Hot desert characteristics, interdependence and adaptations

Overview

Where hot deserts lie and why, rainfall, day and night temperatures, thin soils and sparse plants, the links between climate, soil, plants, animals and people, and plant and animal adaptations.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Where in the world are most hot deserts found, and why there?

   Model answer

   In broad belts roughly 15–30° north and south of the Equator, where air that rose at the Equator sinks again, warming and drying as it descends.

2. 2

   How much rain falls in a hot desert in a year, and how reliable is it?

   Model answer

   Less than 250 mm, and it is very unreliable, often arriving as rare heavy downpours with dry years in between.

3. 3

   Why do hot deserts have scorching days but cold nights?

   Model answer

   Cloudless skies and dry air let the sun heat the bare ground strongly by day, and let that heat escape straight back to space after dark.

4. 4

   Describe the soils and plant cover of a hot desert.

   Model answer

   The soils are thin, sandy or stony and low in nutrients, and vegetation is sparse and widely spaced with bare ground between the plants.

5. 5

   How does the desert climate control the soil and the plants that grow in it?

   Model answer

   Scarce rain and rapid evaporation allow only drought-tolerant plants to survive, and because so few plants shed litter the soil stays thin and short of nutrients.

6. 6

   How do desert animals depend on desert plants, and what happens when those plants are lost?

   Model answer

   Plants give animals food, shade and much of their moisture, so removing them means the ecosystem can support far fewer animals.

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