Why is deforestation damaging the world's ecology?

The world's tropical rainforests are being lost at an alarming rate, and already the effects of the loss can be seen. Rainforest trees are cut down to provide timber as well as land for grazing and raising crops. The remaining scrub and branches are usually burned, providing a rich source of fertilizer for one or two years. Then the land becomes barren. Rainfall washes away the topsoil, leaving bare rock in which very little grows.

The results of deforestation are seen in countries such as Bangladesh, where heavy rains are no longer soaked up by forests in the foothills of the Himalayas. Instead the rainwater sweeps down the valleys, causing enormous flooding and loss of life.