The mineral elements needed by living organisms in very small amounts or traces are called micronutrients. These elements enter the living organisms at the producer level in the ecosystems and from the producer levels they get transferred to other tropic levels. The form in which the elements can enter the food chain of the producer level is known as usable form. The transfer and circulation of these substances takes place through soil, water, air and living organisms. The circulation of the essential chemical nutrients in a biosphere is referred to as bio-geochemical cycles.
The decomposers play a very important role in recycling of these materials. The elements present in the living organisms are released in the system after their death. When the plants and animals die and decay, then the decomposers decompose their dead bodies to produce original elements. These elements go back into the nutrient pool from where they were originally taken. From the nutrient pool, these elements are again put into circulation through re-absorption by plants.