Hot Desert Climates

Hot Desert Environments

Location

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• 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.

Characteristics

• 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.

Plant and Animal Adaptations

Interdependence in Hot Deserts

• ​​​​​​​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.
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• The food web in hot climates is very fragile due to the lack of biodiversity.
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Desertification

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• 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.

Tackling Desertification

• Planting trees:
• 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.