Hot deserts Flashcards
(35 cards)
Describe the hot desert climate.
Very dry – <250mm rainfall per year. Very extreme temps – up to 45˚C in the day; below freezing at night.
Explain the hot desert climate.
At 30˚N and 30˚S of the equator, air that has risen at the equator descends to form high pressure = lack of cloud formation = lack of precipitation.
Describe hot desert soils.
Sandy/stony, dry & shallow. Soak water up quickly. Little organic matter due to lack of leafy vegetation. Not very fertile due to salinisation.
How are hot deserts interdependent?
Animals spread seeds through dung = plants reproduce. Sparse vegetation keeps animal population sizes in check. Extremely dry so adaptation by people & animals is necessary.
How have plants adapted to hot desert conditions?
Long plant roots to reach deep water supplies. Cacti – large stems for storing water & thick waxy skin to reduce transpiration. Low surface area to reduce transpiration.
How have animals adapted to hot desert conditions?
Some are nocturnal to avoid searing daytime temps. Camels – store fat in hump; break down into water. Long eyelashes to bat sand away. Large, flat feet to spread weight over sand to prevent sinking.
How are cactus mice adapted to hot desert conditions?
Get all the water they need from cactus fruits & insects.
What is biodiversity like in hot deserts?
Fairly low. Highest on temporary ponds on edges of deserts.
How do humans affect biodiversity in hot deserts?
Building roads divides habitats & affects migration patterns of animals like desert bighorn sheep.
Define ‘transpiration’.
The evaporation of water from plant leaves, stems or flowers.
How do mineral resources provide opportunities for economic development in the Sahara?
Increase export income and GNI. Create jobs. Morocco – world’s largest exporter of phosphate. Holds 75% of world’s phosphate reserves.
What can phosphate be used in?
Fertilisers, cleaning products & batteries.
How do oil & gas provide opportunities for economic development in the Sahara?
Increase export income and GNI. Create jobs. Algeria – 60% of income comes from oil & gas industry; employs 40,000 people.
How does solar energy provide opportunities for economic development in the Sahara?
Increase export income. Create jobs. Help meet targets. Tunisia – 400 hectare power plant in Gafsa will produce 30% of Tunisia’s renewable energy by 2030.
How does tourism provide opportunities for economic development in the Sahara?
Create jobs. Marrakech – desert treks & sandboarding are popular activities.
How does farming provide opportunities for economic development in the Sahara?
Increase export income and GNI. Increase food security. Egypt – Aswan Dam provides year-round water supply; important for irrigating crops.
Challenges of economic development in the Sahara: Population
Harsh weather = only 2 million people live in Sahara, many nomadic. Lack of workforce to develop industries.
Challenges of economic development in the Sahara: Extreme temperatures
Exposure to big temp. range = illness & death. Tourism can only be seasonal; many months too hot for tourists.
Challenges of economic development in the Sahara: Inaccessibility
Sahara is huge. Expensive pipelines built to transport oil, gas & mineral resources from remote parts of desert. 5 days needed to transport salt from mines in Mali.
Challenges of economic development in the Sahara: Water supply
Rainfall is unpredictable = difficult to provide enough water for workers, irrigation & industry.
Define ‘desertification’.
The degradation of land so that it becomes more desert-like.
What proportion of the world’s land is at risk of desertification?
A third.
How many people live in areas at risk of desertification?
Approximately 1 billion.
Natural causes of desertification: Climate change
Climate will become drier in already-dry places = less rain for plant growth = less roots to stabilise soil = loose top-soil = easily blown away by wind.
