Hot desert regions are found near the Tropics of Cancer and Capricorn.
They occur where there is a hot climate and very little rainfall.
The largest desert in the world is the Sahara Desert, located in Northern Africa.
Deserts have a hot climate with temperatures ranging from 20 to 25 degrees year round.
Rainfall is sparse and unpredictable. Most desert regions receive 100-200mm per year.
The lack of clouds means that there is a large diurnal (overnight) temperature range with temperatures sometimes dropping below freezing at night.
Vegetation is sparse and is mostly made up of cacti, shrubs, and lichen.
Soils are limited by the lack of water, though there are few shallow sandy soils.
The ground is mostly covered by loose sediment in the form of sand. This sand builds up into sand dunes.
Desert soils have the potential to be fertile with the addition of irrigation as the minerals have not been leached by rainfall.
Plant and Animal Adaptations
Plants that can survive in desert conditions are called xerophytes.
Many of the trees in deserts are drought and fire resistant, such as the acacia tree.
Cacti can store water in their tissues. Their waxy skin prevents transpiration and their spikes protect them.
Lichen survive by breaking down rocks using their own acids. They do not need soil to survive.
Desert flowers have seeds that can lay dormant for years and only germinate when there is significant rainfall. Their bright colours invite insects and they have short life cycles.
The lack of water means that few animals survive in the desert. Areas with more water have greater biodiversity as plants can act as the basis of larger food webs.
Desert foxes have light-coloured fur to reflect light and fur on their paws to protect their feet from heat.
Kangaroo rats do not perspire and retrieve all of their water from food.
Camels can store large amounts of water in their humps.
There is interdependence between biotic and abiotic parts of hot deserts:
The food web depends on plants that can store water and nutrients.
Vegetation roots stabilise soil to stop the process of desertification.
The food web in hot climates is very fragile due to the lack of biodiversity.
The fringes of deserts are very fragile environments.
Desertification is the turning of fertile land into a desert landscape.
Up to 20% of the Earth's land is at risk of desertification.
The Sahel region in Africa is in particular danger.
Causes of Desertification
Desertification is primarily caused by a change in climate conditions that limits rainfall and increases temperature.
Areas at risk of desertification are mostly inhabited by a rapidly growing, low-income population.
These areas are prone to migration and high birth rates.
The population pressure means that more food must be produced, this means that already weak land is overcultivated and overgrazed to sustain the population.
Overcultivation exhausts the soil's fertility and drains aquifers of any remaining water.
Commercial agriculture promotes the growth of water-hungry cash crops.
Overgrazing removes vegetation, promoting soil erosion. Hooves compact the soil, preventing the regrowth of vegetation.
Exposed topsoil can become baked in the heat, making it susceptible to being washed away by rainfall.
Tree roots help to stabilise soil.
Leaf litter helps to add fertility to the soil.
Aids with climate change.
Changing cooking methods:
Removing trees for firewood is common in desert fringe areas.
New cooking technologies can be introduced to reduce the dependence on fires for cooking. One example is the Toyola stove in Ghana.
Some stove designs incorporate thermocouple, which can generate energy from stove heat.
There have been recent shifts towards solar power in these regions also.