我又来改改拉~
Over-population is the main cause of desertification,which means having many people living in one area is a big problem.Just take India in July 2003 as an example,it had a population of just over one billion with around 170 million hectares of arable land.The children in India will not have good education individual on the case that the population of India is still increase .But,over-population is only an indirect effect,since it can not directly be the cause of desertification.On the contrary,it can leads to some other causes such as over-cultivation,over-grazing and deforestation.The reason is :when the population keeps increasing,more farm land and more cattle are needing.The last resulting are vegetation cannot grow back and land will exposed to wind and rain,soil is bare either.For land not infiltrate rain,it will have more risk of soil erosion.
Therefore,growing population can bring desertification.