Desertification

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Ecosystems GCSE

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Desertification

  1. 1. DESERTIFICATION DEFINITION process by which the land is turned to desert CAUSES NATURAL – climate HUMAN – non-sustainable farming methods . HUMAN LAND USES ARABLE FARMING – vegetation cleared for crops e.g. millet, maize. CATTLE FARMING _ cows graze on grass. CASH CROPPING – Large expanses used e.g. tobacco and cotton. TOURISM – Safaris.
  2. 2. The Sahel
  3. 3. Desertification ~ the process More food, fuel & housing needed Population growth Grassland is overgrazed Soil becomes bare Soil is eroded by wind & water Trees are cut down Land becomes infertile No plants grow Land becomes desert Climatic change Less rain
  4. 4. Case study ~ The Sahel ( Foundation Wider World P198) <ul><li>Complete your map – stick it into your book </li></ul><ul><li>What is/where is the Sahel? </li></ul><ul><li>What is happening here? </li></ul><ul><li>Study B ~ describe what has happened to rainfall in the Sahel in the second half of the 20 th century? </li></ul><ul><li>What is making the problem worse? </li></ul>
  5. 5. CONFLICTS CASH CROPPERS v SMALL SCALE FARMERS. CONSERVATIONISTS V POACHERS. 3 MAIN CAUSES OF DESERTIFICATION. Climate change. Increased population. Commercial Agriculture.
  6. 6. Strategies for dealing with the problem <ul><li>Water conservation </li></ul><ul><li>Contour ploughing allows water to soak in </li></ul><ul><li>Stone lines reduce water run-off </li></ul><ul><li>Rotate crops </li></ul><ul><li>Have fallow periods </li></ul><ul><li>Allows soil to retain fertility </li></ul><ul><li>Controlled grazing </li></ul><ul><li>Limit size of herds </li></ul><ul><li>Have fewer, better quality animals </li></ul><ul><li>Shelter belts </li></ul><ul><li>Plant rows of drought-resistant trees and shrubs </li></ul><ul><li>Reduces loss by evapo-transpiration </li></ul>
  7. 7. Strategies for dealing with the problem ~ other ideas <ul><li>Education of people ~ population control </li></ul><ul><li>Fill in gullies/replant ~ reduces water flow </li></ul><ul><li>Wells must be deep and lined to reach permanent water table </li></ul><ul><li>Natural fertiliser improves quality and water retention of soil </li></ul><ul><li>Use branches for fuel wood not whole trees </li></ul><ul><li>Strip farming –harvest crops at different times – soil not left bare </li></ul>
  8. 8. NON-SUSTAINABLE FARMING CAUSES DESERTIFICATION OVERGRAZING OVERCULTIVATION . SOIL EROSION IS TURNING LAND INTO DESRT THESE LEAD TO SOIL EROSION
  9. 9. Sahel (desertification) case study <ul><li>Create a factfile to include: </li></ul><ul><li>Map </li></ul><ul><li>People affected </li></ul><ul><li>Traditional farming methods </li></ul><ul><li>Rate of growth of desert </li></ul><ul><li>Climate change </li></ul><ul><li>Population growth </li></ul><ul><li>Results </li></ul>
  10. 10. Living with wet season/dry season regime The purpose of this exercise is to show that farmers of the savanna are seriously influenced by the climate and river regimes found in this ecosystem Location:
  11. 11. The Farmers Youssouf Home is on one of islands near confluence of Niger with River Bani. Cultivates small area of land on floodplain ~ guinea corn & millet. Supplements income by fishing Tatta Traore Cultivates land on floodplain. Needs moist land which appears when river recedes. Harvested towards end of dry season Mohamed Cultivates land near edge of floodplain. Grows millet & sorghum for family & sells surplus (usually to pastoralists in exchange for milk & meat Ibrahim Pastoralist who spends part of the year with cattle & goat herds on floodplain of Niger near Mopti <ul><li>Your Task…………. </li></ul><ul><li>Read each of the statements </li></ul><ul><li>Study the graphs </li></ul><ul><li>Decide which statement would be most appropriate for each month </li></ul>

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