4. desertification

• Desertification


  The process by which environments become more like desert
• Desertification

  • Natural vegetation decreases
  • Soil is exposed to hot sun
  • Rainwater runs over surface rather than soaking in
  • Soil becomes degraded or worn out
  • Harder to grow crops
  • Food and water shortages become more common
• Desertification affects over 1 billion people around the world
• Desertification affects large parts of North America, Africa, Central Asia and Australia
• Desertification has the most serious effects on people who already live in poverty
• It is estimated that 90% of the people affected by desertification live in the world's poorer countries
• US $42 billion worth of income is lost due to desertification every year
• Regions at risk of desertification

  • Have low rainfall totals each year
  • Have a long dry season followed by a short rainy season
  • Have a savanna ecosystem of grasses, shrubs and scattered trees
• The Sahel region of Africa is at high risk of desertification
• The Sahel has a long dry season of 9 months followed by a wet season of 3 months
• The wet seasons in the Sahel have become unpredictable, with short periods of heavy rainfall running off the land rather than soaking in
• The movement of the ITCZ (Intertropical Convergence Zone) causes the wet and dry seasons in the Sahel and savanna grasslands of Africa
• Latitude also plays a part, with savanna grasslands located in areas where air descends rather than rises like at the equator
• Northern Ghana is the driest part of the country, with a dry season up to 8 months long
• The natural vegetation in northern Ghana is grassland and savanna woodland
• Huge numbers of trees have been felled in northern Ghana to increase farm size and for firewood
• Soil erosion has become a serious issue in northern Ghana due to the damage to vegetation
• Deforestation may be contributing to local climate change in northern Ghana by reducing evapotranspiration
• Causes of desertification

  • Drought
  • Overgrazing
  • Deforestation
  • Overcultivation
• How trees help prevent desertification

  • Leaves act as an umbrella slowing down rain
  • Roots hold soil together
  • Evapotranspiration keeps air cooler and moist
  • Shade prevents soil from drying out
• Removing trees on a large scale (deforestation) can actually increase the rate of desertification
• The traditional bush fallow farming system in Ghana's savanna region is becoming unsustainable as the fallow period is now too short
• The urban population has grown

  Pastoral cattle farmers are more settled (less nomadic)
• Pastoral cattle farmers are more settled

  The amount of grazing land has decreased
• Razing with farmers

  • Keeping cattle for both their milk and meat
  • Crops are grown using a traditional bush fallow system
  • Scrub vegetation removed by slashing and burning
  • Crops such as maize, root crops and vegetables are grown between one and three years
  • Land is then abandoned for between eight and fifteen years (fallow period)
  • During fallow period, natural shrubs grow back
  • Leaves from shrubs decompose in soil, replacing organic fibre and nutrients
• This system is sustainable as long as the fallow period remains long enough
• In some villages the fallow period is now only two to three years, which does not give the soil enough time to recover
• Soil loses its organic content and its structure becomes dusty
• This means the soil is at risk of erosion from both wind and rainfall
• 3 Solutions to combat desertification

  • Dant onops may help areas at risk of drought and desarsfication produce food, even when rafalevels
  • Local, small-scale solutions
  • National large-scale solutions - the Great Green Wall
• Local, small-scale solutions

  • Crops like chickpen, pigeonpee, groundnut and can all grow in hot semiarid regions and are at sutable for growing on smallholdings
  • The Ghanaian nenet is encouraging farmers to use four new varietes of maize that have been developed with the help of the Foundation which is a non-govemment organisation (NGO)
• Local farmers have complained that the new maize varieties are more expansive than the usual varieties that they grow
• This method (local, small-scale solutions) doesn't actually stop the issues of on and de-scation ether
• Terracing steeper slopes

  1. Water will move slower (or at all) on a flat surface so sloping hills have been converted into giant slaps

  2. Rainfall is reduced, soil erosion is prevented, and small farming nels have been created
• Drip irrigation

  1. A series of small pipes or rubber tubing with small holes are placed around the crops and drip water onto the roots of individual plants and crops

  2. No water is delivered or dropped onto soil where plants are not growing, and wastage due to evaporation is reduced
• Bunds aka Magic Stones

  1. A series of low-lying stone walls have been constructed in cra growing regions of Africa consisting of places along contours on gende slopes and revered by perting ugh grasses along the ines

  2. The stones and press encourage naw to inate the sal and reduce the ascunt of rawater far is lost by a oft as well as preventing sol erosion and loss of nutrients

  3. Have actualy been used to help create the terracing method described above in areas with steep slopes
• The Great Green Wall


  • Eleven countries signed an agreement in 2010 to begin planting a "wal-a 15km wide strip af land with trees and shrubs across the width of Africa
  • It is hoped that this wall of vegetation will help prevent further so erosion from the Sahel and improve economies
  • The plan is to encourage local communities to plant a mixture of native trees including fruit and nut trees
  • Small fields between the trees can be planted with food and cash crops-this is known as AGRO-FORESTRY as it combines farming and forestry
• Progress of the Great Green Wall

  • Niger has made huge progress, with five milion hectares of land in the Zinder ragion planted with trees
  • Senegal has also made good progress, with even million trees planted across 27,000 ectares of land
• The Senegalese Ovemment wants local communities to velop ecotourism in the newly planted forests to take advantage of the larger number of bird species that now live in these new forests, and bring in additional some in a sustainable way
• The Food and Agriculture Organisation (FAO) of the United Nations claims that tree-planting in Niger and Senegal has been a success, with increased crop yields and better-fed livestock