People say that nothing goes waste in a forest. Can you explain, how?

The dead plants and animal tissue is converted into humus, a black coloured substance, by the micro-organism. This humus is rich in the nutrients. The humus ensures that it gets readily mixed with the soil, so that it could be absorbed by the roots of the plants. The dead animals are eaten by the eagles, hawks and vultures.

That is why, it is said that nothing goes waste in a forest.