在很久以前,世界陆地几乎全部被苍郁茂密的森林所覆盖。大约在二百万年前,当地球表面温度下降、冰期到来的时候,森林面积迅速减少;随着人类社会的发展,人们开始从事农牧业生产,毁林开荒,刀耕火种,辟林放牧,特别是,历代统治阶级为了自己的穷奢极侈,破坏了很 A long time ago, almost all of the world’s land was covered by lush forests. About two million years ago, when the earth’s surface temperature dropped and the ice age came, the area of ​​forest decreased rapidly. With the development of human society, people began to engage in farming and livestock husbandry, deforestation and wasteland, slash-and-burn farming, It is that the ruling class of the previous generations have destroyed a lot for their own extravagance