Deserts

1
Deserts

• All deserts are not alike, but they all receive
  very little rain
• Desert soil is rich in minerals at the top layer
• Leaching does not occur often
• Leaching-rainwater moves through soil carrying
  minerals deeper into the soil
• Desert soil does not have much topsoil
• the lack of rain slows the decay of organic
  material which makes up topsoil
• Deserts have a pavement-hard-baked sand and bare
  rock particles that make up the floor
• when wind blows, the loose sand blows away and
  exposes the pavement

2

• The US has two types of deserts cool and hot
• depend on levels of elevation and latitude
• Cool deserts east side of Sierra Nevada and
  Rocky Mountains
• Hot deserts southwest (Arizona, New Mexico, and
  west Texas)
• CLIMATE
• Most deserts receive less than 10 cm of rain each
  year
• rain comes in few short thunderstorms
• long, dry periods follow
• little water is absorbed into the ground because
  of the hard pavement floor
• temperatures rise and fall dramatically between
  night and day
• there is no moisture in the ground or air to
  control the temperature

3

• Desert Organisms
• all the living things in the desert must be
  adapted to lack of water and extreme temperatures
• Cactus-have spines(leaves) to prevent water loss,
  because they have less surface are for water to
  evaporate
• Cactus is a succulent plant-plants which have
  thick, water-filled tissues
• the stored water helps the plants to survive long
  dry periods
• spines help protect cacti from being eaten by
  other animals for its water
• Aloe vera is a succulent plant found in Africa
• Desert plants have special roots short roots
  that spread out over wide area
• or very deep roots (20m)

4

• Desert animals
• types of animals depends on plants, types of
  plants depend on precipitation
• so precipitation is the limiting factor in
  deserts
• desert animals include insects, reptiles, birds,
  and mammals
• they must also adapt to reducing water loss
• get most of their water from plants
• insects and reptiles have outer coat that reduces
  water loss
• many animals are nocturnal-animals that are
  active at night and sleep during the day
• desert rodents are nocturnal to survive the high
  heat of the daytime