What is called decomposers?
In this world all living organisms require a constant supply of nutrients for growth. The death and decomposition of plants and animals, with release of nutrients constitutes an essential link in the maintenance of nutrient cycles. When an organism dies, an initial period of rapid leaching takes place and populations of macromolecules. The dead organism is disintegrated beyond recognition. Enzymic action breaks down the disintegrating parts of the litter. Animals invade and either eat the rapidly recolonized by micro- organisms, and the litter biomass decreases. It becomes simpler in structure and chemical composition.
Process of Decomposition
Leaching is a physical phenomenon operating soon-after litter fall. Soluble matter is removed from detritus by the action of water. Sometime over 20% of the total nitrogen content of litter maybe leached off.
The process in a plant or animal by which living tissue is changed into waste products.
Comminution to make small to reduce to power or minute particles. Comminution means the reduction in particle size of detritus. During the course of feeding, the decomposer animals community detritus physically. And utilize the energy and nutrients for their own growth (secondary production). In due course, the decomposers themselves die and contribute to the detritus.
Function of Decomposition
The role of decomposers within ecosystems are as under:-
(1) The mineralization of essential elements,
(2) The formation of soil organic matter to inorganic form.
The formation of soil organic matter in nature is a slow process. The decomposition of any piece of plant detritus may take hundreds of years to complete. However, some residues of decomposition within this period do contribute to the formation of soil organic matter.
Community of Decomposer
The community of decomposer organisms includes several bacteria, fungi, protests and invertebrates. The different species in such a community function in an integrated manner. For example, a fungus decomposes plant litter and is eaten by an animal. Upon death, bacteria decompose the animal, and protozoa may eat the bacteria.
Fungi and bacteria are the principal organisms that break down organic matter. Certain protozoa, nematodes, annelids and arthopods strongly influence their functioning (i.e. of fungi and bacteria) due to their feeling activities. Microarthopod fauna, comprising mainly of oribatid mites besides other mites and collembolans, are abundant in most forest, grassland and desert ecosystem.
Varying Relations of Decomposer
Some decomposer organism’s cannot be assigned a rigid or fixed position in the food web. Their trophic relations can vary from time to time.
- Nectroph: Some decomposers are nectrophs. They cause rapid death of the food source because they have a short-term exploitation of living organism. Nectrophs include may plant parasitic microbes as well as some herbivores, predators, and microtrophs (organisms which feed on living bacteria and fungi.)
- Biotrophs: On the other hand biotopes resort to a long-term exploitation of their living food resource. For example, root-feeding nematodes and aphids, obligate plant parasites, e.g., and mycorhizae and root nodules, etc.
- Saprotophs: The apostrophes utilize food already dead, and most of the decomposers belong to this category
There are some such organisms causing decompositions as can occupy various trophic levels under different conditions. For instance the root parasites like Fusarium and Thizoctonia are necrotrophs, which often show a saprotrophic tendency. In the same way, the predators (foxes and kites) sometime behave as saprotrophs. Biotrophs sometime act as necrotrophs or as saprotrophs.
There are some soil invertebrates e.g. earthworms and collembolans distribute organic matter throughout the soil whereas others e.g. termites and ants, concentrate it at localized sites around or near the royal chamber or in mounds. The following table shows the estimated activities of major groups of soil animals.