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A desert is an area of land where temperatures are hot and there is very little rainfall. These are known as hot deserts. Cold desert areas such as the Tundra are areas where rainfall is low and temperatures are very cold.
In any desert rainfall is always less than 250mm per annum. In hot deserts temperatures can reach as high as 50C and minimum temperatures can fall below 10C, therefore similar to cold deserts, there is a large range of temperature. Temperatures during the day are hot but at night all the heat escapes into the atmosphere because there are no clouds to trap the heat.
Few plants can survive in hot deserts other than XEROPHYTES. Xerophytic plants have adapted to the lack of moisture by having very small leaves (to reduce transpiration), long tap roots (to reach for ground water) and succulent tissue (to store moisture). Other plants have adapted in other ways.
The cactus stores water in its tissues. Its leaves are small and spiky which reduces water loss and of course deters animals.
Tumbleweed pulls up its roots so that it can be blown to wetter desert regions
Date Palms are generally found around oases. They have tap roots which obtain water from groundwater and are very useful to desert people (leaves can be made into baskets, young leaves can be eaten by animals, dates can be consumed and the tree provides shade
Some plants can lie dormant in drought conditions but as soon as the rainfalls they can grow and bloom in a matter of days
Desertification is occurring in many countries of the world but is most noticeable in the Sahel zone which is south of the Sahara desert. The Sahel has a higher population than the desert because the climate is not as severe. Increasing population has put too much pressure on the land.
1. Area of farmland supporting a large population 2. Area is deforested and cultivated without periods of fallow or use of fertiliser. Cattle overgraze the land 3. Soil begins to lose its fertility and becomes exhausted through overuse 4. Soil is left bare of vegetation and nothing will grow 5. Heavy rains or strong winds will blow the soil away as there is no vegetation binding soil together 6. Land becomes desert-like and because soil has been removed, it is no longer farmable. 7. Population will starve so many leave the land to go to the cities. DESERTIFICATION
In Burkina Faso stone walls have been built along contours to act as dams to hold back soil and water run-off. This has been very effective resulting in thousands of hectare of land being reclaimed. It is a cheap solution which does not require the use of expensive equipment.
Reforestation of land that was previously forested can be a very effective way to halt the spread of deserts. Tree planting is easily done and is relatively inexpensive. The only problem is the length of time it takes for trees to mature and therefore be beneficial to an area. It is very much a long-term solution.
Overcrowding has contributed to desertification. Governments could reduce population numbers by encouraging the use of family planning to limit family sizes. This is also a long term solution and has not, as yet, been very effective. Many people in Sahel countries want large families as the children can work from an early age and can support their parents in old age. It is still an important part of the culture to have large families – this can take a long time to change.
Educating people about the reasons why desertification happens and the ways it can be reduced is believed to be very important. Farmers could be told about the need to have periods of fallow on their land to prevent overcultivation. Pastoralists could be educated about the need to limit herd sizes to prevent overgrazing. If people understand what is causing the problems, they are more likely to take a proactive approach to help reduce the problems.