Geography & History Notes | KCSE, NECTA, ZIMSEC & GCSE

  Desertification is a type of land degradation in which a relatively dry land region becomes increasingly arid, typically losing its bodies of water as well as vegetation and wildlife. It is caused by a variety of factors, such as climate change and human activities. In East Africa and other parts of Africa, a number of steps have been taken to combat desertification or reverse the trend of desertification. Causes of desertification. Desertification is basically caused by environmentally unfriendly human activities . However, to a small extent, it may be brought about by naturally existing conditions in the atmosphere that may lead to cycles of drought. Such atmospheric systems that result in cyclic changes or occurrences in the atmosphere have compounded the problem of desertification. Human activities that have contributed to desertification in East Africa in general include the following: Deforestation. Overgrazing. Overstocking. Bush burning. Reclamation of wetlands. Boreh...

Afforestation is the planting of trees where trees had never existed while reafforestation means planting trees where the forest had been cleared. The planting of trees plays a big role in soil conservation. Trees can be planted on homesteads, on the field, or on special tracts of land to form the forest. They can also be planted on embankments of terraces. The following are roles of trees in soil conservation They protect the soil below from raindrop erosion by reducing the force with which it falls on the ground. They provide shade and reduce the loss of moisture through evaporation. They act as windbreak hence reducing wind erosion . The roots of trees bind the soil particles together. Holding of soil particles by roots help to reduce soil erosion and washing away of nutrients by run off They reduce the speed of running water thus reducing its erosive power. The leaves of trees decay to supply humus to the soil which improves the infiltration rate of the soil. Also humus pr...