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Fragile environments. The next 4 weeks. Key Idea – only the one. Environmental abuse has serious consequences. Its causes need to be tackled to ensure a more sustainable future. But there are still 3 sections to study …. Section 1 (already covered).

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Fragile environments l.jpg

Fragile environments

The next 4 weeks

Key idea only the one l.jpg
Key Idea – only the one

  • Environmental abuse has serious consequences. Its causes need to be tackled to ensure a more sustainable future.

  • But there are still 3 sections to study …..

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Section 1 (already covered)

  • The fragile nature of environments; the concept of sustainability.

  • Causes of soil erosion and desertification: drought; population pressure; fuel supply; overgrazing; war; migration.

  • Consequences (reduced agricultural output; malnutrition; famine; refugees) and management of soil erosion.

  • A case study of an area affected by desertification (eg the Sahel).

  • Examples of farming practices to alleviate soil erosion.

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Section 2 (already covered)

  • Causes of deforestation: commercial timber extraction; agriculture; mining; transport; settlement.

  • Consequences: loss of biodiversity; contribution to global warming; economic development.

  • Managing rainforests in a sustainable way (eg agro-forestry); the need for international co-operation.

  • A case study of a threatened tropical rainforest (eg the Amazon, West Africa, Indonesia)..

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Section 3 (new)

  • Causes of global warming and climate change: deforestation; use of

  • fossil fuels; air pollution; agricultural change; CFCs.

  • Consequences: rising sea levels; more hazards; ecosystem changes; new employment opportunities; changing settlement patterns; health and well being.

  • Environmental abuse has serious consequences. Its causes need to be tackled to ensure a more sustainable future.

  • Managing the causes (anti-pollution legislation, alternative energy sources, international cooperation) and adapting to the consequences of global warming and climate change..

  • A case study of the threats posed by global warming and climate change to one country (eg Bangladesh, the Maldives).

  • A case study of attempts to tackle the problems of global warming and climate change (eg UN conference at Rio de Janeiro, Kyoto Protocol and its successor).

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Starting now …

  • What makes environments fragile?

  • What is meant by sustainability?

  • What are the causes of soil erosion and desertification?

  • What are the consequences?

  • How can it be managed?

  • With reference to the Sahel

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  • There is a natural but delicate balance between the non-living soils, rocks and climate and the living plants animals.

  • There are natural disasters such as volcanoes and cyclones but the world has always recovered from these in the past.

  • Until recently, man has trod lightly on earth, living in harmony with it. Some native tribes still do this, e.g. the Awa in the NE Amazon. But this is a rare example. 90% of the Earth has been disturbed by man.

  • We focus on 3 processes that have increased fragility – soil erosion, desertification, deforestation. These link to climate change as they are both a cause and a consequence of it.

  • These are not the only ones – river and coastal management, pollution in general, and exploitation of natural resources also figure in this as well.

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In fragile environment studies …

  • Ecological foot print

    • [The amount of land, resources etc we need to support our lifestyle. To find what we use, add the land to give us enough water, food, energy, raw materials and waste disposal. It has been worked out that 2 hectare per person is sustainable – the 5.5hectare per person in the UK is not]

  • And

  • Sustainability

    • [Activities and forms of progress that meet the needs of the present without reducing the ability of future generations to meet their needs.]

  • keep coming up

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So.. rest of us!

  • The link between ecological foot print and sustainability is that the footprint informs us about just how sustainable (or not) we are being.

  • We know the footprint is influenced in turn by how fast the population grows (could mean we need to have a smaller footprint if it goes up too much), what we consume and the type of technology we use.

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Soil erosion rest of us!

  • This was gone into in quite a bit of detail on , so I am not going to do it in that much detail again

  • Basically there are 3 types

    • Sheet erosion – where a thin layer of soil is washed away over large area

    • Gully erosion – where heavy rain erodes away a deep ditch – remember the Durham Canyon?

    • Wind erosion – where wind removes the loose dry soil, a real problem in areas subject to drought.

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Although soil erosion is a largely natural process, man can make it worse

  • Removing trees and bushes for fuel leaves the soil loose and exposed

  • Overgrazing by stock – giving the same result

  • Over-cultivation – removing the soils goodness without putting it back, often leaving the soil bare between crops

  • Compacting soil with heavy machines means rain cannot infiltrate the soil and so it runs off taking the topsoil with it.

  • Ploughing at all is increasingly seen as a bad thing in areas subject to soil erosion (use of no-till or minimum-till is preferred) but in particular ploughing down the contours creates readymade gullies for the next rain storm.

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In summary make it worseSoil erosion increases with

Lack of vegetation cover

Population increase which puts more pressure on the land

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So how does all this tie in with desertification? make it worse

Ripe for soil erosion – why?

Next step – desertification

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What is desertification? make it worse

  • The process by which once-productive land changes into desert-like conditions. The places are usually on the margins of existing deserts and have a tendency to be dry already. The causes are both natural and human and some are the same as for soil erosion. Note the similarities between this map and slide 13

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Man made causes of desertification make it worse

Over 20% of the world’s population are coping with desertification in about 60 countries

  • Over the 4 main human causes:

    • Population growth

    • Overgrazing

    • Over cultivation

    • Deforestation

  • Which the most serious? Why?

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The consequences of soil erosion make it worse

  • The main consequence is fall in food production

  • This leads to:

    • Malnutrition – lack of essentials vitamins and minerals – increased sickness and rising death rate, in particular child mortality.

    • Famine and starvation –

    • Migration – if things become too tough, people leave – often the men leave to work in the towns in the hope of making money for their families

    • Food aid – if things get serious enough, aid may be brought in to tide the people over, b ut it does nothing for the soil erosion.

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The management of soil erosion make it worse

  • Putting right soil erosion once it has occurred is difficult.

  • The best way to manage it is to prevent it happening in the first place, by:

    • Maintaining vegetation cover – this reduces wind erosion, as the roots bind the soil and make it harder to erode. Also roots reduced run-off and increase infiltration of rainfall.

    • Use of trees and hedges reduce the effects of wind erosion and steep slopes can be protected from sheet/gully erosion by the roots encouraging infiltration.

    • Reduce water erosion by trapping the water before it runs off, either by bunds, terraces.

    • Maintaining water in the soil allows plant growth and helps reduce erosion, e.g zai holes

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Organic farming make it worse

  • Is effective in reducing soil erosion

  • Does not use artificial fertilizer (unsustainable) but relies on crop rotation and compost/manure making.

  • Actually grows legumes for manure crops. E.g. clover

  • This adds humus that soaks up and retains water

  • Permaculture is a form of organic farming - also called agroforestry. The trees provide protection, mulch from the fallen leaves, food for the livestock and fuel and often fruit for the people. The fields are not ploughed so that after harvesting the soil is never bare. Another key idea in permaculture, is that they intercrop, that is a few greens will grow right next to some bean plants and next to that may be a few maize plants. The idea being that they support and protect and nourish each other.

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Permaculture in Ethiopia make it worse

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The Sahel – what is it like? make it worse

  • What do you notice about the temperatures in all these places?

  • The rainfall?

  • When does it occur?

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Please be aware the rainfall part of the climate graph in the textbook on p184 is WRONG. It shows rain during the February to March!

Its natural vegetation is savanna – mainly grass with trees and shrubs

The Sahel

In which months were these 2 taken?

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On the southern edges there are more trees and less grass and there are more wild animals – lions etc

Towards the middle there are large herd of gazelle and giraffe ( the book says zebra! It is too far North for them).

Some are under threat as they are in competition with the farmers who are growing crops.

Nomadic herders with goats and cattle follow the rain.

The Sahel

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If there are dry years, then the plants do not have the chance to regenerate and there is more soil erosion, and a greater chance of desertification.

Can you work out what this graph is saying about rainfall in the Sahel?

Can you explain why there are greater worries about the Sahel becoming part of the Sahara.

What are the 2 possible causes of this?

Which do you think is most likely?

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As we saw from the previous graph … chance to regenerate and there is more soil erosion, and a greater chance of desertification.

  • Up until the 1960s there was more rainfall than average for the time, so the crops grew better and the population increased.

  • So more and more trees were felled for fuel and more animals ate the grass and more crops were produced to sustain the extra people.

  • This led to over-cropping and overgrazing, soil left bare in the dry season and no humus being added to the soil. With no humus to act as a sponge for water when it did fall, the loose soil was washed away in the wet seasons.

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Consequences etc chance to regenerate and there is more soil erosion, and a greater chance of desertification.

  • Go to slide 19 – these were exactly the problems that occurred in the Sahel

  • As for management – you need 3 different but good ideas that seem to address different issues

  • E.g. stopping the soil erosion

  • Increasing the soil fertility

  • Meeting the people need for example for fuel and forage for the animals, without laying bare the soil in the process:


  • The desertification in the Sahel book and the video at the bottom – push the slider to the 11th minute! All about Burkina Faso

  • Also

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I want you to visit those sites chance to regenerate and there is more soil erosion, and a greater chance of desertification.

  • I need one project and can you put in textbox these 4 things:

  • What problem is it trying to solve?

    • It is trying to …

  • Where is it?

    • It is in …

  • What is the method?

    • Brief phrase: e.g planting hedges or whatever

  • How does it work?

    • Brief phrase: By stopping or By increasing ….

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In conclusion: chance to regenerate and there is more soil erosion, and a greater chance of desertification.

  • Sustainability and the ecological footprint – know what they are and what is sustainable is in terms of foot print and how bad we are at this.

  • Know the 3 types of water erosion and 1 wind and the effects they have.

  • The manmade impacts that make erosion worse. Be aware of how much of the earth suffers from it.

  • Know what desertification is, where there is a danger of it and links to soil erosion

  • Distinguish between natural and manmade causes

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In conclusion: chance to regenerate and there is more soil erosion, and a greater chance of desertification.

  • Know the consequences of desertification and some management techniques

  • The Sahel: know where it is and some of the countries involved, what it is like climatically and ecologically and also the history of the current problems – long period of wetter weather so more people etc. etc.

  • Tie in at least 3 management techniques with named places in the Sahel – or you may like to concentrate on one country like Burkina Faso and look at different ways in which they are overcoming their problems.

  • You may like to consider other methods that manage the situation in other part of the world as well.