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Sec 1 g_-_unit_3_-_part_iii[1]


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Sec 1 ppt for uint 3 2014

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Sec 1 g_-_unit_3_-_part_iii[1]

  2. 2. YOU WILL LEARN • How deforestation impact people and the environment • To understand and describe the impact of deforestation on the 1. Environment 2. Economy 3. Social factors
  3. 3. ENVIRONMENTAL IMPACT Loss of biodiversity • Refers to the loss of the variety of plants and animals resulting in millions of them becoming extinct • It has resulted in the loss of the variety of resources that can be obtained from the forest. Read pg 98 for further information Loss of water catchment areas • Clearing forest disrupts the water cycle • Trees absorb water through their roots and release it into the atmosphere through evaporation and transpiration. • Loss of water catchment results in decreased water supply
  4. 4. ENVIRONMENTAL IMPACT Incensed risk of flooding, soil erosion and sedimentation • Flooding • Soil absorbs rainwater and releases it slowly into the rivers. • Forest intercept the rain and allow it to seep into the ground • When trees are cleared, the ground is left bare and rainwater flows as surface run-off • This causes flooding in the surrounding areas
  5. 5. ENVIRONMENTAL IMPACT Incensed risk of flooding, soil erosion and sedimentation • Soil erosion • Refers to the removal of the top layers of soil by rainwater, wind, destructive human activities • Trees hold the ground, the leaves and moss keep the ground stable • When trees are removed, land is exposed. Therefore water washes the soil away when it rains. • Refer to TB pg 100 – the Great Red Island in Madagascar • This affects water quality which affects aquatic life- see TB pg 101 Fig 3.44
  6. 6. ENVIRONMENTAL IMPACT Enhanced greenhouse effect • When the sun’s rays pass through atmosphere, part of the heat is absorbed by the earth and the rest is reflected back to the atmosphere towards space. • Greenhouse gases( carbon dioxide, methane, water vapour and other gases) trap some of the heat and prevent it from escaping into space. This causes warming of the atmosphere and is known as greenhouse effect. • Without greenhouse effect the earth average temperature will be -18°C instead of the current 15°C. • There is an increase in greenhouse gases due to increased human activities like logging, industries, transportation, power stations resulting in more heat being trapped. This is called enhanced greenhouse effect
  8. 8. DEFORESTATION AND EMISSION OF GREENHOUSE GAS • Deforestation Increases the amount of carbon dioxide in the atmosphere • Trees absorb carbon dioxide in the atmosphere and store as carbon and when tress are cut the stored carbon is released into the atmosphere • Burring of forest also releases carbon dioxide into the atmosphere • Less trees means less carbon dioxide is absorbed and more remain in the atmosphere • Refer to TB pg 103 Fig 3.46 World map showing contribution of greenhouse gases emission due to deforestation
  9. 9. ECONOMIC IMPACT Depletion of natural resources • Natural Resources • Rapid deforestation results in the depletion of the natural resources faster than it can replenish. • This affects the earning of industries that rely on natural resources like timber • Social impact • The indigenous people in Amazon forest face threats of losing their land due to loggers • Read and try the exercise on TB pg 105 if to find out more ……..
  10. 10. Deforestation results in: a. Loss of biodiversity b. Loss of water catchment areas c. Incensed risk of -flooding, - soil erosion -sedimentation a. 4. Enhanced greenhouse effect 2 Economic impact – loss of resources 3 Social impact – affects the lives of indigenous people 1. Environmental impact
  11. 11. HOMEWORK Workbook • Activity 3.3 • Pg 42 Activity 3.4 Pg 43, 44, 45 • Activity 3.6 • Pg 51 Activity 3.7 Pg 53 – 56 Activity 3.8 Pg 57 – 60