Hot Deserts Flashcards
All 26 cards in this deck
Describe the climate of a hot desert.
Less than 250 mm of rainfall a year, daytime temperatures over 40°C in summer, and nights that can drop close to 0°C (a large diurnal range).
What are hot desert soils like?
Thin, sandy or stony, dry and low in nutrients because there is little leaf litter; evaporation often leaves a salty crust on the surface.
Give one example of interdependence between climate, plants and soil in a hot desert.
Low rainfall means sparse vegetation, so little leaf litter reaches the soil; the soil stays thin and infertile, which further limits plant growth.
Give two ways desert plants such as cacti are adapted to the physical conditions.
Long tap roots or wide shallow roots to reach water, and thick fleshy stems that store water with spines instead of leaves to cut water loss.
Give two ways desert animals are adapted to extreme heat and lack of water.
Behavioural: nocturnal, sheltering in burrows by day. Physical: large ears to lose heat and the ability to go days without drinking (e.g. camel, fennec fox).
True or false? Hot deserts have low biodiversity because of the extreme conditions.
True. Very few species can cope with the lack of water and extreme temperatures, so food webs are simple and easily damaged by development.
Name one mineral extracted in the Western Desert (USA) and a mine where it is extracted.
Copper, at the Morenci mine in Arizona, one of the largest copper mines in North America.
Give two sources of energy developed in the Western Desert (USA).
Hydro-electric power from the Hoover Dam on the Colorado River, and solar power such as the Sonoran Solar Project in Arizona.
How is commercial farming made possible in the Western Desert (USA)?
By irrigation with water from the Colorado River, e.g. the All-American Canal supplying the Imperial Valley, which grows salad crops and fruit.
Give two tourist attractions that bring development to the Western Desert (USA).
Las Vegas hotels and casinos, and the Grand Canyon; Lake Mead also attracts water sports.
Give one way extreme temperatures make developing a hot desert difficult.
Summer temperatures over 40°C make outdoor work dangerous, so buildings, vehicles and mines need costly air conditioning and extra water.
Give one reason water supply is a challenge to development in the Western Desert (USA).
Rainfall is under 250 mm a year, and demand from cities, irrigated farms and tourism over-abstracts the Colorado River — Lake Mead's level has fallen sharply.
Give one way inaccessibility limits development in a hot desert.
Huge distances with few roads or railways make reaching remote mines and settlements slow and expensive, and heat, sand and flash floods damage routes.
Give one argument that the opportunities in the Western Desert (USA) outweigh the challenges.
Technology such as dams, canals and air conditioning has allowed Las Vegas, large irrigated farms and copper mining to thrive — though all depend on the over-used Colorado River.
Give one way climate change increases the risk of desertification.
Rainfall totals fall and become less reliable while higher temperatures increase evaporation, so vegetation dies and bare soil is exposed to erosion.
How does population growth on desert fringes lead to desertification?
More people means more land is grazed, cultivated and cleared for fuel, so the soil is never given time to recover.
How does the removal of fuel wood lead to desertification?
Trees and shrubs cut for cooking fuel leave the soil unprotected from wind and rain, with fewer roots to bind it together.
How does overgrazing cause desertification?
Too many animals eat vegetation faster than it can regrow, and their hooves break up the soil, leaving bare ground open to erosion.
How does over-cultivation cause desertification?
Growing crops year after year with no fallow period strips nutrients from the soil, leaving it dry, dusty and infertile.
True or false? Soil erosion is both a cause and a result of desertification.
True. Bare soil is blown or washed away, removing the fertile topsoil, which makes it even harder for plants to grow and exposes more soil.
Give one example of water management used to reduce the risk of desertification.
Drip irrigation, which delivers water straight to plant roots, wasting less water and reducing salinisation.
Give one example of soil management used to reduce the risk of desertification.
Leaving land fallow or rotating crops, and adding manure or mulch to restore nutrients and hold moisture in the soil.
How does tree planting reduce the risk of desertification?
Roots bind the soil and the canopy shelters it from wind and heavy rain, e.g. the Great Green Wall across the Sahel.
Give one example of appropriate technology used to reduce desertification.
Stone lines ('magic stones') along contours to trap rainwater and soil — cheap, made from local materials and easily maintained by local people.
True or false? A hot desert is defined by its high temperatures rather than by its low rainfall.
False. A desert is defined by low rainfall — under 250 mm per year — not by how hot it is.
True or false? 'Appropriate technology' means using the most advanced, high-tech equipment available to stop desertification.
False. Appropriate technology is small-scale, low-cost equipment that local people can build and maintain themselves, e.g. stone lines (magic stones).