Hot Deserts

• Hot deserts

  Most of the world's hot deserts are found in the subtropics between 20 degrees and 30 degrees north & south of the Equator
• Tropics of Cancer and Capricorn

  Run through most of the world's major deserts
• Hot deserts are located in this region because of the global atmospheric circulation model
• Cactus

  • Large roots to absorb water soon after rainfall
  • Needles instead of leaves to reduce surface area and therefore transpiration
• Camels

  • Hump for storing fat (NOT water)
  • Wide feet for walking on sand
  • Long eyelashes to protect from sand
• Desertification


  The turning of semi-arid areas (or drylands) into deserts
• Desertification


  The spread of deserts
• Causes of desertification

  • Climate Change: Reduce rainfall and rising temperatures have meant less water for plants
  • Fuel Wood: People rely on wood for fuel. This removal of trees causes the soil to be exposed
  • Overgrazing: Too many animals mean plants are eaten faster than they can grow back. Causing soil erosion
  • Over-Cultivation: If crops are grown in the same areas too often, nutrients in the soil will be used up causing soil erosion
  • Population Growth: A growing population puts pressure on the land leading to more deforestation, overgrazing and over-cultivation
• Fuel Wood

  People rely on wood for fuel. This removal of trees causes the soil to be exposed.
• Overgrazing


  Too many animals mean plants are eaten faster than they can grow back. Causing soil erosion.
• Over-Cultivation


  If crops are grown in the same areas too often, nutrients in the soil will be used up causing soil erosion.
• Population Growth

  A growing population puts pressure on the land leading to more deforestation, overgrazing and over-cultivation.
• Hot deserts

  • Aridity - annual rainfall below 250 mm
  • Heat - rise over 40 degrees, but cold at night
  • Soils tend to be sandy and stony
  • Limited leaf matter means little organic matter and fertility
  • Soils are saline (salty) because of high evaporation rates
  • A wide diversity of plants, animals and birds find ways to survive
• Desert interdependence: Different parts of the hot desert ecosystem are closely linked together and depend on each other
• Aridity


  Hot deserts are extremely dry, with annual rainfall below 250 mm
• Hot deserts

  • Rise over 40 degrees, but cold at night
• Soils

  • Tend to be sandy and stony
  • Limited leaf matter means little organic matter and fertility
  • Saline (salty) because of high evaporation rates
• A wide diversity of plants, animals and birds find ways to survive in hot deserts