Which organisms play a crucial role in nutrient recycling through the breakdown of dead organic matter?

Decomposers

The correct answer is Option (2)- Decomposers.

Decomposers play a crucial role in nutrient recycling through the breakdown of dead organic matter. Decomposers are organisms, mainly fungi and bacteria, that specialize in breaking down and decomposing dead plant material, animal remains, and other organic waste.

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, constitute detritus, which is the raw material for decomposition. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation.

Decomposition is largely an oxygen-requiring process. The rate of decomposition is controlled by chemical composition of detritus and climatic factors. In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugars. Temperature and soil moisture are the most important climatic factors that regulate decomposition through their effects on the activities of soil microbes. Warm and moist environment favour decomposition whereas low temperature and anaerobiosis inhibit decomposition resulting in build up of organic materials.