Geography IGCSE Fragile Environments (7.1, 7.2, 7.3)

Fragile environment

Any natural environments/ecosystems that are sensitive and vulnerable to change, in particular by human activity

Ecological footprint

The impact a person or community has on the environment, expressed as the amount of land required to sustain their use of natural resources

Influencing factors of ecological footprint

- Rate of population growth

- Levels of consumption of resources per person

- Type of technology

Desertification

When areas of fertile land turn to desert

Distribution of desertification

Mostly in semi-arid regions of hot deserts: Southern Asia, Middle East & North Africa (sahel region)

Characteristics of desertification

- Absence of surface water

- Dried up rivers and ponds

- Water table lowered

- Vegetation becomes degraded or completely lost

- Increased soil erosion as bare soil is exposed to win

- Increase in salt content of the soil

- Soil becomes less stable

- Increasing presence of dry, loose sand

2 main causes of desertification

1. Human activity

2. Non-human induced climate change

Climate change

Less rainfall leads to bare soil and increased water-flow overland.

3 possible things that follow:-

1. Water drained from soil, so soil is dry and blown away more easily creating a dust bowl.

2. Water table lowered

3. Water washes soil away

All of these lead to few plants growing and little farming possible leading to dertification

Natural causes of desertification

Changing rainfall patters - less predictable rainfall and year-long extended droughts results in vegetation cover dying leaving bare soil.

Soil erosion - the removal of soil means less support for vegetation.

Rainfall intensity - short or intense periods make it difficult for the soil to capture and store water so there are less water resources

Human causes of desertification

Population increase - this means more fuel wood is needed so trees are cut down and deforestation occurs leaving the soil bare and expose to soil erosion leading to desertification

Population increase - more food needed resulting in over cultivation and overgrazing so soil becomes worn out and eroded leading to desertification

Agriculture puts more strain on the soil making it vulnerable to soil erosion .- desertification

Poverty means that people are unable to afford fertilisers and the soil becomes worn out and eroded

Migration - as desertification takes place in one area, local people migrate elsewhere in search of food and water. Wherever they settle, they increase population pressure on the environment

Over cultivation

Intensive use of marginal land exhausts the soil and crops will not grow

increases runoff - soil erosion - few plants

Over grazing

Too many goats sheep ad cattle can destroy vegetation.

bare soil - wind erosion -desert

Impacts of desertification

Soil quality is degraded - Soil is made up of a mixture of dying vegetation & minerals from broken bedrock. In areas where desertification is spreading, the quality of the soil becomes degraded as there is no vegetation

Agricultural output decreased - As soil is degraded, less farmland to grow crops. It'll become common that crop yields decrease and fail and farm animals die

Famine malnutrition and death - If farms are the backbone of how people gather food and suddenly these farms turn into desert, many people become ill and die.

Migration and conflict - since people are threatened with famine and unemployment, they will have to move to find new sources of food and work. If the migrants arrive in areas where people are only just barely surviving, they will feel threatened and conflict may rise

Preventing desertification

Building small dams to collect the small rainfall before evaporation by the sun

Water spreading weirs since they use floods to rehabilitate degraded landscapes and river beds

Afforestation (A great green wall) which is a huge initiative to plant a wall of trees across the sahel (also decreases unemployment)

Contour ploughing is the action of digging holes to put crops into. Ploughing across a slope slows surface run off from rainfall

Education - teach local farmers which types of crops harm the oil and which protect it

Adding mulch (dead leaves and plant waste) to farms to slow down evaporation.

Preventing desertification pt 2

Permaculture - relies on rotating spoil crops to protect soil, no chemicals used. Growing crops to use as natural fertiliser. Trees planted around the farm to protect from wind erosion. Dead leaves create mulch and livestock can be used to collect extra natural fertiliser

Fuelwood farms - Cultivate fast growing trees for harvesting as fuel wood. Having specially created farms for fuel wood reduces stress on the indigenous forests and keeps soil protected.

Location of Sahel

Narrow belt of sand in central Africa. It borders the southern edge of the Sahara desert (sub-saharan Africa). Most of the countries are underdeveloped including south sudan, nigeria and ethiopia

Climate of the sahel

Semi - arid. Temperature always hot and reaches 38 degrees during June. Dry season between June and January. Some rainfall from February and march for plants to grow.

How does vegetation change as you move from North to south

As you move north - climate becomes drier and there is nothing more than thin grassland

Causes of desertification in the sahel

Climate change

Human activity

Over cultivation

Absence of vegetation

Impacts of desertification in the Sahel

- Since 1970s, crop failures are an annual event

- Over 100,000 people have died of starvation

- More people have migrated to less arid areas

- Millions of animals died

Methods of management in Sahel

1. Planting more trees to hold soil and reduce soil erosion

2. Improving quality of soil - encourage people to reduce number of grazing animals and instead grow crops. Animal manure used as fertilisers (sustainable farming)

3. Water management - store water in earth dams during wet season and irrigate crops during dry season

4. 'Magic stones' - Placing circles of stones on the ground to hold water and prevent surface run-off

5. Drip irrigation - minimise water loss and maximise effectiveness

Deforestation

The large scale cutting down and clearing of forests

Primary forests

Forests that have allowed to grow at a great age the without disturbance

Deciduous trees

lose leaves during colder months

Coniferous trees

Maintain their leaves all year; evergreem

Causes of deforestation

Commercial logging - valuable trees are specifically selected to be chopped down, however, they damage surrounding trees. Further damage caused by clear filling where other trees are chopped and chipped for pulps.

Commercial Agriculture - large areas of are cleared for plantations to grown single crops.

Road building - Roads are being built through rainforests to ease the transport minerals, timber, cattle and crops.

Land for local farmers

Mining - iron gold and copper

Hydroelectric power - rivers are damaged and huge areas of forest are flooded

Impacts of deforestation

Atmospheric CO2 increased - when trees are cut, hey do not only stop taking in CO2 but also release all of the CO2 they had stored in them previously

More soil erosion - no trees to protect the soil - soil infertility - desertification

Migration - indigenous tribes are moved from their home. Troublesome because indigenous tribes may not be able to adapt to living in new and modern areas - conflict.

Landslides and mudslides - The roots of trees hold soil together when its wet. With no trees, soil isn't stale so it is more vulnerable to landslides

Lack of biodiversity

Managing rainforests

- Protection of forests

- Controlled logging

- Selective logging

- Heli-loggingg

- Replanting of forests

- Policing and surveillance

- Alternative sources of energy

Sustainable management

- Respect the environment and cultures of local people

- Use traditional skills and knowledge

- Gove people control over their land and lives

- Use appropriate technology (cheap and do not harm environment)

- Generate income for local communities

- Protect biodiversity

Amazon rainforest

- Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname

- 5.5million km2

- 390 billion trees divided into 16000 species

- 10 million species of animals

Reasons for deforestation in the Amazon rainforest

- Mining - the iron ore mines at Carajas

- Road building - the Trans-Amazon rainforest

- Dams - Large hydroelectric dams in Xingu clear large areas of forest for their reservoirs

Impacts of deforestation in the Amazon

- 330 tribes in 19000 but now only 240 , centuries of useful knowledge about sustainable living lost

- soil erosion - makes it hard for anything to grow

- Local climate change - local climate dried and increasing temperatures disrupts commercial farming

- Global warming-

- Loss of biodiversity - currently contain abut half of the most known animal species

Management of deforestation in the Amazon

- The forest code - implemented in 1965, a lar that requires all landowners to maintain up to 80 percent of their property. Unfortunately, it is hard to monitor.

-The Amazon Region Protected Area (ARPA) created in 2012 by the Brazilian government. Over a 10 year period, 45 million hectares were made into parks and reserves

- Replanting project - A project in the Atlantic Rainforest (REGUA) proved its possible to return rainforests to almost their original state. This is done by collecting seeds from patches of the primary rainforest - growing these seed and then planting them in deforested areas.

- Encouraging cultivation of commercial timber on plantation located outside the rainforest. There are now 5 million hectares of forest plantations.

UN-REDD

United nations programme on reducing emissions from deforestation and forest degradation

- deals with counter forces driving deforestation

- ensures the needs of local and indigenous people

- makes payments if forested areas are left untouched

UNFF

United Nations Forum on forests

- promotes management, conservation and sustaiable development

CITES

Convention on International Trade in Endangered Species

- international agreement between governments

- ensures international trade in specimen of wild animals and plants does not threaten their survival

Global warming

The rise of the average global temperature over time

Climate change

Long term changes in atmospheric conditions

Natural causes of climate change/global warming

Solar variations - Suns energy is not constant, sometimes it is more active than others. Sun spots are large black spots seen on the sun during times of high activity - scientists have linked more of these with rising temperatures

Volcanic activity - large scale volcanic erruptions eject huge amounts of dust and ash into the atmosphere. Such mega eruptions can block out solar radiation leading to global cooling

Cosmic material - similar to volcanic activity but meteorites

Milankovitch Cycles - Changes in the earths orbit. Over 1000 of years the orbit changes. Sometimes the orbit is closer to the sun and temperature on earth heats up or vice versa.

3 types of orbital variation

Eccentricity, Tilt, precession

Eccentricity

shape of Earth's orbit around the sun

Tilt

The earths tilt is currently 23.5 degrees which is why we have seasons. The tilt changes between 21.5 and 24.5 every 41000 years

Precession

The way the earth wobbles as it spins also changes every 19-24 thousand years

Mlankovitch theory

Every 100,000 years, these variation match up in a way to significantly reduce the amount of solar radiation and put us into an ice age.

After this, the solar radiation increases and global temperatures rise

greenhouse effect

Sun rays travel to earth in the form of shortwave radiation (light)

Incoming solar radiation is shortened to insolation

Insolation can pass through the atmosphere

When the insolation makes contact with a surface, ot changes to heat energy (long wave radiation)

Long wave radiation (heat) cannot pass through the atmosphere easily as it gets trapped by the greenhouse gases and so the planet stays warm

Enhanced greenhouse effect

Similar to the natural greenhouse effect but when humans add extra gases to the atmosphere, less heat will be able to pass through to space and the planet warms up causing global warming

Global greenhouse gas emissions by gas

Carbon dioxide (fossil fuels and industrial processes) 65%

Carbon dioxide (forestry and other land use) 11%

Methane (16%)

Nitrous oxide (6%)

Impacts of climate change

- More hazards

- ecosystem changes

- Rising sea levels and drowning cities

- Changing settlement patterns

- reduced employment AND increased employment

- Conflict