Fragile EnvironmentsFragile Environments

The last Unit Guys!(Only the coursework exam to

do after Christmas)

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What does it involve?What does it involve?

The fragile nature of

environmentsCauses of

desertification

Consequences

Case study Sahel

Deforestation

Case study Amazon

Management

Greenhouse effect and global

warming

Causes

Consequences

Named egs of causes/

consequencesExamples of solutions eg

Kyoto

Causes

Consequences

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So today, we start with …So today, we start with …•A brief look at biomes or ecosystems –

different words that mean the same thing.

•A quick look at some of the issues we will study in more depth later

•A definition of sustainability

•An example of a group who continue to live sustainably

•The causes of soil erosion

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Fragile environments and Fragile environments and sustainabilitysustainability•Unique biomes/ecosystems

each with specific characteristics. They are climatically and geographically defined areas. They have similar ecological communities of plants, animals, and soil organisms. They have related plant families which are alike in structure (such as trees, shrubs, and grasses), the same leaf types (such as broadleaf and needle-leaf), plant spacing (forest, woodland, savannah), and climate..

•The map opposite is interactive on http://ih-igcse-geography.wikispaces.com/7.1Fragile+envirnments+and+sustainability

•Bright green – rainforest•Orange – savannah•Yellow – desert•Brown – Chapa

(Mediterranean)•Khaki – deciduous forest•Dark Green – boreal forest

(Coniferous)•Grey – Tundra•Purple – alpine (mountainous)

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Fragile environments and Fragile environments and sustainabilitysustainability

•These biomes depend on climate, rocks, soils, natural vegetation, animals and human activity.

•Man has changed most of the Earth’s surface but there are still those indigenous groups who live in harmony with their environment

•People have always made use of the ecosystems to provide themselves with food, fuel and building materials, and there are groups that still do that in a way that does damage the environment

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People have always made use of the People have always made use of the ecosystems to provide themselves with ecosystems to provide themselves with

food, fuel and building materialfood, fuel and building material• The Awá are a small tribe

living in the Amazon state of Maranhão. They are one of only two nomadic hunter-gatherer tribes remaining in Brazil.

• Some live in tiny family groups living in the rainforest outside legally recognized territories while approximately 40 individuals living in the Araribóia reserve.

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People have always made use of the People have always made use of the ecosystems to provide themselves with ecosystems to provide themselves with

food, fuel and building materialfood, fuel and building material•If the Awá are to survive it is vital that their forest home remains intact and that they are not exposed to diseases transmitted by outsiders and to violence at their hands.

•The Awá hunt, fish and gather forest produce such as nuts and fruits. Those who are nomadic live in highly mobile, self-sufficient groups of no more than 20-30 people.

•As they travel, they keep the embers of their fires lit, relighting the fire as they arrive at their destination.

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You can see more about these You can see more about these people onpeople on

• http://www.survivalinternational.org/tribes/awa

• These tribes are part of a group labelled by various organisations such as Survival International, as ‘uncontacted’.

• This does not necessarily mean that no outsider has ever seen them but it does mean that they have chosen to (and been supported by their governments) to live their own lives, with little or no input from outside.

• Although if you follow the link, you will see that there are problems there too.

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What are fragile environments?What are fragile environments?

•Fragile environments are those biomes that under threat form change, damage or unsustainable use.

•Although natural hazards, such as earthquakes, volcanoes, hurricanes, can cause a lot of damage, it is mainly human intervention that causes the most – even seemingly natural events like floods and droughts are often made worse by man.

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What are the issues?What are the issues?• Issues include • Undeveloped land is becoming scarcer: as

there is less undeveloped land available, the pressure increases on that that remains.

• Protecting biodiversity (plants and animals) is more difficult: we want to conserve that which we have but our desire to visit and see these areas is destroying them

• Desert edges are becoming deserts through overgrazing and the removal of trees/shrubs which give rise to soil erosion, and the decreasing rainfall all combine to turn productive farmland into useless scrub.

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What are the issues?What are the issues?• At the other end of the scale, deforestation

of rain forests flows as the natural resources are exploited.

• Illegal logging - 20% of the timber supply comes from illegal sources.

• "Europe remains one of the main markets for illegal timber despite a 2003 EU action plan to combat illegal logging and related trade. Strong legislation to halt illegal timber trade and to decrease Europe's devastating impact on the world's forests should be adopted as a bare minimum - there is no time to lose," said Friedrich Wulf from ProNatura / Friends of the Earth Switzerland.

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What else are we doing wrong?What else are we doing wrong?

• Human and industrial waste pollute rives and seas.

• At sea, oil spills and deliberate toxic dumping causes widespread pollution.

• Many local problems cause more widespread difficulties.

• Traffic in towns causes congestion and pollution.

• Building new roads can solve these problems but causes others such as the destruction of rural environments.

• This can also lead to more traffic and acid rain, production of greenhouse gases and global climate change.

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What else are we doing wrong?What else are we doing wrong?• If the diversity and the environment are

to survive then careful management is necessary.

•Local decisions have international effects.

• International co-operation and legislation will be the only way to resolve the issues which will help us work together and sustain the world for future generations.

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What else are we doing wrong?What else are we doing wrong?•This diagram shows some of the ways the

world is being used in an unsustainable way.

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What else are we doing wrong?What else are we doing wrong?• "Sustainable development is

development that meets the needs of the present without compromising the ability of future generations to meet their own needs". World Commission on Environment and Development.

• This means that if you need timber, for example, you must replant as much as you cut down.

• If resources are managed sustainably, then present and future demands for food, shelter, clothing and recreation will be met.

Soil erosionSoil erosion

One of the major problems in fragile

environments

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What are the causes of soil What are the causes of soil erosionerosion

•There are 3 main physical causes of erosion Sheet erosion Gulley erosion Wind erosion

•And then accelerated or human induced erosion

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Sheet ErosionSheet Erosion

• Where there is sufficient rainfall, exposed soil will be moved downhill as a mass movement – sheet erosion

• Raindrop impact is the major cause of soil particle detachment which can result in the particles moving down slope as sheet erosion during a rainfall event.

• Sheet erosion is the removal of fairly uniform layer of surface material from the land surface by continuous sheets of runoff water rather than concentrated into channels.

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Sheet ErosionSheet Erosion

• Heavy rain that leads to a sheet of water removing a more or less uniform layer of fine particles from the entire surface of an area is sheet erosion. It often includes the best soil particles along with much of the organic matter.

• While it causes severe erosion, it is very difficult to see, as the amount removed is often slight from any particular spot. Notice how these ploughed areas in Romania have been covered by the sheet erosion.

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Gulley ErosionGulley Erosion• More frequently, the water gathers together and

quickly erodes a channel. This is called gulley erosion.• The example below can be seen in it all its glory in the

blog (http://lindym.wordpress.com/2009/07/22/the-power-of-water/ ). It was named locally as the Durham Great Canyon and appeared literally over night in a cornfield.

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Gulley ErosionGulley Erosion• You may also see mention of rill erosion which is

a diminutive example of something similar. • This is an example of a rill forming during one

particularly heavy rainstorm in Autumn 2008 in the field behind our house – notice the murky colour of the water – that is soil erosion

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Wind erosionWind erosion

• Soil erosion by wind may occur wherever dry, sandy or dusty surfaces, inadequately protected by vegetation, are exposed to strong winds.

• Erosion involves the picking up and blowing away of loose fine grained material within the soil.

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•Dust storms are very disagreeable and also the land is robbed of its long-term productivity (humus (vegetable matter) is lighter and likely to be removed first).

•Crop damage, especially of young crops, can be serious.

•Either the roots are exposed as the wind blows away the top soil or else wind blown soil from elsewhere cover the seeding up – either way the crop will be lost.

Short-term effects of wind Short-term effects of wind erosionerosion

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•Long term damage is even greater.

•Finer soil fractions (silt, clay, and organic matter) are removed and carried away by the wind, leaving the coarser fractions behind.

•This sorting action not only removes the most important material from the standpoint of productivity and water retention, but leaves a more sandy, and thus an even more erodible, soil than the original.

Long term effects of wind erosionLong term effects of wind erosion

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The Impacts of humans on soil The Impacts of humans on soil erosionerosion

• The most common human impact is due to population growth.

• This leads to increased pressure on the land and its resources.

• Overgrazing is a major problem. • This causes vegetation loss and makes the soil much

more vulnerable to erosion without the protective net of roots to withstand the pressures of water and wind.

• Intensive cultivation can cause loss of nutrients and soil exhaustion. This may lead to deforestation.

• Another major cause of deforestation is the cutting down of trees for fuel wood or clearing it for agriculture.

• In practice the causes of soil erosion are usually a combination of physical and human causes, as you see below.

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An example: The impacts of human An example: The impacts of human activity and the natural environment activity and the natural environment

on National Parkson National Parks• Most types of vegetation can withstand some

disturbance and will recover naturally in time. The level of recreational disturbance which an area can tolerate without damage is described as its recreational carrying capacity.

• The effects of recreation are not evenly spread. They are mainly found around places such as car parks, pony trekking routes, river crossing points, riverside picnic sites and on popular walking routes such as from a car park to a a viewpoint.

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An example: The impacts of human An example: The impacts of human activity and the natural environment activity and the natural environment

on National Parkson National Parks• Erosion is often caused by a combination of factors. • Livestock grazing, farmers’ vehicles, hikers’ boots,

horse riding and mountain bikes can all play a part in damaging the vegetation.

• These factors, combined with natural forces, determine the extent of erosion and the speed at which it occurs.

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What are the problems? What are the problems? • Erosion Problems

Trampling by walkers, climbers and livestock has exposed the soil around the base of the rocks.

People have driven vehicles onto the open land causing damage around the car park and roadsides.

Popular routes used by thousands of visitors which created erosion gullies and muddy impassable ground

Paths suffer from both narrowing by gorse encroachment and increased erosion from water runoff.

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What can be done about it?What can be done about it?

• Techniques Used to improve the situation Low grassed banks have been created beside the roads and

in car parks Access using boulders can block off grass parking areas in

the winter when the ground is soft and more vulnerable to damage from tyres. This both protects the grass and reduces the number of people using the area.

These gullies have been filled in and the turf restored on the steeper parts of the path.

Gorse clearance (burning and mowing) has been undertaken so as to widen or increase the number of paths and so spread the load of walkers walking between the two points.

Grassed over, open drainage gullies have been created to divert rainwater away from the well used paths and reduce the possible gully erosion.

Granite paving slabs and rocks have been used to create a solid base on a wet, boggy part of the path

Education by way of information sheets and notices are used to ask people to behave in a way that protects the environment.

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In summaryIn summary• What is an ecosystem or biomes?• What are the Awá people an example of? Where are

they found?• We mentioned 4 main issues. What are they?• Can you think of some other things that we are doing

to damage the environment?• What is sustainable development?• What are the causes of soil erosion?• What is the Durham grand Canyon an example of?• What is the short term impacts of wind erosion?• What are the impacts of humans on soil erosion?• What are the causes of soil erosion in National

Parks?