
Mixed farming, crops and animals so that
manure can be used to fertilise fields.
Re-planting trees so that roots bind the
soils and limit erosion.
Building earth dams to collect water
during wet periods and store it for dry
periods. This reduces need for
underground supplies that deposit salt
crystals.
Desertification
Desertification = Over time, the quality of vegetation and soils is reduced. This
causes more desert-like surfaces.
Vegetation declines due to either climatic drought (which may be caused by global
warming) or human removal. Less vegetation means less organic matter. The soil
dries out, and the fine organic matter and mineral particles are blown away. When it
rains no water reaches the soil.
Impacts:
Deforestation is one cause of desertification.
A lack of vegetation exposes the soil, therefore causing soil erosion.
Overgrazing and overcultivation can cause desertification (this is more evident in
poorer parts of the world e.g. Sahel in Sahara Desert).
A solution is to use crop rotation; however, many people in the Sahel may not do this
as they are too poor to reduce production.
Desertification can cause an increase in poverty. This is because there is no
opportunity for agriculture due to the soil being infertile.
Table of keywords
Temperate
Mild temperatures, not too hot or cold
Deciduous
Trees/shrubs that lose leaves seasonally
Coniferous
Evergreen trees, needle leaves
Precipitation
Water falling / rainfall
Photosynthesis
Turn light energy into chemical energy
Humid
Large amount of water
Transpiration
Loss of water from plants
Evapotranspiration
Total evaporation from plants and the land
Equator
Imaginary line- equal distance from polesdivides Earth
Latitude
How far North or South you are from the
equator, measured in degrees.
Tundra
Low temperatures, few trees
Endemic
Found only in a specific location