Decomposers help the environment by breaking down large organic molecules into forms that other organisms can use, releasing them into the ground, water and air. They can get energy from organic compounds other species cannot. Without decomposers, many of these compounds would remain unusable and would even obstruct new life.
The primary organisms that perform the role of decomposition are fungi and bacteria. Fungi are particularly prominent in forests, although they survive in a wide variety of habitats, including tundra. The forest environment is particularly hospitable to fungi, however, since the forest floor is dark and damp and collects the remains of many dead plants and animals.
Fungi are crucial for living ecosystems to continue, particularly because some elements, which are not plentiful, are nonetheless necessary for many organisms. Phosphorus and usable nitrogen are relatively rare, and are consumed and bound in plant tissues. In order for new plants to grow, these nutrients must be made available. Fungi can do this because of their method of obtaining nutrients. Fungi digest food items with enzymes prior to ingesting them. Because the dead organic matter is broken down outside of the fungi, some of it remains available for other organisms to use.