Deserts

• Desert is a biome characterized by low amount of rainfall (>250mm), high temperature (40 - 50 °C in summer), and sparse vegetation.
• Characteristics of a hot desert:

  • near tropics of cancer and capricorn
  • very little biodiversity
  • very hot (in summer cand be over 50 degrees)
  • cold at night (0 degrees)
  • less than 250 mm of rain
  • soil is sandy,rocky,thin and has a crusty layer of salt
• Plant adaptations in a hot desert:

  • Small leaves/spikes - less water lost by transpiration
  • Tap roots - long roots (7-10m) that reach deep underground to access water
  • Waxy skin - thick,waxy skin to reduce water loss by transpiration
  • Water storage - some plants store water in stems,leaves,roots because of infrequent rainfall
• Desertification prevention:

  • Planting more trees
  • Planting drought resistant plants
  • Bunds
  • Flat roofs, water can collect on top
• Desertification causes:

  • Population growth
  • Cutting down trees
  • Overgrazing (when land cannot sustain the number of animals feeding on it)
  • Soil erosion
  • Climate change
• Examples of deserts are Sahara desert in Egypt, Africa and Thar desert in Rajasthan, India.
• Soil in a desert:

  • Lack of organic material due to lack of vegetation
  • Very dry and soaks up water rapidly
  • Evaporation draws salts to surface, leaving white power on the ground
  • Not very fertile
• Animal adpatations in a desert:

  • Fennec fox - large ears to hear prey and regulate body temperature
  • Thorny devil - has thorns that cover body to protect against predators
• Camel adpatations :

  • Long eyelashes - to protect against sand
  • Thick fur - provide warmth at night
  • Fat filled hump - supply energy
  • Long legs - efficient for travelling long distances
  • Wide padded feet - easier to walk on sand and rock
  • Padded knees - protect when kneeling on hot sand
  • Thin slits for nostrils - closed during a sandstorm
• Desertification - the process of land turning into desert
• If vegetation is removed then there will be no roots to bind soil together. So if strong winds or heavy rainfall occurs, the soil will be washed away, this is called soil erosion. Overtime this can lead to desertification.