Hot Deserts Flashcards
All 35 cards in this deck
What is the annual rainfall of a hot desert?
Less than 250 mm per year.
Why are hot deserts cool at night despite daytime temperatures of up to 50 °C?
There is little cloud cover, so heat is lost rapidly at night.
Describe two characteristics of hot desert soils.
Dry and loose in structure, largely sand/rock/stone with limited organic matter so infertile.
How does water availability link plants, animals and people in a hot desert?
Water sources such as oases and wells support plants, which feed animals, and people settle and graze livestock near them.
Give one way a cactus (succulent) is adapted to the hot desert.
A large fleshy stem stores water, with a thick waxy skin to reduce water loss.
How are the roots of desert plants adapted to the dry conditions?
Either extremely long to reach deep water, or spread wide near the surface to catch rainfall quickly.
Why do many desert plants have small leaves, hairy leaves or no leaves at all?
To reduce water loss by transpiration.
Give two adaptations of the camel to the hot desert.
Stores fat in its hump for energy, and can go a long time without water, losing little through sweating or urination.
Give two adaptations of the desert fox to the hot desert.
Large ears to give off heat, and it is only active at night to avoid the heat.
True or false? Hot deserts have high biodiversity because the climate is warm all year.
False. Hot deserts have very little biodiversity because of the harsh climate — extreme heat and lack of water.
Why is hot desert biodiversity described as fragile?
Species are specialised and food chains are short, so small changes such as water extraction or overgrazing can wipe them out.
What type of plant growth follows rainfall in a hot desert, and what does it mean for biodiversity?
Seeds germinate and plants flower briefly, so biodiversity is seasonal and appears only after rain.
Name the four development opportunities in hot deserts named by AQA.
Mineral extraction, energy, farming and tourism.
Why is farming possible in hot deserts despite the low rainfall?
Irrigation supports commercial farming; elsewhere people practise subsistence farming such as nomadic pastoralism.
Why are hot deserts suitable for energy development?
Clear skies and high insolation suit solar power, and dams on desert rivers can supply hydroelectric power.
Give two economic benefits of development in a hot desert.
Employment and spending in the local economy, creating a multiplier effect and improved infrastructure.
Name the three challenges of developing hot desert environments named by AQA.
Extreme temperatures, water supply and inaccessibility.
Why do extreme temperatures make development in a hot desert difficult?
Temperatures can exceed 50 °C, so it is too hot to farm, mine or guide tourists, and heat can cause illness or death.
Why is water supply a challenge for development in hot deserts?
Rainfall is low (under 100 mm in places) and unpredictable and most rivers are intermittent, so water for irrigation and industry is scarce.
Why does inaccessibility make hot deserts hard to develop?
Huge distances and poor infrastructure make travel and services such as medical care expensive, and pipelines to remote areas cost a lot.
How does the removal of fuel wood cause desertification?
Trees are cut for fuel, leaving soil bare and unprotected so it is eroded by wind and rain.
How does overgrazing cause desertification?
Too many animals eat the vegetation faster than it regrows, exposing the soil to erosion.
How does over-cultivation cause desertification?
Growing crops continuously without fallow periods strips the soil of nutrients, so it becomes infertile and erodes.
True or false? Climate change can cause desertification by bringing higher temperatures and less reliable rainfall.
True. Greater evaporation and drought kill vegetation, leaving soil exposed.
Name the three types of strategy used to reduce the risk of desertification.
Water and soil management, tree planting, and use of appropriate technology.
How does tree planting reduce desertification?
Tree roots bind the soil and counter erosion, and the trees slow wind speeds, stopping the spread of the desert.
What are bunds, and how do they reduce desertification?
Low rock walls built along the contour of a slope; they capture running water and trap sediment, building up soil for cultivation.
Give one example of appropriate technology used to reduce desertification, and say how it helps.
Solar cookers or more efficient stoves — they cut the need for fuelwood, so fewer trees are removed.
True or false? Desertification only happens inside existing hot deserts.
False. Desertification is the degradation of land on the semi-arid margins around deserts, which turns fertile land into desert.
How does population growth lead to desertification?
More people need more food and fuel, so land on desert margins is overgrazed, over-cultivated and stripped of trees, leaving soil bare and easily eroded.
Give one water management method that reduces the risk of desertification.
Drip irrigation, which delivers small amounts of water straight to plant roots, or growing crops that need little water; both stop soils being overused or salted up.
Give one soil management method that reduces the risk of desertification.
Crop rotation, so the same nutrients are not drained from the soil every year. Also accept: leaving land fallow to recover, or adding manure or compost to restore nutrients.
Where is biodiversity highest in a hot desert, and why is it under threat there?
Around water sources and on the desert margins; people also settle and farm in these places, so habitats are damaged and water is used up.
How could global warming affect biodiversity in hot deserts?
Deserts may become even hotter and drier, so species already living at the limit of what they can survive could die out.
Why are hot desert soils often salty?
High evaporation draws water up through the soil, and when it evaporates it leaves salts behind at the surface.