Deserts

1
Deserts
2
Climate

• Very hot throughout the year, the temperature of
  ten remains above 30C for long periods.
• Deserts are also very dry places, usually placed
  in the central regions of a continent.
• They tend to receive an average of less than
  300mm of rain each year.

3
Soils

• Desert soils are alkaline, and are very dry with
  little humus.
• However they are not infertile, as areas that
  have been irrigated have produced good crops.
• Most plants could not survive in the desert soil
  but some have evolved to cope with the lack of
  water and nutrients.

4
Vegetation

• Plants have to cope with very little water in the
  hot desert.
• Species such as cacti have evolved to reduce
  water loss to a minimum.
• Their waxy skins and spiky leaves reduce
  transpiration, whilst their thick stems act as an
  excellent water store.
• Other plants have evolved extensive, deep root
  systems that search out the last drops of water
  underground, whilst others have all their roots
  very close to the surface in an attempt to
  capture all available rainwater.
• Due to lack of water plants are often found
  widely spaced apart.
• Many plants have seeds that only germinate when
  the rains come.
• They can lie dormant for years, and then burst
  into life with the rains.

5
Human Uses Of Deserts

• Oil
• Humans have found little use in the hot, dry
  desert regions of the world.
• However one very important resource that is found
  in some desert regions is oil, which is essential
  for most countries of the world.