仔细观察下面两幅图画，运用合理的想像和推理，用英语写一篇短文，阐明人与环境的关系及其重要性。
注意：
短文应包括两幅图画的内容
词数100左右
参考词汇：沙丘sand dune
进 advance
退 retreat
水土保持 water and soil conservation
这是一篇看图作文，作文体裁夹叙夹议，先描写图画内容，人们滥伐森林，造成水土流失，导致沙丘、沙尘暴的产生，人们重新植树，有效抵制沙丘的进攻；再议论图画所暗示的深刻含义，呼吁人们重视生态平衡。
参考例文：
As is shown in the pictures，trees play an important part in water and soil conservation. In the left picture， people are fleeing from sand dunes because they cut down all trees. In the right picture， people have planted many trees and the sand has retreated.
People should realize the important relation between human and nature. If we continue to destroy forests， destroy the balance of nature， the real victims will be us humans.
It's never too late to mend. After suffering from sand storms， people have now realized the importance of trees in water and soil conservation. They are planting more and more trees to fight against the greedy desert