Deserts and Desertlife
Many deserts combine lack of water with very hot summer temperatures. The temperature usually drops at night and the desert becomes cool, because there are no clouds to keep in the earth's heat. The difference between day and night temperatures can be as much as 20°C (36°F).
Not just sand
Deserts have a variety of different landscapes.
Some deserts are endless ‘seas of sand’ where the wind piles the sand into great big dunes. Other deserts may be flat, stony plains, or have rugged, rocky hills and mountains. Most deserts are a combination of landscapes.
The Sahara is the world’s largest desert after Antarctica. It stretches 9,000,000 km2 across north Africa. Other deserts are found in the Arabian Peninsula, India, Australia, central Asia, and southwest Africa. Smaller deserts are found in North and South America.
Deserts appear to be dead landscapes. In fact, they harbour animals and plants that are specially adapted to the harsh, dry conditions. Most of the plants remain dormant until a rare downpour of rain. Then short, wiry grasses and delicate flowers spring up, growing and flowering quickly before the desert dries up again. These plants are called ‘ephemerals’ as they only appear for a short time. After a good shower of rain, the desert becomes green for a brief time and pulsates with life.
Other desert plants, like the cacti of North and South America and the Euphorbias of Africa, absorb and store water. Typically, these drought-resisting succulent plants have very small or even no leaves, thick waterproof skins and pores that shut tightly to reduce evaporation.
Most of their leaves have become thick thorny spines, to prevent water loss and protect the plant against herbivorous animals. Acacias are desert trees with long tap roots that reach down far below the surface to access deep moisture, and spreading surface roots that are able to gather rain water before it evaporates. Acacias have leaves that are dropped during a long drought, and many spines.