Class 12 Biology Ecosystem Decomposition


Decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients and the process is called decomposition.

Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter is called detritus.

Detritus is the raw material for decomposition.

Detritivores are the organisms break down detritus into smaller particles. Example-millipedes, dung flies, woodlice, burying beetles.

The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and

Fragmentation is thr breaking down of detritus into smaller particles.

The process by which watersoluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts is called as leaching.

Th eprocess by which bacterial and fungal enzymes degrade detritus into simpler inorganic substances called as catabolism.

Humification is the accumulation of a dark coloured amorphous substance called humus.

The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation.


Factors affecting the rate of decomposition

Large amount of oxygen is required for decomposition as it is an energy requiring process.

Chitin and lignin present in detritus slower the rate of decomposition.

Nitrogen and water-soluble substances like sugars in detritus increases the rate of decomposition.

Warm and moist environment favour decomposition whereas low temperature, dryness and anaerobiosis inhibit decomposition.


Fig. millipedes, dung fly

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