Friday, January 20, 2012

BIOMES: Desert

Deserts are hot during the day and cold at night. Animals and plants that live in deserts have adapted to survive in these harsh conditions.

Characteristics and climate of deserts
Deserts have extreme temperatures. During the day the temperature may reach 50°C, when at night it may fall to below 0°C. Deserts have less than 250 mm of rainfall per year. The rain can be unreliable. Most deserts are found between 20° and 35° north and south of the equator. The Sahara is the largest desert, covering 9 million km2.

There are three factors which form desert areas:
  1. the presence of high pressure, creating cloud-free conditions
  2. cold ocean currents
  3. mountain ranges to create rain shadows

Climate graph for the Sahara Desert

Diagram of the rain shadow effect in South America

Vegetation adaptation
Plants and animals need to cope with the dry conditions. Compared to other biomes, deserts have limited numbers of plants and animals that are able to survive. Some plants are succulents and store the water in leaves, stems or roots. One example is the cactus.

Other ways plants tolerate the dry conditions include:
  • long roots to tap into the water deep underground
  • short life cycles - a plant or seed could remain dormant until the rains come
  • Animal survival
  • Some may burrow to escape the heat.
  • Nocturnal animals sleep during the day, sheltering to help prevent dehydration.
  • Animals may hibernate during temperature highs or lows.

Courtesy: BBC

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