Large amounts of dead matter are produced in nature constantly. This dead matter needs to be decomposed and the nutrients contained within it brought back to the use of the forest's producers in order for the ecosystem to function. 

In nature, this decomposition is done by many invertebrates, bacteria, and fungi. The importance of fungi decomposers can be seen when studying the leaf and needle litter found on the forest floor. Numerous fungal mycelia run through this litter, gaining energy by breaking down the chemicals contained within it.

Many polypores found in the forest are examples of such decomposer fungi. The picture on the right shows a decaying birch trunk being broken down by a polypore fungus.