Climate: Very hot throughout the year, the temperature of ten remains above 30°C for long periods. Deserts are also very dry places, usually placed in the central regions ofa continent. They tend to receive an average of less than 300mm of rain each year.
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.
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.
Oil: Humans have found little use inthe 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.